6 replies to this topic

[Wright&Wright]

Does anyone know what kind of maximum compression ratio is suitable for the Cooper D top pistons?

 

I'm rebuilding the 998 engine for around 60bhp on a +20 thou overbore. The head is a 295 and hasn't been skimmed but did does appear to have an appropriate amount of port work done. 

 

I want to run around 10.5:1 comp ratio but I'm not sure whether the original pistons will be good in coping with this? Any help would be appreciated.

[Carlos W]

If the engine is apart, I'd measure the compression ratio

[blacktulip]

What cam are you using?

[Spider]

Just to be clear - you'd like to know if the original Raised 'D" Cooper Pistons are OK with a CR of 10.5:1?

 

Yes, my wordy.

 

In fact they'd be OK right up to about 14:1.

[grck1]

can you still buy 998cc d top pistons?

[gazza82]

Try F W Thornton's ... they hold new old stock of a lot of engine parts (and knew that before they were on Car SOS with the Austin 12!)

[Wright&Wright]

I'll most definitely be measuring the comp ratio before the build is finished but thanks for the advice.

The cam is a 266.