 3" downpipe power increase?, about how much? |
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 Nov 28, 2011 - 11:43 PM
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 Enthusiast  Joined Feb 1, '05 From Charlotte NC Currently Offline Reputation: 14 (100%)  |
Hi guys, Ive been wondering how much HP increase do you get when you add a 3" downpipe to your turbo setup? ive been told in the past at least 10hp, but before making a thread i decided to do some searching....
http://www.mr2oc.com/showthread.php?t=2714...horsepower+gain and now I have a headache... on our 3s its obvious that a wider diameter exhaust makes room for more power, but ABOUT how much typically? I actually read 98% of that thread, and while VERY informative, i didnt get a question answered after all the searching. anybody know the answer? cheers! --------------------  QUOTE (Galcobar @ Oct 15, 2008 - 2:44 AM)  You want power but have no money. That's a problem. Cheap. Reliable. Fast. Pick two. |
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Nov 29, 2011 - 1:39 AM
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Enthusiast Joined Jun 25, '06 From Box Elder, South Dakota Currently Offline Reputation: 2 (100%) |
I see and understand your dilemma EasternPiro....There dosent really seem to be much hard concret dyno proof, just alot of talk on how much more PSI a persons engine/turbo setup can run. But i think the general acceptance is around 10-15hp.
EDIT: Ran across this on GTfours.co.uk... QUOTE Why do I want to fit a downpipe? To improve turbo spool up time, increase output power ~15bhp/~15lbft, and to save weight ~9kg. My 205 used to have a fairly noticeable "flat spot" at approx 5500 - 6500, this has now disappeared... Are there different down pipes available? There are a few different ways to replace the catalytic converter, you can either make one or buy a downpipe. The only available ones at the time of writing are: Blitz - a replacement "top section" of the cat. Well made, fits bang on, heavy and will improve gas flow, but if your spending the money you might want to consider a full down pipe. Hyper Sports and Racing (HSR) - 2.5" pipe, but the wastegate gas path is not as free flowing as the Aussie. Fitment is also crap. I suffered a cracked pipe then a replacement had a warped flange and I had to drill EVERY hole in order to fit the damn thing, NOT recommended. Hayward and Scott - 3" good alternative to the Aussie, however this is stainless so will last longer, but will be prone to cracking more so than steel as it is fabricated from stainless, but then again it's got a lifetime warranty! An all encompassing solution for you exhaust, as you can get a full 3" system fitted at the same time Aussie 3" - superb. Good fit, can get a HPC coating as well...thoroughly recommended. Manufactured from steel, corrosion may be an issue long term...An optional extra is holes in the DP so that you can put "stuff" in there later e.g. wideband oxygen sensor KO Racing 2.5" downpipe - click here to visit their website C2 Power - quality seems fine but the closest stud to the radiator does not fit... XS power / JJ Japcars / SS Autochrome - a little early to say but these seem to be okay Also i can understand a person purpose on research, but considering there is little to say that adding a 3in downpipe is bad why not just go for it. ...also i do have some help for you. I remember there was a thread on GT4OC that actually did explain the differnce in terms of horsepower btwn a 2.5in, 3in, and 4in downpipe. Maybe you can move your search there? This post has been edited by 3WayStunna: Nov 29, 2011 - 1:51 AM -------------------- (\__/)
(='.'=) This is bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. |
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Nov 29, 2011 - 3:07 AM
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Enthusiast Joined Jul 14, '08 From Mauritius Currently Offline Reputation: 0 (0%) |
Hi. In my Opinion;
Having a bigger downpipe will just help your engine to breath easier, in other words, a better flow compared to stock. But having a 3" downpipe will just give your engine more potential to make more power later. To make more HP, an optimum use of your new downpipe, would require an aftermarket manifold and a boost controller. Because such modifications will make u face other issues like boost creep or overboost and fuel cut. You may also like to get a better turbo and if possible a standalone ecu so that you take the maximum advantage of your new modifications. Such modifs should get u, I'd say like 50-60 HP (all together)!!! But getting only the downpipe may only allow like 4-5 hp. Downpipe + manifold may get u around 12 hp. Downpipe + Manifold +decat may get u around 15-20 hp. Downpipe + manifold + decat + new turbo + ecu may get u around 50 hp. Downpipe + manifold + decat + new turbo + ecu + injectors may get u around 60-100 hp (depending on your tuning and engine capacity). You may also modify step by step like i am doing, take ur time and get the maximum of your investment in the future. But you will need to tune your boost. On my side i have bought a 3" downpipe and a manifold + decatted. But I had to tune the engine since I was reaching fuel cut and overboost on only 4500 Rpm. I am taking my time but will surely get the other modifications as soon as i get some $$$ |
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Nov 29, 2011 - 4:51 PM
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Enthusiast Joined Dec 8, '03 From Lancaster CA Currently Offline Reputation: 6 (100%) |
the larger downpipe isnt giving you more power, its allowing your turbo to work more efficiently, it will raise the boost level which raises the power
-------------------- 2001 Celica GT-S Turbo
1997 Supra TT 6speed 1997 Celica 3MZ/1MZ swap 1990 Celica All-Trac |
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Nov 29, 2011 - 8:22 PM
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 Moderator Joined Oct 1, '02 From fall river, ma Currently Offline Reputation: 13 (100%) |
There is a dyno sheet running around on mr2oc that shows a berk tech 3" vs a ko racing 2.5" dp.
