Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
(OP)
Ok, I am a bit out of my league with this one and this is the only place I have found that seems to have people that really know what they are talking about.
Quick rundown of my setup. I have a 2000 Toyota 4runner 4wd with a 5vz 3.4l DOHC engine. Right now it has an eaton MP-62 TRD supercharger on it running about 10.5psi of boost making ~250-260whp if I had to guess. I am using methanol injection as it is and plan to use more with the turbo, I figure around ~2000cc all said and done (need the fuel since the stock injectors are maxed out).
I want more power out of it mainly because I can.
I have pretty much decided on doing a remote mount turbo setup (planning on a 6262 turbo). These trucks have no options for turbo manifolds up front and getting a custom one made will cost more then this whole remote setup.
At first I was just going to remove the supercharger and run the turbo alone but then started thinking about twin-charging it.
I have put a lot of thought into this and I am just not sure if it is a good idea in the long run or not.
First off the 5vz motor I am working with while pretty strong does have a limit of around 400hp on stock internals before the rods become a weak link. I plan to get as close to that as possible and want room to grow later when I build the motor but till this one blows thats about the limit.
The supercharger uses power to make power and as such would put more stress on the motor for a given power output then the turbos.
Next up is the supercharger adding a LOT more heat to the air charge then the turbo and no ability to intercool it after the supercharger on my setup.
These were my reasons for ditching the SC in the first place.
I then got to thinking about the by-pass valve. What if I took control of it and opened it once the turbo is spooled. Would that basically render the supercharger as doing nothing?
My theory (no idea if it is correct, thats why i am here) is the supercharger will not know the turbo is doing anything before it and the by-pass valve should still vent off any extra boost from the supercharger allowing the turbo to produce all the boost.
Thus giving me the fast spool of the supercharger and the top end power of the turbo.
I am sure there are flaws in this plan as I have never done or even seen a twin-charged setup myself and there is remarkably little info on these setups.
Is it practical to open the by-pass valve once the turbo is spooled to stop the supercharger from working? Or will the by-pass valve turn the supercharger into a heat pump?
Should I just nix the supercharger and run the turbo alone?
Is a 6262 (62mm) turbo about right? Any larger would be pretty laggy if the twin-charging doesn't work so I didn't really want to go bigger in case I decided to ditch the supercharger afterall. Without the supercharger I expect the turbo to spool around 3500-3750rpm which is about perfect with my 5500 redline.
I already ordered the turbo but the order won't go through till tomorrow so could use a response quick. Thanks
Quick rundown of my setup. I have a 2000 Toyota 4runner 4wd with a 5vz 3.4l DOHC engine. Right now it has an eaton MP-62 TRD supercharger on it running about 10.5psi of boost making ~250-260whp if I had to guess. I am using methanol injection as it is and plan to use more with the turbo, I figure around ~2000cc all said and done (need the fuel since the stock injectors are maxed out).
I want more power out of it mainly because I can.
I have pretty much decided on doing a remote mount turbo setup (planning on a 6262 turbo). These trucks have no options for turbo manifolds up front and getting a custom one made will cost more then this whole remote setup.
At first I was just going to remove the supercharger and run the turbo alone but then started thinking about twin-charging it.
I have put a lot of thought into this and I am just not sure if it is a good idea in the long run or not.
First off the 5vz motor I am working with while pretty strong does have a limit of around 400hp on stock internals before the rods become a weak link. I plan to get as close to that as possible and want room to grow later when I build the motor but till this one blows thats about the limit.
The supercharger uses power to make power and as such would put more stress on the motor for a given power output then the turbos.
Next up is the supercharger adding a LOT more heat to the air charge then the turbo and no ability to intercool it after the supercharger on my setup.
These were my reasons for ditching the SC in the first place.
I then got to thinking about the by-pass valve. What if I took control of it and opened it once the turbo is spooled. Would that basically render the supercharger as doing nothing?
My theory (no idea if it is correct, thats why i am here) is the supercharger will not know the turbo is doing anything before it and the by-pass valve should still vent off any extra boost from the supercharger allowing the turbo to produce all the boost.
Thus giving me the fast spool of the supercharger and the top end power of the turbo.
I am sure there are flaws in this plan as I have never done or even seen a twin-charged setup myself and there is remarkably little info on these setups.
Is it practical to open the by-pass valve once the turbo is spooled to stop the supercharger from working? Or will the by-pass valve turn the supercharger into a heat pump?
Should I just nix the supercharger and run the turbo alone?
Is a 6262 (62mm) turbo about right? Any larger would be pretty laggy if the twin-charging doesn't work so I didn't really want to go bigger in case I decided to ditch the supercharger afterall. Without the supercharger I expect the turbo to spool around 3500-3750rpm which is about perfect with my 5500 redline.
I already ordered the turbo but the order won't go through till tomorrow so could use a response quick. Thanks
Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.





RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
http://www.eng-tips.com/viewthread.cfm?qid=267889
and all of the referenced material.
Then, get back to us.
Mike Halloran
Pembroke Pines, FL, USA
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
By methanol injection I presume you mean an add on kit that adds water/alcohol or a mix as manifold pressure builds. That is a dangerous way to add extra fuel with maxed out injectors. You really need fuel pump, injectors fuel lines etc to cope with your fuel requirements.
