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Discussion Starter #1
I'm considering changing my combo to run in one of the local 1/8th mile street classes. I have a 383" SBF, and I would need to make around 1000 hp to run in the pack. Heads are limited to stock valve angle, no restrictions on Cam. Turbo is limited to 75MM compressor inlet, as measured.

What turbo should I run? (car has an S475 on it now)

Who should I go to for the head/cam combo?

What kind of RPM should I expect to turn to make that kind of power on a turbo that small?

Thanks!
 

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Get the biggest hotside and biggest AR cold side setup you can for the 75mm especially with those cubes. Call bullseye power. They should be able to set you up. I assume you have a s400 with a 96mm turbine and a 1.36 hotside.
 

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Discussion Starter #3
Get the biggest hotside and biggest AR cold side setup you can for the 75mm especially with those cubes. Call bullseye power. They should be able to set you up. I assume you have a s400 with a 96mm turbine and a 1.36 hotside.
I believe it is a 1.32 hotside. I have a call in to Louis @ paradise about a new cover for the compressor that will flow more.

I am thinking that I am going to have to build the motor more like a Naturally aspirated combo and just spin the piss out of it to make the power, does that seem logical, or am I totally off track?
 

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I would start with that "race cover" which I understand is readily available for the Borg Warner turbos.

For what it's worth, smaller cubes might actually go faster with that turbo size limitation... and having a dedicated camshaft done up would probably be worth the money. Good luck!
 

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I'm considering changing my combo to run in one of the local 1/8th mile street classes. I have a 383" SBF, and I would need to make around 1000 hp to run in the pack. Heads are limited to stock valve angle, no restrictions on Cam. Turbo is limited to 75MM compressor inlet, as measured.

What turbo should I run? (car has an S475 on it now)

Who should I go to for the head/cam combo?

What kind of RPM should I expect to turn to make that kind of power on a turbo that small?

Thanks!
What are the EXACT rules? Inlet measurement? No tip to tip?
 

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I'm considering changing my combo to run in one of the local 1/8th mile street classes. I have a 383" SBF, and I would need to make around 1000 hp to run in the pack. Heads are limited to stock valve angle, no restrictions on Cam. Turbo is limited to 75MM compressor inlet, as measured.

What turbo should I run? (car has an S475 on it now)

Who should I go to for the head/cam combo?

What kind of RPM should I expect to turn to make that kind of power on a turbo that small?

Thanks!
Inlet rule or tip to tip???? The answer to that question can vary the HP of the turbo by 300-400hp at least.
 

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Discussion Starter #7
This is the only verb-age in the rules regarding turbo:

"Turbo limited to 76mm, no air to water, no methanol injection, must run commercially available air cleaner."
 

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This is the only verb-age in the rules regarding turbo:

"Turbo limited to 76mm, no air to water, no methanol injection, must run commercially available air cleaner."
Whoever wrote those rules has no idea :rolleyes: . 76mm inlet Thumper my friend......you will own the class.
 

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This is the only verb-age in the rules regarding turbo:

"Turbo limited to 76mm, no air to water, no methanol injection, must run commercially available air cleaner."
Lots of options there and none are 76mm tip to tip..........................
 

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Discussion Starter #10
Well, my concern is this: If I show up with a "76mm" turbo that actually has a much larger inlet, I will just get protested. If they take a pair of calipers across the inlet of the turbo and the inlet measures much larger than 76mm, I'm sure they would consider that to be a cheater turbo. The spirit of the class is to be a low cost entry level street car class, and I would like to play within the rules. I would probably just build a nitrous combo, if I didn't already have a turbo car that meets all the rules and weight as it sits.

I was wrong about the minimum weight, which means that I wouldn't have to make quite so much power. To be competitive, I would need to run 5.60s- 5.70s at 3300 lbs. I would think that would be doable with an S400 with the upgraded cover wouldn't it? If I'm not mistaken, 850-900 hp would get me in the ballpark at that weight.

If this seems possible, what kind of camshaft profile would I be looking at to squeeze every last HP out of an undersized turbo?
 

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The idea is to show up with a turbo with a 76mm inlet and a foot away from that inlet sits a larger turbo.
If not at least get a clipped 80-88mm.
 

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Discussion Starter #12
The idea is to show up with a turbo with a 76mm inlet and a foot away from that inlet sits a larger turbo.
If not at least get a clipped 80-88mm.
I'm not sure I understand. You are only allowed one turbo, so I can't have another one a foot away.

If I got a "clipped" 80 or 88, would it not have an 80 or 88mm inlet?
 

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you buy a cheater turbo or big tirbo and reducer you will need more turbo the borg will run the times just small for your size engine . i got a 88 but is really a 98 if you take the cover off and on a little mod motor
 

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I'm not sure I understand. You are only allowed one turbo, so I can't have another one a foot away.

If I got a "clipped" 80 or 88, would it not have an 80 or 88mm inlet?
You should give us a call and we can explain the details.
A clipped turbo will not have a large opening. The "cheater" turbo have a 76mm tip to tip measurement and opening. Under the 76mm opening there maybe a much larger turbo. There are other ways to achieve this also.
 

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I'm not sure I understand. You are only allowed one turbo, so I can't have another one a foot away.

If I got a "clipped" 80 or 88, would it not have an 80 or 88mm inlet?
No we build units that the compressor cover measures 75mm inlet, or whatever size you want and then CNC the back side of the compressor cover for a larger wheel, but still keeping the 75mm inlet. Essentially it funnels out from the inlet to the tip of the inducer of the larger wheel.
 

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Assuming you can get the largest hot & cold sides that are properly "augmented" ($$$), have your cam ground to match - i.e. an earlier exhaust valve opening will help kick the charger's heavier rotating mass with the larger A/Rs.
 
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