Phil99vette

iTrader: (11)

Yuuuuup

Phil99vette

iTrader: (11)

Turbo sounds small for a 427. What kind of cam is in that thing?

93camaro_zzz

iTrader: (13)

^ Lmao! Good thinking!

^ Very true.

green94z

iTrader: (6)

Was going to be a grudge car, changed after I ordered the motor to a 275 car
I gave you the specks on yb

95bowtie

I understand that but was looking for actual numbers with dual 2.5 inch pipes on a 5.7 with a tc 7875 turbo.

2.5 will tuck nicely in the tunnel 3 inch duals however will not. My car has dual tail pipe exits and wanted to use them so if 2.5 pipes will work and not restrict then o want to use them. Just am not sure on that yet.

Phil99vette

iTrader: (11)

You definitely need a new cam.

Sarg

iTrader: (6)

I guess the reason I used 2.5 was becaust the vette manifolds I used had 2.5" outlet and the t6 turbo was just about perfect for a 2.5" pipe to either side of the flange. I honestly saw no reason to neck it down to 2.25" coming out of the manifold only to increase it again going into the turbo. I figured keeping it the same throughout would work better. Is this incorrect thinking?

F110Mech

iTrader: (2)

I thought that the 2.5" had to be trimmed to fit on either side of a divided T6 Flange. someone mentioned that the 2.25" actually fits perfect.

Chicago TDP

iTrader: (3)

If the T6 flange is a divided flange, two 2.25" pipes fit snug after a little hammering.
Looking at the area needed to feed a T6 flange, two 2.5" pipes equates to the open area.
That little divider will make a difference if a 2.25" or 2.5" crossover should be used (if you are basing your piping on matching the cross-sectional areas).

Sarg

iTrader: (6)

Donno, maybe my divider was a little on the slim size, but after hammering the pipe to a rectangular shape that pretty much matched the flange it was almost perfect. I tested with a 2.25" and it was pretty loose. So I decided to step up to 2.5" since that was what fit the c6 manifolds I was using. The flange matched the gasket and the turbo well though. Ideally something in between 2.25 and 2.5 would have been perfect.

But does necking down from the collector to a smaller size have any advantages?

Phil99vette

iTrader: (11)

Here is an analogy... You got a 1 mile race....
You run your ***** off for the first 200'(intake valve)
then you slow down to speed walk for alittle(header)
you transisition into a slowwww jog(crossover)2.5"
then you run at a good pace(merge)3"
then for the last 200' you run your ***** off again(turbine housing)

Or

run your ***** off for the first 200'(intake)
then you slow down to speed walk for alittle(header)
then run with a very good pace (crossover)2.0
transiition into a short sprint(merge)2.5
and run your ***** off at the end(turbine housing)

Sarg

iTrader: (6)

But slow and steady wins the race right? J/k.

So assuming you are not merging the two together (in my case divided housing), it seems like it would be a flow restriction going from a 2.5" collector to a 2.25" pipe only to widen back out to 2.5" again at the turbo. Am I missing something? I am sure I could rework my hot side piping later if need be, I just would like to know your thoughts on necking down then back up like that.

Sarg

iTrader: (6)

Doe double post.

LS1NOVA

iTrader: (12)

Its all about VELOCITY. The turbine is going to be the restriction not a 2.25 pipe.

Phil99vette

iTrader: (11)

When you get time to look at a turbo like yours, measure the cross section at the throat where it starts to turn. On a standard un-divided turbo, your not widening it at the 2.5" section, its combining pulses from both sides and velocity increases again.

header tube sees 1/8 of the total airflow
Crossover tube sees 1/2 of the total airflow
merge at the turbo sees the entire engine airflow.

Sarg

iTrader: (6)

And on a divided turbo?

94 slow

Does velocity remain constant with every fuel available to us? For example, 91, e85, e98, 100, c16?

Sarg

iTrader: (6)

I would say no, as E85 will produce increased exhaust volume to the best of my knowledge.

Phil99vette

iTrader: (11)

A divided turbo still necks down, Just because the inlet is = to an "x" size pipe doesn't mean thats the best size for your motor.

Phil99vette

iTrader: (11)

These calculations are based on gasoline combos that have worked well, methanol or an ethanol based fuel would be slightly different. I am using the same sized pipes from C16 and have changed over to methanol, you can tell there is more exhaust velocity/mass based on the additional fuel in the exhaust. The air is still the same just have more of a fuel mass.