The easiest way would be to use the blower as is and just feed boost into it via the blower inlet. Leave bypass etc alone.
I think remote turbo setups are pure junk due to the losses between the turbo and the engine. The blower might help offset the extreme lag they have, but you will still end up with all the complexities of a twin charger but still with lag.
Blowers take power to make power. SO DO TURBOS. It's just normally not quite so much and not nearly so obvious where the power is taken from. A bad turbo will leach of just as much or more power to drive it as a good blower will. An Eaton is a good basic design and should be reasonably efficient if sized and installed correctly.
I think your truck should have plenty of room under the bonnet (hood) for the turbo to go in the engine compartment, close to a front mount inter cooler.
Don't put water/alcohol into the system before the inter cooler and especially before the turbo. In my opinion it is best added just before the blower to cool, lubricate and seal the rotors. I would run 50/50 water alcohol at most. The alcohol can be methanol or ethanol, depending on what's available at what cost. Methanol has more potential to increase power, but is a lot more problematic to handle due to corrosion, attack on plastics and toxicity.
There have been several previous in depth twincharger threads on here. You would do well to read them.
If your looking for power, 5500 is a really stupid low redline unless your a diesel, 1960s technology with flimsy rods, crank and block and long heavy flexible push rods, or have about a 6" stroke.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Pat, Yes, I have a coolingmist meth injection kit. While not commonly recommended or common for that matter. I have been running this way for over a year on this truck with no issues and GREAT results. Also ran my MR2 this way before with 2000cc pumping into it and know of a lot of other guys doing the same thing.
It is quite common to make 100whp over the stock injectors. With the right failsafes in place it is very reliable as well.
I have played with everything from pure water to pure methanol and with nozzles from 5gph to 2x 14gph on this truck. The best results have always been on pure methanol or almost pure and with as much of it as I can pump in without going overly rich. Same for all my other cars.
Right now I have about 1000cc being injected just before the SC and AFR's stay in the 12:1 range and it runs better then ever.
Meth injection systems is something I have spent a lot of time with myself. I run it on all my cars.
I agree with you on the remote mount setup, it is far from my first choice. It comes down to cost. I can put together the whole remote mount setup for well under $1000 excluding turbo cost. A manifold to mount it under the hood would cost $2000-$2500 alone and take weeks to have it fabbed up. Just can't afford that.
If there was a manifold for these I would run it for sure and a 6766 turbo since it would spool nice. Not even worry about twincharging either. But got to work with what you got, or in this case can afford.
Another note is I have an automatic transmission with a high stall ~3500rpm converter. So lag is not as big of a deal as it would otherwise be. My powerband is 3500-5500.
You are right that the turbo robs power to make power as well but the turbo uses power be reducing exhaust efficient and thus VE, the engine is not actually working any harder, just not working as efficient. This will not cause the rods to let go any earlier.
The supercharger is using power the engine has already made thus putting more stress on internal components so the rods will let go at a lower HP level then with a turbo.
Thats where the by-pass valve comes into play. If i can "disable" the supercharger once the turbo comes online so as to lesson the strain on internal parts and let the turbo do the work then I get the best of both worlds.
I just can't find an answer as to what will happen with the by-pass open or if it is a good idea. Controlling the by-pass is easy, my piggyback can take care of that no problem.
I agree the redline is low but I am on the stock ECU and stock valve springs. Even if I could raise the redline the valve springs need to be upgraded for that. When I build the motor it will be able to rev to ~8k-9k but that is out of the budget for a long while.
Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
At full boost you still get an advantage from the boost multiplication in the blower. This helps by increasing boost, but also by increasing pressure in the inlet relative to the exhaust and so giving better exhaust scavenging than a turbo engine gets. This helps cool exhaust valves and reduces charge dilution with hot exhaust gas and makes more power with less inclination to detonation at the same boost.
I don't know your engine and I don't know your access to welding, but $2500 sounds like a hell of a lot of money for a simple manifold. Turbo manifolds do not need to be long runner or equal length or any of that. They can be a basic log design, they just need to be beefy re wall thickness and flange thickness. A stock cast iron manifold can often be adapted with moderate skill with an electric welder and the right rods or a simple adaptor plate made with hand tools. Your local exhaust man should be able to make the dump pipe and a good cat back system.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I don't want the boost multiplication. Getting enough boost is not my problem, I am limited to mid-high teens for boost anyways before I am making too much power for the rods. The only thing I want the supercharger to do is spool the turbo.
The engine is a 3.4l V6 in a truck. No call for a manifold for it. I have already got a few quotes for the manifold and all were in the $2k+ range.
You are right that the stock cast manifolds can be used but are FAR from ideal and would still cost a fair amount to have a custom setup to make a turbo work due to the tight space for the crossover.
I have a feeling my headers running to the remote mount turbo will preform about as good as that setup would, they would have about the same amount of piping before the turbo all said and done, which is why I decided to go remote. Not to mention the nightmare dealing with the manifolds is due to space.
Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
If you did want to open the bypass (my opinion is that you should*) once the turbo spools, just rig your bypass solenoid to a pressure switch (hobbs switch) on the blower inlet. 5 psi from turbo = open the bypass.
* = Because of you specific concern about losing CRANK HP to drive the blower. That's an important distinction between blower and turbo losses. There's a few considerations.
