iiilgsrlll

I know a number of people have argued in the past that test pipes don't do crap for your car and all we're doing is screwing up the environment. I have always contested that a test pipe is the best bang for your buck on a turbo car but didn't have dyno numbers to prove it. Well now I do.

These are dyno charts that were done today at Church Automotive. The green line is the first run with the stock cat. The red line is today's run. Notice the gain of almost 30hp with no other modifications to the car other than replacing the stock cat with a test pipe which cost all of $60. The boost was slightly higher by 1 psi but that should not have affected power that much.



*Wideband was placed in the tailpipe. Reading is about 0.8 leaner than actual.





Modified by iiilgsrlll at 3:46 PM 9/18/2004


Modified by iiilgsrlll at 10:41 AM 9/20/2004

SSBPGSR

i hope my autozone test pipe made me that much HP! all i did was cut the cat off, and clamp on a 2.5 straight pipe in place of the cat. test pipe!? SURE!

Mr. Softee

you made more power because you ran more boost-- what a surprise.

boostincoupe

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94goldjungsr &raquo;</TD></TR><TR><TD CLASS="quote">you made more power because you ran more boost-- what a surprise.</TD></TR></TABLE>

Yeah, even 1 psi makes a difference, whether you want to admit it or not.

ComputerJLT

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

Yeah, even 1 psi makes a difference, whether you want to admit it or not.</TD></TR></TABLE>

not 30hp worth.......
cats are crap; ditch them

Ri5e

Slightly higher than 1 psi eh? You should've decreased the PSI so that it's at the same PSI that you were before putting on the test pipe. Then dyno it and see

95GSRTT

Ive seen plenty of dyno's where they made 25-30 whp with 1 extra pound of boost. Some engines and turbos do better at some lbs of boost, others dont.

danl

30 hp per psi boost WHATEVER.

Going from a stock cat to a high flow one is a big difference. Going from a cat to a straight pipe is another pretty big difference. The extra pound of boost is probably due to creep. With less restriction to exhasut flow with the test pipe the car makes more power and then creeps.

Now its nice to run a cat on the street, no need to be a mass polluter when its your daily driver. On a racecar though, ditch it. Or, for a street car get an electric cutout.

DSF

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danl &raquo;</TD></TR><TR><TD CLASS="quote">30 hp per psi boost WHATEVER.

Going from a stock cat to a high flow one is a big difference. Going from a cat to a straight pipe is another pretty big difference. The extra pound of boost is probably due to creep. With less restriction to exhasut flow with the test pipe the car makes more power and then creeps.

Now its nice to run a cat on the street, no need to be a mass polluter when its your daily driver. On a racecar though, ditch it. Or, for a street car get an electric cutout.</TD></TR></TABLE>

Yeah. I'd actually like to see a comparison between a high flow 2.5"-3" cat vs. straight pipe. The way I see it is that most of our turbo B series rides make on average 10-20hp per psi. So, take the middle of 15hp. Given equal boost pressures between tests, that makes this comparison a 15hp difference between a stock 1.x" cat and an unknown diameter testpipe. Even if a high flow cat makes zero gains, you're only talking a 1psi of boost difference in power. Not worth it for a street car in my book. I feel that not only can imports make power more efficiently as compared to "bigger" V8 domestics, they can do it cleaner as well.

...but at the track...that's a whole other ballgame

.nate

I seriously doubt he gailed 30whp from 1psi of boost. Remember turbo exhausts are all about less restrictions... and a cat is a helluva restriction. All in all it is likely that the extra lb of boost made maybe 10whp and the cat made the rest... just a guess tho...

Regardless more whp is more whp no matter how you cut it.

Nature's Renewal

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

Yeah. I'd actually like to see a comparison between a high flow 2.5"-3" cat vs. straight pipe. The way I see it is that most of our turbo B series rides make on average 10-20hp per psi. So, take the middle of 15hp. Given equal boost pressures between tests, that makes this comparison a 15hp difference between a stock 1.x" cat and an unknown diameter testpipe. Even if a high flow cat makes zero gains, you're only talking a 1psi of boost difference in power. Not worth it for a street car in my book. I feel that not only can imports make power more efficiently as compared to "bigger" V8 domestics, they can do it cleaner as well.

...but at the track...that's a whole other ballgame </TD></TR></TABLE>
Yeah, compare it with a hi-flow cat and the same amount of boost

95GSRTT

Im not saying he made 30 whp just from 1 psi, Im saying I have seen dynos where they did over a 4 psi spread. I think a test pipe vs a high flo cat nets maybe 5 whp on a good day.

iiilgsrlll

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94goldjungsr &raquo;</TD></TR><TR><TD CLASS="quote">you made more power because you ran more boost-- what a surprise.</TD></TR></TABLE>

I know that the boost is not the same but I don't think the 1 psi gained me 30hp. Whether the test pipe gained me 30hp or not the car feels a lot better overall compared with the stock cat. I've seen the flow rate numbers on a stock cat vs test pipe and the flow rate of a test pipe is almost double at something like 450 cfm vs 215 cfm (est.).

I know I should have probably done something like turn off the boost controller so the wastegate was controlling boost but we were running short on time due to a more important issue (idle surge) so I let Shawn do his thing on whatever numbers he wanted to run. Overall he was surprised himself as in his own words "Wow, the test pipe made a hell of a difference."

