S4 TII quick spool
06-25-05, 01:25 AM
#1
Nipples
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S4 TII quick spool
From Single Turbo Forum:
My friend just purchased an 88 10thAE (basically an S4 TII). The previous owner installed a 3 inch exhaust from the turbo back, with no cat. MBC is set at 10 psi. For fuel the car has an FD fuel pump (BTW..weren't these supposed to be unreliable...killing many FDs back in the day??) and some sort of fuel cut defensor. HKS filter at the front leading to a stock turbo I believe, then to the stock TMIC.
First off..the MBC was set at 10 psi but the damn thing creeped to 16~17 psi at the top of almost every gear. Not surprisingly, the car smokes as if the turbo is blown but I haven't gone down and checked for end play.
The part that really surprised me, though, is that the turbo FC had little boost before 3.5K...car was almost as much of a dog to drive as an NA. Since the turbo is shot, we're looking to replace it with something that will spool earlier.
So:
Current setup-- builds boost from 3.2K all the way to redline...satisfied with the power (Butt dyno says around 220 hp?).
Looking for-- a whole lot less lag. Looking for boost as early as 2.2K and would like a broad power band, but I understand that it will probably trail off at higher rpm. (Rather have low down torque than peak power...looking for 230 hp...reasonable with the afforementioned mods I think)
What would you guys recommend we look for? Is a ball bearing turbo worth the expense? We are on some sort of budget, so there is a price cap. I read that a T25 on ball bearings will spool really fast. I don't know what kind of A/R or trim I should look for. What do you guys recommend?
Thanks in advance,
Grant
My friend just purchased an 88 10thAE (basically an S4 TII). The previous owner installed a 3 inch exhaust from the turbo back, with no cat. MBC is set at 10 psi. For fuel the car has an FD fuel pump (BTW..weren't these supposed to be unreliable...killing many FDs back in the day??) and some sort of fuel cut defensor. HKS filter at the front leading to a stock turbo I believe, then to the stock TMIC.
First off..the MBC was set at 10 psi but the damn thing creeped to 16~17 psi at the top of almost every gear. Not surprisingly, the car smokes as if the turbo is blown but I haven't gone down and checked for end play.
The part that really surprised me, though, is that the turbo FC had little boost before 3.5K...car was almost as much of a dog to drive as an NA. Since the turbo is shot, we're looking to replace it with something that will spool earlier.
So:
Current setup-- builds boost from 3.2K all the way to redline...satisfied with the power (Butt dyno says around 220 hp?).
Looking for-- a whole lot less lag. Looking for boost as early as 2.2K and would like a broad power band, but I understand that it will probably trail off at higher rpm. (Rather have low down torque than peak power...looking for 230 hp...reasonable with the afforementioned mods I think)
What would you guys recommend we look for? Is a ball bearing turbo worth the expense? We are on some sort of budget, so there is a price cap. I read that a T25 on ball bearings will spool really fast. I don't know what kind of A/R or trim I should look for. What do you guys recommend?
Thanks in advance,
Grant
Last edited by I Hate Ricers; 06-25-05 at 01:27 AM.
06-25-05, 03:06 AM
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Nipples
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lol ..sigh.. i'm starting to notice there's so little of it that noone cares about torque anymore in the rotary forums! But yeah, anyone?
Last edited by I Hate Ricers; 06-25-05 at 03:13 AM.
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06-25-05, 04:37 PM
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Nipples
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So how do you know if the twin scroll doesn't work? It's a flapper valve on the S4 model right? Howcome an S5 is better down low w/o the flapper system?
My 04' SAAB 9-3T get's plenty of power below 2300 rpm...I don't think turbos are for high end performance exclusively. But for rotaries, I just don't know anymore.
It isn't worth taking apart the engine and bumping up the compression for this. And I fully intend to stay turbocharged...kinda on a time and money budget here.
So should I be going for a hybrid turbo or an S5 turbo and manifold? What gives me the best response per dollar spent?
If boost is kept below 10 psi, can I get away with the TMIC? I can always add an aquamist system.
Any other suggestions or advice?
My 04' SAAB 9-3T get's plenty of power below 2300 rpm...I don't think turbos are for high end performance exclusively. But for rotaries, I just don't know anymore.
It isn't worth taking apart the engine and bumping up the compression for this. And I fully intend to stay turbocharged...kinda on a time and money budget here.
So should I be going for a hybrid turbo or an S5 turbo and manifold? What gives me the best response per dollar spent?
If boost is kept below 10 psi, can I get away with the TMIC? I can always add an aquamist system.
Any other suggestions or advice?
06-26-05, 09:49 PM
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Try the TB mod or just wire open those out board butterflies. Thats what I did and holy crap does my BNR stage III spool quickly. I am through 1st gear in the blink of an eye almost, and 2nd is just as quick. It damn near makes the car feel as responsive as a well built N/A V8. I am not and would not support the V8 in a RX7, but I have owned a few nice V8 powered cars and this really brought back the punch in the stomach feeling those gave me on take off.
06-26-05, 10:03 PM
#19
Rotary Freak
first of all you should port the wastegate or you will end up blowing it up from boost creep also your injectors might be maxing out since it's going up to 16 psi the stock turbo only is good up to around 15psi then it is useless bc its just creating hot air maybe give the turbo to BNR to upgrade your turbo that will make it have more power and you dont have to worry about custom dp or manifold
06-27-05, 02:38 PM
#20
Nipples
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Originally Posted by Swany
Try the TB mod or just wire open those out board butterflies. Thats what I did and holy crap does my BNR stage III spool quickly.
What can BNR do for me?
06-27-05, 02:44 PM
#21
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Originally Posted by I Hate Ricers
If boost is kept below 10 psi, can I get away with the TMIC? I can always add an aquamist system.
You can run 10 psi with no problems.
But you will always benefit with an aftermarket intercooler.
Personally i feel aquamist or other cooling "spray" systems with the top mount is more as a bandaid.
But again, with limited funding comes limitied performance.
-Justin
06-27-05, 06:06 PM
#22
No money. No love.
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I thinkmy 10th ae has stock internals..just a mild port. Anyways, on my stock turbo it would start building power at 2.2k and be fully boosted at 10psi (or more...boost creep sucks..) by 3k
06-28-05, 03:08 AM
#23
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Originally Posted by I Hate Ricers
So how do you know if the twin scroll doesn't work?
It's a flapper valve on the S4 model right?
Howcome an S5 is better down low w/o the flapper system?
Last edited by NZConvertible; 06-28-05 at 03:11 AM.
06-28-05, 05:57 PM
#25
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my car hits boost pretty damn quick ...
check my sig for mods
i swear i hit 5 psi before i hit 1, and by 4k or so im maxing out my boost .. which is usually around 10psi
check my sig for mods
i swear i hit 5 psi before i hit 1, and by 4k or so im maxing out my boost .. which is usually around 10psi