Could you put a 1.8 head on a 205 block that has cossie piston and rods..
I know you have to up the compression on a 2.0 head as compression ratio abit low but wasnt sure what it would do if you put a 1.8 head on??
Would it make any diffence
Could you put a 1.8 head on a 205 block that has cossie piston and rods..
I know you have to up the compression on a 2.0 head as compression ratio abit low but wasnt sure what it would do if you put a 1.8 head on??
Would it make any diffence
It depends if the Exhaust valves are the same as the 1600 or the 2ltr, which I'm not sure of I'm afraid. Preferred would obviously be the 2.0ltr.
Its been a while since I did the calculations, but i think you would be better with a 1.6 head as a base and then modify it with bigger valves etc. Or just skim the 2.0 head.
Duck how much did you skim your head mate???
1600 head from an early non emax engine ( so not from a 165 block) is probably a better bet, you can skim 2.5 mm of a 2.0 head
Cant remember exactly how much it was now as it a while ago and didnt document that. I know we ended up at about 8.2:1
Do you know how far the piston should sit down the bore as wanna try see if they have decked the block??
Cossie conrods and cosworth piston
Depends on piston quality and how well you can control boost pressure, fueling and ignition! Not the same as a pinto but my bike runs at 9.5:1 CR and 2 bar boost but all the above measures were incorporated.
I agree that 8.2 or 8.5 is not that much of a difference but what you "want" depends on how you build the engine - fuel (gasoline/E85), engine management, required torque range and so on.
IMO if you can get to around 8.5 with YB rods and pistons that's great as long as you dont need a 2 bar Holset Pinto turbo that lasts forever.
Gustaf
So I take it that standard yb Pistons are still only cast an not forged anyway.
They are, but they are are good to like 450-500bhp
Well it has pinto crank cossie rods and mahle piston only shooting for about the 250 mark so should be ok
The trick with an Escort Cosworth Turbo Rally engine was to fit Cosworth 2wd pistons to the 4x4 engine and this would increase the compression to 8.6.1. The engine would reliably run all day with 2.2 bar boost pressure. Due to a 34mm Turbo restrictor fitted the engine would only make approx 300 bhp.
You won't have a problem with std YB pistons for your engine as long as it's correctly mapped.
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