Phil99vette

iTrader: (11)

We're making 1 3/4" headers and using a 5" down pipe as far back as we can and downsizing to 4". What size pipe should you run between the turbo and the 1 3/4" header tubes? 3" or 2.5"?
Phil

otherwhitemeat

iTrader: (3)

im in the middle of a fab too. and was going to use my old 2 1/4 piping for my t91, but not sure if it is big enough. i maxed out my old pt88 at 22-24 psi. On the new set-up its a t91 and the same size motor "383" as before.....so i dont see that it will matter much if it is bigger.....but i would like to know if i need to go bigger too.

Josh@KY-Turbo

iTrader: (120)

I would do 2.5 inch pipes. Thats what I use on all my setups. I have used 2.5 inch pipes in several builds that made over 1000hp.

otherwhitemeat

iTrader: (3)

would going smaller affect spool time or power, or both? i plan to use all of this 1600hp turbo too!

black98ws6ta

iTrader: (77)

I would think going to a 3 inch intermediate would slow spool time down, but not affect power.

otherwhitemeat

iTrader: (3)

takes what i was thinking.... because the turbo itself is back pressure anyway. anyone elso with some info?

TwnTrboCE

iTrader: (43)

We use 2.5" on our stuff.

cablebandit

iTrader: (37)

Mike, good to know for us sub 1000hp guys. I dont guess you could use a 1" pipe cause it would choke like Ohio State University I had to do it

1fstTA

iTrader: (25)

use 2.5 your spool time will definitely be slower with the 3ich.

otherwhitemeat

iTrader: (3)

would i loose power using a 2.25? or anything significant anyways?

LASTLS1

iTrader: (7)

Is this a race car with the 1 3/4 headers? Spool time?

DrTurbo

iTrader: (3)

We use 2.5", and we have made 1500rwhp with 1 5/8" primaries.

qqwqeqwrqwqtq

It's always hard convincing people of that.

eviltwins

"My 302 motor makes 1177 RWHP and 1097 RWTQ and that is with 1 5/8" headers, 3" crossover and a 4" DP thru a "FULL" exhaust system inlcuding tailpipes. This is with a 88mm turbo at 32 psi of boost. I too was told go with a 2.5" crossover too but I opted to go with 3" instead so I can't give you any data with a 2.5" but with the 3", I wanted to have as less exhaust backpressures as possible. I am sure that you will have a 350+ cubed motor and I'd go with 3" but that is just my opinion. I may make up a 2.5" so that I could see the difference between the two sizes."

That's from Brent Davis on turbomustangs.com. He claims to make full boost on the street at around 4000 RPM's with a 306" motor and a Majestic T4-frame 88mm turbo. I really don't think a 3" crossover will hurt you at all, I did a friends car with a 284" modular with a 3" crossover and a GT47-88 and it doesn't seem abnormally slow to spool.

LASTLS1

iTrader: (7)

Yea, that's why I was asking why he was going with 1 3/4. Jim used 1 5/8 on mine and it seems to be working well.

Dustin11

Small block Chevy

1 7/8 header with 2.5 crossover...2000hp

My own 23* motor made 1500hp with 1 5/8 and 2.5 crossover

Why go bigger. You still have to neck that pipe down into a merge at the flange

otherwhitemeat

iTrader: (3)

Why go bigger. You still have to neck that pipe down into a merge at the flange[/QUOTE]


thats what im saying