ok exactly what it says ive done a search with no results all i see is that 3 inch exhaust is always better and thats it with no explanation what EXACTLY makes it better and how does it make it better not just like " o it spools faster" answer y it spools faster also what does exhaust frequency have to do with turbo

 

Its the volume of air you can get rid of and allows you to get more in faster.. less backpressrue for a turbo application means that more air can get in wehre the old air was.... which also means the turbo will spool faster since it has more air passing through it...

make sense?

 

thanx my moms bf is tryin to tell me that u need a lil backpressure for turbo but ive been arguing for him for hrs hes a domestic muscle car guy who races pro 5.0s and shyt he worked on steve grebecs pro 5.0 that was the fastest in its class it ran a biiig *** turbo ion it but thats besides the point i need more info thanx

 

well your mom's bf is telling the truth. us hondas need a bit of back pressure. it helps out for our torque.

 

yes but hes sayin 2 1/2 inch pipe would b the best for my aplication not 3 inch is he right?

 

This topic has been covered in many other forums as well... I think the concensus is that it all really depends on the size of your turbo, and the hp numbers you're looking at. So it all depends, there isn't one "magic" exhaust diameter that rules surpreme.

Feel free to correct me if I'm wrong.

Henry

 

ya i got drag gen 3 boostin round 8

 

There's no such thing as backpressure. It's a matter of not having a pipe so big as to cause the low frequency exhaust pulses (at low rpm) to slow down and collide with each other in the larger pipe. You just need one that's appropriate to your power output. Three inch is fine if you're going for over 250-300 on a small engine, I'd wager, but I'm not sure of the numbers. If it's virtually stock, you'll lose power down low, but if it's a bigger turbo this will be good.

 

3 Inch will always make more HP in the upper range over 2.5 inch. So if your goal is to make as much top end power as possible, 3 inch is what you should get.

However, with a 3 inch you will lose a little bit of torque in the lower rpm versus 2.5 inch.

 

the turbo provides the back pressure you need. Getting a large diameter helps out. When I upgraded to a 3" downpipe and thermal exhaust I gaind 10whp and 10ft/lbs plus my boost comes up alot quicker than it did before.

art

 

so why do 1600 hp mustangs use 3- 3 1/2 in exhaust while drag impots use a side pipe (i think thats what its called) like an open exhaust


[Modified by turbo craig, 6:09 AM 6/8/2002]

 

You cant compare mustangs to Hondas. Plus the high HP mustangs use something like a 5" downpipes.

art

 

art they dont he said they use 3 1/2 inchs on the gran national that they had and around that on the pro 5.0 mustang


[Modified by turbo craig, 6:39 AM 6/8/2002]

 

sssshhhyeah right.

you get 'featured' in Turbo magazine and now you think you're a stunna?

j/k

 

in that case he's full of ****... here is steve grebeck's mustang (r.i.p.) if he worked on it i would guess he knows what size exhaust he was running... and when u can tell me that that is a 3.5" pipe... then maybe this gu makes some sense... doesnt look it to me though...



iv seen turbo camaros and such being built... 5" exhausts... 4" ic piping... nothing smaller anywhere... i dont where 3.5" pipeing would be used on a turbo v8!

 

V8s use sidepipes alot, too. I think it just depends on the class you run in. Some have to have the exhaust exit behind the rear axle...or is it the driveaxle?(would explain being up front on a FWD car)

I'm still pretty sure there is no such thing as back pressure, it's just the velocity of the exhaust...it has to be smaller on less powerful engines so that the exhaust doesn't slow down in the pipe.

 

I know mike murillo and chip haveman. Mike Murillo runs in pro 5.0 while chip runs this year in the outlaw class. All the pro 5.0 run 5" exhaust, and I to have pics of Grebeck's car (RIP) along with Dan Millen's car. I wish I would have uploaded the pics up on turbomafia so I could show you.

art

 

you need a little backpressure bf the turbo but after the turbo the more flow the better. go 4" if you can.

 

Do they have to have the exhaust exit past a certain point on the car?

 

my bad i ment downpipe but i aslo i said 3 1/2 on the gran national and around that on the 5.0 he didnt say the size ill ask him when he gets home today

 

If you are not running high boost a 2.5" dp and 3" exhaust combo is excellent for a street Hunda.

 

yes but why?? when i searched i got that answer all the time with no explanation and my moms bf is tellin me to go 2.5 all the way bak


[Modified by turbo craig, 6:34 PM 6/8/2002]

 

i am going with 2.5 all the way back for 1) cost 2) slightly quieter

 

here's a better question! Why do you need a 3" DP? Are you boosting past 10psi? With some of the smaller turbos you will get boost spikes because the turbo will effective try to push out more air than it is pulling in. This is why a 2.5"DP 3" exhuast is better for street driven cars. Now if you are romping 14psi+ with an T3 AR.82 housing or a T4 ex housing then a 3" exhaust is a must. I hope this helped you a little more.

 

A turbo is a major restrictor... this is why turbocharged cars are quieter. No magical formula to that. Plain and simple, you have a big ol thing blocking off air flow.

Why the need for large exhaust piping? simple. The turbo's do not rely on exhaust scavenging. Normal engines rely on this pulsing to help remove exhaust gases more efficiently. Which is why they require a smaller diameter than a turbo, to maintain high exhaust velocity, which creates a vacuum behind it, sucking out more exhaust. BUT as i said, a turbo does not produce this pulsing and does not rely on this scavenging effect, instead it's pushing out so much air that all it needs is room for the air to get out! There is really no "too big" for a turbo exhaust, aside from the boost spiking problems that occur on honda's.

Hope you were able to understand my babbling, I am tired, so I am kinda unorganized, but that is why exhaust diameter makes a difference on turbos.