Thread: head gasket

Originally Posted by rovercare

Seeing as you've got the book out Ben, what's bore size, and I'll find the formulae to work out what difference it makes to compression

Bore x Stroke is 102x118

Using the extreme values, it could vary compression between 16.7 and 17.7:1 (should be 17:1)

Originally Posted by isuzurover

Bore x Stroke is 102x118

Using the extreme values, it could vary compression between 16.7 and 17.7:1 (should be 17:1)

Couldn't see 1 point of compression ratio being the cause, considering its so stupidly low

Originally Posted by rovercare

Couldn't see 1 point of compression ratio being the cause, considering its so stupidly low

I doubt it would have been the cause of your problem - as it was leaking all over the place.

Not sure what you mean by stupidly low??? The LR Tdi engines are 16:1. Most other DI diesels I am aware of are between 15:1 and 19:1 Indirect engines like my 2.25D have ratios like 23:1, but that is pretty high.

Originally Posted by isuzurover

I doubt it would have been the cause of your problem - as it was leaking all over the place.

Not sure what you mean by stupidly low??? The LR Tdi engines are 16:1. Most other DI diesels I am aware of are between 15:1 and 19:1 Indirect engines like my 2.25D have ratios like 23:1, but that is pretty high.

Pretty much that^^^, you wouldn't think the sealing ring would accomodate 17:1 no worries, but then blow out at 23:1 would you

Its not like your adding 15psi to 23:1 therefor increasing static comp further again

How much does 15psi add to static compression anyway

Also almost all direct injection oilers are turbocharged, that I'm aware of

Originally Posted by rovercare

How much does 15psi add to static compression anyway

Atmospheric pressure at sea level is almost 15psi. So assuming 100% Volumetric Efficiency and 15psi boost at the entrance to the cylinder at the same temperature as an NA engine, you are effectively doubling your compression ratio.

Regarding head gasket thickness, IMHO people are barking up the wrong tree if they think it is about compression ratio.

With a direct injection diesel, the crown of the piston should be as close to the head surface as practical at tdc. It has to do with squishing the air into the combustion chamber.

IMHO 17:1 compression is good value for a turbo diesel - I don't care about na diesels

Was talking to some performance guys last night and they recommend if pratical to fit studs & nuts instead of head bolts far better pull down when torqing up. Also they are going to give me the name of a manufacturer of head gaskets to see if a 4BD1T is on their list of modified turbo gaskets.

Worth a look

Justin

I bought a set of ARP head studs. Think I have posted the part numbers!