How much power with a 2.5inch downpipe?
10-20-2003, 09:41 PM
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How much power with a 2.5inch downpipe?
Just out of curiousity, I was wondering how much power people are getting out of their setups with 2.5 inch downpipes? The most I've seen is 370whp. I've had bigger motors, bigger turbos and everything else, all end up around 350-370whp no matter the boost or turbo size. Is it purely coincidence? Anyone cracked the 400whp barrier with a 2.5 inch downpipe on pump gas?
10-20-2003, 09:44 PM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
turbotegb18c (Paul) made 45Xwhp w/ a 2.5" downpipe, and 2.75" full exhaust w/ SC61 at about 25psi. the 2.5" downpipe is actually covering part of the SC61 exhaust wheel and it still pulled off sick #'s. not pump gas though. on pump i think he made 360ish @ about 1bar. paul?
10-21-2003, 07:57 AM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
I believe...well I know i could have made more power if i had a 3in downpipe. i can't think of too many with a 2.5dp and made over 400whp with pump gas.
10-21-2003, 08:35 AM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
i currently have a 2.5,should i upgrade,my plans are for 350 hp or so.using a t3 on a built LS motor,the rest of the exhaust will be 3 inch soon.is it worth it to do the 3 inch dp also?
10-21-2003, 08:47 AM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
I guess if you run an external wastegate with a dump tube, you'll make more power than a internally gated turbo. It all depends how much exhaust the turbo dumps out and how fast the 2.5" dp is filling up.
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10-21-2003, 01:53 PM
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Re: How much power with a 2.5inch downpipe? (civictypenos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civictypenos »</TD></TR><TR><TD CLASS="quote">i currently have a 2.5,should i upgrade,my plans are for 350 hp or so.using a t3 on a built LS motor,the rest of the exhaust will be 3 inch soon.is it worth it to do the 3 inch dp also?</TD></TR></TABLE>
if u r not worried about ground clearance or AC then you have no excuse to not go 3" all the way. 350hp is pushing it on a 2.5" downpipe but it can be done. a 2.5" downpipe to clear AC and then flared to 3" to match the exhaust is a good option for those looking to keep AC.
if u r not worried about ground clearance or AC then you have no excuse to not go 3" all the way. 350hp is pushing it on a 2.5" downpipe but it can be done. a 2.5" downpipe to clear AC and then flared to 3" to match the exhaust is a good option for those looking to keep AC.
10-21-2003, 02:45 PM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
not on pump gas but i made 522whp@26psi on a 2.5 downpipe with my 1st setup. the car made 380hp i think on pump before we switched to race gas. that was with a shitty turbonetics 62-1 too.
10-21-2003, 08:45 PM
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Re: How much power with a 2.5inch downpipe? (MotorMatrix.com)
I did an integra a couple years ago that made 450whp on 2.5" downpipe and tanabe racing medallion exhaust (2 3/8). That was at 28psi though!
10-21-2003, 10:42 PM
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Re: How much power with a 2.5inch downpipe? (tony1)
ha ha! I'm taking a stab here that it too was not on pump gas. Seems the vaunted 400whp on pump gas barrier cannot be broken on 2.5 inch exhaust.
10-22-2003, 12:11 AM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
Actually you can make any power you want on a given downpipe size. You need to look at it this way. If your exhaust manifold has exhaust pressure of say 16psi and your downpipe has an exhaust pressure of 2 psi then approximately 14 psi of flow energy went into turning the turbine. With losses it works out to about 12psi of flow on the compressor side (now all turbos are different but for the most part the comparison is right). So the secret is to reduce exhaust backpressure. However, this only relates to compressor flow and not engine output. You can easily increase horsepower and torque without even touching your turbocharger setup. Simply increase the compression ratios of the engine. I plan on running a 2.5" downpipe with a 2.5" cat.
