Transplant Z32 DOHC Heads onto Z31 Block?

[Pdfflyer]

Has anyone ever read/seen/heard of of a successful transplant of Z32 DOHC Heads onto a Z31 Block? Same displacement, do the bolts line up? Can any engine work be done to adopt the later heads. I've read of a 4 cyl stroke being lenghtened with a spacer block and the increased heighth threaded to accept later heads on a Mazda. I have the VG30 Block and the DOHC non-turbo heads. I also was curious about the single turbo VG30DET Heads if these would bolt up or could be adapted.

Thanks

[proxlamus©]

I don't know for sure, since I have never researched it...

 

BUT YES...

 

they are both VG30 engines.. same engine code.. just the later heads have DOHC dual over head cams.. but I see nothing wrong with swapping on the heads.

[mario_82_ZXT]

I'm pretty sure you can't, just like you can't swap a KA SOHC head for a DOHC.

 

I don't think things line up. Search to be sure though.

 

Mario

[evildky]

as I recall it can be done but required block modifications, which makes it cheaper and easier to just use the whole VG30DETT

 

but for the life of me I can't figure out why you would want to? don't get me wrong the VG30ET and VG30DETT are both great motors but the extra parts and expence required for the twin car are just not worth it the power potential is quite similar, I guess the twin cam is a better platform if you must have over 600 whp

[mtcookson]

The VG30E(T) and VG30DE(T)(TT) blocks are basically the exact same design, however, the head bolt holes and I believe coolant and oil passages differ quite a bit between the sohc and dohc VG's. There are even differences in those between the 84-86 VG30E(T) and 87-94~ish VG30E(T) due to a upgrade of the design.

 

Basically, without some major modification it most likely can't be done. Also, you probably wouldn't really want to unless you're planning on changing the internals of the VG30ET as well. The VG30E(T) has a larger combustion chamber than the DE(TT) which would make the compression ratio very different if you mixed and matched the rods and pistons or heads. If I remember correctly the VG30E(T) has a combustion chamber volume of roughly 55 or so cc and the DE(TT) heads between 40 and 45 cc.

 

Basically, if you're wanting a DOHC VG your best bet is to get a DOHC VG. It would be too much work to really make swapping the DOHC heads onto the SOHC block worth it. Granted the VG30DE(TT)'s are quite expensive, I think the time and money that you'd have to put into converting the VG30E(T) would make it not worthwhile.

 

This is all basing off of information I've gathered. No one has tried it to my knowledge so there's the slight chance that it might be a worthwhile task... I'm 99% sure that won't be the case though.

[Mack]

uhm, no you cannot. SOHC VG engines use 5 head bolts per cylinder, arranged in a star type pattern, DOHC VG's use more conventional 4 head bolts per cylinder, arranged in the more typical square pattern. So, you would need MAJOR modification to do it. just get a DOHC VG, they are plentiful enough. Just look for infiniti J30's or NA Z32 300zx's. Or if you want a single turbo VG, look at a japanses Cima. they came stock with a VG30DET, thats right, DOHC and 1 turbo. Plus, the heads outflow TT heads.

 

on a side note, MARIO>>>>> yes you CAN put a DOHC KA head on a SOHC KA block. it takes ome timing gear modification, but it can be done. There is a guy over at NICO that did it. SOHC KA block + DOHC KA head = 12:1 compression.

 

McAdam

[mario_82_ZXT]

Nice to know, thanks Mack (on the KA).

 

A friend really into 240sx's is considering getting another one to mess with while up in chitown. That'd be a cool project.

 

Mario