Single Turbo RX-7's Questions about all aspects of single turbo setups.

Lag and HP loss with on center housing?

Old Jul 5, 2005 | 12:24 AM
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Exclamation Lag and HP loss with on center housing?

I have been looking and searching for two days now....

Im looking for some turbo people in the know to help me out with some info. If we cover this right maybe make it into the archive so others searching for this info can find it all in one spot.

I have read that using a .84 and .96 undivided... 1.00 and 1.15 divided A/R turbine housings are the recommended sizes on a 13b. I have read that the Tang housings are a better design and flow better (10%? )than a On-center one of the same size.

I have read that a bigger a/r housing is less restrictive and allows for better flow and more peak power... but will spool slower.

What id like to get answered is:
1. How much slower the oncenter housing will spool a turbo and a tang of the same size? ... Spool is relative so use 3rd gear for rpm estimates (start to make boost and full 15psi rpm marks).
2. Also how much peak power will actually be lost using a on center housing comapired to a tang of the same size?

Then there is a few divided/undivided manifold mated to a divided/undivided housing questions.

I read the optimum setup is a fully divided manifold and divided housing. But is seems people run log style undivided manifold and divided housings very often on here. I know divided manifolds cost more, the hks FD one is divided but a tang housing will hit the LIM.

1. How much benifit is ther in running a divided/divided setup over divided/undivided or undivided/divided manifold and housing setups? Spool and Peak HP.... Spool is relative so use 3rd gear for rpm estimates (start to make boost and full 15psi rpm marks).


personal info questions about my setup. Master power t70. stock port s4 block. 3" turbo back no cats (Might go 4" for the DP), Ported and modded TB, haltec e6k (no afm), 4" TID/CAI.


I have a hks FD divided manifold and would like to run a divided 1.00 a/r housing on the t70 i just got. But due to design of the maniold only a on-center housing will clear without cutting and rewelding the manifold. The only size of on-center housing i can find is a .96 undivided one.

1.Would it be better to get a undivided manifold made for the fc and mate it to a 1.00 divided a/r housing... or keep the manifold i have and run a on-center .96 housing?

2. Or mod the divided manifold with cutting/welding or spacers and run the divided 1.00 housing.

If there is no huge difference then ill just use the oncenter to make the FD divided one work because thats what i already have.



Post any other info on spool and HP related to a/r sizes you have. Maybe some 3" and 4" DP effects on spool too.
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Old Jul 5, 2005 | 12:43 AM
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From: Pulling you over
*wrong thread*
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Old Jul 5, 2005 | 06:10 PM
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a 1.00 split pulse housing IS WAY TOO SMALL for a 13b.
a 1.15 is ok but will run out of puff early.
Rotarys like revving,if you want to make power, choose an exhaust housing that will make them peak higher.
a 1.32 exhaust housing will be better suited 13bl.

In 3rd gear, on a non ported 13b a 1.32 exhaust housing will have 15psi by 4200rpm.
On a ported 13b 15psi will be there by 3500rpm.
And youll have peak power at 8000rpm. And that would be around 450rwhp.
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Old Jul 5, 2005 | 06:34 PM
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1.32 on a non porrted 13B is way to big..
get a .96
i wont run out of steam
my buds running a .84a/r on a 70 trim wheel and still want mroe boost at 19psi
with .96 youll get full boost around 3500-4. should be happy with that
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Old Jul 5, 2005 | 07:02 PM
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Originally Posted by bcty
1.32 on a non porrted 13B is way to big..
get a .96
i wont run out of steam
my buds running a .84a/r on a 70 trim wheel and still want mroe boost at 19psi
with .96 youll get full boost around 3500-4. should be happy with that
Dont know were you get your info from.

A split pulse 1.32 is not way too big for a 13b.
And i bet you, yo have not tried it and your just talking from "internet experience"?
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Old Jul 5, 2005 | 07:22 PM
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:grabs popcorn: fight fight fight!


soooo anyone have any info on the questions i made this thread to answer?

Last edited by sleeperfc; Jul 5, 2005 at 07:24 PM.
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Old Jul 11, 2005 | 08:08 PM
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the 1.32 w/any trim wheel will spool like a tortis with rigamortis PERIOD. the "on-center" seems to hurt air speed due to it's restrictive nature by design. you need a the .96 open or a 1.0 divided with a std "p" trim wheel. the 3" dp is good for 450-500 hp.
HPbyRJ
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Old Jul 16, 2005 | 03:42 AM
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Originally Posted by rx72c
Dont know were you get your info from.

A split pulse 1.32 is not way too big for a 13b.
And i bet you, yo have not tried it and your just talking from "internet experience"?

Are both of you guys talking the same Turbine wheel? "O", "P", "Q" ? Being polite will get you much more respect than that last shot in the dark, especially considering general concensus is that .96 "P" trim is spot on for a 13BT.

Kenn
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Old Jul 16, 2005 | 04:08 AM
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From: lebanon
Originally Posted by kenn_chan
Are both of you guys talking the same Turbine wheel? "O", "P", "Q" ? Being polite will get you much more respect than that last shot in the dark, especially considering general concensus is that .96 "P" trim is spot on for a 13BT.

Kenn
Most Aussies have a weird fascination for massive exhaust housings, lots have no experience running smaller housing that make just as much power in lots of cases. I found this out the only way by experimenting and indeed 1.0 housing size (TO4) on a P trim wheel works very well indeed !

1.32 is soft in lower rpm's and the gains up high are not as much as people think
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Old Jul 17, 2005 | 01:00 AM
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From: Edwards, CA
Originally Posted by RICE RACING
Most Aussies have a weird fascination for massive exhaust housings, lots have no experience running smaller housing that make just as much power in lots of cases. I found this out the only way by experimenting and indeed 1.0 housing size (TO4) on a P trim wheel works very well indeed !

1.32 is soft in lower rpm's and the gains up high are not as much as people think

Wow! Thought I'd never hear that.


FWIW, Carl Byck made over 500 rw with a .81 P-trim with nice spool -I would tend to agree that .8-1.0 is the sweet spot on a street 13b.
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Old Jul 17, 2005 | 08:14 AM
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From: lebanon
Originally Posted by Marshall
Wow! Thought I'd never hear that.


FWIW, Carl Byck made over 500 rw with a .81 P-trim with nice spool -I would tend to agree that .8-1.0 is the sweet spot on a street 13b.
Yeah, If you realy want some urgency at 3.5k rpm's you need the smaller housing to start things working earlier. Back to back with similar set ups there is not such a big top end power difference, since on such a small compressor your limited by air flow anyhow.
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