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Discussion Starter · #1 ·
I have a 1980 I an runnig on a 1/4 mile dirt track, I recently blew the stock engine.

I would like to raise the compression, whith a early z car head or pistons and keep
fuel injection, what would be the best way to do this and from what other engines
should I get parts, I want a 11-13:1 CR.

I also have a a R200 rear-end under it, I also have a R180 fron a 81', what are the gearings of these diffs?

I was also wondering how high a lift cam I can run without hitting the pistons?

One more thing I would Like to stroke this engine, where should I look for a new crank?

Thanks alot,
I will start racing this car again in March.
 

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Hi clintn-----------------Most folks seem to use the E-31 or E-88 head from an early (pre '73) 240Z for a high compression motor. To get the 11-13/1 ratio you want, you would need to mill the head and shim the cam towers. You can also do this with one of the later P-90 heads, which still has the square exhaust ports and no liners. You'll need to cut relief notches for the valves on the cylinder bore tops if you use the early head. It's also recommended that the larger 280Z exhaust valves are installed on early heads, along with steel valve seats. The P-90 head already has the steel seats. You will want flat top pistons for the increase in compression.

If the R-200 diff you are running came with the car and is stock, it should be a 3.90/1 ratio. This is assuming it is a manual trans car. The R-180 is most likely a 3.545 unit, but I'm guessing here.

Hitting the pistons isn't the main problem with high lift cams. The real issue is binding of the valve springs. Over .460 lift will get you in the danger zone with the springs, they are fully compressed and solid at this point. The pistons can be relief cut to clear the valves.

Stroking the engine is best done with an LD-28 crank from a Maximum diesel. This crank is usually coupled with KA-24 pistons from a 240SX to avoid severe angles between pistons and crank. Be advised that stroker engines may be slower revving, and may not yield the power curve you need for short track racing.

Hope this answers some of your questions. Good luck with the upcoming racing season!

Roadman
Gulfport, MS
.
 
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