1) Look at the Eaton blower charts, any parasitic loss you see with increase directly based on the incoming air density. Leaving the bypass closed, the blower has to do more work to add pressure to higher density air.
2) When you open the bypass, the blower will still make a small amount of boost (bypass acts as an orifice at high RPM, at idle it pretty well can keep up with the recirc flow 100%). Not completely sure how the supercharger's boost with bypass open will be affected with pressure on the inlet, but a detailed orifice calculation should be enlightening.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I have the coolingmist progressive CMGS controller, just the normal one that can inject off boost or a 0-5v signal.
I then use a piggyback (right now using the coolingmist "smart controller" but moving to an AEM FIC shortly) to create a map based on RPM and boost.
I then tune that map like any other fuel map through the RPM range. The controller outputs a 0-5v signal to the CMGS which then controls the methanol flow rate based on the signal. Works GREAT, keeps AFR's nice and steady when tuned right. It's only weakness is that it can't turn the flow down to less then ~50% of the overall nozzle flowrate but thats not a problem for me.
Been running it this way for over a year with GREAT results. The timing control/knock detection on the stock ECU is very good so that takes care of itself. It actually can run more timing with the supercharger and meth injection then it did stock with 87oct.
Now onto the by-pass valve. I have already figured out how to control the by-pass valve real simply. I have a spare solenoid laying around that I will hook up to an output on the piggyback so I can set it to open the bypass anytime I want, under any conditions.
The valve is vacuum activated so I will need to add a vacuum resivor but thats easy and no big deal. The setup I have planed will have the valve working normally until the noid trips and opens it manually.
I have spent a lot of time looking at those charts actually and If the supercharger reacts like I think then everything should fall into place real nice.
I am going to copy/paste a post I made on another board on this subject that should give you a few more pieces to the puzzle. I tried running the supercharger with the by-pass open as it is and these were the results:
Today I did an experiment by zip-tieing the by-pass valve open to see what would happen. With my 2.0 pulley (10.5psi with the bypass closed stock is 2.37 (~6psi with the bypass closed), I am technically overspinning the SC with this one to ~17,000).
With the valve tied open I found 2 things. First off this thing is SLOW without boost. I had forgot how slow it was!
Next it will still build ~2.5-3psi of boost with the valve open.
With the stock pulley used instead of the 2.0 pulley I am guessing that it will only make ~.5-1psi of boost. I think I tried it before with the stock pulley and that is about what it was many years ago.
Looking at these graphs It looks like with the by-pass open and it making ~1-2psi to be on the safe side it will be using ~5-10hp to drive the supercharger. It will also be adding ~30-75 degrees to the air temp.
I found some underdrive pulleys as well that will lesson the boost more if needed. Down to ~3psi if I need it.
So looks reasonable to try it. The meth injection (estimate ~2000cc-2500cc total split between pre-turbo and pre-SC will be needed for the fuel) should net me ~ambient air temps going into the supercharger from the turbo. It will then hit another nozzle at that point which should equal out any temp gain from the supercharger netting me ~ambient air intake temps if all goes to plan.
From experience on my MR2, 2000cc of methanol was enough to bring 160 degree+ intake temps down to ~20 degrees below ambient.
The 5-10hp loss from the supercharger are acceptable if spool gains are worth it.
Overall, I am thinking the twincharge might work and it will be an interesting project for sure. I can also pickup a stock intake manifold to swap out without much hassle to test the differences back to back. Maybe even back to back dynos.
I am still looking for a second opinion on my earlier predictions on how the by-pass will work under these conditions.
The bypass will always be feeding air out of the plenum and it is impossible to actually bypass the supercharger?
The supercharger and by-pass will not know the difference with the turbo pumping boost into it. The supercharger should still do the same work which as I showed above should be in the 1-2psi range with the bypass open.
That all sound right so far? If all of that is a go then it is almost time to start picking out parts to make this work.
Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
In my experience with turbo cars, the biggest problem is the time related changing relationship between pedal movement and power delivered. The bypass flipping open or closed after the throttle might give time delayed surges if it;s not carefully tuned.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
The biggest thing I am wanting to know is how it will act with the by-pass open. Will it just turn the supercharger into a heat pump circulating hot air round and round? Will it still draw off more then the ~1-2psi worth of power that should? Will it add more heat then the 1-2psi should add? Will it really unload the supercharger?
Any other issues with having it open under WOT with the turbo making the boost? What are the downsides?
Can't find an answer to those for anything, I know SOMEONE out there has done it or know what will happen. If I knew for a fact that with the by-pass open it would work like I hope, I would get a larger 6766 turbo (the turbo I really wanted to get in the first place).
Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Another, related axiom of control systems: when a control system is trying to control a parameter that it does not have control over, the result usually is not very pretty.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I would start with a straight blow through, get that sorted then maybe play with the bypass. I think you are over thinking the parasytic power and heat thing.
Where the heat really matters is in the chamber and turbos scavenge the last remaining bits of hot exhaust gas very poorly due to back pressure created by the small orifice at the end of the scroll. Belt driven blowers scavenge very well, often to well and waste boost. The combination can work very well.
Even with a bypass open you still turn the blower and create friction and heat from friction and shear. How much is hard to say and I would expect quite variable from case to case.
I would drive the blower relativly slow to just give a bit more power when the turbo is out of boost, but to also create extra exhaust gas to spool the turbo faster. The roots blower has a double whammy effect and does not need to pump very hard. By not pumping hard it does not consume so much power.