The berk made more power everywhere. Can't remember the #'s. -------------------- Former Team 5SFTE pro member ;)
 13.6@108MPH, 5SFTE Powered |
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Nov 29, 2011 - 9:26 PM
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Enthusiast Joined Feb 1, '05 From Charlotte NC Currently Offline Reputation: 14 (100%) |
thanks guys! i had a feeling it would be about 10-15 hp, i just wanted to be sure. I will have a def answer once i get my car back, I remember on the stock downpipe with 3 inch (NOT mandrel bent) Exhaust i made 266whp on 15lbs. I will be using a modified 3 inch exhaust with mandrel bent 3 inch exhaust... hopefully no boost creep issues ensue
-------------------- QUOTE (Galcobar @ Oct 15, 2008 - 2:44 AM) You want power but have no money. That's a problem. Cheap. Reliable. Fast. Pick two. |
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Nov 29, 2011 - 10:19 PM
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Enthusiast Joined Jan 10, '11 From Trail BC Currently Offline Reputation: 1 (100%) |
I have a full 3" exhaust, 3" XS Power DP, and a custom Ram Air Intake System with K&N cone filter in the mouth of the bodykit where fresh air hits it straight on, and im at a place where im trying to bring my boost down! with the help and generosity of others on this site, ( 6GC
 ) just to give you an idea, I have to let off at around 5700rpms cause I will, not might......hit fuel cut..
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Nov 29, 2011 - 11:58 PM
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Enthusiast Joined Oct 18, '06 From cincinnati Currently Offline Reputation: 10 (100%) |
now we just need someone to make a 3" front pipe! like NOW!
-------------------- proud =3sgte SWAPPED= '95 Celica ST owner [calling it the GT2 or half-trac]
309,000 miles n' .... |
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Nov 30, 2011 - 1:00 AM
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Enthusiast Joined Feb 1, '05 From Charlotte NC Currently Offline Reputation: 14 (100%) |
man i swear there needs to be a like button for the comments being made! ummmm can u show me pix of that intake?
-------------------- QUOTE (Galcobar @ Oct 15, 2008 - 2:44 AM) You want power but have no money. That's a problem. Cheap. Reliable. Fast. Pick two. |
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Nov 30, 2011 - 8:13 AM
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Enthusiast Joined Jan 10, '11 From Trail BC Currently Offline Reputation: 1 (100%) |
Yeah sure, hopefully I can upload them....have troubles for some reason, if I can't, I will post I'n my profile pics, that I know works, will let you know on this post....
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Dec 13, 2011 - 10:01 AM
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Enthusiast Joined Dec 3, '08 From Summerville, SC Currently Offline Reputation: 0 (0%) |
Allow me to shed some light on this. Prior to finding out that Matt's engine had a bad head gasket, and then in turn needed OS pistons, the engine held 18psi perfectly with no boost creep. VERY VERY strong pulls all the way through the RPM band, even though 1st, 2nd and initial part of 3rd gear are utterly pointless. (Matt, you need wider tires, 225s ain't cuttin it
 ) We are controlling the boost via an AEM Tru-Boost gauge/controller. Also, Matt's exhaust is 3" downpipe to 3"...um...."where-the-cat-should-be" back system. Very free flowing exhaust. With that itty bitty stock turbo that's currently on the engine, there was no surging, or boost creeping like you see on a 1JZ or 2JZ with a full 3" exhaust. With Matt's car properly tuned, and with the water meth, we should see 285-295whp at a "reasonable" amount of boost. -Cam -------------------- www.tweakdperformance.com
sales@tweakdperformance.com |
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Dec 13, 2011 - 12:10 PM
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Enthusiast Joined Oct 18, '06 From cincinnati Currently Offline Reputation: 10 (100%) |
SO does Tweak'd Performance have any interest in making us all a 3" front pipe? to get all of us 3s swappers from downpipe and past the necessary flex? under oil pan, and over subframe section? I think it would be genius!
