HP and Torque values?
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HP and Torque values?
Use will be for Circle Dirt track - Truck Class
Engine specs
400 crank
8.4:1 advertised comp ratio with stock heads
aussie 59cc heads mildly ported
Comp cams 265DEH
RPM range 1500-5750
stock exhaust manifolds (required for my class)
stock intake manifold (required for my class)
Holley 600CFM 2BBL
C6 auto tranny
All ideas for more power in this RPM range will be appreciated
Thanks
Engine specs
400 crank
8.4:1 advertised comp ratio with stock heads
aussie 59cc heads mildly ported
Comp cams 265DEH
RPM range 1500-5750
stock exhaust manifolds (required for my class)
stock intake manifold (required for my class)
Holley 600CFM 2BBL
C6 auto tranny
All ideas for more power in this RPM range will be appreciated
Thanks
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Joined: May 2003
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HP and Torque values?
Compression is limited to "near stock". The aussie heads should put static CR around 9.5:1 and a 0.010 decked block with a 0.020 milled head will bring that up a little.
Compression pressure if checked has to be less than 200 PSI.
For fuel I use a 50/50 mix of 104 av gas and pump premium although it should be fine with straight 93 octane pump gas.
Compression pressure if checked has to be less than 200 PSI.
For fuel I use a 50/50 mix of 104 av gas and pump premium although it should be fine with straight 93 octane pump gas.
Posting Legend
Joined: Sep 2001
Posts: 30,255
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HP and Torque values?
You could bump the compression ratio a bit more with your mixed fuel. Consider a set of flat top pistons. Flat tops were used in 1971 so they are "stockers" -hehe. You can find the flat tops for a 400 on ebay. I don't think anybody is currently producing them due to some mergers and aquisitions. Look around for them. Use the search function here for leads.
The aussie heads are "stockers" also... -hehe!
Does that make the compression ratio near enuf to stock???
I have no idea what this will bring the compression pressure to.
Only use enough octane to satisfy your compression for max power.
Is there a cube limit? Guys used to run 400s until cubes were limited to ~355.
Is this a "claimer engine" class?
The aussie heads are "stockers" also... -hehe!
Does that make the compression ratio near enuf to stock???
I have no idea what this will bring the compression pressure to.
Only use enough octane to satisfy your compression for max power.
Is there a cube limit? Guys used to run 400s until cubes were limited to ~355.
Is this a "claimer engine" class?
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HP and Torque values?
I have been told by some of the racers that 11:1 CR will get very near the 200 PSI compression pressure.
Regarding pistons, I have done some research and bushing the rods and using 351C pistons is an option but I am unsure about doing that. Also, Ross Racing will make custom pistons in any CR for a price, $600-$800.
I am trying not to bend the rules too much but have 2 Chevy's that have bent the rules to contend with. It sure is nice when the Ford truck gets to take the victory lap.
There is no cube limit and it is not a claimer class.
Regarding pistons, I have done some research and bushing the rods and using 351C pistons is an option but I am unsure about doing that. Also, Ross Racing will make custom pistons in any CR for a price, $600-$800.
I am trying not to bend the rules too much but have 2 Chevy's that have bent the rules to contend with. It sure is nice when the Ford truck gets to take the victory lap.
There is no cube limit and it is not a claimer class.
Elder User
Joined: Sep 2001
Posts: 887
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From: Jax FL
HP and Torque values?
some cr numbers.
stock - 1971 - 9.1
stock - 72-82 - 8.4
aussie - 1971 - 10.75
aussie - 72-82 - 11.51
if you port the aussies, you can figure about a 10.0 for dished, and 11.1 for flat tops. having said that, the numbers are....
8.4 - 276hp @ 5k, 374tq @ 3.5k
9.1 - 308hp @ 5k, 386tq @ 3.5k
10.0 - 326hp @ 5k, 403tq @ 3.5k
10.75 - 337hp @ 5k, 415tq @ 3.5k
11.1 - 341hp @ 5k, 418tq @ 3.5k
11.51 - 347hp @ 5k, 425tq @ 3.5k
stock - 1971 - 9.1
stock - 72-82 - 8.4
aussie - 1971 - 10.75
aussie - 72-82 - 11.51
if you port the aussies, you can figure about a 10.0 for dished, and 11.1 for flat tops. having said that, the numbers are....
8.4 - 276hp @ 5k, 374tq @ 3.5k
9.1 - 308hp @ 5k, 386tq @ 3.5k
10.0 - 326hp @ 5k, 403tq @ 3.5k
10.75 - 337hp @ 5k, 415tq @ 3.5k
11.1 - 341hp @ 5k, 418tq @ 3.5k
11.51 - 347hp @ 5k, 425tq @ 3.5k
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Senior User
Joined: Jul 2003
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From: Dallas/Fort Worth
HP and Torque values?
I can't remember the name of the company off the top of my head (maybe someone else can help out? If not I'll do some research), but there is one company out there that forces an abrasive putty through passages (such as stock exhaust manifolds... 
) to greatly increase the flow; they have done the same with heads and stock intakes. This probably would be going a little over the line of cheating, but it would surely give you the edge up on the chebby guys. I'm thinking it was pretty expensive, so it may be out of the price range you want to work in.
) to greatly increase the flow; they have done the same with heads and stock intakes. This probably would be going a little over the line of cheating, but it would surely give you the edge up on the chebby guys. I'm thinking it was pretty expensive, so it may be out of the price range you want to work in.
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From: Dallas/Fort Worth
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HP and Torque values?
Thanks for the numbers GT40man.
The Extrude Honing sounds interesting but it is definately expensive! Thanks for the info johnsalterego.
I will watch EBay for the pistons. Thanks Torque1st.
The Extrude Honing sounds interesting but it is definately expensive! Thanks for the info johnsalterego.
I will watch EBay for the pistons. Thanks Torque1st.