I think an Eaton maxes out at about 60% efficient and a turbo at about 70% efficient.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Pat, True I am sure I will have some issues getting the by-pass just right but I drive 500whp++ cars on the street with twin plate clutches on a regular basis. Needless to say I am not real worried about a small hickup as it comes onto power long as it doesn't hurt the motor.
The problem with running it in compound mode is that the turbo will be making virtually no boost at all. I plan to start off around ~12psi for boost and in compound mode the turbo may be making 3psi. Not really worth it IMO.
The heat is a pretty big problem. I see intake temps right now DEEP into the 300 degree range without methanol. With methanol I am guessing intake temps are still ~200 degrees with the supercharger alone. Add a turbo on top of that and intake temps will get even higher.
Another problem with this line of thinking is the belt drive system for the supercharger. The belt is MAXED out as it is, I am getting belt slip right now and I have done every trick in the book to get rid of it. A 4 rib belt just is not big enough.
Try to pump compound boost through the supercharger and the belt will scream.
I don't mind a little power and heat being used/added with the by-pass open. The idea is to take the ~40hp+ it is using now down to 5-10hp and the 225+ degrees of heat added to the intake temps down to a more manageable 20-40 degrees.
This supercharger is real undersized for this motor, so it is already out of it's efficiency zone in stock form. It really should have been an M90 instead of an MP62.
If the twin-charging doesn't work I will just pull the supercharger off and go with my first plan. I just figured I have a twin-charger setup here, ready and waiting. Why not give it a go.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Uh, no, not necessarily. The belt load is proportional to the difference between the pressures upstream and downstream of the supercharger, not to the absolute downstream pressure. So the turbo may even reduce the belt load a bit.
Mike Halloran
Pembroke Pines, FL, USA
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
The term "twin charged" is new to me; is it applied to ANY form of two-stage forced induction (two turbochargers, etc.)?
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Mike is correct re the belt slippage.
Reduce the drive ratio on the blower so it only pumps say 5 psi of boost then blow through it with the turbo and the turbo boost will be increased by 1/3, so 10 psi from the turbo will be 13psi after the blower.
What really counts is mass air flow, so the same boost at lower temperature is still more air. The combined gas laws apply.
There is a big difference between driving with a lot of power and a savage clutch and driving something that feels dead as you squeese the throttle mid corner, then 1/2 second later unleashes a truckload, then as you back of a bit nothing happens, then you ease of a bit more and it just dies, then you give it a bit more, then nothing, then all hell breaks loose again. That can happen with a factory turbo and automatic with a crappy shifter (read Toyota Soarer MZ21). It can only get worse with a bypass that is not spot on.
Anyway it's a pretty easy experiment to put a manual control on it and try it open at certain times and permanently closed.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
As it is, ~10psi is the limit for belt slip, 10.5psi on a good day. Without belt slip I should be making ~12psi.
Jack, That is cc/min, same rating system as fuel injectors.
Pat, you are right that the air temp plays a major factor in power which is why I am so concerned with turning the supercharger off. ~ 10psi of boost the supercharger is adding over 200 degrees to the inlet air temps with no way to intercool it.
Right now, normal intake temps with my setup are well into the 300's. Add in the high inlet temps from the turbo before the supercharger and those temps could easily get into the 400+ degree range before the methanol cools it down and even then it could be 200+.
With the turbo alone I know I can get intake temps down to ambient or less with the meth injection for sure. that is a LOT of power gained right there. Using the 10f air temp = 1% power rule that is 10%+ power right there by turning the supercharger off, not to mention a lot safer on the motor.
So 10% power @ the 350whp level = 35hp extra. Then you have the ~35hp savings from not driving the supercharger and there is a total of 70+hp "gained" for free all the while making it easier and safer on the motor.
Thats why I am so worried about turning the supercharger off, it is notoriously bad at making power compared to the turbo. Compound boost would just make the problems worse.
Far as drivability. With proper tuning I am not worried about it, I daily drive all my cars and have yet to experience any of the issues you mention with a proper tune. It is truly all in the tune.
I know lots of 600-1000whp cars that drive like stock.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Assuming it has the same differential pressures with or without the turbo, you're getting an increase in mass air flow (increase in work) without drawing more power from the blower...
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Being able to turn the supercharger "off" under boost by opening the by-pass would seem to be the best of both worlds. I get the super fast spool of the twin charge and the top end power of the turbo.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Smallest I could find was around 3.5" which would not even make boost I bet.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
What is stopping you from putting much better wider, possibly toothed belt pulleys on. They do work on much larger blowers at high OD and boost numbers.
I have driven cars with about 1500hp in a 2600# car with instant, even savage throttle response with huge throttle plates (10:71 MFI Alcohol and Enderley Bird Catcher). I have also driven a car with under 300hp at 3700# with a really bad response rate (Mildly modded Toyota Soarer factory turbo), guess which one was hardest to drive fast.
Guess what a remote turbo and a not perfect bypass will do, but hey it's your car. It will be OK straight line, it's fine throttle control when drifting through a corner that gets difficult. It's easier in a stick shift or an auto with good manual override control.
