Yellow Bullet Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter #1
Looking to build some forward facing equal length manifold for my turbo setup. We were thinking 1-5/8" runners to 2-1/4" crossovers.

Any information or recommendation would be appreciated.

302 9:1 comp.
Ported heads, Sullivan intake, single blade TB
Billet T-76 .96 A/R Q-trim
3" turbo to intercooler
3.5" intercooler throttle body

Thanks,
Nick

 

·
Registered
Joined
·
49,841 Posts
We ran 1 3/4 with a 2.5 cross over on a s400 turbo, is that a "T Series unit " and a t6 hotside big big big. It could be challenging to spool up on th brake. I don't think it was the headers, we started with a 1.36 AR hotside with a 96mm turbine wheel. We ended up with a 1.10 87mm combo and it spooled up pretty good at 3000 rpm. I think we also tried a 1.32 ar 87mm turbine wheel combo to.
 

·
Registered
Joined
·
5,618 Posts
Looking to build some forward facing equal length manifold for my turbo setup. We were thinking 1-5/8" runners to 2-1/4" crossovers.

Any information or recommendation would be appreciated.

302 9:1 comp.
Ported heads, Sullivan intake, single blade TB
Billet T-76 .96 A/R Q-trim
3" turbo to intercooler
3.5" intercooler throttle body

Thanks,
Nick
1 1/2" or 1 5/8" headers tied to a 2 1/4, 2 1/8", or 2" crossover. 1.5" header and a 2" crossover would work very nicely! I assume the combo will make 1000hp +-
 

·
Registered
Joined
·
57 Posts
Discussion Starter #4
1 1/2" or 1 5/8" headers tied to a 2 1/4, 2 1/8", or 2" crossover. 1.5" header and a 2" crossover would work very nicely! I assume the combo will make 1000hp +-
Yes, sorry forgot to mention 6 speed street car made 920 on 24 lbs. on the stock manifolds.

Making 1,000-1,100 wheel maybe a little more with a different turbo
 

·
Registered
Joined
·
5,618 Posts
Yes, sorry forgot to mention 6 speed street car made 920 on 24 lbs. on the stock manifolds.

Making 1,000-1,100 wheel maybe a little more with a different turbo
Right on track with what it should make. 24# of boost puts it right around 1050 at the crank and figure 100-120hp loss through the tranny. :supz:
 

·
1-877-MOD-POWR
Joined
·
1,550 Posts
It depends on the turbo size but 1 5/8 are fine for most 92mm and smaller single turbos. For the crossover we suggest 2.5 for T6 flange and 2.25 for a T4 flange.

Good luck, let us know how if we can help!

MMR



Looking to build some forward facing equal length manifold for my turbo setup. We were thinking 1-5/8" runners to 2-1/4" crossovers.

Any information or recommendation would be appreciated.

302 9:1 comp.
Ported heads, Sullivan intake, single blade TB
Billet T-76 .96 A/R Q-trim
3" turbo to intercooler
3.5" intercooler throttle body

Thanks,
Nick

 

·
Registered
Joined
·
57 Posts
Discussion Starter #7 (Edited)
Funny, just spoke to one of your guys about your T4 hotside kit. For that price I would be happy to take one off your hands and save me a lot of headache. He said you guys hope to have some mid Feb. A little fab work and I could be up and running in a day. I will be checking back with you guys in a couple of weeks.

Thanks,
Nick

It depends on the turbo size but 1 5/8 are fine for most 92mm and smaller single turbos. For the crossover we suggest 2.5 for T6 flange and 2.25 for a T4 flange.

Good luck, let us know how if we can help!

MMR

 

·
Registered
Joined
·
161 Posts
So 1.75 primarys and 3'' crossover is too much for a t4 pt8847?

It depends on the turbo size but 1 5/8 are fine for most 92mm and smaller single turbos. For the crossover we suggest 2.5 for T6 flange and 2.25 for a T4 flange.

Good luck, let us know how if we can help!

MMR

 

·
Registered
Joined
·
263 Posts
So 1.75 primarys and 3'' crossover is too much for a t4 pt8847?
not necessarily.....anyone log backpressure on these recommended setups? on a single?......
 

