Piston Bowls

Fingers

Fingers

Village Idiot
Vendor/Sponsor
Apr 1, 2008
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White Oak, PA
Close to the LB7/LLY ratio. I have a mixed bag of reasons why. I'm happy to hear other people's thoughts on the topic.

If the pistons have to be clearanced for the valves, then the ratio will drop closer to the LBZ ratio.
 
RENODMAX

RENODMAX

Dead Wrong
Mar 4, 2008
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dmaxfireman said:
very cool jon! i say that you said the compression ratio will be close to stock. is that lb7/lly or lbz stock?

i've always been interested in testing a higher compression piston
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High compression pistons have been used for a while...Looks sweet Jon. If there is anyone here to tackle this thing I think it'd be you. I knew when you said a delipped piston is weaker than a stock unit that something was on the horizon.
 
Fingers

Fingers

Village Idiot
Vendor/Sponsor
Apr 1, 2008
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So, why 50% stronger?

Several people have measured the cylinder pressures using my system. One in particular had been running stock pistons at absurd pressures. The stock tune seems to keep the chamber pressures just under 3000 PSI. The measured pressures on this person's application were in the 4500 PSI range. The boost numbers to get there were, well, high.

My goal is to have a piston that should handle those pressures when running hard at high boost.

4500/3000 = 1.50 or 50% more.
 
dmaxfireman

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
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RENODMAX said:
High compression pistons have been used for a while...Looks sweet Jon. If there is anyone here to tackle this thing I think it'd be you. I knew when you said a delipped piston is weaker than a stock unit that something was on the horizon.
Click to expand...

i am talking about 18:1+ compression.
 
minisub

minisub

6-5/6-6;Whatever It Takes
Sep 11, 2006
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These going in your built motor, your stock motor or someone else's? If one of the first two, I am available Superbowl weekend for all but the four hours it will take to watch the Steelers beat the falcons...:)
 
Fingers

Fingers

Village Idiot
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Apr 1, 2008
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minisub said:
These going in your built motor, your stock motor or someone else's? If one of the first two, I am available Superbowl weekend for all but the four hours it will take to watch the Steelers beat the falcons...:)
Click to expand...

Going into the stock spare. I plan to build the short block then swap the heads and such over from the built motor. I've started tearing down the stocker so I can get it to the machine shop.
 
dmaxfireman

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
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Fingers said:
And what do YOU think the advantages would be?

:poke:
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purely to see what sort of efficiency could be achieved. less fuel and less heat on the piston and still make equivalent power to a lower comp. piston with more fuel. i wonder where the gains would stop if they could even be better than stock.


what is your opinion.
 
bullfrogjohnson

bullfrogjohnson

Big Girl!
Nov 20, 2006
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dmaxfireman said:
purely to see what sort of efficiency could be achieved. less fuel and less heat on the piston and still make equivalent power to a lower comp. piston with more fuel. i wonder where the gains would stop if they could even be better than stock.


what is your opinion.
Click to expand...

Higher comp ratio is taking advantage of free HP, but you will create more cylinder pressure which will be much harder on the entire bottom end.
 
bullfrogjohnson

bullfrogjohnson

Big Girl!
Nov 20, 2006
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Fingers said:
Nothing is cost efficient for the Dmax.

Special order slugs were > $200 a piece.
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Thats the truth, there is nothing cheap for a Dmax.

I was curious more about cost of blanks vs. forged units. At 200.00 a hole plus machine work it will be comparable to the forged units. And if the pistons hold up it will be great for the guys that still want to daily drive there trucks with big power.
 
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