exactly. I did a cast stainless bellmouth downpipe with hi-flow cat....3" tapering down to 2.5" to mate with the stock 2.5" exhaust and 260ish at the wheels (awd car). 50% bigger motor and turbo to boot compared to the R56. There's no way a 3" CBE on a stock DP makes any sense.

 

LOL
there is no reason to go bigger then 2.5 on a 4cyl motor.
I have a 71 chevelle that im restoring for a guy that has a 502 crate motor with 506 H.P. and 560 ft. lbs. tourque. He is running a 3" exhaust.

 

actually, this is not true. we did a Deadbolt Superzilla 55 on a built EJ257 with 10.5:1 compression and meth injection. The boost had to be tapered above 5krpm as the 3" was choking it (still put down 440ish). Swapping to a 4" should let the setup make well into the 500's on pump and touch 600 on race gas. That said, this car is also running a Hydra standalone ECU and has more money in the engine than most R56 owners will ever do in mods.

we have another '04 STI to be built with a full Cosworth longblock, Tilton clutch, APS turbo, EWG and FMIC. The motor will spin to 10500rpm safely and handle 800whp. You'd better believe it's getting a 4" APS downpipe.

 

If you can compare an N/A setup with a turbo setup dont work the same. Like i said, an eclipse use to put down 400whp with a 2.5", if you where to have put a 3" im sure it would have made more power.

Oh yeah, my caliber srt4 exhaust STOCK is 3" and comes with 285hp out the box.

 

It does if your into bragging rights and for sure it does if your into sound which 99.9% of people are into sound vs performance. For power not really.

Every forum i post pix of a new exhaust, the second thread is usually yup, you guessed it "how doe sit sound?"

Then a few posts later i ge tthe butt dyno question. lol

 

Well, since you brought it up.
Would there be an appreciable difference in tone between a 3" and a 2.5" CBE?
I'm moving on from an Integra (Apexi WS) and I REALLY don't want to have high pitched fart can for the next 10 years.

That said, will either rumble enough to massage the butt dyno.

 

So is someone making the argument that a 2.5" DP mated to a 2.5" exhaust will produce LESS power overall than a 3"/2.5" combo?

And why did hector say we want more power in the high end? I don't know about you guys, but I rarely push my car over 4K rpm unless im in a racey mood. I want my power way down low so I can feel it off the line. Am I crazy?

 

that remains to be seen, but, the tuner you spoke with is advocating a stock DP and 3" exhaust right?

 

Not quite. He says 2.5" all the way through is the single best option for our car. He is quite adamant that 3" is not only unnecessary but will actually cause NEGATIVE power effects.

 

if you want your power way down low a 4 cyl is not the rite choice. They make power in the mid to upper RPM's by design. So if you want more power its going to bennefit in the mid to upper, not the lower.

 

Not this motor

 

what do ya mean?
all 4 cyl have the most power in the mid to upper. You can add to the bottom, but youll always have more in the upper.
Unlike a straight 6 where torque is real low.

 

In the R56 all the power is way down low...
I could show you on a dyno, but mine loses torque from 4300rpm onwards.... But I have 269lb-ft torque at 4300 and around 220 at 1900rpm, whereas at 6000rpm Im down to about 170lb-ft
The r56t is designed for low down power

 

4300 is considered mid range.
1800 -3K is considered Low end.

you also have to remember that if you were to follow you hp curve it would show more power in the hi rpm not the low

 

on the stock turbo, I'd agree with that based on my previous experience with larger 2.0L motors working better with 2.5" over 3"

 

Give me half an hour... I'll scan in my graph
My peak hp is at 4500rpm :s

Totally different engine than the 53

 

im not denying that.
Im saying that 4300 is mid range not low range.

 

 

Officially the craziest dyno image I've ever seen.

 

I'm going to make a really general assumption and say I doubt there are very many other motors that make their torque/power down low as the R56 motor does. Aside from Turbo-Diesels, and other advanced turbo cars (ie 997 Turbo).

Your statement applies very well to the R53 motor, but not so much the new Prince R56 motor. This motor does nothing up top. Something that a bigger turbo should solve though .

I rarely find myself reving above 5.5k, because there really just is no need to. Whereas in my R53 I'd love to rev it out up to my 7250 redline!

 

- drives well tho lol

 

Amen brother, I cant even begin to explain how many times I have to say this .

Jack

 

The great thing bout a turbo setup vs an N/A is that the turbo kills alot of that buzzing rice noise your use to hearing.

 

Well tomorrow I should have my catback setup ready to be jigged. Ill have on my site multiple options. 2.5 into 2.5, 2.5 into 3", 3" into 2.5", 4" into 2.5" what ever you want ill bang it out for you.

Ill be like Nicolas Cage in the movie Lord of ware, ill just support both camps.

 

k, slim chance of fart can sounds with either one. that's very good to hear, cause i dont want to be one of THOSE cars.

So, now i wonder if i should just do a 2.5" instead of a 3" CBE, i doubt i'll swap the turbo at any point in the foreseeable future (lets say 5 yrs). If anything, the 3" DP to 2.5" CBE seems like the way to go, assuming i can pass visual and CARB sniffer once the time comes.