Aftermarket Exhaust; More Power?

[myt]

Hi all,
I tried a search here and even on google but still haven't gotten the answer I am looking for, well at least I don't think I did. I am going to buy a Megan racing exhaust for my LB in the next month or so. But my question is I see that it advertises more power. I don't see how an exhaust can add more hp, but is the claim simply stating that it makes the car significantly lighter therefore decreasing the weight of the car?

Or can it be that the unrestricted air through the exhaust actually gives the car a boost like a turbine enging? J/K

Thanks,
MYT

[kurokoma-kun]

Originally Posted by myt

can it be that the unrestricted air through the exhaust actually gives the car a boost

As I understand it, that's the general idea. I replaced intake and exhaust on previous car and it made a worthwhile difference.

[WRBlue]

Originally Posted by myt

But my question is I see that it advertises more power. I don't see how an exhaust can add more hp, but is the claim simply stating that it makes the car significantly lighter therefore decreasing the weight of the car?

Engines do one thing, move air. By removing restrictions in the in or out of an air system allows more flow. Thats how the "make" more power.

Lighter weight makes no power, just allows the power to better utilized.

On any NA engine, your lucky to get an additional 5hp from a cat-back

[AlphaFox]

dont expect any power gains from that exaust, you will most likely loose some low end.

[ya_RS]

its all about back pressure

read on ...
http://www.yarisworld.com/forums/showthread.php?t=7510


also


http://www.warnertechnology.com/Cars/backpressure.shtml

[myt]

Thanks for the info guys...this really helped a lot.

[Black Yaris]

I much better investment than a axle back would be a full cat back and increase the diameter of the pipe, it cost about the same as an axleback and better preformance

[Spades]

ok, time to clarify...ENGINES DO NOT NEED BACKPRESSURE... your ECU does not measure back pressure and most new engines are designed to run with low back pressure.

you wont throw codes, you will only loose a little bottom end horsepower.

The engine will run just fine...there is nothing in the engine that will fail or cause it to run poorly with no back pressure. dont take my word for it, do some research and talk to a couple mechanics.

Next...it isn't just about backpressure, its also about exhaust velocity. exhaust velocity is how fast the exhaust exits th exhaust piping.

Going from larger to smaller pipe then back to smaller or splitting the pipe into two (so-called "dual exhaust") will slow the gasses exit speed, there by creating more restriction AND back pressure.

So, to recap, the worst that can happen by having massive pipe is that you loose bottom end, and that because of the large pipe it dissipates heat more efficiently than the stock piping, you may not get the most out of your factory cataletic converter and it may burn out prematurely. I doubt you would loose any hp do to exhaust velocity lost do to expansion from a smaller header pipe to a larger pipe unless you were going from a 1.5" pipe to a 3" pipe...might not be the ideal thing, but i doubt you would notice any high end hp loss...but what do i know?

higher exhaust velocity and lower back pressure = more horsepower

always has always will. is it worth it? personal preferance.

EDIT: Alphafox..."dont expect any power gains from that exaust, you will most likely loose some low end"
you dont look at dyno results much do you? yes, you get horsepower, even on small engines, however, its not much. expect to loose a couple horsepower at 2k rpm and gain a few at 4k+ rpm. do some research before you start posting drivel.

[jdium]

lol

somebody found a soapbox...

You will gain very little power on this little car. Toyota will not leave much on the table, competition is too great. You will gain noise, which does not seem like a good trade to me. No power + annoying sound = money stays in my wallet...

[Spades]

LOL...found a soapbox? LOL...i never leave one. I am always on it,lol.

yeah, performance gains are little at best, and you have to be very careful on your muffler selection or you will end of sounding like a un muffled chain saw.

so yeah, worth it to some, not to others.

<picks up soapbox and carries it with him to the next post>

[Astroman]

The TRD ver. S dynos about 2+ hp. The NST pulley felt about the same for gains, and was a lot cheaper.

[AlphaFox]

dude, I know. you will 'loose low end' like you AND I said, I didnt mention high end. you would obviously gain some high end as there is less restriction. sorry for not posting that part. Carry on, Spades, with YOUR drivel. YOU HOAR!!! ;)

[kurokoma-kun]

MYT, does that make things less confusing for you?

But I agree with the idea that gains with the Yaris might be minimal. On previous car I experienced a very noticeable boost across entire power band, even w/o replacing header. But it had about 30 lbs of stock air box and baffles and shit blocking the flow, Yaris does not seem to have that problem.

[Spades]

Originally Posted by AlphaFox

dude, I know. you will 'loose low end' like you AND I said, I didnt mention high end. you would obviously gain some high end as there is less restriction. sorry for not posting that part. Carry on, Spades, with YOUR drivel. YOU HOAR!!! ;)

heheheh, when i get started on a rant i really do get carried away

anyway, i think we are all in agreement,low end power will be lost with larger piping but you will get some high end gains...its a give and take kind of thing.

[ya_RS]

Originally Posted by Astroman

The TRD ver. S dynos about 2+ hp. The NST pulley felt about the same for gains, and was a lot cheaper.

with all due respect... " you felt a 2 HP gain" ?

Originally Posted by Spades

anyway, i think we are all in agreement,low end power will be lost with larger piping but you will get some high end gains...its a give and take kind of thing.

I agree

[Astroman]

I was just saying for comparison purposes that the difference with the NST pulley performance wise was about the same as when I first put the TRD v. S exhaust on. My exhaust was used as a test unit from a DC Sports dyno run. They needed a stock yaris to run on the dyno with stock & TRD exhaust for R&D. I bought my exhaust from the owner of the test Yaris (they had given him the exhaust for allowing them to test on his car.) The previous owner said the dyno resulted in 2+ hp increase. The exhaust was the first mod to my car and I did notice a modest difference. About the same modest difference in acceleration was noticed with the NST pulley. I am in no way saying I know what a 2hp increase feels like, just that the addition of the pulley felt the same as the addition of the TRD exhaust. I have no dyno numbers with the pulley and TRD exhaust together, just the TRD on a stock yaris. I will be doing a dyno run after I install my AEM intake this weekend, but that of course will be showing the results of the TRD exhaust, NST pulley and AEM intake.

[jdium]

2hp is probably not feelable, if that's a word, unless you have a really sensative ass I'm guessing it's a placebo effect type of thing, you expect to feel more power, thus you do...

[Astroman]

Originally Posted by jdium

2hp is probably not feelable, if that's a word, unless you have a really sensative ass I'm guessing it's a placebo effect type of thing, you expect to feel more power, thus you do...

Well, I did manage a 17.356 quarter mile time, about a half sec quicker than stock.