What is the stock compression of a g4cs engine? I picked up an entire short block for $75 and I'm thinking about dropping it into my 91 TSI roller, boosting it with a 2g 4g63 head and 60 over 1g pistons. But I need to know the stock compression of a g4cs before I can roughly calculate the CR with the 2g head and 1g pistons.
g4cs stock compression ratio?
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What is the stock compression of a g4cs engine? I picked up an entire short block for $75 and I'm thinking about dropping it into my 91 TSI roller, boosting it with a 2g 4g63 head and 60 over 1g pistons. But I need to know the stock compression of a g4cs before I can roughly calculate the CR with the 2g head and 1g pistons.
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Also, is this even do-able at all?
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The 4g64 is 9.5:1 so I would assume it's close to that. But the compression ratio will be whatever the new pistons are. If you use 8.5:1 pistons with a 4g63 head, you will get 8.5:1 compression.
It is very do-able so long as you have all the right parts. I'm sure there are threads on here about G4CP and G4CS swaps.
It is very do-able so long as you have all the right parts. I'm sure there are threads on here about G4CP and G4CS swaps.
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But supposedly the 4g63 head on the g4cs stock block raises the compression to 11:1 so if I used 60 over 7.8:1 1g pistons wouldn't it be higher than 7.8:1 in the g4cs/4g63 because the piston CR is rated for a 4g63?
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Well after getting bored and doing about 3 full pages in math equations lol, 7.8:1 1g pistons (86.5mm bore) in a g4cs would yield roughly a 9.5:1 compression ratio IF the stock CR of a g4cs is 9.5:1 to start. Basically meaning the volume lost by swapping the 4g63 head is about equal to the volume gained by the dish of a 1g piston.
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It is doable and has been done before. One thing that many people who have built these "frankenstein," engines realize is the crazy about of parts that you have to use from other cars. I know that you have to use the G4CS timing belt, you have to get a set of older model hyundai cam gears and a few other miscellaneous parts. I'm not trying to deter you from doing this because they are monsters once assembled, but understand it is a lot of work and research. There was a guy on tooners who built one with a 2g head, oversized (.040 over if remember right) evo 9 pistons and 15 lbs of boost on an e316g and he made 385 HP...Keep that as motivation if you end up going through with the build. Good Luck!
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Oh I'm up for the challenge lol. I like doing something that not many people have done. To swap a 4g63 head requires cam gears and timing belt from a dohc 4g64. The block I bought came with the 156mm rods with stock g4cs pistons, still need the 100mm crank. The pistons can't be used for boost and a set of 60 over 1g pistons would still have too high of a CR after swapping the head. They sell special forged pistons for the 2.4 block with 4g63 head swap but it's going to take me a while longer before I can afford a set of $500 pistons from Wiseco as compared to a set of custom ordered 60 over 1g pistons for $140
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Manley makes them as well. Still pricey though.
http://vr-speed.com/store/manley-613000c4-9599-4g64-4g63-head-86mm-bore-piston-p-16723.html
Look up the specs on them. If they have a something like a -16 dish and 8.5:1 compression then that's what you need.
http://vr-speed.com/store/manley-613000c4-9599-4g64-4g63-head-86mm-bore-piston-p-16723.html
Look up the specs on them. If they have a something like a -16 dish and 8.5:1 compression then that's what you need.
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Thanks! I'll do a little more searching so I know what pistons to get when I have the money.
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