Useful link for Z18 head on L20 block, and RB25 head on RB30 block, pretty short but they explain what is needed for the conversion.

http://www.autospeed.com/cms/article.html?&A=0004

in regards to the Z to L conversion, I found the article to be not much more than a primer only, they skim over things that are quite important.

in most cars, (even my 200B) the inlet manifold will not fit unless the engine is leaned over the other way, swapping engine mounts left for right leans the engine over, but what about your gear lever? do you remove your passenger seat to engage first, do you heat and bend your existing gear lever so now changing gears feels like you're stirring a bowl of marbles with a wooden spoon, or do you purchase a Z18 gearbox that leans the same way as your engine now does.

now they mention timing chain, cover and gears, but fail to mention chain guides, (they are different, and from what Ive learnt, you need a Z18/Z20 curved guide, and the rest can remain L20B stuff).

They make it sound like you just whack a head onto it and away it goes, I've learnt that really isnt the case.

rgds Eddie
Z18ET/L20B Hybrid on the build, while waiting for a head for the blown L18

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'80 810 wagon, EFI L20B, 5spd, Verada front discs, VL Turbo calipers, Bluey rear discs, H190, Gold TRX wheels.

Never argue with an idiot, they'll drag you down to their level, then beat you with experience.

too right vx225.. but typical for a magazine article.

hehe, i was going to build a tough l20 short block for my z18et, then realised all that crap too! Going to commercial wreckers now to get a rebuildable z22 short motor, rebuild that instead with real pistons! heaps cheaper than trying to make a 2.3l stroker 'L' block. Only question is......RODS!!!

The Z22 block is the same height as an L20B and rods are the same as L20B. They are fitted with a 32mm comp height piston to make up for the 6mm longer stroke.

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Cheers
Feral Errol

As far as the RB25DE head onto an RB30 block conversion is concerned, that is quite simple and at the same time, makes you realise what a great leap forward for the General back in 1986 if he had sold the VL with a twin cam engine
However the SOHC RB30 was a quantum leap for the General anyway
David Keen at Turbo Tune asked me to do one of these conversions some years ago.
It really is plug and play
The DE head matches the RB30 block and head gasket exactly and if the head is not V.V.T. the only modification required is the addition of a cam belt idler to the front of the block.
David supplied a cam belt from the Gates cattledog and the dimensions for the idler location and job done
Fresh out of the box the Dyno showed a jump from the RB30s 80RWKw to 120+RWKw, no other changes made.
This is just another example of the rationalised engineering that Nissan is famous for, this goes with that at ......
The RB20 DE head is not worth the hassle for various reasons, the intake runner diam. is wuzzy compared to the RB25 runners.
The only drawback I can see is the total trashing of another sweet RB25DE engine just for the head conversion

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Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net

so would the rb25det head go on to the rb30det found in a vl commodore? just asking on behalf of a mate with a calais turbo.
thanks,
dave

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Dave W

The 1600

Recommended traders: Nissanman, pro240c, 2door510, Datsport, mkyle, Green510, Um_510, jdmdatsun510, Ludachris

Dave, YUP certainly will, BTW may have been a typo, but the RB30 is an ET not a DET (D= twin cam)

rgds Eddie

_________________
'80 810 wagon, EFI L20B, 5spd, Verada front discs, VL Turbo calipers, Bluey rear discs, H190, Gold TRX wheels.

Never argue with an idiot, they'll drag you down to their level, then beat you with experience.

Sorry to dig up an old thread, but I've been browsing the forums a bit! With regards to RB25 head on RB30 block, there was a couple of extra mods required. I did this for my brothers R31? Skyline( it came with an RB20). It was several years ago, but I do remember putting a brass plug in the block to restrict oil feed to the head. I drilled a small hole in the plug, can't remember what size now. We had to aluminium weld the head to block off a water passage, I think too. There was also a passage that needed drilling in the head for oil to the lifters. Finally , I had to extend the timing cover filler piece due to belts being exposed. I apologise for some of this sounding a bit vague but just wanted people to know there was more to it than a bolt on. In fairness, it wasn't overly hard to do any of the above, I worked as a machinist and did a cheap job to help out my bro. Definitely doable and a worthy upgrade. The engine itself, I only used std bottom end, arp head bolts and cometic gasket in place. It had a decent turbo on it, I'd have to check on what his power ended up at, but it held together fine before he sold it. Definitely a budget build and bang for buck! There would be a decent resource somewhere on line that would walk you through, but again, I was pushed for time and just did what a fellow machinist and Nissan fan had found out. Be nice, I was into Valiants back then before the mrs, kids and house came along. Thank God for my 200b...