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12.5 to 1 compression pistons

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Old 09-26-2010, 12:10 AM
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Default 12.5 to 1 compression pistons

is it possible to use the 12.5 to 1 pistons found in the 2azfxe engines (hybryd) engines found in the lexus HS 250h and the hybryd camry

if so will they hold up under full pressure and non nitrous use
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Old 09-26-2010, 12:27 AM
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Originally Posted by mustb3ds
is it possible to use the 12.5 to 1 pistons found in the 2azfxe engines (hybryd) engines found in the lexus HS 250h and the hybryd camry

if so will they hold up under full pressure and non nitrous use
Good question. I don't kow but suspect the answer is no. However JE makes a 11:1 piston that should work.

Can you run E85 exclusively? That might be one way to use 12.5:1 pistons. I don't think 93 pump would cut it.
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Old 09-26-2010, 12:45 AM
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good point Fred

i was thinking 93 would run but im not completely sure

i found that these pistons are a standard toyota piston here http://en.wikipedia.org/wiki/Toyota_AZ_engine#2AZ-FE

but they do not run these as a high compression engine

and i wouldnt have a clue if they have e85 here
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Old 09-26-2010, 12:56 AM
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and i just checked on the e85

of coarse they have e85 here 1 just a mile from me but its on a military post i cant get on and the other that has it isnt open to the public so the closest to me is 110 miles from my house but only 12 from where i work
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Old 09-26-2010, 01:19 AM
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E85 alone wouldn't do it anyway. I doubt the oe fuel injectors would flow enough for E85 and greater than oe power levels. I believe for 12.5:1 you'd need at least a Unichip piggy for timing and bigger injectors to run E85. OTOH, you might get away with 11:1 on 93 pump or E85 with 370-440cc injectors and the ECU knock control.

I found those 2AZ-FXE pistons for sale on-line. Only $50 each suggests that they are cast and unlikely to hold up in a performance app.
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Old 09-26-2010, 03:46 PM
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93 oct should be fine but with some tuning.. E85 definitely possible but again you would need tuning.
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Old 10-05-2010, 07:42 PM
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yea i know id definately need to tune for almost any combustion mod and i was certain the pistons were cast not forged

but my qwestion was if they would hold up running them as a hi compression engine as they are not used in that way in the hybrid engines

in the hybrids they change the cams and have a crazy grind that allows the cylinder to start the up stroke before the intake valves close thus not utilizing the full compression capability of the piston in the stroke

they were the only pistons with that hi of a compression ratio that ive found for our engines without having them specially made in a forged piston

but hey it was just a thought and an observance of whats available
to build a n/a motor

ill also ask the mechanics at toyota for there thoughts on running them in a hi-compression engine setup

any other inputs on this is appreciated
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Old 10-05-2010, 11:09 PM
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Mill the head a little?
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