Thread: Decreasing TD5 compression

19psi isn't a reason to lower compression. Double that might be.

I ran a turbo technics vnt which runs 20psi+. Which I'm yet to transfer into my new td5 90.

Before that I ran the std turbo at 25-26psi with no problems.

D2s run about 19psi anyway with the boost modulator.

Thanks for the replies.

Diesels are a compression ignition engine. Even though a 3 hole gasket will make a small difference. You dont want to lower your compression.

Dont confuse petrol engine princibles with diesel.

More boost on a diesel engine will mean more air, same fuel (you have the ability to add more fuel with a remap) and a cooler motor. As you have VNT I assume you have an upgraded ECU map.

Head gasket thickness (1,2 or3 holes) is primarily based around piston protrusion, not compression ratio. There is 6 thou difference across the 3 sizes.

If you want your motor to be sorted, you will need to identify and understand what the cause of your real issues are, before you start changing things.

cheers

Thanks Strangy, yep I must admit I was thinking of the petrol engine theory of the more boost the lower the compression you need.

From my experience rebuilding the TD5, compressions not what you should be thinking about -

1) the head gasket hole numbers offered, as said earlier, are because of piston protrusion;
2) it is not hard to measure the clearance with just a feeler gauge; and
3) when you assemble the motor the rods are cold - when the piston rods get about 80 degrees hotter then they get maybe 6 thou longer I think, so be careful to measure your clearances well.