I have a 94 max and i just got my car out the shop this weekend. The mechanic said that cylinder #4 piston is shot so i was already planing on puting some vg30de pistons in. i want to know how much will that cost and will those pistons perform good when i put a turbo in later. i know that the 300zx is twin turbo but i want to know if i get used pistons will it hold up or will i need new pistons?

 

How did he come to this decision that it needs a new piston?

 

If a piston is "shot" it would be making some horrific banging noises while running.

If it doesn't sound like that check the fuel injectors. VG engines are tough but the injectors are far from it.

~Alex

 

Is this a reliable machanic? A bad piston would be slapping and eating up the walls in the block, spitting rings into your cat and possibly swearing at you the whole time.

 

VG30DE pistons != VG30DETT pistons.

do you want to go low compression or high?
either piston will drop right in for a VE, but you need to know which way you want to go. I certainly wouldn't turbo using the VG30DE NA pistons. they're cast pistons with pretty high CR.

 

as for the VG "shot" pistons.. i doubt it.... how many miles are on the car??? and ask him why he thinks it is "shot"???? do a compression test for yourself.......

 

Actually, VG30DE pistons in a VG30E would put the compression ratio right about the same since they're both flat tops. One problem would be the valve reliefs in the pistons though, there might be issues there.

 

i want to go high compression. by the way the mechanic is reliable and he looked at the pistons him self, he also changed the feul injectors to.

 

the VGDE NA pistons are domed, not flat tops.
I dunno about the TT pistons tho.

 

in order to have seen the piston he either needs to have pulled the heads (not a chance) or put a camera into the plug hole and look at it that way.
any other way is a guess at best

 

That would explain the .5 bump in the cr but I could have swore they were flat. Now I have to go take a look at them again when I drop by my friend's house.

TT pistons are definitely dished. I have a set of those laying around.

 

get it looked at at different places. the more opinions the better.

 

Skunk4 Racing told me that my Block can handle up to just about 500 HP, depending on the guts I choose to put into it. Reason was, its nearly the exact same engine as the 300ZX.

 

Thanks for the decade-old information. What does it have to do with this thread?

 

Nope.. definitely domed.
These are my JE VG30DE- NA pistons, but you can sorta see the dome on them.
http://blehmco.com/pics/car/engine/n...s/100_1552.jpg
http://blehmco.com/pics/car/engine/n...s/100_1553.jpg

also note the combustion chamber on the VG *looks* to be slightly larger than on the VE, so it's likely the VE will have even higher compression with these pistons than with flat tops. just doing a straight ratio between my old and new compression numbers, mine shows to be around 12:1 now.

 

The block itself will definitely handle much more than that. The stock internals will handle upwards of 500 hp but they're definitely at their upper limit. The IMSA GTP ZX was making over 1,000 hp in qualifying trim and around 900 in race trim on the stock block and head castings.

Those you can definitely see it. I'll have to look at the stock ones a little better next time. I think I'm going blind or something.

 

Take a look at this as a referrance: http://www.theultralightplace.com/pistons.htm

I doubt piston damage but I'd like to hear your mechs explaination and how he came to conclusion. I could definately see him assessing bad RINGS. If that is the case, I have a brand new set of Nissan rings for the VG. They are for turbo, but will work and would be perfect if you're looking at going boost at some point.