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Discussion Starter · #1 ·
Building a turbo motor and cubic inch plays a big role in weight in this class...SBC based

I can get a major weight break with building as close to a 300" motor as possible........

So with that said, is the bore size going to make a major difference in the game or not? Pro's & Con's? I realize bigger bore = valves unshrouded....but then smaller bore = more gasket material

Need to make 1500-1600hp
 

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Building a turbo motor and cubic inch plays a big role in weight in this class...SBC based

I can get a major weight break with building as close to a 300" motor as possible........

So with that said, is the bore size going to make a major difference in the game or not? Pro's & Con's? I realize bigger bore = valves unshrouded....but then smaller bore = more gasket material

Need to make 1500-1600hp
well unless your building a stock block id do 4.125
 

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With todays cylinder technology.... A 4 inch bore is plenty.

5 hp per ci with a 300 inch motor? wow. Not asking for much are ya?

Honestly, If it were me, Id be.looking to go LS based on the engine. 4 inch bore with a 3.266 stock 4.8 stroke yields 328ish inches. So does a .020 over 5.3 setup( 3.8x3.622). Honestly for this i dont know which way would be better to go. I like having stroke in a turbo motor so it makes the power without spinning a ton of Rpm. Ive seen 5.3's make 500 n/a on the dyno setup for boost. Put 29 psi on that and thetes 1500 theoretically.

4 inch bore with a 3.25 stroke, 10:1 compression, a 225-235cc sized head and a big single plane should be able to make 500-525 on nuts spinning up around 7600-8000 rpm. Pick the right turbo that can handle making 30 psi and what you want should be possible. I wouldnt want to run any less stroke than that though.
 

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3.3 lb per CI added to 3100 above 300 cubic inch?
 

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Discussion Starter · #7 ·
Yes 3.3lbs per CI above 3100

Na...5HP per cube isnt that much.....is it :)

I want to stay away from the LS stuff......they're missing too many headbolts for my liking.

-Carm
 

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Theres the 6 bolt RHS block which would probably seal better than a typical SBC arrangement. Trickflow amongst others have affordable 6 bolt castings.

328 inches puts you at 3193 lbs.

The organization that wrote these rules doesnt like turbo combinations too much evidently. 1500 with an 88mm restriction isnt going to be easy. Where do they measure at? Within a 1/16th of the impellers?

A 6 bolt LS with a 4 inch bore and a 3.25 stroke is prolly what i would do.
 

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Discussion Starter · #10 ·
Theres the 6 bolt RHS block which would probably seal better than a typical SBC arrangement. Trickflow amongst others have affordable 6 bolt castings.

328 inches puts you at 3193 lbs.

The organization that wrote these rules doesnt like turbo combinations too much evidently. 1500 with an 88mm restriction isnt going to be easy. Where do they measure at? Within a 1/16th of the impellers?

A 6 bolt LS with a 4 inch bore and a 3.25 stroke is prolly what i would do.
I REALLY want to stay with a conventional SBC though.....

As for the rules, turbo can be any size but needs to have an 88mm restrictor and "must end no more than 2” from the impeller directly below the end of the
reducer"
 

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An 88mm reducer that ends 2 inches from the impeller isnt really gonna do anything to restrict flow. Design a restriction thats shaped like a venturi with an 88mm throat 2 inches from the impeller and go bust these guys asses.

A typical SBC will do this knowing that. Only reccomended LS stuff based on how they can flow with smaller sized valves.

Do it with a typical SBC and a 220-230cc sized runner with a 2.055 intake valve. An 18 or 15 degree head would be killer here if you could get a port designed to work with a 2.08 valve to clear the small bore.

It does sound like a class that a mod motor would be perfect for.
 

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Trying to run some X275 stuff so i'd like to stick with an 88mm.......this is why the low cubes/low weight deal
Just have two turbos because your probably going to leave a little on the table with the x275 legal 88 on a 300 inch engine.

Have you talked to Reed at Work turbochargers? Based on my conversations with him I get the idea that he is a fan of small cube v8 turbo combos.
 
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