Mechanic has his doubts

[J3FF]

So I was talking with the master mechanic from my old school. He graduated from Lincoln Tech (NO, BEFORE ANYONE ASKS!!! not a ford university) so I think he knows what hes talking about. He was telling me that the Exhaust and intake would not provide any horsepower numbers...I got on LSkoncepts and showed him the Dyno just for the exhaust and he laughed and said that wouldnt be able to achieve that number of 11. Now, I think this dude is wrong, but he knows cars like crazy and all he had said to me was it'll eat me more than it will show me results.

I think youll find this funny, a kid that drives a Cavilier chimmed in and said "Oh plus you have a luxurious transmission, so your transmission will lag." OUR CARS ARENT TURBO!!!!!!!!!

This is just kinda how my day was, while I was talking about the mods on my car. The SCT should really wake it up though.

 

[SoonerLS]

It's possible for experts to be wrong. The dyno numbers don't lie; there is power tied up in the 1st gen LS's exhaust. There are precious few cars out there that couldn't benefit from a freer-flowing exhaust--even the '03+ LSes could, though the $/hp ratio makes it a non-cost effective solution.

On the 3.0 SHO V6, for example. there's approximtely 20-25hp to be gained simply by changing to a freer-flowing exhaust.

The internal combustion engine is, essentially, a fancy air pump. The more easily you can make the air flow in and the exhaust flow out, the more power it's going to generate. As you've seen, the claims of the exhaust and intake companies are being tested by enthusiasts--if they were full of BS, they'd be busted in no time. It's not like the "these results are not typical" weight loss non-drug claims; if Magnaflow says switching to their exhaust will gain you 15hp, you can take your car to a dyno, get a baseline figure, then install the exhaust system and test again. If the claim doesn't hold up, it'll be exposed in no time.

 

[eeprete]

It's all about the flow and efficiency of air and fuel. Air flowing in and mixing with fuel in the combustion chamber, then burning, then flowing through the exhaust valves, into the exhaust manifolds and then out the exhaust. The less restrictions through the system, and the more efficient the burning of the fuel, the better, however there always needs to be a certain amount of backpressure maintained for most efficient power.

This is why many individuals with performance cars or race cars will spend time and/or money porting and polishing intakes, heads, exhaust manifolds, etc, as well as installing an aftermarket performance exhaust.

Most aftermarket parts advertised claims of XX horsepower added are for the most part false. If I add on three different parts, and all claim 10 hp each, the likelihood of realizing 30 HP is slim to none. However, often you will find one of those parts has added perhaps 8-9 HP.

However, just because that 2.5" dual exhaust system may have netted you 10 hp, don't think a 3" will net more. It could in fact net less due to lost backpressure.

 

[SoonerLS]

Yeah, there is a certain break-over point where the exhaust doesn't maintain enough backpressure, but that normally results in a loss of torque, not necessarily HP. (IIRC, it can also result in burned valves, which is why you're not supposed to run an engine without the exhaust manifold/headers.)

Bolt-ons are not necessarily additive, but since we're only talking about exhausts, that's all I was considering...

 

[02V8Sport]

This mechanic is blowing a lot of smoke your way. A lot of times, even if a modification does not add significant horsepower, it will shift your torque and horsepower curves around. Basically you will have more power all around your RPM range just than at peak HP RPM's. So if you were to punch it from 20-40 or 30-60 and so on, the car will be much faster with a free flowing intake and exhaust, even if it technically didnt add any more HP to your peak HP numbers. But dyno numbers dont lie, so ask the Lincoln Tech guy how this increase happened??

Dont want to offend anyone, but a friend of mine went to LincolnTech and he changes oil and tires at Wal-Mart. Hes not very bright either.

 

[crab daddy]

Well, I think he is right on a technicality.

when you put a restrictive intake and exhaust onto a car it loses hp that it already had. An engine dyno would show the same numbers (because its the same engine) though a chassis dyno would show lower numbers with the restrictions in there.

so technically you aren't gaining hp... you are simply not losing as much hp through the intake and exhaust.

 

[2001LS8Sport]

That guy is nuts. If what he said were true, you would never sell another set of headers. There is horsepower in a good exhaust. Dr. Gas is another great example. He developed the original (and still the best) X pipe. It is good enough that the NASCAR boys use it.

My Cobra...and just about every 03/04 Cobra ever built picks up a solid 30 hp...and usually more...with a CAI and exhaust.

 

[KD00LS]

My Cobra...and just about every 03/04 Cobra ever built picks up a solid 30 hp...and usually more...with a CAI and exhaust.

I agree, Cobras pick up some nasty hp of minor modifications.

 

[jokken]

i agree with 02v8sport LincolnTech hasn't really impressed me much either.

i like crabdaadys comment though. he is right, it is not making more horse power it just has more available since it used less to push the exhaust out.

but I doubt this is what the guy meant.

 

[StinkinLinkinLS01]

However, just because that 2.5" dual exhaust system may have netted you 10 hp, don't think a 3" will net more. It could in fact net less due to lost backpressure.

There has been evidence that 3" exhaust will cause a loss of power. I know when I converted to 2.5" custom exhaust with 40 series flowmasters I felt the HP increase. I still want to take my car to the dyno....

 

[machlsowner]

Well, I think he is right on a technicality.

when you put a restrictive intake and exhaust onto a car it loses hp that it already had. An engine dyno would show the same numbers (because its the same engine) though a chassis dyno would show lower numbers with the restrictions in there.

so technically you aren't gaining hp... you are simply not losing as much hp through the intake and exhaust.

If you change the intake and exhaust, you change the engine, it all works together. Yes it is flowing more freely, which allows it to produce more hp but there is more to it than that.

Using your "mechanic" friend's reasoning an exhaust with no back pressure would allow the engine to make the most hp but, this is not the case. He sounds like a newbie with a bunch of "book" ideas. A few years in the real world of engine and he should have a better grapse of the real concepts.