Bigger dia pulleys top and bottom will help reduce belt slip a little
OD for 5 psi will help reduce slip a little, but yes higher charge density will hurt it. What OD and pulley sizes are you now. I can run the numbers if you like or you can run them yourself. Just remember to use pressure absolute, not pressure gauge for your calculations. ie 5# boost is 20# absolute.
Turbos do increase charge temperature in the chamber relative to intake air temperature and they do cause drag on the engine as the piston has to push against a higher pressure on the exhaust stroke and the other pistons have to press harder on the power stroke to overcome this, just like they do on a belt drive. It is not free power or not all power from waste energy as turbo promoters claim.
Compressing a gas makes it hotter no matter how you do it.
It is easier to install an inter cooler on a turbo to cool the charge after compression. It can also be done with roots, but is normally more expensive and harder to install.
Water/alcohol injection (I hate the term methanol injection for these kits as it confuses them with stack injectors and MFI systems or real methanol injection) will cool the charge but it displaces air volume as it does so. That is why down nozzles work better than nozzles in the manifold on MFI/methanol systems.
Methanol injected against the wheel of a turbo will damage the wheel over time on modern quick spool turbos designed for performance spark ignition engines.
Methanol puddling in the bottom of an inter cooler will cause corrosion and inconsistent fuel delivery to the engine.
2000cc/min is quite a bit of fuel, I imagine somewhere about 1/2 of your fuel on a volume basis or about 1/4 on a f:a requirement basis. That will require a fairly substantial tank capacity and supply system.
Methanol is quite corrosive of aluminium components. Rubbish bins are full of broken parts that belonged to people who did not believe this because they got away with it for a year or two.
The corrosive potential for methanol varies from batch to batch and under different ambient conditions. It also seems to have no effect on anodised surfaces, particularly hard anodised, but it slowly eats through the anodised layer.
Once through the anodised layer, the corrosion rate sky-rockets and the so called white rust problem suddenly appears after a year or two. The white crud eventually blocks nozzles, then pistons develop large holes very suddenly. I have heard the excuse and seen the result to many times.
I have also helped people smash pistons to small pieces to get them out of the bores after leaving methanol in the engine over the off season, but admittedly this is on engines running only methanol as the fuel. They have called me a scare monger and panic merchant before this happens to them. They become very quiet and learn respect for the potential for corrosion after it has happened.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Wider/Toothed pulleys are not an option due to cost. To have a full custom set made would run at LEAST $1000 and it is simply not worth the cost. Spinning it any harder then it already is, is pointless. It is already a heat pump.
Same for using bigger pulleys, just cost too much. Got to remember ALL the performance parts for this are custom.
The supercharger pulley on it now is a 2.0", I have not been able to find the crank pulley dia anywhere, it is around 5"-6" if I had to guess though from running some crude math on numbers I do know. Like I said before, the supercharger is WAY too small for this engine. It should have at least an M90.
The is a 5000lb SUV, won't be doing much drifting or racing around turns with it. I actually drive very responsibly on the street for the most part anyways even in my cars. In the case of the truck, it only needs to preform well in a straight line. the few times I light the tires up around a corner I will make do lol.
You are right that turbos rob power, I have had this debate many times with people. But in my case I am not worried about how they rob the power since it is not any harder on the motors internals except for making the motor a little more knock prone. The methanol will more then make up for that.
The supercharger on the other hand robs power after the motor has made it, making it much harder on the internals. The roots blower is also VERY inefficient compared to a turbo. My supercharger @ 10psi is pumping mid 300 degree heat into the motor. A turbo at that same boost would be in the low to mid 100's. thats worth ~15-20% power right there and more then makes up for any extra heat the turbos keep in the cylinders.
This has been backed up by the few turbo 5vz's floating around. at 10psi they commonly make over 300whp vs me making around ~250-260whp.
Now to the Meth injection, yes the methanol takes up room when injected into the air stream but it also cools the air charge. In all the cars I have tried it in the cooler air charge MORE then equals out the volume the meth displaces and nets more power.
Pre-turbo injection is highly debated. I have never known what to make of it with all the mixed views floating around so like normal I am just going to try it myself. Done right I have seen turbos last plenty long with pre-turbo injection. Done wrong will spell quick death.
The results are real that is for sure. Reliability is the only question.
Methanol puddling is an problem I have NEVER seen but even so won't be a problem for me since I will not be running an intercooler to start with. The methanol pre-turbo would render it useless anyways.
You are right in your guess of how much fuel the methanol will be providing. Right at 1/2 by volume and 1/4 by the wideband. That may not even be enough. Tank and pump ect are not a problem, that has been taken care of.
Methanol engines like you are talking about that run on pump methanol due suffer from those kinds of problems, it is not as common as you make it sound by any stretch of the imagination but it does happen. I know a few guys that run methanol (fuel of choice around here) and none of them worry about dumping the fuel after the season ect and none of them have any of the issues you are talking about. These are in EFI cars though, The carb guys seem to complain about those problems more.
I am not running on methanol though, I have a methanol injection kit that only comes online under boost. To date I have NEVER seen someone complain of corrosion with a meth injection kit, EVER. I have done a lot of reading on the subject as well.
The other option for tuning is to use a 7th injector mounted in the same place as my meth nozzle. Both options have the same adjustability and tuneability. When I had the 7th injector I was only making 225whp though and running ~12 degrees peak timing. With the meth on the other hand I am making ~250-260whp and able to run over 20 degrees of timing without knock at WOT. More then it ran stock NA BTW.
