Chevy Nova Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
852 Posts
Discussion Starter #1 (Edited)
Ok all, what is the difference in these and which is best to use? Putting my 383 together. I know it has to do something with differences in comp ratio, but i need some expert input. ALSO IM RUNNING TRICK FLOW ALUM HEAD 64CC COMBUSTION CHAMBERS. THANKS.

len
 

·
Registered
Joined
·
3,895 Posts
Flat-top:


Reverse Dome (sometimes called a dish but is a little different):


Dish piston (NOT reverse dome...No "Squish" pad)


Dome or "Pop-up"


As for which one is right for your build????? That depends on what you're doing with it and how much compression you want.:yes: There's several calculators available out there like this one that will help you calculate your compression.
http://www.kb-silvolite.com/calc.php?action=comp
 

·
Premium Member
Joined
·
15,966 Posts
The "BEST" is a different for different engines.

In the Small block Chevy the flat top piston has been proved to be the best.

A flat top piston with the small block head chamber design will provide the best flame travel. This is what is best for a SB, not the ultimate flame travel like found in a HEMI or Canted valve design head chamber. This is the best for a SBC!

Flame travel IE: Combustion chamber air flow can have a great effect on performance.

Compression goal has more important choice of the piston design.

Example: Based on same compression with both combinations.
A Flat top with a small chamber head will out perform a Pop up with a large chamber head.
Why? Flame travel, piston is lighter.
This is on a SBC, In some other type engines this is not true.

IMO
AL
 

·
Premium Member
Joined
·
13,309 Posts
383. with flat tops can make anywhere between 11.0:1 and 10.5:1 or higher depending on prep, and gasket.. with 64cc heads
 

·
Registered
Joined
·
852 Posts
Discussion Starter #6
i just figured outr my heads are 62cc comb chamber. would this make a huge difference? Will I be able to run pump gas 93 octane?

Len
 

·
Registered
Joined
·
3,895 Posts
i just figured outr my heads are 62cc comb chamber. would this make a huge difference? Will I be able to run pump gas 93 octane?

Len
There's several calculators available out there like this one that will help you calculate your compression.
http://www.kb-silvolite.com/calc.php?action=comp
How much compression you can run with pump gas will depend on a LOT of things. Quench/squish distance, cam specs, intake style, Torque converter, gearing, how low of an operating temp you intend (and can) run, and most importantly HOW WELL YOU CAN TUNE IT!!
 

·
Registered
Joined
·
852 Posts
Discussion Starter #8
I spoke with the engine builder ( wheeler power products) and they advised to go with the forged dish piston with my heads which will put the compression around 10:1. Thanks

len
 

·
Premium Member
Joined
·
11,072 Posts
I have an engine builder friend with a dyno--he likes tiny chambers, and if you need less compression he likes inverted domes. He found a lot of power in a boosted application compared to the same engine with a flat top/larger chamber combo. On a big budget project he'll have the pistons made to mirror the shape of the chamber.
My 410 has flat tops and 64cc heads and is just about 12-1.
91 octane pump gas is what we have in So.Cal. and that's what I run.
 

·
Premium Member
Joined
·
15,966 Posts
I have an engine builder friend with a dyno--he likes tiny chambers, and if you need less compression he likes inverted domes. He found a lot of power in a boosted application compared to the same engine with a flat top/larger chamber combo. On a big budget project he'll have the pistons made to mirror the shape of the chamber.
My 410 has flat tops and 64cc heads and is just about 12-1.
91 octane pump gas is what we have in So.Cal. and that's what I run.
You say boosted?
Blower application?
Seems this might be good for NOS!!!!!!

I would like some info on this deal!!!

Who's doing the pistons?

Thanks
Al
 

·
Registered
Joined
·
3,849 Posts
i just figured outr my heads are 62cc comb chamber. would this make a huge difference? Will I be able to run pump gas 93 octane?

Len
Good question, how much will it increase the CR from a 64cc chamber. FYI, I have eddy aluminum heads (RPM performer) with a 64cc chamber and Manley flat top pistons. CR is 10.5:1. Not bad at all for pump fuel, I do have EFI so that helps a lil. JR
 

·
Premium Member
Joined
·
11,072 Posts
You say boosted?
Blower application?
It was a Vortech blown 383 in a 5000lb. van that ran 11's--The 39° air temp inside from the A/C was nice in summer too!

I think he used JE at the time. I just read a story from JE in the new Chevy High that came today-says kinda the same thing about inverted domes.
 

·
Premium Member
Joined
·
15,966 Posts
It was a Vortech blown 383 in a 5000lb. van that ran 11's--The 39° air temp inside from the A/C was nice in summer too!

I think he used JE at the time. I just read a story from JE in the new Chevy High that came today-says kinda the same thing about inverted domes.
Got my CHP today, I guess I need to open it up!!

Al
 
1 - 13 of 13 Posts
Top