Piston perfromance

Joe DeMarzo · 09-01-2013, 04:58 PM

Ok, so I am home and not at Indy racing so my mind starts thinking.....

How much performance difference is there between "flat with notches pistons VS a dish piston"? All other things being equal, valve, cam, same carb etc...

Doubt anyone has back to back this but someone has to be smart enough to figure this out.

P.S. the last thread on FI vs CARB was great.

Chipper Chapman · 09-01-2013, 07:07 PM

Flat pistons should give a better quench and more efficient burn. There is a trend toward d-shaped dishes for big inch pump gas engines, to keep a good quench and still lower compression.

Chris Hill · 09-01-2013, 11:10 PM

I don't think you can look at an A to B comparison for piston top for performance.

If you ask,"What effect does combustion chamber shape (head and top of piston) have on engine performance with everything else the same?" I think that is what you mean.

Joe DeMarzo · 09-02-2013, 08:43 AM

Chris, Chipper or anyone else: would a flat piston with notches be faster than a dish piston (everything else is equal)?

I thought the dish allows for a better burn rate but losing out on compression. Would you advise some one to build a dish if it was rated 20HP less than a flat with notches?

Would the combustion chamber in one be that much better than the other?

Dwight Southerland · 09-02-2013, 09:17 AM

Joe,
Assuming comparable compression ratio, there are instances in SBC Super Stock combinations where a properly shaped dish has a alight advantage over a similar combination with a flat top piston with valve reliefs. There are lots of other factors in that equation though, not just the dish vs. flat top comparison. That being said, the shape of the dish is critical for the advantage. For Stock combinations, the factory dish shape is a disadvantage in every situation I have seen.

carl hinkson · 09-02-2013, 10:52 AM

Same compression and reverse dome VS flat top the reverse dome whens every time.

Joe DeMarzo · 09-02-2013, 01:29 PM

Dwight, thank you for the insights on the factory stock dish shape ... there are some 305 combo's that are identical except the piston. The flat top is rated 20 HP more, and killer fast. Was thinking why not run the dish piston -260lbs.

Lee Valentine · 09-02-2013, 01:41 PM

Joe ,I believe there are other differences I think in cameros flat top engines are big cam dish are small cam.

Joe DeMarzo · 09-02-2013, 01:45 PM

Lee, they are not both Camaro's, one is a Camaro and the other is a different body style.

Dwight Southerland · 09-02-2013, 04:06 PM

Joe -

Are you talking Stock or SS? In either case, the flat top engine and the later shallow dish piston engines are at least a point more compression than the early dished piston engines, so its not apples to apples.

09-01-2013, 04:58 PM	#1
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 113 Times in 9 Posts	Piston perfromance Ok, so I am home and not at Indy racing so my mind starts thinking..... How much performance difference is there between "flat with notches pistons VS a dish piston"? All other things being equal, valve, cam, same carb etc... Doubt anyone has back to back this but someone has to be smart enough to figure this out. P.S. the last thread on FI vs CARB was great. __________________ Joe DeMarzo 1317 STK

09-01-2013, 07:07 PM	#2
Chipper Chapman Member Join Date: Jan 2004 Location: Belmont N.S. Canada Posts: 473 Likes: 246 Liked 166 Times in 71 Posts	Re: Piston perfromance Flat pistons should give a better quench and more efficient burn. There is a trend toward d-shaped dishes for big inch pump gas engines, to keep a good quench and still lower compression. __________________ Chris Chapman 1969 Chevelle NHRA F-G/SA 1090

09-01-2013, 11:10 PM	#3
Chris Hill Senior Member Join Date: Jan 2002 Posts: 655 Likes: 8 Liked 244 Times in 26 Posts	Re: Piston perfromance I don't think you can look at an A to B comparison for piston top for performance. If you ask,"What effect does combustion chamber shape (head and top of piston) have on engine performance with everything else the same?" I think that is what you mean. __________________ Chris Hill https://ihmusedparts.com

09-02-2013, 08:43 AM	#4
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 113 Times in 9 Posts	Re: Piston perfromance Chris, Chipper or anyone else: would a flat piston with notches be faster than a dish piston (everything else is equal)? I thought the dish allows for a better burn rate but losing out on compression. Would you advise some one to build a dish if it was rated 20HP less than a flat with notches? Would the combustion chamber in one be that much better than the other? __________________ Joe DeMarzo 1317 STK

09-02-2013, 09:17 AM	#5
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 778 Times in 193 Posts	Re: Piston perfromance Joe, Assuming comparable compression ratio, there are instances in SBC Super Stock combinations where a properly shaped dish has a alight advantage over a similar combination with a flat top piston with valve reliefs. There are lots of other factors in that equation though, not just the dish vs. flat top comparison. That being said, the shape of the dish is critical for the advantage. For Stock combinations, the factory dish shape is a disadvantage in every situation I have seen.

09-02-2013, 10:52 AM	#6
carl hinkson Member Join Date: Feb 2007 Location: NORTHEAST Posts: 287 Likes: 1 Liked 18 Times in 10 Posts	Re: Piston perfromance Same compression and reverse dome VS flat top the reverse dome whens every time.

09-02-2013, 01:29 PM	#7
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 113 Times in 9 Posts	Re: Piston perfromance Dwight, thank you for the insights on the factory stock dish shape ... there are some 305 combo's that are identical except the piston. The flat top is rated 20 HP more, and killer fast. Was thinking why not run the dish piston -260lbs. __________________ Joe DeMarzo 1317 STK

09-02-2013, 01:41 PM	#8
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 319 Times in 68 Posts	Re: Piston perfromance Joe ,I believe there are other differences I think in cameros flat top engines are big cam dish are small cam. __________________ Lee Valentine 1661 STK

09-02-2013, 01:45 PM	#9
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 113 Times in 9 Posts	Re: Piston perfromance Lee, they are not both Camaro's, one is a Camaro and the other is a different body style. __________________ Joe DeMarzo 1317 STK

09-02-2013, 04:06 PM	#10
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 778 Times in 193 Posts	Re: Piston perfromance Joe - Are you talking Stock or SS? In either case, the flat top engine and the later shallow dish piston engines are at least a point more compression than the early dished piston engines, so its not apples to apples.