GokuSSJ4

went would you need to upgrade from a 2.5 to a 3" piping and exhaust
how much hp do you need to make to have best gains with a 3' set up and not have an over kill ...

eg_type_r93

2.5 is sufficant enough enless your making 4 -5 hundred hp thats my guess

00 FBP ItR

i would think around ~300+ whp.

kungfuSiR

iTrader: (1)

backpressure doesn't make horsepower, most people would agree that all motor cars can make great use of a 3" exhaust, i'd say around 200+ at the wheels, and you'll make good use of a nice mandrel bent 3" exhaust

Mr Hammond

When you actually have positive intake manifold pressure.

evilxkid

bump, i'd love to hear more on this.

on a big stoke, high compresion, 2.0+ ltr motor with high exhaust velocity would a 3" pipe keep up the velocity?

GokuSSJ4

or even if the 2.0l would get stroke to a 2.2l
but can a 2.0l benefit from it ??

Unsung

I usually recommend 3" when you're in the low 200's.

TrboInteg

This is a great question and a few people gave there opinions. But, who is actually running a 3 inch exhaust(on a N/A car)? Wouldn't a 2.75 inch exhaust be the next logical step up from a 2.5 setup? So, if a 2.5 inch exhaust is good up to about 200whp, then 2.75 should be better for 200-230whp. And then, maybe, run a 3 inch for a car making over 230whp. Does that make since to anybody else? Or, should we even use a peak whp number to determine what size exhaust we should run?

jwaked

Back pressure does not make HP but does help with torque. 3" is too much for an all motor unless you have tons of compression and over 300 HP. You might gain some HP in the top end but you will loose alot more torque in low RPMs that you will actually be slower. If you want to make your car faster, look for upgrades that help the entire power band and not just a bit of top end sacrifying lots of low end.
Jay

TrboInteg

That is why I'm starting to think a 2.75 inch exhaust might be a better choice then the 3 inch. It'll give you better top end then the a 2.5, and possibly won't disrupt the velocity of the air in the low end. Just some food for thought.

WAFFLES

Why do you guys think Header Tech recommends 3" exhaust with their headers? They have found that it makes more power. But then again, what do they know? They are only in the business of making badass headers that actually make power.

Unsung

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WAFFLES &raquo;</TD></TR><TR><TD CLASS="quote">Why do you guys think Header Tech recommends 3" exhaust with their headers? They have found that it makes more power. But then again, what do they know? They are only in the business of making badass headers that actually make power.</TD></TR></TABLE>

Exactly. Too many people playing the guessing game in this thread.

speedyonez

hmm.... i got 2.5 on mine after i dyno it.. i might try 3" and see if it makes any difference..

SMSP

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jwaked &raquo;</TD></TR><TR><TD CLASS="quote">Back pressure does not make HP but does help with torque. </TD></TR></TABLE>

HP = (Torque x RPM)/5252, so if you have more torque down low you also have more HP at a given rpm.

You need torque to make HP or you need revs. Back pressure is a myth, if it helps at all something else in the combination is wrong.

SMSP

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WAFFLES &raquo;</TD></TR><TR><TD CLASS="quote">Why do you guys think Header Tech recommends 3" exhaust with their headers? </TD></TR></TABLE>

Probably because no one makes a 2-3/4" exhaust. I have 2-1/2" systems supporting 230+ whp and there was less than 1 whp difference from running an open header.

I'll be debuting a 2-3/4" cat back system on my H1 Honda Challenge car and plan to run a full exhaust in the races. I'll then bring the system to market for the 2l cars.

evilxkid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jwaked &raquo;</TD></TR><TR><TD CLASS="quote">Back pressure does not make HP but does help with torque. </TD></TR></TABLE>

back preshure dosn't make torque, smaller pipes have greater velocity at lower rps thats all.

i don't think people people run 2 3/4 because it's hard to find 2 3/4 exhaust piping, manderal bends, and i have never seen a 2 3/4 inlet muffler.

SMSP

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by evilxkid &raquo;</TD></TR><TR><TD CLASS="quote">i don't think people people run 2 3/4 because it's hard to find 2 3/4 exhaust piping, manderal bends, and i have never seen a 2 3/4 inlet muffler.</TD></TR></TABLE>

Not anymore

evilxkid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">Not anymore </TD></TR></TABLE>

your a good man!

but i don't think i can afford you price's.

will you sell 2 3/4 strait pipe and u'bends? if so i'll probloly have to pick some up.

SMSP

Hopefully I can keep it priced between a 2-1/2" T1R and the 60mm Mugen.

WAFFLES

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">

Probably because no one makes a 2-3/4" exhaust. I have 2-1/2" systems supporting 230+ whp and there was less than 1 whp difference from running an open header.

I'll be debuting a 2-3/4" cat back system on my H1 Honda Challenge car and plan to run a full exhaust in the races. I'll then bring the system to market for the 2l cars.</TD></TR></TABLE>

True. Also, Header Tech recommends 3" exhaust with their headers. I'm sure your headers would only need the 2.5 because yours are custom and a better design. But I'm no engineer or fabricator, so I guess I should be quiet about things that I'm not 100% on. In this case, I'm just trying to fully understand the whole spectrum of different exhaust/header combos.

TodaSi

3" exhaust will benefit a 185+ whp VTEC Honda.

Tested on a 98 ITR with bolt-ons, stock cams. No losses in power across the board.

2 3/4 would be very nice Dave

real9999

Tony Leung (Tony the Tiger) is running a 3" Thermal on his 14:1 CR beast. Seems to work pretty well for him.

--
Tom

ultrab20

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TrboInteg &raquo;</TD></TR><TR><TD CLASS="quote">This is a great question and a few people gave there opinions. But, who is actually running a 3 inch exhaust(on a N/A car)? Wouldn't a 2.75 inch exhaust be the next logical step up from a 2.5 setup? So, if a 2.5 inch exhaust is good up to about 200whp, then 2.75 should be better for 200-230whp. And then, maybe, run a 3 inch for a car making over 230whp. Does that make since to anybody else? Or, should we even use a peak whp number to determine what size exhaust we should run?</TD></TR></TABLE>
i had 2.5" on my B20VTEC and gained about 6-10 hp all the way through the power band when i put 3" mandrel (under the axle on my del sol) i think i only lost about 2-3 ft-lb , butwhen your putting down 160+ its ok....it raised me up to 210whp

K20 EG

loww 200's N/a ??

interesting