I am currently rebuilding my block and I have a set of OEM s13 pistons, and I was wondering if I could use them in a u12 bluebird motor.

Thanks for the help in advance:biggthump , did some searching but coulnt find anything.

same pistons, they should be 54c stamped on top as well as the grade which is most likely 2

how about the rings?

same rings ;)

thanks man, that leaves me a few extra hundred dollars to spend in something else. :biggthump

ok we took everything apart today and the BB pistons look a bit different than the RWD ones, the rwd pistons have 54C stamped on them, and the ones that came out of the block have 72J stamped on them, the pistons look similar but the ones that came out of the BB look like they have higher compression than the 54C ones, as a matter of fact they do not even look like turbo pistons, they look almost flat. I was wondering if there would be a problem if I use 54Cs?

No problems, other than the fact that you'll now have lower compression ratio that will let you run higher boost.

I thought all DETs were 8:5:1.

The rwd "blacktop" engines have the stronger 54C pistons, same ones that are in the GTi-R. The fwd DETs and rwd "redtops" have 79E pistons. The 54C pistons are stronger but there is no difference in compression.

All DETs except for the GTi-R have 8.5:1 compression.

The rwd "blacktop" engines have the stronger 54C pistons, same ones that are in the GTi-R. The fwd DETs and rwd "redtops" have 79E pistons. The 54C pistons are stronger but there is no difference in compression.

All DETs except for the GTi-R have 8.5:1 compression.

so even though the 54Cs have a deeper surface than the stock bluebird pistons the compression is the same?

so even though the 54Cs have a deeper surface than the stock bluebird pistons the compression is the same?


Yes. Technically, alongside how dished the pistons are, C/R can also depend on wrist pin height, rod length etc. which determines how far up or down the piston goes in the cylinder relative to crank motion. At least that's how I understand the concept, which I want to explain a bit.

Myself, I'm using 300ZX TT pistons in my RWD SR20DET. I've noticed two things. The Z pistons are slightly less dished and the wrist pin sits a bit lower than the SR20DET piston. This wrist pin sits lower because there is more piston above the wrist pin, which to me means higher compression ratio. It isn't travelling up any farther than the SR20DET piston, but it makes the difference with the fact that there is less volume of cylinder available for the air and fuel to mix in. This subsequently helps create more power due to higher compression, but also leaves the motor vulnerable to detonation at higher boost levels. Instead of 8.5:1 C/R, my motor is at 8.7:1, which isn't bad. I do plan on using a thicker HG than the Cometic piece I have to lower the C/R down to stock. Also, I've gained slightly more displacement, which I think was about 45cc, IIRC.

Anyhow, that's all I have to say.

I took a better look at the pistons that came out of the Bluebird they have 63J stamped on top, and 62J on the side.

Am starting to think somebody else installed SR20DE pistons in this motor before I bought it, I bought it from somebody else, so I dont know.

Are you 100% sure your block is a DET block? Do you have piston squirters, etc? What's stamped on the shortblock itself?

I don't know exactly what to look for other than piston squirters, so sorry I can't be of any additional help.

Well the fittings for the coolant and oil feeds on the block would be a good indicator that its a DET. :)

thanks man, that leaves me a few extra hundred dollars to spend in something else. :biggthump

Bigger Turbo :biggthump
No problems, other than the fact that you'll now have lower compression ratio that will let you run higher boost.

Mooooore boost for that bigger turbo :rofl:

Are you 100% sure your block is a DET block? Do you have piston squirters, etc? What's stamped on the shortblock itself?

I don't know exactly what to look for other than piston squirters, so sorry I can't be of any additional help.

Yes the block is a DET, week to a closer look and it turns out that who ever sold me the motor took othe DET internals and installed DE internals, now I feel violated, so last night I spent all night matching everything trying to make sure that the pistons and rods are the only DE parts, I checked the crank, injecs, block, head, and evything is DET, I can't believe I this crap, again I feel violated, so that's why I blew my head gasket, now it all makes sense.

well, anyways now am installing 54C pistons with S14 rods.