·
Registered
Joined
·
49,841 Posts
not necessarily.....anyone log backpressure on these recommended setups? on a single?......
at the turbine housing we saw 1-1 give or take till 15 psi. that was with a 1 3/4 primary and a 2.5 inch cross over. turbo acted starved actually. Had a big turbine housing to.
 

·
Registered
Joined
·
161 Posts
not necessarily.....anyone log backpressure on these recommended setups? on a single?......
I never did. But it was harder to get on boost than Id like. After seeing what these guys are recommending its making me rethink and maybe redo my setup.
 

·
Registered
Joined
·
5,618 Posts
Based off the several hundred log files I've looked at over the last 2 years, the larger size primaries and larger crossover is going to be tougher to get up on boost and stage. I now size the header tubes and crossover based off velocity. Our newest project should make 2500-2600hp if we're lucky and we're using 1 7/8" headers and a 2.5" crossover. We ran a similar combo on our old motor that made enough horsepower to go 164 to the 1/8 mile at 33xx, 2" headers which we did not like and a 2.5" crossover.

From what we saw last year, the 2 highest velocity points in any system is the turbine housing and at the exhaust valve. Most of the SBF and SBC stuff have 1.32-1.34" valve seats and 8mm or 3/8" stems. We're just trying to make the velocity more consistent across the system.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #13
The only reason for my change is to come on boost earlier. As long as the size doesn't restrict the top end power I will be good.

Anyone know what 1-5/8's and 2-1/4" crossover is good for power?

Thanks,
Nick
 

·
Registered
Joined
·
49,841 Posts
The only reason for my change is to come on boost earlier. As long as the size doesn't restrict the top end power I will be good.

Anyone know what 1-5/8's and 2-1/4" crossover is good for power?

Thanks,
Nick
Should be able to make upper 700's with a auto, think low 9's without any trouble and easily far faster. The biggest problem your going to face is that ugly ass geometry change at the exhuast port.
 

·
Registered
Joined
·
632 Posts
The only reason for my change is to come on boost earlier. As long as the size doesn't restrict the top end power I will be good.

Anyone know what 1-5/8's and 2-1/4" crossover is good for power?

Thanks,
Nick
Its kinda a broad question, if its a street/strip deal that your ultimate goal is to spool well and run hard which is what I assume you are trying to achieve then yeah I would say stay with 1.625 prim and 2.25 cross.

Now if its a full race/peak power combo that you spin to +9000RPM and want to make +1000hp then peak exhaust flow comes into play.

Craig
 

·
Registered
Joined
·
5,618 Posts
Should be able to make upper 700's with a auto, think low 9's without any trouble and easily far faster. The biggest problem your going to face is that ugly ass geometry change at the exhuast port.
Maybe Nelson will sell a set of his 3/4" mod motor header flanges that have a tapered transition.
 

·
Registered
Joined
·
161 Posts
Now if its a full race/peak power combo that you spin to +9000RPM and want to make +1000hp then peak exhaust flow comes into play.

Craig

Say 1100-1200rwhp? What design then? And trying to keep good spool on the transbrake.
 

·
Registered
Joined
·
5,618 Posts
If we are at the limits of airflow @ 164mph and 33xx estimated horsepower 2200 - 1 3/4" header and 2.5" crossover, going to a 1 5/8" header and 2.25" collector, it drops the horsepower to 1750 and still yeild the same airspeed.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #19 (Edited)
If we are at the limits of airflow @ 164mph and 33xx estimated horsepower 2200 - 1 3/4" header and 2.5" crossover, going to a 1 5/8" header and 2.25" collector, it drops the horsepower to 1750 and still yeild the same airspeed.
Thanks, so you are saying it's enough for my caged 3,500 lb street car.:-D

Now the question is can I bump the compression 8.9:1 to around 10:1.
 

·
Registered
Joined
·
5,618 Posts
Thanks, so you are saying it's enough for my caged 3,500 lb street car.:-D

Now the question is can I bump the compression 8.9:1 to around 10:1.
If it were my car, yes. Just make sure your tuneup is correct, creep up on the timing and run C16.
 
1 - 20 of 21 Posts
Top