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VG30DE Compression


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Ok so i know that VG30DE compression is a 10.5:1 and the VG30DETT is a 8.5:1. No my thing is can you lower compression without changing pistons? Do they make a head gasket spacer to lower compression? I know that VW has a spacer that you can buy to lower compression to your liking. Or can you just get head work done to change the compression? I know on muscle cars and certain stuff when they turbo or tt the cars they will get head work done to lower compression a little and get stronger head bolts. I also know that on diesels guys that are running 800hp and up usually do not change internals to lower compression. Yes, they are already turbo stock, but they have a really high compression. All they do is head gaskets and stronger head bolts. Basically i am looking for a way to do it diff then everyone else. My dad being that he has been building drag cars since he was a teen, is saying that he finds it hard to believe that they only way is to change pistons and internals. His 87 coupe mustang had a built small block. He then wanted to TT it and took they head in and had some work done to lower compression. He then put a different head gasket and stronger bolts and called it good. He never had a problem with it. Is there something similar that i can do to my VG30DE? Also, if i just were to change pistons, will the VG30DE run at a 8.5:1 c/r without turbos? I know its some weird questions but if anyone can throw so advice/input my way that would be great! :mrgreen:

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You may have to go to a dedicated Z32 forum for full answers, particularly re a thicker head gasket. But personally I would not lower the comp ratio on such an engine as much as you want to other than by changing the pistons. NA it will run OK on 8.5:1 pistons, maybe use a lower grade fuel? Either way it will lose a bit of performance.

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Alright thanks for the advice guys! Here's the deal.. i want to eventually turbo it, but i dont have the money to do it all right away. Now there is a TT motor for sale that i want to buy. But i cant afford the rest of the stuff, like turbos, intercoolers, piping, etc. So i was wondering if i can just throw it in my car and run it like an N/A but the TT motor. Or i want to buy a JDM N/A motor and throw it in, then do a head job to get compression lower. So what would be a safe C/R to do if im going to turbo it if i were to do a head job? The reason i want to swap engine already without all the other stuff is because i have high miles on my engine now. Its bout time for a new one. I just dont want to buy the N/A motor and then like 6 months later have to pull it and rebuild with TT pistons.

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Alright. But i will lose a little bit of performance right?

 

Yes...you'll probably lose 20-30% engine power going from 10.5:1 to 8.5:1 compression. Also there is no difference between the JDM and USDM engines so you'd be better off just getting an engine here from the US. If you can't afford to do the turbo swap just save up until you can do it all at once...you're wasting your time and money buying a TT block without the turbos/intercoolers etc. and trying to run that until you can tear it all down again and finally boost it.

 

Why don't you just pull your engine, replace the pistons with TT pistons and add the turbo manifolds,turbos,injectors, intercoolers, piping,ecu etc. Probably be the cheapest most efficient route.

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