Reason i ask is the fact that the pistons were dished was as the standard ones were not??
The guy who put my engine together mentioned this wey back then!
The reason i'm questioning this now is the fact i may have to have head skimmed.... again, this is worst case scenario tho, hoping just the gasket has failed!! fingers crossed?
Does having the head SKIMMED have much of an effect on the CR? I know spesso do a few different thickness gaskets and am not sure which one to go for as i can't remember which on i had in the first place?? DOH......

Nick

On 20VT wossner drops from 8.5:1 to 8:1. Not sure about 16VT.

You can work out your new CR ratio but doing some maths.

(VC + VS) / VC = CR (i think)

VC = Volume Clearance
VS = Volume Swept
CR = Compression Ratio

Does it make much difference dropping that 0.5??
What i'm getting at is does it have an adverse affect on performance??
Is there a way of getting the 0.5 back i.e by using thinner gasket??
Or does it really not make that much of a difference??

Nick

The standard 16v pistons are dished with little cuts for the inlet valves whereas the wossners look to have an identical dish but with big valve cuts for both the inlet and exhaust valves so I'd bet on them being lower compression, never had a set in my hand to get a true opinion but that's my thinking.

Nik

Before you do anything you need to find out your, bore size, stroke, VC & headgasket thickness (compressed & uncompressed) and the CR the Wossner pistons are supposed to be, only then you can begin to do some calculations.

lower CR will allow you to run higher boost, but it WILL affect off-boost driving slightly (although you can probably play with the ignition advance to compensate)

Wossner pistons do not lower the CR on the 16v engine, so it is still 8:1

Yes correct Begbie, i have set of them and it is same CR

Thanks for this confirmation!!

Nick