What is the RB25DE Motor???

[dhayes5]

I noticed that one member in the photo galleries section had an RB25DE motor. A couple of questions come to mind:

1) Is this the Skyline GTR Motor?

2) Does this use the same block as the L6 (i.e. is this a direct bolt in for a 240Z)?

If that is the Skyline motor, from what I read it has many many ponies.

[Alfadog]

1) Yes, although I'm not sure if it might be jut the GTS engine, as I thought the GTR was a RB25DET ?

[Cuong Nguyen]

Hi all, the RB25DE motor is from a Nissan Skyline, but not the Skyline GTR.

RB25DE is a twin cam engine, non turbo ie. n/a

RB25DET is as above but with turbo, from Nissan Skyline R33 & R34 models

RB26DETT is from the Skyline GTR (R32, R33 & R34), note the TT = twin turbo.

I have a '73 240z that is fitted with an Rb26DETT, as well as a '74 260z with an L26 + E88 head.

Will post photos of the 240z as soon as I get it finished!

Cuong Nguyen,

Perth, Western Australia

[dhayes5]

Does this engine share the same block with the L6? Will it bolt up to the Z transmission?

How many horsepower does each of these engines have?

[EricB]

No... the RB series and the L series do not share the same blocks... The conservative bhp estimate on an RB26DETT is 280hp but truth be told it's probably more in the 300+ range....

You COULD put an S20 (original Skyline GT-R 2000 + Fairlady Z 432) cylinder head on an L series block (any one of them actually) but you can expect to pay upwards of US$15K it. Yes $15,000 for a twin cam cross flow cylinder head.... amazing....

-e

PS: If you're not sure: S20 = 2000cc straight six triple carb'ed (Mikuni/Solex) 160bhp.

[Ivan]

It's not uncommon to see RB26DETT's with 1000 to 1300hp, It's one very cool / expensive engine.

[darren]

OK yes that is a skyline r32 r33 motor the make great power but also a cheaper motor that makes great power is the rb30 sohc from the r31 skyline . You are able to bolt a twin cam head on for little cost and you will get a 3ltr over a 2.5 also these motors are good for 500hp + i am currently fitting one to my 260z.If you are interested in these motors they are readely avaliable and not to bad priceed darren from oz:D

[HS30-H]

Just a quick note to put ericB straight about the head from the S20 engine. It will certainly NOT fit any of the L6 blocks, or any other block apart from the proper S20 block.

This engine was derived from the Prince GR8 racing engine, and is quite fundamentally different to the L-series sixes.

There WAS a bolt-on crossflow head for the L-series sixes offered by the factory, which was called the "LY" ( usually nicknamed the "Crossflow" head ) and that was actually a single-cam head with a hemispherical combustion chamber. These were made available to the public through the Sports Option parts lists in Japan in the early '70s, and were homologated mainly for race use in Japan and on the Works rally cars. In fact, to build a "true" LY28 engine you would need the rods, pistons and cam-drive parts that go with it, as well as all the manifolding parts. These engines used a different bellhousing and engine mounts to the normal L-series engines, as the mounting position was "straight" rather than canted over.

So, don't get mixed up between the LY28 "Crossflow" and the S20 - as they are quite different animals. There are very few LY28 engines or heads left in the world now - and most of them are in Japan ( where they are very sought after ). Some of the Works rally car parts dissipated through Europe, and there are two cars that I know of in the UK that have ex-Works LY28 Crossflow engines installed.

There was an aftermarket Twin-Cam Crossflow conversion available in Japan in the late '70s, manufactured by a small company called "O.S.GIKEN". This was called the "TC-24" and was a true bolt-on conversion for the L-series six block, but was extremely expensive and was only made in limited numbers. This too is now very sought-after in Japan. "O.S.GIKEN" still make many high quality parts for high-performance Nissan cars, and are particularly well known for their excellent clutch and transmission parts.

The RB-series Nissan sixes are not technically related to the L-series sixes, the S20 or the LY28 - but they do share a common family tree.

[Gav240z]

Hey Darren tell us more about this RB30 with a Twin Cam head conversion like how much it would cost all up to stick it into a Z. I'm currently considering working an L28 Motor to around 200kw at the wheels but I've also considered the cost and how much cheaper It would be just to buy a RB26DETT and engineer that to my Z.

I'm looking for a rough quote not a completely worked RB30.

Any ideas..

Thanks,

Gav,