g4cs stock compression ratio? 1g pistons?

[ReEducation]

What is the stock CR of a g4cs? I picked up a g4cs short block for $75. I also have a 2g head from an old project and a 91 TSI roller. I've read that the 4g63 head raises the CR of a g4cs to 11:1, but my question is raises it from what? My next question is could I use 60 over 1g pistons in the build to lower the compression for boost? I need some definite answers!!

 

[Gasolinebaptism]

by g4cs you mean 4g64?
The 4g64 has a bigger bore so you wouldn't be able to use 1g pistons that are 7.8:1.
they have a 9.5:1 compression ratio.
I'm not sure of the difference in chamber volume on the 4g63 head as compared to the 4g64 head.
I just saw a guy quote to a 4g64 website. I'll look for it.

4g64 : Mitsubishi 2.4 Litre 4G64 owners group

 

[Yamahaulin]

G4cs is not a 4g64 it's a 6bolt not a 7

 

[ReEducation]

by g4cs you mean 4g64?


4g64 : Mitsubishi 2.4 Litre 4G64 owners group

The g4cs is a 6 bolt 2.4L engine used in 89-91 Hyundai Sonata which is what mine came out of. Same block as 4g63 but 6mm taller deck. 156mm rods identical to 150mm 6 bolt 4g63 rods. 6 bolt 100mm stroke crank. And an 86.5mm bore compared to 85mm 4g63. So basically yes a 6 bolt 4g64. I can custom order 60 over (86.5mm) 1g turbo pistons that fit directly on the g4cs rods. But by swapping a 4g63 head onto a g4cs block it raises the compression, and the 1g pistons will lower the compression compared to the g4cs pistons. I'm trying to figure out if this combination will produce a CR that's ideal for boost. Do you follow?

G4cs is not a 4g64 it's a 6bolt not a 7

Correct. Do you happen to know the CR of a stock g4cs?

Ok so I did about 3 full pages in math. Assuming the CR of a stock g4cs is 9.5:1, the swap of 60 over (86.5mm) 7.8:1 1g pistons and a 4g63 head would result in roughly a 9.5:1 final compression ratio. Basically meaning the volume lost by the 4g63 head swap is roughly equivalent to the volume gained by the dish of the 1g piston.

 

[Kapok6]

Back from the dead. Did you ever get definitive answers to your inquiries above?