10-22-2003, 05:52 AM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VaporTrail »</TD></TR><TR><TD CLASS="quote">ha ha! I'm taking a stab here that it too was not on pump gas. Seems the vaunted 400whp on pump gas barrier cannot be broken on 2.5 inch exhaust.</TD></TR></TABLE>
Haha, yeah, 28psi was definitely on race gas!
Haha, yeah, 28psi was definitely on race gas!
10-22-2003, 04:28 PM
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Re: How much power with a 2.5inch downpipe? (lazer)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lazer »</TD></TR><TR><TD CLASS="quote">Actually you can make any power you want on a given downpipe size. You need to look at it this way. If your exhaust manifold has exhaust pressure of say 16psi and your downpipe has an exhaust pressure of 2 psi then approximately 14 psi of flow energy went into turning the turbine. With losses it works out to about 12psi of flow on the compressor side (now all turbos are different but for the most part the comparison is right). <u>So the secret is to reduce exhaust backpressure. </u> However, this only relates to compressor flow and not engine output. You can easily increase horsepower and torque without even touching your turbocharger setup. Simply increase the compression ratios of the engine. I plan on running a 2.5" downpipe with a 2.5" cat.</TD></TR></TABLE>
this is jibberish. You will never see a condition such as 14psi manifold and 2psi exhaust - best you can hope for is a 1:1 ratio, and that's extremely difficult, if not impossile to achieve.
You even contradict yourself several times, especially the underlined section.
I'll leave it at that
this is jibberish. You will never see a condition such as 14psi manifold and 2psi exhaust - best you can hope for is a 1:1 ratio, and that's extremely difficult, if not impossile to achieve.
You even contradict yourself several times, especially the underlined section.
I'll leave it at that
10-22-2003, 06:55 PM
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Re: How much power with a 2.5inch downpipe? (VaporTrail)
Trackmaster Sport FWD civic/integra made 460hp on 2.5 inch DP if i remember correctly on 24psi. Call them up at 661-254-6055 ask for ERIC the owner.Great guy 
10-23-2003, 08:03 AM
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Re: How much power with a 2.5inch downpipe? (camp1320.com)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by camp1320.com »</TD></TR><TR><TD CLASS="quote">Trackmaster Sport FWD civic/integra made 460hp on 2.5 inch DP if i remember correctly on 24psi. Call them up at 661-254-6055 ask for ERIC the owner.Great guy </TD></TR></TABLE>
pump gas? This is the root of my question. I know more power could be made with more boost and race gas, but for pump gas power, seems like 3 inch is the only way to eclipse the 400 mark
</TD></TR></TABLE>pump gas? This is the root of my question. I know more power could be made with more boost and race gas, but for pump gas power, seems like 3 inch is the only way to eclipse the 400 mark
10-23-2003, 06:00 PM
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just wondering, the people that are pushing 400+ hp...are they running high flow cats or test pipes when they post these numbers? Reason i ask, is because i live in florida...smog/emissions is not necessary, A/C however IS... wondering if 2.5" downpipe/test pipe/tanabe catback exhaust will cut it on a b18c1/sc61 setup? will a 2.5" downpipe w/ no cat equal the performance of a 3" downpipe w/ cat?
10-23-2003, 06:41 PM
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Re: (TRUST8383)
well IMO, depends on how where turbo is sitting and clocked...
I ran a 3" d/p on my 99 Si without clearance problems...
The more st8 through flow you have the better...less restriction allows a faster spool...
on my 1.6 stock bore w/the SC61, i got boost @ 4900 full at 5400
your Tanabe is restrictive because its only 60mm (2 1/4")
2.5" is always gonna be 2.5" no matter how you look at it
I ran a 3" d/p on my 99 Si without clearance problems...
The more st8 through flow you have the better...less restriction allows a faster spool...
on my 1.6 stock bore w/the SC61, i got boost @ 4900 full at 5400
your Tanabe is restrictive because its only 60mm (2 1/4")
2.5" is always gonna be 2.5" no matter how you look at it
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