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Compression Question?

664 views 5 replies 4 participants last post by  Roushturboedzx3 
#1 ·
I have a 2002 SVT that I have pieced together a turbo kit for. This past Saturday my father borrowed my car to go to drive to work and ended up towing it home. He called me saying that while he was driving it there was a big cloud of smoke followed by the car shutting off. He said it would turn over but it wouldn't start. He thinks that one of the problems is the fuel pump is gone. He says that before it went poof, the fule pressure guage was all over the place. I'm hoping that it is just the seals in the turbo. Either way we are going to be working on it and what ever is wrong he is footing the bill.

Hopefully this week we will be tearing into it. If the problem turns out to be somthing in the bottem end and some pistons or rings need replacing I figured this would be a good time to upgrade my internals, since I'm not paying for it and we will already have it torn down. This brings up a few questions I have about compression ratios and boost.

My question is what compression is recommended on FI. I know that most say the lower you go the more boost you can run. But wouldn't keeping the compression somewhat high, around 10:1, allow you to run less boost but recieve the same power gains as running lower compression and higher boost. I would think doing this would be better because this would give you low end power, faster spool times and since the boost is low the turbo could maintane the boost easier. When I mentioned this to my dad he said the problem I would have is detonation. He said that I would most likley have to run over 100 octane. If this is the only problem with going this rout then I would think the pros would still outway the cons.

My goal, if I end having to build the motor, is to hit somewhere around 300 on as little boost as possable. As it stands now before this happned I was at 268hp on 10psi on the factory internals, which I believe are somewhere around 10:1 cr. This makes me believe my goal really isn't that farfetched.

Once I figure out what compression I should be going for then I'll figure out what brand of piston/rod to get and where to get them.
 
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#4 ·
Well we pulled the plugs and the first and third were covered in oil. We then did a compression test and that confirmed my fathers fears. Thoes cylinders had almost no pressure. So were tearing it down as soon as we can and going to rebuild it.

Tom, what pistons/rods would you recommend for the compression you suggested? Price is not really a problem, since it isn't coming out of my wallet [cool]
 
#5 ·
probe pistons and eagle rods are the typical choice for the zetec. or you could go big money wit Diamond pistons and Crower rods.
 
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