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TUNED 3" Exhaust Vs Untuned 3"

29K views 99 replies 43 participants last post by  neonxiii 
#1 ·
Here is the final dyno session for my 3" Exhaust (blake you can add this to your exhaust theory article)



Tuned 2.5" Vs Tuned 3"


Untuned 3" Vs Tuned 3"

I was amazed when i laid the 2 graphs on top of each other from 2.5" to 3" Both Tuned
 
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#4 ·
this is a crush bent setup yes, I will try to get sound clips soon.

It has a summit racing 18" resonator and vibrant flat black 3" in and 3" out muffler
 
#8 ·
Finally, we're learning something!!!

I've said this since I had my setup, it WORKS!

Stock headers arent bad either on it, i hit 163wtq stock header and 3" exhaust.

okay.. i just wanna clear things up.. cause ive seen 2 of these threads now.. and still a little confused.. :-?

Did we just prove that... on a stock motor!! a 3" Cat-back produces more power than a 2.5" cat-back??
 
#29 · (Edited)
http://www.youtube.com/watch?v=hGmO83fzAaM

Fully-built NA.

3" all-motor exhaust. 300whp, 13:5:1 compression, stroked h22a, 9,500RPM screamer, RMF Drag Header, 2.5"3" megaphone, 3" QTP Cut-out, 3" Mandrel bends, Greddy Evo 1 Canister. NO Cat, NO Resanators
 
#30 ·
I have the apexi ws2 exhaust right now, would it be an incredibly loud change if i cut it all out and made all the piping 3" and just kept the apexi ws2 muffler on?
 
#40 ·
Exhausts

Well you really need to be running mandrel bent piping otherwise a 3" pipe is more like a 2.75" pipe a 2.5" pipe more like 2.25" pipe not to mention killing the air speed velocity from constantly being shunted from large bore pipe to tight bend and back continuously till it exits.

A well designed and professionally made 2" mandrel is good for upto 220bhp, a 2.25" upto 250bhp 2.5" exhaust will be good for upto 280bhp and still give excellent torque as it won't be killing the velocity of the exhaust gas out, now what i would like to see is a dyno of a mildly tuned up engine with both types of exhaust a pro made 2.5" mandrel versus 3" from local shop and then a pro made 3" on top, maybe with all the crazy mods under the sun including longer stroke and bigger bore to make 2.4l, and ITB's with headwork and larger valves a well made 3" might see some gains in Hp but i would expect to see torque to not gain as much, in this scenario a 3" mandrel bent system may help but i still think that a 2.5" mandrel bent system thats well made will still be more than enough for most people while not effecting torque curve so much.
Also specs of the camshafts really effect the size of the piping and lenght of the primaries and secondaries so if you plan on some substanstial cams you need to go custom header and system which you tune to those cams, means a lot of dyno work and lot of cutting and welding but thats how you would maximise those two mods. So really you need to leave your exhaust till last and have everything in place before hand this is the most expensive route but will gain you the most at the end of the day. Don't you guys have any proper race exhaust specialists around??? In the U.K. we have plenty of choice none too cheap but if you gain an extra 5-10bhp then the extra $1000 is acutally well spent!!
 
#55 ·
Well you really need to be running mandrel bent piping otherwise a 3" pipe is more like a 2.75" pipe a 2.5" pipe more like 2.25" pipe not to mention killing the air speed velocity from constantly being shunted from large bore pipe to tight bend and back continuously till it exits.
the 2.25 i took off was mandrel skunk2. So theoretically it should be very close to my supposed 2.75 inch bends and it still out proforms it by a maximum of 12whp and 8lb-ft, as well as making more power at virtually every rpm where you would need it while beating the piss out of it.

Tuned and Untuned means, i put the exhaust on and didnt adjust the airfuel ratios nor the timing, did a dyno pull, then turned around and adjusted the air fuels and ignition timing till i got my peak numbers and packed it up.

I Dyno for free, and i tune all my own cars so it didnt cost me a penny but a couple hours of my time and my equipment
 
#42 ·
this is my idea...what do you guys think. i want a 3" all the way back and want it to be the LEAST restrictive as possible. Well as we all know our header is a 4-2-2-1 design. where the Y is, figure out about where 3" is gonna be and cut it there. then get a 3" flex pipe. you may have to make the one end on the flex pipe oval just a tad...just enough to butt up nicely to the downpipe of the header where the Y was cut. then from the other end of the flex pipe, go 3" (no resonator no nothing, just nice flowing 3") all the way back to a muffler. I know a muffler is a restriction but just so it's not SOO loud find a muffler that is actually 3" all the way through...enough to muffle but still wouldn't create hardly any backpressure...think that would work? I think it would. this is kinda what i'm thinking:
http://img.photobucket.com/albums/v2...nchexhaust.jpg

edit: hmm...where would the o2 sensors go:S
 
#45 · (Edited)
sorry for the DP


no......i dont mean double penetration either....head out the gutter
 
#46 ·
i wouldnt mind seeing some more vids of a full n/a 3" piping. i have mines sitting in the living room right now and wanted to make sure it doesnt sound all riced out. im not spooling just yet, and i know its gonna sound sick when i do, but in the meantime, i dont wanna be ricey.

btw....its a cat back, should i get rid of the cat alltogether.....or would it do more harm than good?

talking about gains and noise level...thanks
 
#54 ·
Dude I am trying my ass off. This is SO ridiculous how complicated it is to get a damn mini DV video off a camera to a computer.

Pinnacle wont recognize it there, so thats out.

MS movie maker requires a extra output for sound, and when I do that it doesn't always sync right plus it sounds shitty.

Still trying to figure this out.
 
#56 ·
exhaust

I take it thats a crush bent 2.75" might be worth considering a 2.75" or 3" mandrel bent system you may get more with a bit more tinkering and some additional mods. Is this just stock engine with bolt ons or have you done any other work to the engine? What header are you using?
 
#58 ·
Any videos up of another 5th Gen with a 3 in' on? I've come to the realization that with the h22 you need to tune it for it to reach it's potential, not just throw bolt ons and up the exhaust diameter.
98vtec, don't be surprised if you get a PM from me about tuning. I think I have your one wiki site saved.
 
#59 ·
i've limited the amount of appointments that i make because summer school starts monday and i'll be doing that to late august. But PM me and maybe we can set something up.

I'll be getting my car back sometime this coming week from the paint shop and my 3" is going on the car soon after I get it.
 
#61 ·
engine tuning

You can't expect to throw a load of bolt on's and expect it to give you instant power the ECU's aren't quite clever enough to sort it all out, the increase in flow in and out the engine needs to be recalculated and the ECU mapped to take advantage of the new increase in flow. This is the only way to do this properly not doing so in some extreme conditions actually leans out the engine too much and can result in shortened life span of the engine internals.

Trouble with stock ECU is it's not easily tuned and has to be re-programmed on a dyno having an aftermarket system or an easy way of modding the stock one with a mappable ECU via PDA or Laptop system or even onboard computer is much more easier and can be tuned at the dragstrip which to be honest is better than rolling road as it's real world. You just need to pinch yourself a computer car geek who knows what he's doing off!!!
 
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