View single post by Sylva
 Posted: 05-18-2007 06:15 pm
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Sylva

 

Joined: 09-14-2006
Location: Malaysia
Posts: 54
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 I've blown my engine up again, last year I went through two sets of JE Pistons due to Con Rod stretch, and I've just damaged a set of Cosworth pistons due to overheating, but the damaged car did win the race.

I have now ordered another a set of JE/Cp pistons from Greg, but I have now decided that I'll go for new 'steel rods'

My crank is bored off line (not a rebore lotus did it that way), so that Number 4 bearing is some 14thou of an Inch lower from the 'head face' than Number 1.

With Lotus rods I get away with the rod stretch if I allow up to 48 thou of piston stand out, so with a 70 thou head gasket I'm getting 22 thou of clearance to the squish plate on the head.

Lotus tell me 20thou of stretch occurs on Std rods at 7,800, rpm. so my figures are about right for Lotus rods.

My plan is to use steel rods and deck all the pistons at 60 thou clearance, (or 10thou stand out at TDC). This will mean taking 52 thou of No 1, 46 of 2 and 3, and 38 thou of No 4 piston.

So question is

Has anyone machined 50 thou of the JE or Cp pistons? I know this will drop the CR but I'm not worried, I have enough power

Any comments on the 60 thou clearance?

What experience do people have of steel rods?

My engine is a 2.2 910 Esprit S4 Block, runs to 9000rpm and Lotus calculate around 270 bhp at 9000. The engine has been taken down 3 times and 9000 rpm does no damage to the bottom, I've reused he same mains the last 3 times the engine has been taken down.

 Thanks for any advice

Kelvin