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Aftermarket Intakes for Modern Cars
7

Aftermarket Intakes for Modern Cars

Aftermarket Intakes for Modern Cars

(OP)
Hello to people who are TANGIBLY USEFUL to society! I have great admiration for engineers and in my next life will be one:)

I have a question to which I am not able to find an answer, and I have been searching for several years now, and actually have run out of words and key-phrases to input into a search engine. I hope someone could give me a comprehensive answer, or maybe point to a mildly technical articles (no books, my caliber is too small) that would point a way to my general comprehension of the subject.

Here it is: DO AFTERMARKET INTAKES ADD POWER TO A MODERN (2014+) CARS? Like from a more or less "reputable" aftermarket company for a 4 or 6 cylinder NA engine car from a major automaker: Chevrolet, Mazda, Toyota, etc.

As you can imagine the forums with blissfully ignorant are full of all sorts of rants, which to me resemble religious sects arguing who's "truth" is closest to god. The skeptic in me leans heavy towards "no they don't add any power", but I am really open-minded. I appreciate your time you took to post your opinions.



RE: Aftermarket Intakes for Modern Cars

Pretty much no. A cold air intake may be of some value, but nine times out of 10 the OEM will have spent a while optimising the pickup location.

Ditto air filters. The pressure drop across a standard air filter is essentially zero.

The reason for this is that hp is one of the few hard numbers manufacturers can boast about so they spend a bit of time on it.

The exception is tuned runners on the intake. They could usefully modify the torque curve.

The other gotcha is heat pickup in the intake, it would be a good idea to get your intake air to the plenum without warming it up too much.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Aftermarket Intakes for Modern Cars

(OP)
Gregory, thanks!

What would be a counterargument to the claim that OEM intake is also tuned for relative quietness, and therefore its restrictive, and therefore an aftermarket intake - which is louder - is less restrictive, so it adds 3-10 horsepower. It sounds intuitive, but I know there is a high chance for a catch here. I've red somewhere that "..... if you know the internal laminar flow cross section, the intake will not be affected by that. IOW, as long as the laminar flow section of flow is wide enough to handle the mass flow, it is all good, ugliness not withstanding...." Would this be an answer?

Thank You

RE: Aftermarket Intakes for Modern Cars

Quote (SlavaYkraine)

DO AFTERMARKET INTAKES ADD POWER TO A MODERN (2014+) CARS?
I agree with Greg, probably not any appreciable amount if at all, and certainly not cost-effectively. Tuned runners are a double edge sword (unless variable) - what you gain at one rpm, you tend to lose at another.
Probably the most practical way to get the maximum available power out of modern engines is to feed them the highest octane fuel you can get from your local filling stations.
Other than that, for any significant power gains, these application specific options come to mind:
  • re-calibrating the performance maps - this requires a considerable knowledge base and depends on aftermarket support (hardware & software) for the particular application; and therefore is best left to experts. This is particularly effective with boosted applications, however.
  • reduced exhaust restriction - depending how bad the original system is, there may or may not be worthwhile gains to be realized here
  • high power crate motor if there is one that fits your application

  • Other than the above, you might as well just buy the vehicle that already comes with the performance you want, or else roll up your sleeves and start learning about hot rodding from the ground up.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

RE: Aftermarket Intakes for Modern Cars

If you think your intake is costing you power due to restrictions use a water U tube to measure the pressure change along its length. I'll eat my hat if the intake, including filter, of a modern car from a sensible company has a pressure loss of 2 kPA (8 inches of water), which would be a pumping power of say 6000 rpm/60/2*2*10-3*2000=200W, or 1/4 hp, for a 2 litre car at 6000 rpm.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Aftermarket Intakes for Modern Cars

It is quite possible that an aftermarket intake manifold can allow a production engine to produce higher peak hp than the factory manifold at certain operating conditions. The reason is that the factory intake manifold is designed to provide the best compromise of many competing requirements like driveability, NVH, emissions, packaging, weight, cost, etc. Factory engine components, such as intake manifolds, are very highly engineered devices. I doubt any aftermarket company has the financial and technical resources available to produce a better overall manifold design.

