2.5 turbo rule

Here ya go proposed.

Turbocharger:
S-4 turbo is the largest turbo allowed. T-4 mounting flange is the largest allowed. Turbos
must be a true 2.5 charger. No clipped wheels or step down covers. Billet compressor
wheels are allowed. .200 inch MWE groove maximum. Inducer bore must be nonremovable.
All air must go through the 2.5 inducer bore or the MWE groove. The wheel
must protrude into the 2.5 bore 1/8 inch. Turbo will be checked with a 2.550 plug or
internal calipers. The driver will be responsible for making turbo accessible for tech
personnel to measure and inspect. If you have any questions regarding turbo rule contact
Battle of the Bluegrass Technical Department.

I have had several ask to run a single runner intake. They say no.

good luck gang see ya in the spring.
 
Why did you guys choose to keep the "S-4 turbo is largest allowed" baloney?

What's the biggest non-Borg Warner turbo that's legal, for the other half of people who don't run BW?

And please define how big an S-4 is.
 
nwpadmax said:
Why did you guys choose to keep the "S-4 turbo is largest allowed" baloney?

What's the biggest non-Borg Warner turbo that's legal, for the other half of people who don't run BW?

And please define how big an S-4 is.
Click to expand...

X2 I think a lot of people are wanting alittle more clearification on that size regulation.

Sent from my PC36100 using Tapatalk 2
 
No individual runners yet whatever pump(s) makes almost no sense. But then again, what rules in the US hardly ever make sense?
 
It'd be a tremendous favor if someone could either pdf or post a link to the entire rules and sticky it to the top of this section.
 
SmokeShow said:
Cool... 2.5 gets to be a 1,000hp club?! Sweet!!


:D
Click to expand...

Is this a serious statement?

The Majority of the "National" 2.6 trucks with Clipped 2.6/3.X Inducers are not quit putting 1000HP to the ground. I could start rattling off half a dozen trucks in the finals at Scheid's this past year that I know wont...

Your on it if you can put an honest 800HP to the ground with a true 2.5" or 63.5mm comp wheel. The Fleece Performance best peak HP number in true 2.5" is 785 RWHP. And thats from the Silver, rhino lined, and green accented, mega flared 06 5.9... most that pulled 2.5" in Indiana got to see.

Caleb
 
nwpadmax said:
Why did you guys choose to keep the "S-4 turbo is largest allowed" baloney?

What's the biggest non-Borg Warner turbo that's legal, for the other half of people who don't run BW?

And please define how big an S-4 is.
Click to expand...

I ran a gt4088r but the wheel wasn't clipped. I doubt you could get 750rwhp out of that turbo anyways. The best thing about that turbo is it sounded sweet.
 
carpenca said:
Is this a serious statement?

The Majority of the "National" 2.6 trucks with Clipped 2.6/3.X Inducers are not quit putting 1000HP to the ground. I could start rattling off half a dozen trucks in the finals at Scheid's this past year that I know wont...

Your on it if you can put an honest 800HP to the ground with a true 2.5" or 63.5mm comp wheel. The Fleece Performance best peak HP number in true 2.5" is 785 RWHP. And thats from the Silver, rhino lined, and green accented, mega flared 06 5.9... most that pulled 2.5" in Indiana got to see.

Caleb
Click to expand...

Do you all allow intake plenums up there?
 
I think they copied Indianas (itpa) rules for the most part. Look at the rules there the same with a few differences. So they don't allow plenums. Unless theres a bigger truck series in Indiana, there may be as I'm not from there

Sent from my PC36100 using Tapatalk 2
 
Last edited:
The lack of runner intakes seems like a real hindrance to us Dodge guys especially when you compare factory flow numbers.
 
smokin said:
Here ya go proposed.

Turbocharger:
S-4 turbo is the largest turbo allowed. T-4 mounting flange is the largest allowed. Turbos must be a true 2.5 charger. No clipped wheels or step down covers. Billet compressor
wheels are allowed. .200 inch MWE groove maximum. Inducer bore must be nonremovable.
All air must go through the 2.5 inducer bore or the MWE groove. The wheel
must protrude into the 2.5 bore 1/8 inch. Turbo will be checked with a 2.550 plug or
internal calipers. The driver will be responsible for making turbo accessible for tech
personnel to measure and inspect. If you have any questions regarding turbo rule contact
Battle of the Bluegrass Technical Department.

I have had several ask to run a single runner intake. They say no.

good luck gang see ya in the spring.
Click to expand...



Read above in the red... also no one allows sideairs for 2.5....
 
You can get a 99mm turbine wheel in a T4 housing. When you say no side air, I assume this does not include a stock style bolt-on shelf with top entrance?
 
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