4" Exhaust system??!

[eXploitedGST]

probably not since the whole exhaust system would be custom (flange angles, length of dp, ect.)

 

[doug]

Originally posted by H.A.R.T 4G63DSM
I was thinking of getting a 3 inch downpipe but now I wanna get a 3.5 downpipe. Would I make more horses?

No.

 

[Slappster]

Try finding an HKS Titanium muffler. Its 4" all the way through I believe.

 

[boostedinaz]

Really not that hard. find a company that makes exhaust for somehting like a Powerstroke or Duramax desiel. They will have everything you want up 5 inches. All the bends all the mufflers everything. I had a buddy thaat built 4inch exhaust for his Fbody and he just got it all from a place like I said above. It will still be overkill and hard to make fit but its not my car or money so go for it.

Michael

 

[swing lo]

Man all of you are crazy, shit i run a 6 1/2 inch exhaust with my 50 trim. I like my 6 inch exhaust, plus it makes me spool to 23 psi by 2200 rpm's. Let me know if anybody needs one, and i'll be glad to make it. Oh it will be madrel bent titanium for a mere price of 200 bucks.

 

[BrnOutKing]

Personally I'd break it down like this:

0-300whp = 2.5" exhaust
300-500whp = 3" exhaust
500-700whp = 3.5" exhaust
700-900whp = 4" Exhaust
900+ = 5" and up.


The only person I've ever talked to face to face that runs more then 3" exhaust is Brent R. - who I believe is now running a 5" pipe out the side of his car. (when I talked to him at his shop when he was first building his RWD he was running a 4" but said that he's more then likely going to have to upgrade to do properly sizing the piping to flow rates)


-brian

 

[gsxstac]

let me modify this a tad


0-300whp = 2.5" exhaust
300-700whp = 3" exhaust
700-800whp = 3.5" exhaust
700-900whp = no exhaust


this argument is like saying a 10" exhaust pipe is better then a 9" one. the outlet on the turbo is 2.5" at most so a 3" exhaust is fine. plus at full throttle prob a 1/4 of the exhaust is going out the external gate anyway. i've seen well over 600 whp on 3" exhaust. if its mandrel bent and its on a gsx theres barely any bends anyway. I just cant see someone actually having backpressure when there exhaust tubine is 2.5" and they have 3" exhaust thats mandrel bent and pretty much straight. jus think about it. is exhaust flow from a 2.5" hole really gonna have back pressure???

 

[Turbo II]

Originally posted by Clipse
Not unless your running a T78 or something of the like

, T78 its not a damn skyline dude j/k , But that is one big turbo.
Just, run no exhaust man you'd be killing em.

 

[mitch83]

sup swing lo this is usaf-jdm from the kutsuju board. anyway I didnt see anyone mention that massive boost creep you would get unless you were running like a 40mm external wastegate. but with a 14b,16g,18g, or 20g with an internal wastegate you would get mad boost creep because the exhaust would rather flow out of the turbine discharge then the tiny little internal wastegate. just my $0.02
mitch

 

[AWDlaserRS]

Originally posted by eXploitedGST
bigger exhaust = fast spool, but i dont want to a cut out, id rather it go strait out the back

Running a 4" exhaust on our cars is stupid, Your basically running out of the downpipe. There is such a large diameter that if you dynoed with a 4" system and without a system at all you would get the same results. Are you getting my picture?

 

[swing lo]

Originally posted by mitch83
sup swing lo this is usaf-jdm from the kutsuju board. anyway I didnt see anyone mention that massive boost creep you would get unless you were running like a 40mm external wastegate. but with a 14b,16g,18g, or 20g with an internal wastegate you would get mad boost creep because the exhaust would rather flow out of the turbine discharge then the tiny little internal wastegate. just my $0.02
mitch

I was joking about the 6 inch stuff. What up though?

 

[BrnOutKing]

Originally posted by gsxstac
let me modify this a tad


0-300whp = 2.5" exhaust
300-700whp = 3" exhaust
700-800whp = 3.5" exhaust
700-900whp = no exhaust


this argument is like saying a 10" exhaust pipe is better then a 9" one. the outlet on the turbo is 2.5" at most so a 3" exhaust is fine. plus at full throttle prob a 1/4 of the exhaust is going out the external gate anyway. i've seen well over 600 whp on 3" exhaust. if its mandrel bent and its on a gsx theres barely any bends anyway. I just cant see someone actually having backpressure when there exhaust tubine is 2.5" and they have 3" exhaust thats mandrel bent and pretty much straight. jus think about it. is exhaust flow from a 2.5" hole really gonna have back pressure???

You are correct I was just being "General"

I'm sure for the most part once people start to get serious about drag racing they just end up going straight out the side with the exhaust.

But again I hope you all get my point that A key point to max HP / Air Flow is correct/proper diameter piping for your set up.

 

[TurBoGs-T]

Originally posted by gsxstac
let me modify this a tad

0-300whp = 2.5" exhaust
300-700whp = 3" exhaust
700-800whp = 3.5" exhaust
700-900whp = no exhaust

Are these real numbers or are you just throwing them out as common standards??