All said and done, I am not worried about the tuning side of things. I will play with it and learn as I go. There are only a handful of other trucks with setups anywhere close to this so I am pretty much on my own anyways.
I am not worried about the meth injection, it has worked great for this long, I see no reason it will not work now. Biggest problem would be having enough methanol being injected. May need more then 2000cc very easy.
I am not worried about trying to beef up the supercharger/pulleys. Twin-charging is purely an experiment to try it for myself. If it doesn't work I don't care and will just pull the supercharger off and sell it.
The only way I see myself keeping the twin-charge setup is either if it works better then I could dream in compound mode or opening the by-pass really does disable the supercharger with no other ill effects.
The turbo alone will make FAR more power then this motor can handle, spool should also be acceptable with my high stall converter. Faster spool is also nice though which is why I am going to try twin-charging.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
against his will...
Is of the same opinion,
still.
Mike Halloran
Pembroke Pines, FL, USA
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I was suggesting to slow the blower not speed it up.
How does a blower miraculously generate all this heat without generating pressure. Sure a roots does typically make a bit more heat than a turbo at the same boost, but this is more at high boost or very high blower speeds, hence the advice to slow it down and drop the boost. The heat comes from the rotors and housing getting hot from friction and from extra shear mainly as the air leaks between the two rotors and the housing. Hence the advice to add the methanol there.
Turbos also add heat above the adiabatic level, but typically to a lesser degree than does a roots. A lot of course depends on the installation and the differences you are quoting seem excessive. There seems to be some apples to oranges here somehow.
The M62 displaces 850cc per turn and your engine displaces 1700cc per turn so you need about 2.5 engine speed to pump 5 psi @ 100%VE without accounting for heat so you are correct, the blower is a bit small and is getting to the rpm where it starts to drop off in efficiency. It should be OK at the current redline.
If you want room to grow, you really need an M90 which displaces 1130cc/turn so 2:1 would give you 5 psi @100%VE etc. That only spins the blower to 11,000rpm which is well inside its efficient range The M90 is bigger in all dimensions I think, so installing one might be more than trivial.
Ummmm robbing power is robbing power. It still has to be transmitted through the piston and rods to the crank. Only difference is it gets used at the crank inside the crankcase instead of at the crank snout. In fact seeing as how it is via increased blow down pressure it is transmitted through the rods and pistons as both the extra power and the drag components whereas a belt driven only transmits the extra power via the pistons and rods. The drag is transmitted via the crank snout, which has it's own set of problems of course.
An Eaton is way more efficient than an old GM type roots blower due to better internal geometry. If the coating on the rotors is intact that also helps efficiency. Very well set up which yours is not, they can better a bad turbo but will never match a good turbo for peak power, but most street races are won or lost in the first two seconds which is where the Eaton shines, well at least for the first second.
I agree methanol injected as a secondary fuel will work well if metered well enough. I have yet to see a water injection unit that will do it. A piggy back designed for fuel enrichment via an extra injector could well do it so long as everything is rated for methanol. Methanol is a lot more expensive than water but not as effective at evaporative cooling, but if you need extra fuel anyway, I guess it can work. Extra primary fuel to get the mixture correct with plenty of water injected also, could work better I think. E85 could also work probably at lower cost and less risk of corrosion.
If you do not think methanol is corrosive, I guess you will have to learn that one the hard way. The only think that might save you is that there is not a lot of methanol being injected and it will not be injected as the engine runs down against a closed throttle before switching off. If you where just into boost, I would let it idle for a few seconds before switching off for an extended period.
Also, methanol absorbs water rreadily and the water content leans it out. Once again though using it as a secondary fuel only mitigates to reduce the impact of that.
Injection of methanol pre turbo is not debatable. It does erode compressor wheels, the only debatable point is how fast it does it. You can minimise damage by aiming the stream at the bolt holding the wheel on. I have never seen any advantage in injecting pre turbo other than not having to pressurise the tank with manifold pressure.
The way you plan on doing this, you will end up taking the supercharger off as it will not work well
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I looked into pulleys pretty hard a year or so ago when I decided to really fight the belt slip I was getting and with the way it is setup on these trucks you have to get a fully custom CNC machined crank pulley along with all the other accessories. The crank pulley alone would run well over $500+. Then the rest of the pulleys would cost you another $500 easy. Was not worth it so I made up an extra tensioner that wraps the belt around the supercharger pulley more to get it more surface area to grip. Worked great, belt slipped lessened so that I could then make over 10psi and get rid of the slip everywhere except at redline.
Slowing the blower down will be a must, agreed there. I still have the stock 2.37 pulley I will try first, that is about ~5-6psi. I can also get larger pulleys as well, if needed.
How it managed to produce that much heat is exactly why I am not a big fan of it.
If you look at the above chart showing the heat gains you can where the problem lies. @ 10psi (I run ~11psi when the belt is not slipping) it adds 180-200 degrees to the air temps. Combine that with my overspinning the supercharger to ~17,000-17,500 and that the supercharger casing sits around 140-150 degrees and that I am in Texas with normal temps at around 100 degrees. Add it all up and mid 300's is easily seen.
This has been verified by other people as well. They have logged outlet temps from the supercharger well into the 300 degree range with larger pulleys then me.
