Reply With QuoteI'm running 9:35/1 pistons 20 thou over composite head gaskets no issue with 91ron fuel. Also a crower 50230 camshaft which is working well.
Master
SupporterHi again,
My engine from my 79 RRC has finally made it to the front of the queue with the machinist.
The cylinders are going to need a 20 thou rebore. Looking at pistons, I can get +20 in both standard 8.13:1 and HC 9.35:1.
Is this a good time to raise the compression? Are there negatives to this, other than needing decent fuel?
I’m also looking at camshaft options…can anyone offer some experience here? The car will be staying with the LT95 gearbox and dual strombergs with electronic ignition.
im not looking for any drastic changes, just improvement upgrades that would make sense whilst replacing these parts anyway.
thanks in advance!
Marcus
2014 Defender SWB
1959 Series II 109 Ute
1998 Range Rover P38 4.6 (cremated)
2012 L320 5.0 Supercharged
1979 2 Door RRC
Wizard
SubscriberI'm running 9:35/1 pistons 20 thou over composite head gaskets no issue with 91ron fuel. Also a crower 50230 camshaft which is working well.
Master
SupporterI have just put together a 3.9, which was 8.13:1, with some 9.35:1 pistons. I had material taken from the block and heads to give me around 9.8:1 compression. Also used composite gaskets.
I run on LPG, but the higher compression has made a huge difference. If I were at your stage and you need new pistons anyway, I would go for the high compression ones.
Master
SupporterThanks guys,
High compression it will be.
I’m also leaning towards a stock camshaft. I think I’ve over researched it and come full circle…
Marcus
2014 Defender SWB
1959 Series II 109 Ute
1998 Range Rover P38 4.6 (cremated)
2012 L320 5.0 Supercharged
1979 2 Door RRC
Master
SupporterI also went with the standard camshaft, ERR5924, for the 3.9 EFI motor. Gives good torque down low, its great between 2000-4000rpm. Maximum power is at around 4500rpm and it won't really rev past, this but there is no need to. I would rather have the power and torque where I can use it rather than having to rev it harder to get maximum power.
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