Aftermarket Intakes for Modern Cars 7

[SlavaYkraine]

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.

 

[dgallup]

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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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Nereth1]

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.

 

[LionelHutz]

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.

 

[ivymike]

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)

 

[MacGyverS2000]

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 . 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

 

[Lou Scannon]

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

 

[tbuelna]

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.

 

[LionelHutz]

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

 

[GregLocock]

True, but I don't see anybody else posting anything other than opinions. I've told you how to measure the pressure drop in your system, go for it.

Cheers

Greg Locock


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[LionelHutz]

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.

 

[Nereth1]

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.

 

[NormPeterson]

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

 

[LionelHutz]

Nereth1

LS1 catback gains;

http://forums.corvetteforum.com/1573303063-post11.html

http://www.superchevy.com/how-to/73978/

LS3 header gains with no tuning;

http://www.lsxtv.com/tech-stories/exhaust/kooks-ls3-header-dyno-test-install/

LS1 intake and header gains with tuning;

http://forums.corvetteforum.com/c5-tech/3458784-dyno-before-and-after-arh-headers-and-halltech.html

 

[GregLocock]

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

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[MacGyverS2000]

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

 

[GregLocock]

But those are much bigger changes than just an intake.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[SomptingGuy]

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

- Steve

 

[MacGyverS2000]

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

 

[NormPeterson]

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

 

[MacGyverS2000]

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