-------------------- proud =3sgte SWAPPED= '95 Celica ST owner [calling it the GT2 or half-trac]
309,000 miles n' .... |
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Dec 14, 2011 - 8:31 AM
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Enthusiast Joined Jan 19, '11 From Paraguay, Winchestertonfieldville Currently Offline Reputation: 1 (100%) |
that section of downpipe...that goes down twists up and back down from the subframe is a real pain in the !$*(&!@$( to fab...took the exhaust shop like 3 hours just to make that part...to the flex pipe
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Jan 19, 2012 - 7:58 AM
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Enthusiast Joined Sep 9, '08 From Jamaica Currently Offline Reputation: 1 (100%) |
hey guys, these people made mine and i love it to death, its not on their site but if you contact em (email or call) and tell em 3S-GTE front pipe (and decribe it however u like) they will do an amazing job...i forgot how much i paid but i guarantee they have the design and stuff. I connected mine to a c-one 3"exhaust system (no longer made i think) but it lines up perfectly and everything.
http://www.haywardandscott.com/ here is a pic of it....(the shiny set is theirs and fuddy looking one is stock.....front pipe specifically is on the right)  and another pic 
This post has been edited by Island_Racer: Jan 19, 2012 - 8:06 AM |
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Mar 28, 2012 - 10:40 PM
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 Enthusiast Joined Feb 11, '08 From Auckland, New Zealand Currently Offline Reputation: 0 (0%) |
Most GT4s ex-japan are fitted with 3" aftermarket systems from the mid section back to the tail, as mine was, the standard portion of exhaust with the flexi and mini resonator tube tappers down to 2 1/8 inches, which i had the entire lot replaced with a 3" system from the back of the turbo through to the tail and it barely made a difference on the stock turbo, pound for pound it was a little faster to spool up, acceleration was a little bit better, car weighed a little bit lighter, etc....
in itself not so much gain, a full 3" system is just good preparation for when you get a big turbo, and in that case your better off going 3" cat-back and only getting the 1 downpipe made the day you do upgrade turbo & manifold -------------------- Mike W
1996 Toyota Celica ST205 GT-FOUR GT2860RS turbine, TiAL mvr44, JE 86.5φ piston, Clutchmasters FX400, APEX P-FC 269awhp / 273ft-lbs |
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Mar 28, 2012 - 10:43 PM
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Enthusiast Joined Feb 11, '08 From Auckland, New Zealand Currently Offline Reputation: 0 (0%) |
I must say, the engine roars alot louder with a 3 downpipe & 3 full exhaust
 -- on boost you hear the separate tone of the motor as the wastegates open up with the downpipe
This post has been edited by delusionz: Mar 28, 2012 - 10:55 PM -------------------- Mike W
1996 Toyota Celica ST205 GT-FOUR GT2860RS turbine, TiAL mvr44, JE 86.5φ piston, Clutchmasters FX400, APEX P-FC 269awhp / 273ft-lbs |
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Mar 29, 2012 - 2:10 AM
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Enthusiast Joined Dec 16, '11 From The Netherlands Currently Offline Reputation: 5 (100%) |
hmm on my old car, gen2 3SGTE RC...a 3'' ebay downpipe and a custom made 3'' exhaust made a huge different. with the stock ct26 turbo i got 250bhp. when i changed to the ct20 turbo (gen3 turbo) and the boost was increased i managed to get 320bhp...and that was with the gen3 turbo and the basic BPU.
so i think with the st205 with a BPU (3''dp , 3''exhaust, intake, 1.0bar boost) you should get near 300bhp or even more. |
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Mar 29, 2012 - 3:27 AM
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 Enthusiast Joined Nov 24, '07 From Tucson, Az Currently Offline Reputation: 2 (100%) |
I haven't dyno'ed my car yet, but it is interesting that I could have a 15-20HP gain with my set up. just running a berk 3" downpipe, 3" full exhaust with no cat and a Magnaflow at the end.
I don't know how I pass emissions with an OBD2 check but *shrug* just glad I do. Kevin |
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Mar 29, 2012 - 4:22 AM
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Enthusiast Joined Feb 11, '08 From Auckland, New Zealand Currently Offline Reputation: 0 (0%) |
hmm... 300+ is quite wishful, i think those levels are above fuel cut level with some kind of water injection safeguard,
http://www.youtube.com/watch?v=EuAdAhXlH98...e=plpp_play_all these guys are struggling to push past 250 hp atw which in itself is an increase probably max boost 17psi before cut since factory is just 250 at the engine -------------------- Mike W
1996 Toyota Celica ST205 GT-FOUR GT2860RS turbine, TiAL mvr44, JE 86.5φ piston, Clutchmasters FX400, APEX P-FC 269awhp / 273ft-lbs |
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Mar 29, 2012 - 3:13 PM
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 Enthusiast Joined Apr 17, '06 From New Jersey Currently Offline Reputation: 105 (100%) |
250AWHP at 17 psi is not the same as 17 psi on a Front wheel HP, the drivetrain loss is a big factor here, 3rd gen 3s make right around 300 HP at 18 psi ( 2WD )
This post has been edited by Culpable04: Mar 29, 2012 - 3:16 PM --------------------  |
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