Anyone running an exhast larger than a 3"?

[laser90]

I understand there is no need to run larger than 3" on a 14B, 16G etc. Im more curios to see what guys with larger frame turbos are doing. The guys running 50 trims, 60 trims, holsets and such. If you are running a larger diameter did you notice any difference performance wise?

 

[GRAVEDIGGER]

I think what you'll find is that you just need the larger exhaust with the big frame turbos because they flow so much more. Most people are dumping straight out the side of the car (side exit), or they are custom building their own full exhaust from scratch.

 

[1995gsx20g]

by no means am i saying it's set in stone but im pretty sure at around 600hp you run out of breath on a true 3inch all the way to the back with only a highflow muffler.

 

[laser90]

Im starting my Drag/street AWD talon project sometime after summer. Im going to be using a 60-1. This will be my first REAL project (Modding daily drivers is a bit of a hassel) I'm wanting to try somethings that I think would be pretty cool. Im building the car for ME to enjoy. So there are some things on my list that arnt neccessarily conventional or needed but It's sort of a dream build for me.

Like the 4" exahaust and I wanna rev the car to 9K and there are some other things that im looking into. Just giving you guys a little insight as to why I asked my question.

 

[1995gsx20g]

personally i would go with a 3inch all the way back even with the 60-1 but that's just me even with revving to 9k.

 

[sag1441]

4 inch is harder to tuck underneath

i dont see why anything other than drag cars with massive turbos would ever run more than 3 inches

 

[laser90]

4 inch is harder to tuck underneath

i dont see why anything other than drag cars with massive turbos would ever run more than 3 inches

Well I'm a big time supra lover. I surf supraforums more than I do here. I've noticed some of the stock turbo guys are still moving up to 4" exhaust. Even with no plans to go single turbo. So it got me thinking are they doing it to gain a bit more performance or just to get different tone? How would effect performance on a build such as mine? Would it rev a bit cleaner through the RPMs? Could it offer open downpipe like flow. Like I said some of my goals for the car arnt needed, I would just like to try something out of the ordinary I guess.

 

[andy4g63]

Well if anything, you won't be needing an 3" exhaust... Mostly you would benefit from 3.5" DP, cause the exhaust gases are hotter/therefore taking more volume in the DP/, after that full 3"... Even GT42 cars are mostly with 3.5" piping...

On Supra's, is different.. They use GT 45; 47; or 475 T6 BW turbos...

 

[airmail96]

I thought you could get away with smaller piping right after the turbo and the air expanded as it cooled. That's why a lot of DPs go from 2.5 to 3in.

 

[mindset]

I thought you could get away with smaller piping right after the turbo and the ari exapnded as it cooled. Thats why alot of DPs go from 2.5 to 3in.

That is correct.

 

[laser90]

On Supra's, is different.. They use GT 45; 47; or 475 T6 BW turbos...

In my last post I stated stock twin Supras are using 4" as well

example

YouTube - Supra w/ new 4" Exhaust System

Look around a bit more i've seen some VW guys doing it as well.I've pretty much convinced myself im going larger than a 3". Why??? well just because .

 

[kmj 4g63t]

Well if anything, you won't be needing an 3" exhaust... Mostly you would benefit from 3.5" DP, cause the exhaust gases are hotter/therefore taking more volume in the DP/, after that full 3"... Even GT42 cars are mostly with 3.5" piping...

On Supra's, is different.. They use GT 45; 47; or 475 T6 BW turbos...

This! I'm not running a gigantic turbo just a 50 trim with a 2.5" Exhaust, no cat, resonator or muffler. I know someone currently building a talon with a Gt42, he's thinking of either going side cut out or sticking with his original 3" that was on his gt35 setup.

 

[CPHunter]

i just run 2.5 exhaust to the rear( i like to keep it stealth on the street) and just run a cut out in between them. i have the cut out ran to a window switch. in order to turn on it has to be at 4.2k rpm and WOT for the Cut out to opens.

 

[9!'clipseDOHC]

Laser90, if your building a mostly track car then forget the rear exit exhaust and go for the front bumper exit. That setup is hot!

 

[TSimage]

If by "hot" you mean sounds bad and attracts cops then yes .

