Hi

Does anyone know the combustion chamber volume of 681F chambered heads for 1300 and 1600?

Cheers

9cc

Thanks

I don't suppose that you'd know the volume of the combustion chamber in a 1300 82.5mm 711m piston would you?

Hi Nick
JPE in south Australia do a very nice 83.5 piston with 1300 bowl and deeper and wider valve cutouts in crown giving a CR around 10.5 (from memory)with 240 datsun thin rings, using std head gasket. I have used these in several engines giving 1340 or 1700 depending on block used. I also ran with flat head cos you get bigger valves without chamber restriction. I think I have 3 good ones and 1 brand new in the shed. (droped a valve seat 100ks after hardened inserts fitted, wasn't to happy about that).

Thanks for the info.

Reason I'm asking is that I'm obsessed with doing a blow through turbo set up on something. The motor i have is a 1600 bored out to 1660 with pistons from a 1300 giving the just over 10:1 CR and a chambered head would drop the CR down into the region suitable for taking a bit of boost. I realise it's a bit like putting grandpa on viagra but just the same it would be interesting to see what happened while it lasts.

PJ and Theo have built turbo x flows,send em a pm, Iam sure they would be able to help with info.

The chambered head wont be enough if you use the 1300 pistons. You will have to use 1600 pistons and a de-compression plate to get the comp down to where you need it to be.

Back of a coaster stuff but
1660cc = 415cc per pot
With a chambered head:
= 421cc per pot
415cc 10:1 cr means a 41.5cc combustion chamber vol
Plus the 9cc in the head = 50.5cc
So 421/50.5=8.33 CR
Not after a huge amount of boost but that should be enough to take 14psi wouldn't it?
A stock 1600cc with 9:1CR would drop to 7.65CR with a chambered head losing what low end torque you start with.

So does anyone have a chambered 681f head or complete motor they want to sell in the interests of science? Sydney area ideally.