RE: Aftermarket Intakes for Modern Cars

Are you talking "cold-air" intakes or intake manifold. I think you're talking cold-air intakes but you weren't clear.

As with many questions such as this, the only real answer is "It depends." You may gain power on certain applications. You may not gain any power on other applications. You could also lose power on certain applications. By application, I mean a certain aftermarket intake applied to a certain vehicle.

RE: Aftermarket Intakes for Modern Cars

(OP)
@hemi

Would aftermarket "louder" axel-back exhaust qualify for "reduced exhaust restriction"? Let's take 2014 Mazda 6 with a 2.5L NA engine as an example.?


@Greg

No, I don't think it causes any restriction - I do not have an aftermarket intake on my car, as I don't think an aftermarket one is any better than the OEM. But many people on plebeian forums make all sorts of claims for these aftermarket intakes (short-ram and col-air) and come up with all sorts of sophisticated-appearing theories of why they add 5-10HP and improve fuel economy. That's why, not being an engineer, I decided to ask real engineers to give their answers. I mean, it's easy to find information from real scientists that vitamin supplements are duds, but NOWHERE can I find an engineer's view on these magic devises - aftermarket air intakes - that add power and fuel economy.

@tbuelna
the claims such as that an OEM air intakes are designed to satisfy multiple parameters (NVH, fuel economy, etc.), is what people claiming 5-10hp gains from simple $189.95 SRM or ColdAir aftermarket intakes use to support their claims. An aftermarket intake is nosier, and therefore more free-flowing than OEM, and therefore produces gains. As I've written earlier, I understand that automotive engineers are not idiots, but I don't know a proper rebuttal to such positions

RE: Aftermarket Intakes for Modern Cars

The perceived correlation between radiated sound level and performance has sold many "free flowing" aftermarket exhausts. An exhaust need not be restrictive to do its job, although that's often the easiest way.

- Steve

RE: Aftermarket Intakes for Modern Cars

(OP)
@SomptingGuy

I understand:) But when OEM muffler is twice larger in diameter than an aftermarket (I'm talking about axel-backs only here) the claims that they are more free flowing seems logical, at least on the surface. Could you please tell me why it isn't so? Thank You

RE: Aftermarket Intakes for Modern Cars

(OP)
correction: I mean OEM muffler is twice longer and wider. I'm not talking about muffler tips, but muffler itself

RE: Aftermarket Intakes for Modern Cars

One of the ways that you make a muffler quiet and non-restrictive at the same time, is to make it big.

If the aftermarket muffler is physically smaller, it's going to be much louder. The physical size is not a sufficient predictor whether it will be less restrictive.

And just because the muffler is "less restrictive" doesn't automatically mean that the engine connected to it will make more power, either.

RE: Aftermarket Intakes for Modern Cars

I agree with all the previous comments about exhausts and mufflers.
Assuming the factory system has sigificant restriction (several psi at WOT/max rpm), to get a worthwhile reduction you probably need to gut it and start from the exhaust manifolds with a completely new system. The catalysts are probably the biggest net bottleneck, and it isn't cheap, and probably not legal to replace them with anything significantly less restrictive. And of course removing them completely is certainly not legal, and probably will cause the control system to go into limp mode due to the incorrect O2 sensor signals that will result.
The long and the short of it is, while hot rodding is great fun, its much simpler, easier, and more fruitful with older vehicles. Newer vehicles just present a lot of difficult obstacles. Not insurmountable ones, necessarily, but it's best to start the learning curve with older vehicles, unless you want to pay a pro big bucks to do it for you. And I haven't checked, but I suspect the late model applications with available legal and significant aftermarket performance upgrades are few and far between.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

RE: Aftermarket Intakes for Modern Cars

I think it is always possible to improve on the top end power of an OEM manifold, but probably at the cost of power in other parts of the range. The OEM design is usually highly optimized for the operational parameters the OEM thinks are most important, with a compromised weighting. So the aftermarket piece would probably be inferior overall for normal operation.
I think where the aftermarket can show best is with manifolds for modified engines.

