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907 2L high compresion pistons whats avaliable  Rating:  Rating
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 Posted: 08-11-2006 02:09 pm
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normv
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I am currently building a Jensen Healey to race in Historic sports car racing in Australia, I looking for pistons in the 10.5-11:1 compression ratio for a 2L 907 , I have not been able to find anyone who lists such a piston, As I am on the other side of the world to most piston manufactures I am a little reluctant to get full custom ones made, however if this last ditch attempt to find some suitable ones fails that is the way I will have to go. I have tried CP and JE with no success so far excluding the full custom option
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 Posted: 08-11-2006 02:13 pm
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Ron Earp
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You try Delta Motorsports? They've got flat top pistons for some decent compression ratios. Club Store might have those too.

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 Posted: 08-11-2006 02:54 pm
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Joel
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Call Jim Bean Engineering.  Even if they don't have them they'll give you good advice.  And it's pretty easy to get pistons thru Ross Racing Pistons.  Check out their website.  I just had some made for a buddies Cobra - and shipped them to Japan. 


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 Posted: 08-11-2006 05:31 pm
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Greg Fletcher
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I think you'll need to go the full custom route on those. Lotus pistons from JE and CP (or any manufacturer) need to be made up in quantity and that is not an item that gets requested, so no one wants to stock it. Typically, if an owner wants higher compression, they also want better bottom end torque to go with and they install a stroker crank and the higher compression 2.2 pistons (which have a revised pin height). Good quality pistons are not cheap. Historic class or not, I'd consider the 2.2 mod as well to make the change worth your time and effort.

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 Posted: 08-11-2006 07:01 pm
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Judson Manning
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Use Delta's off-the-shelf JE Flat-top pistons....As you can see below, the pistons can produce a CR range anywhere from  9.5 to 11.5 to 1.

 

A 0.030" over-bore = 502cc/cylinder

Combustion Chamber volume = 35cc to 40cc (depending on amount of shaving)

Delta's Flat-top 'dish' volume = 8.5cc

Head-gasket (new) volume = 9cc

CR = [502 + (37.5+8.5+9)]/(37.5+8.5+9) = 10:1

use OEM or Aftermarket copper gasket (0.030" thick) => CR = 10.7:1

Deck the head and/or Block an additional 0.020" => CR = 11.5:1

 

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 Posted: 08-11-2006 07:06 pm
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Jensen Healey
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My 2 Liter flat tops (no dish) from Delta make 155 psi on my compression tester which works out to about 10.5:1. The engine idles great and requires what we call 93 octane here in the states to prevent pinging (pinking).

Have fun,

Kurt

JH 13148

Last edited on 08-11-2006 07:08 pm by Jensen Healey

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