The methanol does knock the temps down for sure but it does the same for the turbo so kinda moot (works better for the turbo since it doesn't waste energy cooling the supercharger casing).
The turbo, which I don't have exact temps on this engine I have seen these turbos on other cars and Mid 100's is about what I expect the temps to be going into the supercharger @ 10psi of boost. On my MR2 with a smaller turbo (aka more heat then this turbo) Temps would get to about 160-180 degrees @ 17psi of boost from the turbo.
With a larger turbo running less boost, mid 100's sounds very reasonable. Also backed up by temps I have seen with this turbo on other cars.
Like I said, these results have been backed up on the few turbo trucks running around. At the same boost they are commonly making 50-75whp more then me.
The MP62 that is on there now is already being overspun to around 17k-17.5k which is part of the reason it is putting out so much heat. Only reason it makes any power being spun that fast is the meth injection.
I would love an M90 and looked into it for awhile as well but once again the cost of getting everything custom made was out of my budget and not worth the gains.
Far as the turbos robbing power and being harder on the internals. Yes and no. While it does rob power due to backpressure it doesn't increase cylinder pressure close to the extent that a supercharger does. Cylinder pressure = power = amount of stress on internal parts.
I have seen it on a few occasions in various cars where supercharged motors will start blowing at X power level and turbo cars will blow at a higher power level (generally around 50-75hp more from what I have seen) all else being the same.
We are agreed on the low end grunt of the eaton. I like that but I am also a guy that picks his races. I generally don't race unless I am sure of victory and/or I want to embarrass someone. I actually like a little turbo lag makes them think they stand a chance before you fly past them. This won't apply as much in the 4runner since it will still be lucky to crack 13's even with the turbo though.
You are right about there not really being a meth/water injection system on the market that can control the methanol well enough, thats why I created my own by using a progressive methanol controller setup getting it's 0-5v signal from a piggyback that allows me to map out a 3D map for the methanol according to boost and RPM.
This allows me to have the same amount of control over the methanol flow as an extra injector setup. The nozzles atomize better though. Everything is rated for methanol for sure.
Around here methanol is cheap, i just got a barrel of it for ~$2.75 a gallon. Cheaper then pump gas by almost $1. You use more of it though so it kind evens out. Still not as much extra as you would think.
I wish I had E85 local to me but the closest pump is a good drive from me. If I had a local E85 pump thats what I would run for sure.
I have played around with water injection a fair amount and everytime I find I get more power with pure or almost pure methanol over water.
You are also right as to why methanol injection kits don't have corrosion problems, the methanol is never on anything long enough to do any damage. It is only being injected for a few seconds at a time and then has a lot of time to get cleaned out before the engine is shut down.
That said I decide to see what methanol would really do to aluminum and rubber myself so a few years ago I go a container and filled it half way with methanol. Then I dumped in various aluminum and rubber parts and let it sit for over a year. After all that time, Other then being nice and clean, there was not a hint of corrosion on anything. Yes parts were half sitting in the methanol so that air could get at them. Worst possible conditions. I have seen methanol damage stuff but it is pretty rare from what I have seen.
Like I said before, I do mainly deal with EFI cars which don't seem to have any problems. Carb guys do complain about it a lot more.
Also correct about the water absorption. Doesn't worry me, I can adjust the amount of methanol injected up or done on the fly with a knob so if the AFR's are a little lean/rich I just turn the knob to correct it.
When I said that the pre-turbo works. I meant from a performance standpoint. It does extend the compressor map and is worth power. You are right that it will cause damage long term, how long is the question. If it is 5 years, I won't still have this setup in 5 years. If it is 6 months, then thats bad. I will be doing it right with it spraying dead center of the turbo.
So you are saying that opening the by-pass valve will not work, or has side effects? Thats what I have been trying to figure out for weeks now. No one knows what will happen with it open.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Plenty of manufacturers have used a twincharged setup where there is a bypass around the SC at higher rpms. This is to protect the blower, and to maintain some reasonable IAT. FE is a side benefit of doing this usually as such a system is designed for a performance target, not a effcicency target (like the VAG TFSI engine designed with SC blowing into TC and is clutched).
The Lancia S4 had a sytem just so, no SC clutch:
htt
ht
The Lancia engineers apparently had a hard time getting the switchover point just right.
Basically as the SC can pose no restiction to the volume flow (always multiplying) once the bypass valve cracks open the boost drops (due to less work done by SC), and density increases (due to less work done by SC also meaning less heat). To maintain the required MAF, the TC must now work harder, and the TC wastegate closes. If it is a pneumatically controlled system, so will the SC bypass (control nightmare as they are two unconnected actuators on the same system). In this area there can be a flat-spot as the system controls need time to respond.
Wouldn't it be easier to install the bigger supercharger model and a larger turbo? Then do away with the bypass, add simplicity and a charge cooler between the TC and SC. There are some very neat water to air cooler solutions.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I think I have pretty much decided to just do away with the twin-charging plan. I will try it for a time but don't have much hope for it working that well. I will then sell the supercharger and use the money from that to add some other goodies to the turbo setup to make it better.
Turbo alone should give me plenty of power and with my high stall converter lag should not be a big issue, no worse then my other cars anyways.
Long as I can get full spool at ~3800rpm so as to stay in boost during shifts, I am happy. The setup I have planned should spool right around there, it will be close but should work out ok.
