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std bore 400 compresson problem

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Old Oct 13, 2009 | 04:09 PM
  #1  
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From: parma,OH
Car: 91 camaro RS
Engine: 350, forged 355 in the works
Transmission: 4 speed goin to th400
Axle/Gears: stock 9bolt, 3.27
std bore 400 compresson problem

ok im building a std bore 400 i want to fun forged pistons and have low compression and i have 60cc heads,

the question is is there a place that sells thes pistons in a dish
or can i use pistons for a 5.7 rod on the stock 5.565 rod to get a taller piston to deck witch in return will do the same as a dish piston and then run a 350 crank like a 377 just not .030 over, so that will make a 372cid with atound 8.7-1 to 9.6-1. ive done plento of searching and cant find nothing,

to me it seems like it should work fine, just want a couple of opinions b4 i spend my money, and there should b no clearance problems because of the shorter stroke.
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Old Oct 13, 2009 | 04:47 PM
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: std bore 400 compresson problem

Originally Posted by 5.0slayer
the question is is there a place that sells thes pistons in a dish
What CR you looking to get ?
Your small chamber size is going to limit you as the normal 22-26cc 400 piston dish gives about 8.5 with a 76cc head.
JE # 232514 has a massive 36cc dish and still gives 8.7 on a 60cc head using 5.7 rod.
Head change would be cheapest option to lower CR
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Old Oct 13, 2009 | 04:56 PM
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From: parma,OH
Car: 91 camaro RS
Engine: 350, forged 355 in the works
Transmission: 4 speed goin to th400
Axle/Gears: stock 9bolt, 3.27
Re: std bore 400 compresson problem

im lookin to run about 10lbs on the 400
but yhe question is can i use pistons for a 5.7 inch rod on a 5.565 rod the piston sits farther from the head and will give me more compression room in return it will lower my compression, its a very tight budget build, and the heads have crazy money in them from my 350 i had b4 this
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Old Oct 13, 2009 | 04:58 PM
  #4  
5.0slayer's Avatar
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From: parma,OH
Car: 91 camaro RS
Engine: 350, forged 355 in the works
Transmission: 4 speed goin to th400
Axle/Gears: stock 9bolt, 3.27
Re: std bore 400 compresson problem

and i really think thar 800 is to much for what im willing to spend on pistons i would rather gey a used set off of here for 160 and get it bored then spend that
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Old Oct 13, 2009 | 06:42 PM
  #5  
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: std bore 400 compresson problem

Originally Posted by 5.0slayer
and i really think thar 800 is to much for what im willing to spend on pistons i would rather gey a used set off of here for 160 and get it bored then spend that
I didn't suggest buying them ; just an example of the CR with a 36cc dish on your 60cc head

Originally Posted by 5.0slayer
question is can i use pistons for a 5.7 inch rod on a 5.565 rod .. in return it will lower my compression,
Yes but you end up with some crazy numbers

1.560 CH ( stock 400 w/ 5.565 rod ) to 1.425 CH ( 400 piston for 5.7" rod ) difference is .135" .Add the 0.025 block deck height and you have a quench of 0.160 without a gasket!

Google "quench height " and see how important quench is in preventing detonation especially under boost

Better price
http://www.summitracing.com/parts/STL-H615CP/
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Old Oct 13, 2009 | 06:55 PM
  #6  
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From: parma,OH
Car: 91 camaro RS
Engine: 350, forged 355 in the works
Transmission: 4 speed goin to th400
Axle/Gears: stock 9bolt, 3.27
Re: std bore 400 compresson problem

i was told to only run forged pistons for boost,i did the research b4 i asked ad with a 5cc dome it was a 9.6 to 1, i mean i can make up some compression if i just used domed pistons rite?

or just used the stock 400 crank and made it up there
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Old Oct 13, 2009 | 07:06 PM
  #7  
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Joined: Nov 2007
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From: parma,OH
Car: 91 camaro RS
Engine: 350, forged 355 in the works
Transmission: 4 speed goin to th400
Axle/Gears: stock 9bolt, 3.27
Re: std bore 400 compresson problem

ok i looked and with 7.8cc domed piston and the 350 crank and 60cc heads with 5.565 rods its 9.3-1 on 3 different calcs

http://www.summitracing.com/parts/TRW-L2311F/
these r for 5.565 rods and useing them on a 350 crank will give me the same CR, would this work?, and is it safe to boost a 372 with cast 350 crank

Last edited by 5.0slayer; Oct 13, 2009 at 07:14 PM.
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Old Oct 13, 2009 | 08:21 PM
  #8  
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: std bore 400 compresson problem

Originally Posted by 5.0slayer
is it safe to boost a 372 with cast 350 crank
I wouldn't because 372 is a revver
Ask the guys over in 3rd Gen Power Adder, what CR you can run with what boost first
https://www.thirdgen.org/forums/power-adder/

Then you can work back to see what pistons will give you the right CR. Just guessing otherwise.
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