Super Charged Compression Ratio

[melhookv12]

Looking at different engines. I currently own a Jaguar XKR V8. Stand a Rd compression ration is 8.9:1. The piston and cylinder head are damaged. Piston not available.

The NA 4.0 litre has a compression ratio of 10.5:1.

What would be the issues using the higher compression engine ? Would I need to run less boost? Would pump fuel be OK to use.

Thanks for any replies.

[Evoluzione]

Unless anyone has done it there is no way of knowing for sure. It may run at less boost and/or on 100 pump fuel, only a test on a dyno would tell you.
You could always investigate taking some out of the combustion chamber (if at all possible) or the dish on the pistons if they have any to lower the CR.

[Krikkit]

Could you rebuild with some forged pistons instead? You could get the right compression ratio to match OE without too much trouble. Certainly less expensive than re-engineering the whole thing...

[Boosted LS1]

Or, you could add a simple water injection system if you don't want to change the mechanicals.

[GavinPearson]

I would use a second hand piston.

The NA piston has way too much CR for the engine and isn't sufficiently strong.

[melhookv12]

GavinPearson said:

I would use a second hand piston.

The NA piston has way too much CR for the engine and isn't sufficiently strong.

Can't find a second hand one. No new stock from Jaguar. If I rebuild will probably go forged.

Thanks

[stevieturbo]

Just get a set of pistons made if there are no off the shelf options.