RE: Aftermarket Intakes for Modern Cars

One of the major tuners associated with one of the big three that has occasionally done a low run of modified cars sold through their dealers is offering a manifold spacer for a turbocharged 4 cylinder. They claim a 5 hp gain on a 252 hp engine for $140 and 45 minute install. Has anyone seen one of these for evaluation, the people that have bought one claim an increase on the "butt" dyno, but no one has strapped on a chassis dyno before and after yet - easy considering the 45 minute install.

RE: Aftermarket Intakes for Modern Cars

Quote (SlavaYkraine)

the claims such as that an OEM air intakes are designed to satisfy multiple parameters (NVH, fuel economy, etc.), is what people claiming 5-10hp gains from simple $189.95 SRM or ColdAir aftermarket intakes use to support their claims. An aftermarket intake is nosier, and therefore more free-flowing than OEM, and therefore produces gains. As I've written earlier, I understand that automotive engineers are not idiots, but I don't know a proper rebuttal to such positions

First of all, an OEM would not put an engine cold air intake system into production that cost anywhere close to $189.95. The typical cold air intake system on a production auto engine likely costs less than 1/10 of that amount. As to your question of how to rebut the argument that aftermarket engine air intake systems are technically superior to OEM systems, simply ask for an explanation of what the aftermarket product designers know that the OEM product designers don't know. The OEMs like GM, Ford, Toyota, BMW, etc, each have engine design depts. with hundreds of engineers and analysts and budgets of tens of $millions. Do you seriously believe an aftermarket company with maybe 1 or 2 engineers, a tiny fraction of the budget the OEM has, and far less access to testing resources, can do a better job of designing/developing an intake air system?

RE: Aftermarket Intakes for Modern Cars

I can't imagine a 5hp increase is noticeable on the butt dyno... 10hp is typically the much-cited "minimum", and I would tend to agree with that as a minimum. but who knows, maybe someone out there has a highly-calibrated butt to go with the golden ears others claim they have...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

My experience is that you can get 10% more output with bolt on intakes and cat back exhaust and you are done. Even less than that if the engine is already a high output.

After the air and exhaust replacements! the fuel pump, injectors and other items are at their top end and need replacing. Changing injectors means ecu reprogramming so with that addition you can see a 25% maybe 30% increase. Next, it's stronger cranks, rods and pistons and a big checkbook.

RE: Aftermarket Intakes for Modern Cars

most aftermarket tuning companies that try to sell you CAI type kits (not intake manifolds) also sell software and this is probably where the gains come from. its a way of upselling the software for more profits IMO

RE: Aftermarket Intakes for Modern Cars

There are a lot of instances where the same base engine is used in multiple models from sports car to luxury coupe to econobox. The engine ratings have to change along with the price tag. There will probably be a whole host of changes including compression ratio and cam timing but one thing for sure is the econobox will have more restrictive intake, filter & exhaust. These models will typically benefit the most from the aftermarket mods. The same mods on the sports car model will probably only make more noise.

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RE: Aftermarket Intakes for Modern Cars

The problem is, OEMs have way more people, way better people, way more money, way more time, and way more motivation to design something brilliant.

Though hamstrung by price and other performance parameters, the difference in expertise and resources brought to bear on the target between OEM and aftermarket is colossal.

My stance on this is that if you want to improve almost any performance parameter of a modern car you need 1 of 2 advantages over the OEM engineers:

1) Be willing to spend *way* more money than them, taking into account that their part also had all the economies of scale under the sun to help them.
2) Be willing to reaaaaaaaaaaaally sacrifice 95% of other performance parameters (fuel efficiency, noise, safety, comfort, legality, etc) to maximise the one you are interested in.

Throw extremely advanced, impractical, and cost prohibitive materials and processes at it, and ruin everything else about it, and yes, you too can have ridiculous peak power figures.

RE: Aftermarket Intakes for Modern Cars

There have been some interesting theories posted. Too bad they are wrong.