All else fails, I will use the money from the supercharger and install a nitrous kit to spool the turbo.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Use manifold pressure near the inlet port to control the waste gate, not charge pipe pressure before the supercharger.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I don't think I will make anywhere close to as much power at the same boost level twin-charged as I would turbo alone.
I have done more research since posting this and found a few example dynos from twin-charged cars (with properly sized superchargers) that backed up my fears on twincharging. You did gain a lot of spool down low but once spooled the twin-charged version made less power throughout the powerband vs turbo alone at the same boost.
Twin-charged power also dropped off up top even more.
I plan to try it twin-charged for a time anyways to see how it works but don't have high hopes. The belt won't spin the supercharger anyways I am sure.
I wish I had the funds to really do this right, I would get a larger supercharger, then get a progressive by-pass valve setup and tune it all nice and purdy. But I don't have the funds.
Although if I had the funds, I would just build this motor, build a proper turbo setup with a bigger turbo and call it a day. Built right the turbo alone would work fine, my only problem is the remote mount, just not sure how much more lag it will add.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
This has to be true. As you pass the air through each stage the efficiency of that stage has to be included. The benefit is that you can reach much higher pressures lower in the rpm range. For out and out power, the Twin charged route will never beat TC alone, but it is useful if you need a low-end torque bolster at the expense of top end power/efficiency.
Even PERFECTLY sized TC and SC, to give the optimum total efficiency at peak torque and minimise SC losses at peak power (clutched or bypassed or both), will always be beaten in terms of outright power (det limited) by TC alone, never mind how efficient the IC is.
Twincharging is useful if you need a low-end boost. Through SC boost and helping to bring the TC online, you can improve the torque curve, not the outright power or efficiency.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I just have this big problem with a anything working harder then it needs to, I really like efficiency.
If I had an all out track car that needed both the low end and top end a twin-charge can give and/or an unlimited budget, I would do it.
On a budget though, it is simply not practical.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
I know. I just digressed on a point as I know track guys who have had a huge success across the entire power band.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
A street driven car is not a place that a twin-charge setup would shine IMO. It is rare that spool actually matters on the street, it just makes things more fun.
In my case my only worry is the turbo spooling early enough that I don't drop out of boost when it shifts. I should be ok though. I had an idea on how I can improve the turbo setup to that of almost the same quality of a normal top mount setup. The turbo will be mounted real close to the exit of the headers. Maybe an extra 1-2 feet of piping over a top mount setup at most.
In a top mount setup I would expect this turbo to spool a little under 3000rpm. So hopefully I will be fine with it spooling under the 3750rpm "limit" I want.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
The remote mount won't change the spool up rpm as such, it will change the spool up time in units of time as there is more manifold volume to fill before pressure builds to spool up the compressor then for the compressor to fill the air ducts. It sounds like even though you are calling it a remote mount, the pipes will still be reasonably short. I was thinking of setups with the turbo in the rear of a front engined car. and like an extra 10' of pipe on both sides.
Regards
Pat
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RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Then you have a few other factors like I am in Texas, the land of the arrow straight highways for as far as the eye can see.
Lastly I don't play around with corners on the street very much as it is dangerous not only for me but for others. I stick to straight line pulls on deserted stretches of road where I can only hurt myself. Or better yet I hit up the track whenever I can afford it.
Yeah, this remote mount setup will not be that bad really compared to the setups you are thinking about. Still not as good as a top mount but the cost to performance ratio says this is the way to go. The only thing I am worried about is a crossmember that is right where I want the turbo to go. I can work around it just not sure how till I have the turbo to see fitment.
Overall the combo of headers and a pretty good roughting to the turbo should mean I only have an extra few feet of piping both ways.
Not ideal but at 1/4 the cost of a top mount, It is worth the tradeoff.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
Could you make 550hp with a big turbo only setup, instead of 500hp twincharged? Probably, but how is that relevant when 400hp is the limit, which can be had with room to spare for either option?
Just a quick "reality check." It still may be more trouble than it's worth, but getting there is half the fun right?
RE: Thinking about twin-charging w/ remote turbo, Good idea or utter fail?
If the rods hold up then the limit of the motor is higher then I first expected. It is still unknown how much power it can handle but it is not as set in stone as I first thought.
My goals have also changed after finding this out from just wanting a fast truck to wanting to take the stock block HP record which near as I can find is around 375-390whp proven HP.
The supercharger will make this a much harder goal to complete for many reasons.
A big one is the turbo I got will want to run ~20-25psi of boost to be "happiest". If i leave the supercharger in place the turbo would be lucky to make 10psi of boost.
Not to mention I keep coming back to the fact that the supercharger belt will simply not hold the power needed to run compound boost without putting a super big pulley on it turning the boost down to ~3psi.
In this case I don't think the supercharger would help enough down low to make the top end losses worth it. Which comes back around to wishing the bypass valve would truly by-pass the supercharger.
I have also decided to do things a little different by adding a better piggyback (AEM FIC) and getting a larger fuel system allowing for a better tune with these new plans. This means more money and I really need the money from the supercharger to pay for this extra stuff.
All said and done the turbo/fuel setup should be good for ~600whp if I am brave enough to turn the boost up high enough for that. The transmission won't hold that though, it is good for around 500whp.
You can Call me TA
I carry a gun cause a cop is too heavy.
If guns kill people, then Spoons make people fat.