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-   -   dome pistons vs. flat top (http://www.hotrodders.com/forum/dome-pistons-vs-flat-top-65629.html)

philr 07-10-2005 09:38 PM

dome pistons vs. flat top
 
I was just wondering if you had a 350 with a small dome piston with 10-1 comp. and a flat top piston with 10-1 comp. Same heads same cam and everything which one would run the strongest with a quench of .035.This is something I was just wondering and ther e may not be an engine like this. I waas just wondering how much the dome hurts the power. Thanks philr

HemmiGremmie 07-10-2005 10:17 PM

If your trying to keep the comp ratio at around 10-1 or so, then use the flat tops.
Flat top pistons will have a better flame travel than a domed piston, so only run domed if your trying to get the comp ratio up higher. HG

BigDawgsEatFirst 07-10-2005 10:17 PM

Quote:

Originally Posted by philr
I was just wondering if you had a 350 with a small dome piston with 10-1 comp. and a flat top piston with 10-1 comp. Same heads same cam and everything which one would run the strongest with a quench of .035.This is something I was just wondering and ther e may not be an engine like this. I waas just wondering how much the dome hurts the power. Thanks philr

I would put money on the flat top, with a quench of .040 the flat top would provide a better squeeze into quench area providing
combustion efficiency.

347mustang 07-10-2005 11:19 PM

flame travel is what makes the plain o flat top motors run so good

Triaged 07-11-2005 02:43 AM

Flat tops are often lighter then a dome top too...

baddbob 07-11-2005 06:49 AM

A dished piston will make even more power than a flattop if the quench is the same, better burn and more force on the piston's center. This would be a good test for a magazine to do, build three engines, all the same exact compression ratios, same piston to head clearance, but with different head chamber sizes and pistons to quanify the differences in burn rate and resulting power differences. The only variable would be the flow efficiancy of the heads- most open chamber designs flow bettern than small chamber designs. But a flow test could reveal those differences and adjustments could possibly be made to equalize the three. Bob

philr 07-11-2005 05:31 PM

Going to use flat top piston
 
I am going to use the speed pro flat top piston with 2 valve reliefs.It will do better with pump gas.I can get the quench correct maybe it wont ping and it will run better. philr

Malibu73 07-11-2005 07:18 PM

I have two questions:


1. What is 'Quench'?


2. How many different piston types are out there? e.g. Flattop, Domed, Dished etc.

lluciano77 07-12-2005 12:06 AM

Search in the HotRodders Knowledge Base for "quench" It is in there.

Dome pistons are an airflow restriction. Flat top pistons are the best flowing.

Malibu73 07-12-2005 01:56 AM

What about dished pistons?

Sarrowood 12-12-2012 03:15 AM

Does it hurt to use a wire wheel on cleaning the top of a flat top piston?

MouseFink 12-12-2012 06:24 AM

Were can you find domed pistons that will produce 10:1 compression ratio?

Every domed piston I have seen produce at least 11:1 compression ratio compared to the same engine with a flat top piston.

cdminter59 12-12-2012 07:00 AM

dome pistons vs. flat top
 
Quote:

Originally Posted by Sarrowood (Post 1621868)
Does it hurt to use a wire wheel on cleaning the top of a flat top piston?

Yes, can leave scratches. It is better to use a type cleaner that is compatible with aluminum. GM Top Engine Cleaner is a good cleaner. Soda blasting is another way.

hcompton 12-12-2012 07:22 AM

Quote:

Originally Posted by philr (Post 478668)
I was just wondering if you had a 350 with a small dome piston with 10-1 comp. and a flat top piston with 10-1 comp. Same heads same cam and everything which one would run the strongest with a quench of .035.This is something I was just wondering and ther e may not be an engine like this. I waas just wondering how much the dome hurts the power. Thanks philr


the dome pistons will have more compression. But yes flat tops are best for 350 engines with 64 cc heads.

4 valve reliefs are cheaper since they fit on both sides 2 need to be different on each side. so it cost more.

dome can hurt power if the head is not right for it. with 64 cc heads its not real easy to buy proper dome pistons that are not in the 12:1 range. BBC and hemis run domes with great success but requires a little know how.

vinniekq2 12-12-2012 08:59 AM

kind of what mouse fink said. If you have a short stroke engine (283,289) you will need a dome to make compression,with a long stroke engine things change the other way,like if you build a 434.
you need to find the correct combination of heads and piston design to fit your application and displacement.


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