Thinking about twin-charging w/ remote turbo, Good idea or utter fail?

[TexasAceTA]

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

Call me TA

I carry a gun cause a cop is too heavy.

If guns kill people, then Spoons make people fat.

 

[TexasAceTA]

I had considered that for awhile but after some looking could not find anything close to the right size I would need. That would be the perfect solution though. If you know of a sub 2.7 inch pulley with a clutch I would love to know where it is.

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.

 

[patprimmer]

Hint. The system has 2 pulleys.

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
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[TexasAceTA]

All good points, I will address them in order.

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.

 

[Lou Scannon]

Pat, I hope your words to the wise are heeded by those who can still benefit.

 

[MikeHalloran]

A man convinced,
against his will...
Is of the same opinion,
still.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

Std pulleys can be modified for a lot less than $1000. I would think someone like Summit or Jeggs would have them.

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
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[TexasAceTA]

Once again good points, I think we are starting to understand eachother.

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.

 

[70btdc]

The whole point of the twincharged system was that you could 'oversize' both turbo and supercharger to benefit from higher efficiencies, whilst still having the fast response times. This is where the compound effect has a benefit (TC blowing into SC). So firstly, the SC in this application misses that design specification quite considerably and would NEED to be upsized.

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:

http://imageshack.us/photo/my-images/804/s4inductionsystem.jpg/

http://www.mat.fi/n_index.php?nav=gallery_view&gallery=project1986lanciadeltas4&g=13

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.

 

[TexasAceTA]

Sadly changing the supercharger is not an option due to cost. It would have to be a 100% custom setup for the supercharger which would run many times the cost of the turbo kit and still net me less power.

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.

 

[patprimmer]

Honestly, if you just blow the turbo into the existing supercharger with no bypasses it will work fine. Of course you should run an inter cooler before the supercharger and inject water/methanol after the inter cooler but before the supercharger, preferably in a way so the liquid is distributed evenly along the rotors.

Use manifold pressure near the inlet port to control the waste gate, not charge pipe pressure before the supercharger.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[TexasAceTA]

The problem with doing that besides the IAT's being way higher is that the turbo would simply be way out of it's league in this setup. It would be making maybe 5psi of boost, this turbo doesn't really come alive till the mid ~20psi+.

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.

 

[70btdc]

"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."

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.

 

[TexasAceTA]

Thats what I have found out. I was hoping that you could get the low end boost with only minor losses after that but it looks like a pipe dream. No free lunch as they say.

You can Call me TA

I carry a gun cause a cop is too heavy.

If guns kill people, then Spoons make people fat.

 

[patprimmer]

By using an SC to overcome excessive lag, you can run a big laggy turbo where you otherwise could not and still have acceptable drivability. That can give more overall power.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[TexasAceTA]

This is true but for that to work I would need a much larger turbo and a larger supercharger, costs get way to pricy for that to be practical for my goals.

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.

 

[patprimmer]

TA

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
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[TexasAceTA]

In a track car a twin-charge setup would be killer for sure. No argument there. Twin-charging has it's place no doubt. I still want to try a setup myself someday.

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.

 

[patprimmer]

I think our different points of view are based on different uses and driving styles. I spent a lot of time on winding narrow mountain roads some with a gravel surface.

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
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[TexasAceTA]

Partly it is the driving styles and the context. Got to remember this is all going in a 5000lb SUV, it is not built for taking corners. The thought of that is scary lol. It is a pure straight line truck.

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.

 

[1gibson]

Discussion seems to have moved away from the defined HP limit based on internals. If you can only do 400hp, you want that with as flat a curve as possible, so the twin-charging (on paper) may still have advantages.

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?