A rule of thumb is that if your hotside doesn't exit at a 4", you don't need a 4". Its pointless. 4"s are heavier, although mine is aluminum it may be lighter than any 3" steel exhaust but without needing it it would be pointless due to the hassle and there would be zero gains especially due with the fact there are no 4" exhaust system out of the box so it will be a custom deal and like many said, is not the easiest thing to run properly and tuck properly under your car. You CAN have too big of an exhaust, even on an FI vehicle. A little back pressure is a nice thing to have.

 

[KazooGS-T]

I'm going to be running a 3.5-4'' setup on my car, which will most likely be side exit, but I may do a bullet race muffler and a dump instead.

 

[laser90]

If by "hot" you mean sounds bad and attracts cops then yes .

A rule of thumb is that if your hotside doesn't exit at a 4", you don't need a 4". Its pointless. 4"s are heavier, although mine is aluminum it may be lighter than any 3" steel exhaust but without needing it it would be pointless due to the hassle and there would be zero gains especially due with the fact there are no 4" exhaust system out of the box so it will be a custom deal and like many said, is not the easiest thing to run properly and tuck properly under your car. You CAN have too big of an exhaust, even on an FI vehicle. A little back pressure is a nice thing to have.

I knew from the get go it was a custom deal. Which isn't a huge problem my best friends dad owns a performance shop. I should have clarified a bit more I wanna run a 3" downpipe to right after the oil pan with a v-band to a 3.5" or 4" out back. Oh and no bumper or side exit exhaust for me. The class that I'm aiming to run in is true street and you need a full exhaust.

 

[andy4g63]

I thought you could get away with smaller piping right after the turbo and the ari exapnded as it cooled. Thats why alot of DPs go from 2.5 to 3in.

Wrong........
As I said, this is where you need the bigger side piping. Most of the DP are 2.5 to 3", cause full 3" won't bolt on 1 or 2G O2 housing..

Majority of turbo cars benefit most from large DP, rather, than the whole exhaust system. Gains after the DP aren't that big...

How can I prove it???
Best example is when people install 3" exhaust on 16G/internally gated/ and it starts to creep badly... This is cause turbo flows so well, that even after the air is diverted to WG passage it still builds more BOOST, aka Boost Creep....

 

[slowgsr]

I run a 4" turboback on my street car. Its aluminum, fits well, built it myself

 

[95eclipser]

i just run 2.5 exhaust to the rear( i like to keep it stealth on the street) and just run a cut out in between them. i have the cut out ran to a window switch. in order to turn on it has to be at 4.2k rpm and WOT for the Cut out to opens.

thats a pretty sweet sounding setup

 

[laser90]

I run a 4" turboback on my street car. Its aluminum, fits well, built it myself

Nice!!! Do you have any pics of the set-up? Did you use a 3" on your current set-up then switch to 4"? If so did you notice a gain with your butt dyno or actual dyno?

 

[joescool2008]

Sounds like a waste to me, 3" flows plenty, most people with side exit have that because they don't have room to put exhaust under the car due to manifolds and awkward angles for the dp to go to do so.

 

[dsm-onster]

Since when does pressure pushing BACK onto the turbine blades and/or wastegate a good thing EVER

With that said, yes ther is a point of diminishing returns. But note that length offers resistance as well as diameter. So a full length 4" exhaust could be as restrictive as a 3"exhaust 1/3 the length.

Also, Tthe hotter the gases the more volume you need to contain them. See the basic Ideal Gas Law. This is why larger down pipes net better results than larger catbacks. Not the other way around as infered thus far in this thread.

 

[1gDSM4g63]

I'm running a Holset HX52 70 trim and running a 4" side exhaust because the hotside is 4" v-band.

 

[RipperXX]

I think large exhaust is seriously over rated.



Heres my setup. Evo III exhaust manifold, ported MHI Evo III 16g, MAP tubular O2 housing (2.5") w/external MVS 38mm waste gate dumped to atmosphere. that then flows into a 3" down pipe and into a 3" cutout, after the cutout branch it is reduced and connected to the stock catback.

I get to have my cake and eat it too at the flip of a switch.