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Zetec Turbo comp ratio
coozer - 21/2/08 at 06:38 PM

Following my decision to build a zetec turbo over the coming years the subject of compression ratio has raised a little thought with me.

To upgrade a 1.8 with 2.0 cams its recommended to swap the cams and not the heads because a 2.0 head on a 1.8 block results in a low compression ratio due to combustion chamber shape.

Would that not be ideal for a turbo set up? or as usual am I way off the mark?

Steve

Volvorsport - 21/2/08 at 07:07 PM

forged rods , 8.2:1 CR with custom pistons to get the squish right , with enough boost you should be looking on the good side of 450 bhp .

so yes , a lower CR is ideal .

coozer - 21/2/08 at 08:04 PM

quote:
Originally posted by Volvorsport
forged rods , 8.2:1 CR with custom pistons to get the squish right , with enough boost you should be looking on the good side of 450 bhp .

so yes , a lower CR is ideal .


I know the lower cr is ideal but I'm skint! I want to build a engine on a budget.

I was thinking along the line of Vauxhaull turbo pistons that will bring it down to 8.5:1 I don't mind spending a few hundered on that but forged rods! Don't want to spend thousands!! I'm tighter than a 18" corset!!

Was wondering how low the cr will be with a 2L head on a 1.8 block....

Thanks,
Steve

paulf - 21/2/08 at 08:56 PM

I have been thinking of the same thing recently , i would like a turbo engine but dont like the idea of spacer plate and 2 gaskets etc. I think the comp ratio would be about right but the 2.0 has a bigger bore which would leave a step at the top of the bore in the combustion chamber, which i think would cause a problem, the gasket may also not line up but not sure about that.
I have been tempted to skim the pistons on the 1800 by a couple of mm but this would weaken them and upset the squish band.
Only other option is a change of pistons or shorter rods.
The other idea i had was to keep the comp standard and run a lower max boost or use water injection.
Paul.

Volvorsport - 21/2/08 at 11:37 PM

£200 for a set of rods .

from usa admittedly , but you get the idea .

chunkytfg - 21/2/08 at 11:59 PM

quote:
Originally posted by Volvorsport
£200 for a set of rods .

from usa admittedly , but you get the idea .


Jeez Forged rods for cars must be well cheap!!!

I not long ago paid £320 for a pair of carillo's for my race bike

Volvorsport - 22/2/08 at 12:23 AM

they are , if you have the contacts .