I have seen a number of back-to-back wheel dyno tests on C5 and C6 Corvettes.

A cat-back exhaust can show around a 5hp to 15hp improvement.

A cold air intake can show around a 5hp-10hp improvement. There is one cold-air intake that is track proven by multiple owners to gain around 3/10ths in the quarter mile on C5 Corvettes.

Changing an LS1 from the first design LS1 intake manifold to the newer design LS1/LS6 intake manifold gives a solid 5hp improvement.

Headers with cat converters that will pass a tailpipe emission sniffer can show about a 25-50hp improvement. Headers do require tuning as well.

If you want to go even more extreme, there are supercharger kits that can be added. You can boost the engine by around 100-200rwhp and the car will still drive well and still get good gas mileage off the throttle. Of course this requires improvements to the fuel system and tuning as well.

All of these improvements give a solid power curve that has increased across the whole range of the test, typically around 2000rpm-6000rpm.

My guess would be that percentage wise you might get similar improvements on some smaller engines. So a 180hp 4-cylinder engine might show a 2hp increase with a cold-air intake or a 7hp improvement with a header system for example.

The modern fuel injected engine is fairly immune to intake tract and exhaust system changes (cat-back type systems) affecting the closed loop fuel control system. You would likely have to choke off your air filter badly enough to have driveability issues before you'd see a loss in fuel economy. Most claims that a more free flowing intake allows for less fuel usage are bunk.

RE: Aftermarket Intakes for Modern Cars

Probably the most practical way to get the maximum available power out of modern engines is to feed them the highest octane fuel you can get from your local filling stations.

Eh? I thought that "any higher than required gives no further benefit" was the right answer? (so in most cases the lowest octane is adequate)



RE: Aftermarket Intakes for Modern Cars

Thank you, Lionel... I was beginning to think I was the only one who "magically" saw serious improvements in my cars by using those items wink. For example, adding a catback and a CAI to my S2000 netted an easy 15+ hp, and that is from an engine that was already "strung out from the factory". Sure, I got a throatier growl, and when the cams shifted over to the secondary lobes, she really grunted... but the power gain was obvious.

Was power sacrificed down low to get more upper power? Possibly, but according to the dyno charts any loss was within the confines of statistical error, so it was a fair trade-off (if it even happened).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

Since many years ago modern engines have been sophisticated enough to tolerate any reasonable octane fuel without damaging themselves. That does not mean they are delivering their maximum available performance at the same time.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

RE: Aftermarket Intakes for Modern Cars

One major thing to consider with US vehicle OEM engine components versus aftermarket components, is that the OEM engine components like intake, exhaust, ignition, and fuel system parts is that they must be warrantied for over 100K miles. Not so for the aftermarket parts.

The comments about fuel octane and engine power are also correct. A modern stock engine with electronic controls will not produce much more power than when using a fuel with the octane rating it was designed for. On the other hand, it will not likely suffer any damage from using a lower octane fuel than it was designed for, but it will definitely produce less power.

RE: Aftermarket Intakes for Modern Cars

Dan - Asking here is asking OEM engineers if there is room for improvement in their design. wink

RE: Aftermarket Intakes for Modern Cars

I posted more than just some opinions....

I think I'll stick with the cold-air intake that is track proven to show an improvement rather than wasting time measuring the stock intake to "prove" it's the best intake possible.

RE: Aftermarket Intakes for Modern Cars

I'm not an in the automotive industry, but in my mind, 'track proving' something seems like the worst way, with about the most possible uncontrolled variables (having said that I do believe it's a fairly common tuning tool, but probably because 'feel' is so important).

As for some of the numbers posted earlier in this thread, they do seem questionable. 25-50Hp from legal headers? That's about 10% more power output if you are talking about LS1s, isn't it? Surely it's not losing that much power pushing smoke out the exhaust that you can recover just with some slightly reshaped headers? And surely you won't scavenge your way to 10% more cylinder fill on a reasonable performance engine? I don't know, I know theory but nothing about specific applications, it just sounds unlikely.

