dished or reversed dome pistons??

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dished or reversed dome pistons??

Post  bbcoupe on November 28th 2017, 3:35 am

Pro's and cons for using either dished or reverse dome pistons?

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Re: dished or reversed dome pistons??

Post  rmcomprandy on November 28th 2017, 10:34 am

bbcoupe wrote:Pro's and cons for using either dished or reverse dome pistons?

Quench area is the only advantage to a reverse dome design.

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Re: dished or reversed dome pistons??

Post  gt350hr on November 28th 2017, 12:23 pm

Somewhat dependent on volume needed. More volume favors the round dish as a D or mirror image dish can get too deep on stroker applications and possibly cause rod interference. Less of an issue on aluminum heads. NOT an issue on power adder applications ( boost or NOS).   Just My Personal Opinion.

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Re: dished or reversed dome pistons??

Post  Paul Kane on November 28th 2017, 2:35 pm

bbcoupe wrote:Pro's and cons for using either dished or reverse dome pistons?
Most round dish pistons do have a circular squish band around their perimeter, and so if your cylinder head has a quench pad then there will be some mixture motion from the squish band on the pistons working against the quench pad of the head.

On the other hand when your head has a round open chamber of which none overhangs the cylinder, then there isn't a flat top or dish top piston of any shape that could provide quench effectiveness.

As far as "pro's and cons for using either dished or reverse dome," that depends on the build needs and application of the engine.
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Re: dished or reversed dome pistons??

Post  bbcoupe on November 28th 2017, 5:24 pm

Currently using dished on my 545 with closed chamber BT heads. Will be changing pistons and have been advised a reverse dome will give a benefit. Is going to a custom piston to suit the comp I need worth the expense? (Should've started with this info)


Last edited by bbcoupe on November 28th 2017, 9:12 pm; edited 1 time in total (Reason for editing : error)

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Re: dished or reversed dome pistons??

Post  Mark O'Neal on November 29th 2017, 11:36 pm

You can do a bigger dish with a full round?

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Re: dished or reversed dome pistons??

Post  gt350hr on December 1st 2017, 1:19 pm

VOLUME Mark. You know better.


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Re: dished or reversed dome pistons??

Post  CDMBill on December 1st 2017, 2:41 pm

We have been using JE's with a very shallow spherical dish with a ~.300 quench ring for a Cali 91 pump gas 598" with good results in terms of power and detonation resistance. Quench pad to head distance is .040"

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Re: dished or reversed dome pistons??

Post  bbcoupe on December 1st 2017, 7:31 pm

Some more info regarding my question and current combo....

3800lb street car that hit's the track a couple of times a year. N/A 545 (4.5 with 6.8 rods, probe dished 18.5cc pistons, BT Chev heads) has run 10.47@133.

Motor out and considering upgrades. One suggestion has been to improve quench by using a "mirror image/reverse dome" dished piston.

Value per $$ is on my mind. To replace same pistons in next size $380 v new reverse domes $950???


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Re: dished or reversed dome pistons??

Post  Mark O'Neal on December 1st 2017, 11:50 pm

gt350hr wrote:  VOLUME Mark. You know better.

       

I know better than what?

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"Value per $$ is on my mind."

Post  Paul Kane on December 3rd 2017, 4:17 pm

bbcoupe wrote:Currently using dished on my 545 with closed chamber BT heads. Will be changing pistons and have been advised a reverse dome...to improve quench by using a "mirror image/reverse dome" dished piston.

Value per $$ is on my mind. To replace same pistons in next size $380 v new reverse domes $950???
First, is there currently a problem with your engine combination, such as detonation, that might be corrected with pistons that cost $570 more?  If not, then what other reason are you considering spending $570 more for pistons when the $380 set already works in your combination (ie, will you be increasing compression ratio, etc)?

Second, if the combination works then does your block need to go to the next bore size? Or will a a hone and re-ring with your current pistons suffice?
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Re: dished or reversed dome pistons??

Post  bbcoupe on December 3rd 2017, 11:23 pm

Paul Kane wrote:
bbcoupe wrote:Currently using dished on my 545 with closed chamber BT heads. Will be changing pistons and have been advised a reverse dome...to improve quench by using a "mirror image/reverse dome" dished piston.

Value per $$ is on my mind. To replace same pistons in next size $380 v new reverse domes $950???
First, is there currently a problem with your engine combination, such as detonation, that might be corrected with pistons that cost $570 more?  If not, then what other reason are you considering spending $570 more for pistons when the $380 set already works in your combination (ie, will you be increasing compression ratio, etc)?

Second, if the combination works then does your block need to go to the next bore size? Or will a a hone and re-ring with your current pistons suffice?

Combo has served me well. I've had a couple of unfortumate/unavoidable incidents (pin hole in no.8 on old block, oil pump pickup breaking- new block)
On the highest octane pump fuel(our pump fuel is 91,95,98 and 100) it runs well and no signs of detination on engine components. It will knock a little on 98 under high load acceleration.
This will be the 4th rebuild using current pistons (2 different blocks) and thust side is leaving excessive wear marks on bores.
A few additional C.I. wont hurt either, if a piston with better quench is a benifit maybe the extra expense should go even bigger (4.500 bore)?


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Re: dished or reversed dome pistons??

Post  gt350hr on December 4th 2017, 4:26 pm

Since you have a "modern" chamber design , I doubt you would see more than 10 or so HP with a mirror image design. Better chamber designs aren't as critical on shape. save your money.

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