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G60 swap questions
----- Original Message ----
From: Cory Langford <Cory_Langford@bcit.ca>
> The PG block was build for the pressure. Any other block and you will
> need to do a full rebuild with forged pistons, etc.
Well, that's *sorta* true, depending on how you slice it. The PG block is really not all that different from any other VW block, and the head is really not much different from any other 8v head.
The only thing that is truly and fundamentally important is that the PG has a relatively low compression (8:1) which is good for forced induction. If you went with another engine (ABA, 3A, 9A, etc), you would probably want to lower the compression somehow.
Other things on the PG, which all certainly DO help it handle increased power, but are not technically necessary, are:
- very long skirts on the pistons, with low ring placement (mentioned already by others)
- dished piston crowns
- short rod ratio (136mm rods instead of 144mm)
- forged crank
- extra water jacket volume in the block casting
- piston oil squirters
- sodium-filled exhaust valves
- there's a roumor that the head is a different alloy or treated somehow...I've found no facts supporting this, and the guy who did my head work used a regular Mexican A2 hydro casting.
So...if you've been paying attention and done the math...yeah, you can easily get a "poor man's G60" out of a low compression Rabbit/Scirocco 8v engine. It definitely wouldn't handle tons of boost, but should be OK for at least a little bit more than the 150hp a stock PG/G60 puts out. If anyone wants to try that route, I've been meaning to sell my G60 brackets and alternator setup...you'd basically just need some pulleys, a charger, and do something about fueling.
I decided to stick with the stock block, and make changes from there. I haven't been disappointed yet, but the 8v head does eventually become a limitation at some point (though my head flows better and makes more power than most supercharged 16vs with ported heads). But others have run G60/sc/turbo setups on ABA, 16v, and many hybrid setups successfully. The only major issue is getting the right compression, and if you get a set of forged pistons you can solve the compression issues and the piston ring strength issues at the same time...but obviously that adds to the cost.
Neal