 

[MNGSX]

It is'nt only diameter but the actual resistance to flow.

An AWD car like it has been said already has a really straight exhaust system.

Look at a RWD exhaust system.. F-bodys are a good example.. ALOT of bends...

I actually belive a really large downpipe.. 4" actually flows less due to velocity decreases.. If anything go turbine outlet diameter to 3" gradually with an o2 eliminator dp... Reaching 3" before the DP first bend... Then the rest of the system being a taper from 3" to 4" or whatever diameter. Tapered tubing is scarce. But if you look at high end superbikes they all have conical or tapered piping running from the header collector to the muffler. They get over 100hp without power adders on 600cc's.. Maximizing everything is how it is done.

One thing I'd like to see on a mitsu flange o2 is a connection to the dp being a V-band with another V-band at the catback connection...

Nice clutch changing....

Also
Cutouts and o2 dumps are not legal in some racing clases.

 

[Cirus_93TSI]

this is a very pointless thread, because when were talking about cars like sheps, the size of the atmosphere dumped external gate has as much to do with exhaust flow then the exhaust itself does.

theres a big difference between an internaly gated turbo whose excess gasses are being shoved right back into the exhaust, and an externaly gated one vented to atmosphere.
big turbos need external gates, and the bigger the turbo and the more air your flowing, the more of that air is getting released through the gate instead of the exhaust. you might need a 4" exhsut of your a supra with a t78, but with an external gate dumped to atmosphere and any sensable turbo that people run on our cars(i have seen t61 and t78 2g dsms, not that fast though), our cars dont need anything bigger then a 3.5".

 

[revision27]

man if you people want to buy a 4" exhaust go ahead and waist your money. it is pointless trying to convince someone to change their mind about something they are hell bent on.

 

[nolimitmotors]

Originally posted by revision27
man if you people want to buy a 4" exhaust go ahead and waist your money. it is pointless trying to convince someone to change their mind about something they are hell bent on.

exactly what I said in so many words, and like that other guy said, with a external gate flowing out 1/3 of the exhaust or 1/4 or whatever i bet someone like john shep coule run the same time he does on a 3" exhaust, maybe even 2.75 if it was straight enough

 

[Mirage2LTurbo]

Spend the money you're going to spend on your 4in exhaust, buy a 3 or 3.5 and a tial 46. Be done.

 

[nolimitmotors]

tial 46 is not needed unless the perosn is gonna run like 4 psi on a 60-1, 38mm or 40mm is fine

 

[Mirage2LTurbo]

If you're trying to run 4psi on a 60-1, you're just plain stupid.

And a big wastegate, such as a Tial46, is also needed to run big boost on a big turbo. Or, you could get a smaller exhaust, big wastegate vented externally, and have the same effect as a bigger exhaust.

 

[boostedinaz]

This has been beaten to death by now. I think we all realize that 4 inch is over kill for our cars. If he wants to do it then let him go ahead and be the cool guy at the ricer meets with 4 inch exhuast.

I think this should be closed.

Michael

 

[fastaseagle]

you could just run a 3 inch exhaust with a dump tube that would be the same as a 3.5 or maybe even 4 inch exhaust do to the exhaust going out the dump...

 

[Mirage2LTurbo]

Originally posted by fastaseagle
you could just run a 3 inch exhaust with a dump tube that would be the same as a 3.5 or maybe even 4 inch exhaust do to the exhaust going out the dump...

Exactly my point (and probably cheaper too, and it doesn't scrape bottom)

 

[ItsStockOfficer]

Originally posted by gsxstac
let me modify this a tad


0-300whp = 2.5" exhaust
300-700whp = 3" exhaust
700-800whp = 3.5" exhaust
700-900whp = no exhaust


this argument is like saying a 10" exhaust pipe is better then a 9" one. the outlet on the turbo is 2.5" at most so a 3" exhaust is fine. plus at full throttle prob a 1/4 of the exhaust is going out the external gate anyway. i've seen well over 600 whp on 3" exhaust. if its mandrel bent and its on a gsx theres barely any bends anyway. I just cant see someone actually having backpressure when there exhaust tubine is 2.5" and they have 3" exhaust thats mandrel bent and pretty much straight. jus think about it. is exhaust flow from a 2.5" hole really gonna have back pressure???

so 3 inch is good for a 400 hp range and 3.5 inch is only good for a 100 hp range, hrm... The only time I have ever heard anyone with any real knowledge address the subject, it was a garret engineer saying above 350 whp 3 inch exhuast piping will begin to become restrictive. The truth of that i cannot vouch for but he was one of the smartest guys I had ever found online.

 

[Mirage2LTurbo]

I can name plenty off 500-600whp DSM's on 3in exhaust with a Tial 40-46mm vented EXTERNALLY, that is the key, to vent your wg OUTSIDE of the exhaust piping. a tial 40 is about 1.6inches, and a 46 is 1.8inches, so where you vent your wg makes a HUGE impact on the size of exhaust you need to run.