Exhaust HP Gains
 

After seeing all the different vids on what the various exhausts sound like I'd like to see some HP numbers after the mods. Anybody seen any numbers yet??

Nobody is going to post those yet, not until their products are finalized. Even then the numbers will be scrutinized to death and in the end we wont know which we can believe.

Personally I'll be waiting for independent testing results.

Fujitsubo has some power and torque figures:

http://www.fujitsubo.co.jp/prods/det...04740/00001473

Plus a bazillion.

yeah you can never trust the companies themselves.... and also what conditions the tests were done. I just cant wait until some board members starts getting fitted with custom exhausts like scooby! Anything really lol. :D

not nearly as much as you would hope. most small n/a motors are pointless to do bolton mods for power (there are a few exceptions i will admit, but not many). either gotta go big or just play around.

Sad but true

Cat back exhaust will do nearly nothing for power. They're purely for sound/looks and maybe weight if designed properly.

Headers will be where any exhaust gains are found.

what he said~! Just go straight pipes to save weight :) unless your ears are sensitive :party0030:

Don't say that too loud, or the K20 guys are going to come over here and start getting cranky....

Everyone should spend a little time on the K20 forums and see what these guys are getting. These guys make 70 Wheel HP over stock like its going out of style. Key to all these mods is going to be tuning.

Right now the only header kit I've seen is the HKS, and no results are available yet.

:word: The K20 responds great to even just bolt ons. Now I dont expect this car to be as responsive, but we cant just assume it will get nothing

I think the gains will be somewhere between the K20 and F20/F22.

And you're right, tuning is going to be a huge factor.

The K20's head ports are HUGE right out of the box, and they flow really well. That why they can make so much power. I REALLY want someone to flowbench the FA20 heads.

It does respond good. The few catback only results I found for the K20 show about the same HP as our catback made on the BRZ. So one could say the BRZ should really take to the same kind of easy bolt on gains.

If we could only do some tuning now!

Cosworth has one of these engines and according to them, there is lots of potential for this engine.

The Toyota Rep for TRD said it suppose to get 9 HP from the intake and 4 hp from the exhaust with their products. It might be conservative numbers for the exhaust since they have noise pollution they have to control. Also I talk to their product manager at Toyota Corporate during the first 86 event and he said the motor very untap because they would have to change other things in the car and at the end drive up the cost of the car. I don't expect K20 HP gains from bolt on but I do expect to see a good amount. I want to see 200whp with I/H/E chip and some few other bolt on, but I might just be dreaming.

Well, from their testing, that torque dip was most likely due to excessive back pressure in the exhaust system for emission purposes. I just knew that had to be the reason for the dip based on the RPM range. Cat back exhaust with a minor tune will be the first thing I do to this car.

Thats untuned and pretty sure the exhaust is an axle back, which means negligible gains if any.

The TRD exhaust has gotta be a cat-back because the OEM pipe before the muffler isn't like this:

O_o

I can sleep worry free now.

^^^What he said. :D

Headers on a N/A will be the biggest again for hard parts (except for forced induction options down the road). I don't think there will be much gained on a BRZ/FRS though from the looks of the factory header. I'd be surprised if the entire exhaust gain more than 15whp.

Good catch! :thumbsup:

It' very difficult for just the exhaust to get you 15 whp..maybe at the crank.

I really can't wait to have the car here.

As there's a massive amount of cat and axle-back system being lunched I think we need to concentrate on headers and cats, and they need to be compatible with the stock catback, and all the aftermarket catbacks with it.

Personally I think its there for two different power bands. The first power band is the normal driving type band where you are running from idle to just over 3000 and shifting. I think they reduced the TQ after 3000 is to help fuel economy for normal driving. Then you have the upper power band that perfectly plays into redline-ish shifting. As long as you are shifting at 7000, you won't hit that TQ dip. Very interesting way to help out emissions if you ask me.

*pinch* I'd be impressed by 175rwhp.

Losing weight(Ti) might be the better benefit over the actual power gained from an exhaust... and the sound. :burnrubber:

Is there a chance to gain 30hp with a full straight pipe exhause, deleting all the cat's? And adding a mushroom filter to.

In short, no.

This. We won't know till we start getting independent stats and even then you have to filter through some. Through my time of forums, some shops aren't 100% unbiased

It's also hard to find shops with reliable dynos. I hope this forum doesn't get on the dynojet bandwagon.

Couldn't agree many recipients with both statements. Very excited to see personal projects get dyno. And not on a dynojet lol. Have u guys seen the new aem drive shaft dyno:happy0180:

That is a valid notation however the FTP and RMC cycles to which are used for EPA/CARB work don't work like that. I do however think you are right in them focusing on torque in usable areas.

N/A motors will never get 30whp, you will be lucky to get 15whp with a full exhaust setup.

I find it hard to believe no one has been able to dyno a TRD US style exhaust.

The problem with just basic bolt-on's is that these engines are already so efficient! I'm afraid that direct injection will just amplify that fact. However, if Toyota/Subaru were conservative with the intake/exhaust/head flow, this motor could be a beast with head work! Cosworth head + HKS SC + intake + full exhaust = 300whp? Subtract the SC and you have 250whp maybe? With no weight gain!

Hey guys, for those wanting massive gains on a better flowing exhaust. Prepared to get disappointed. You wont see those 15whp+ gains.

However what I have seen personally is a upwards of a 7whp gain. on a axleback 2.5inch system with no cat. not impressive right? well what you dont see is how much smoother the powerband is especially in attempting to cure the mid range tq loss. which really changes the character of the car. Im scheduled on doing some vids and reviews tomorrow with the nameless exhaust prototype.

Also, for those not familiar with N/A boxers. Much of the important gains can be made at the headers when talking about EJ251-EJ254 and EJ20D-EJ204. This may also be a similar case with the FA20, especially with a restrictive pre-cat and collector before the overpipe. So far i have no personally seen aftermarket header work yet...(not until the end of the month) so im sure Perrin or someone similar will get one working soon.

One big issue that we are encountering is the ECU factory tuning not being kind and compatible to the larger aftermarket exhaust. With its continuous adjustments limiting the power.

Im predicting a 11-14whp gain and 7-9tq gain and a much smoother and direct powerband on Equal Length Headers, and a straight through 2.5-2.75 exhaust.

I agree we really need to see an ecu tuning solution before we can see real gains out of "flow"type upgrades. I would be happy with seeing10 hp from an exhaust upgrade on a NA car. :happy0180:

word...from what Ive been hearing lately elsewhere, these ECUs are a bit tricky, reminds me of the Mopar ecus

I also agree that real power gain from exhaust upgrades lies in the header. With those auxillary ECUs controlling direct injection port, tuners surely have some large homework to do...

I should be getting my APEX-i one soon... Will take to the dyno and the track soon after, both appointments before end of June. :D