RE: Aftermarket Intakes for Modern Cars

I would think that 8 inches of water pressure drop across the intake would make more difference in the amount of oxygen available to support combustion than its cost in terms of HP lost to pumping requirements - but only at or near WOT. 8" is about 0.3 psi, or about 0.02 atmosphere, so 2% power represents a maximum possible gain from completely eliminating all intake restriction if a pressure drop of 8" water is actually present in a properly maintained OE intake tract (including filter).

You'd also want to measure actual air temperatures in the plenum/runners for both OE and aftermarket to see if any benefit was coming from that. To this point, today's OE composite intakes have to be far better at not adding any heat to the air within than the older metal manifolds (that in most V8s were continually splashed on the under side with hot oil and subject to at least a little exhaust crossover flow).

FWIW, I'm more inclined to believe the claims made by the motorsports branches of the various OE mfrs, which are more or less captive aftermarket entities. Particularly where U.S. 50 state street-legal cold air & re-tuning kits are involved. Sharing a few people from the production engine side is likely.


Norm

RE: Aftermarket Intakes for Modern Cars

Norm- ah, great catch. yes that would be measurable hp rather than fractions thereof. now has anybody actually measured the pressure drop on the aftermarket and production intake or are we still pissing into the wind?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Aftermarket Intakes for Modern Cars

As I said, I saw 15hp+ (peak) from a catback and CAI on my S2000 (dyno proven graphs, nut just butt-dyno). They flattened out some dips in the powerband, too, so over all I gained more than just peak power. Saw another 10-15hp+ by swapping out the cat for a test pipe and putting in a new set of headers (meant to polish them but never got around to it).

If people want to think those numbers were all in my mind, so be it, but it's difficult to argue with a 10%+ increase over stock, particularly when it shows at the track.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

New brush, new handle. Same old broom, but with more power.

- Steve

RE: Aftermarket Intakes for Modern Cars

Quote (GregLocock)

But those are much bigger changes than just an intake.
Plenty of other folks did just the CAI (it was the first "real" power mod offered for the S)... saw 5-7hp gains, saw the exact same flattening of power dips. 5hp is getting close to error rates for dyno, but it was still a consistent enough gain every time to be proof positive. I think the hydro dynos are accurate to 2-3 hp? I believe the stock airbox was set up to kill off a specific resonance (Helmholtz resonator, just like in exhausts) that was too loud for the typical driver, whereas the CAI was happy to embrace it. In doing so, it flattened out the powerband and released some power being hidden at the top.

Of course, the dyno did not take into account the reduced weight being carried around, either. The stock airbox being dropped shaved several pounds, the exhaust (Invidia) dropped about 25 pounds, and so on. Adding 25hp+ and dropping 35-40 pounds makes for a peppier car.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

5 - 7 for a CAI still sounds optimistic unless the spark and fuel maps were also adjusted.

Ford Racing only claims 15 HP for its CAI with the reflash, which requires 91 pump octane fuel vs the 87 that the 4.6L 3-valve engine's "normal" 300 HP state of tune was intended to use.


Norm

RE: Aftermarket Intakes for Modern Cars

The stock S2000 maps were a bit rich for the first two years of production, so extra air was a good thing. In following years they leaned out the maps a bit.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

Dan - just give up. Heads are stuck in the sand and it's already been written on the tablet that gains over the factory are not possible.

RE: Aftermarket Intakes for Modern Cars

I always thought if an engineer presented actual evidence of some effect (not pie in the sky dreams), other engineers would say "Even if I do not understand the data myself, it was carefully collected without bias, and the numbers are beyond the statistical minimums for validation... must be valid." Maybe the convincing part is a little harder than I first imagined... wink

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Aftermarket Intakes for Modern Cars

Dan. I don't think anyone doubts your numbers. What I see is yet another one of those "Why do OEMs not give us the full power?" stories. Same answers too. Legislation, homologation & longevity. Plus a bit of branding. Once you've binned those basic requirements, much improvement in your chosen metric is possible. Ever wanted to be a Harley Davidson OE exhaust designer? Thought not.

- Steve

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