In any case, I know I'll be up there again sooner or later once I get the new MAP sensor and on the first run I'll have him turn off the boost controller for you guys so that there are no variations in boost.

Muckman

iTrader: (2)

Of course it makes more power. what a stupid thread. hah jk

bonestockls

Very ironic that I found this topic, I did some exhaust work on a customers conversion van today. He was low on power, had recently replaced the fuel filter, no cels, van otherwise running well. As we both suspected his cat was partially plugged. We did what we had to do to remedy that situation ( lets just say its high flow now) and he happened to mention that his built 11.xx second GTP gained approximately 60 H.P. going from a high flow cat to straight pipe, and as he is a straight shooter and not a moron, I tend to believe him. You know what would be cool, straight turbo, no down pipe or anything, wonder how much h.p. you'd pick up from that just kidding of course.

iiilgsrlll

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">Of course it makes more power. what a stupid thread. hah jk</TD></TR></TABLE>

sly_106

I'd be more interested in a high flow cat vs. test pipe. Gee, a test pipe at 1lbs more boost makes more power than the stock on 1lbs less, amazing

sly_106

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bonestockls &raquo;</TD></TR><TR><TD CLASS="quote">You know what would be cool, straight turbo, no down pipe or anything, wonder how much h.p. you'd pick up from that just kidding of course.</TD></TR></TABLE>

shitty would be my guess... that would totally screw over the flow characteristics...

bonestockls

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sly_106 &raquo;</TD></TR><TR><TD CLASS="quote">

shitty would be my guess... that would totally screw over the flow characteristics...</TD></TR></TABLE>
You clearly don't understand sarcasm, I was kidding, hold on KIDDING understand now. Ok, now that we got that cleared up, lets talk about this further, in a rational way of course. Can you now explain to me and all the other followers of this post how it would "totally screw up the flow characteristics". That is such an arbitrary statement it is as if you have said nothing at all. Now someone help a brother out here and remind me as to which post I have dangling around in my head.... a very informative write up by an anonymous Garrett engineer abouts turbocharger systems, exhaust system designs, this that and the other, anyway, in this write up this brainiac describes various different configurations which would be both benecifial and detrimental to a turbocharged setup. Anyway, he goes on , in his roundabout engineer sort of way to say that the least amount of backpressure is the most desirable. Seems to me that no downpipe or exhaust for that matter would offer the least amount of backpressure possible. Obviously, an open downpipe, routing those nasty exhaust gases away from any critical components and out of the engine bay would be most beneficial. Now someone tell me or slick (sly_106) what the ideal "flow characteristics" of a turbocharger would be. Maybe slick (sly_106) knows something we , and Garrett, don't know.

iiilgsrlll

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95GSRTT &raquo;</TD></TR><TR><TD CLASS="quote">Ive seen plenty of dyno's where they made 25-30 whp with 1 extra pound of boost. Some engines and turbos do better at some lbs of boost, others dont. </TD></TR></TABLE>

Same here...but this is a Greddy 18g I'm using. Its not the best in terms of efficiency so 30 hp is not likely. I could understand if it was like a SC61 or something but I doubt the 18g would net 30hp from 1 psi especially with 9:1 compression pistons.

Mr. Softee

Unless you have a brand new test pipe vs. brand new cat and two charts running the same boost which are tuned within reason... in my eyes the test is pretty much useless. Obviously a new test pipe will make power over an old cat or even an old test pipe... no news there. Obviously a car running more boost will make more power... no news there. I appreciate your attempt, but if you want to say test pipes make a difference over a cat, you need a more concrete experiment / analysis.

Just my $.02

Bailhatch

yup, this could easily be a clogged cat vs. straight pipe comparo. useless from a tuning/scientific POV. The extra .7psi really throws it off too. Nice try though.

iiilgsrlll

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94goldjungsr &raquo;</TD></TR><TR><TD CLASS="quote">Unless you have a brand new test pipe vs. brand new cat and two charts running the same boost which are tuned within reason... in my eyes the test is pretty much useless. Obviously a new test pipe will make power over an old cat or even an old test pipe... no news there. Obviously a car running more boost will make more power... no news there. I appreciate your attempt, but if you want to say test pipes make a difference over a cat, you need a more concrete experiment / analysis.

Just my $.02</TD></TR></TABLE>

I wish I had a new cat to compare with the test pipe. Unfortunately I am not going to go out and spend $700 on a stock cat or a $80 Carsound cat. Let's not get too granular with our analysis as this was a broad comparison and not one meant for scientific analysis and such.

There is no doubt in my mind the test pipe made a difference but I agree with most of you that there are variations in the 2 runs and to say the entire 30hp gained from the test pipe may be inaccurate. Take it for what its worth but this is the 3rd time I have replaced the stock cat on a turbo GSR with a test pipe and driven the car before and after the fact. The results were night and day. Other people can probably attest to that also. But to each and his own.

twkdCD595

I do know it definately makes a noticeable difference in my ride, but I never have been able to test it.

b_ron007

forsho the test pipe will make more power compared to a STOCK CAT......them things have a lil over 2in diameter on the flange, if not a 2in diameter. how can u guys argue with that? more flow=more power, plain and simple.

btw.......remember......the best exhaust for a turbo would be NO EXHAUST! :D