Rb24 Block In Laurel

[RB34Medalist]

Hi, I've got a C33 Laurel with a blown RB25DET (R32 I believe) it has a nistune and some other mods already. I have a chance to get a wrecked A31 Laurel Altima with an RB24S cheap. Will it be fine to use that block? I'm planning to get an RB30 from oz later on so it's just a temporary thing. Thanks

[GTSBoy]

The block is notionally the same as an RB25, so, yeah, it should be OK to use. Depends on what you mean by "use". Are you going to transplant the RB25 head onto it?

By the way, your RB25 is not from an R32 (originally). They had RB20, so your engine is probably from an R33.

[RB34Medalist]

Ah okay thanks. Yes I'm planning to use the head and everything else that's on the car already, just the block in it is shot and rb24s are plentiful

[GTSBoy]

Probably don't need to tell you, but be aware that the RB24 is actually that little bit smaller capacity than the 25 (courtesy of the RB20 crank) so you will need to do a little tuning afterwards.

Edited March 1, 2013 by GTSBoy

[RB34Medalist]

That's fine, lucky it came with a nistune. Plan on staying with low boost until I get the rb30 for it

[StevenCJR31]

Ah okay thanks. Yes I'm planning to use the head and everything else that's on the car already, just the block in it is shot and rb24s are plentiful

[StevenCJR31]

where do you find these RB24S ?

[RB34Medalist]

where do you find these RB24S ?

They were sold in Laurel Altimas (Cefiro) in my country.

[GTSBoy]

South American and (I think) some African markets.

[Roy]

Weren't the factory RB24s SOHC and carbie?

Probably don't need to tell you, but be aware that the RB24 is actually that little bit smaller capacity than the 25 (courtesy of the RB20 crank) so you will need to do a little tuning afterwards.

RB24s actually use RB25/26 cranks so they are not actually using an RB20 crank and have the same stroke. They cant run the same bore so at 81-83mm bores thats where you lose the displacement

The block is notionally the same as an RB25, so, yeah, it should be OK to use. Depends on what you mean by "use". Are you going to transplant the RB25 head onto it?

By the way, your RB25 is not from an R32 (originally). They had RB20, so your engine is probably from an R33.

R32s did come with RB25s. They didnt have VCS and were NA with visually identical manifolds to an RB20 so ...

Also, RB25s head wont be able to be used on an RB24 bottom end. Not without loads of custom work so not going to happen so need to be RB20 based heads

[GTSBoy]

Roy, No.

The RB24S is a factory single cam (basically RB30 head) RB25 block with RB20 crank. We are not talking about RB24s made by stroking RB20 blocks with RB25 cranks.

Also, R32s did not come with RB25 turbos, as per the engine being discussed in this thread.

Edited March 1, 2013 by GTSBoy

[Roy]

Are you sure about the DNA of the engine. SOme lads in Singapore and Malaysia ran them in their drift scene and looking at them in KL (around Puchong) they told me they were RB20Es with different internals, not RB30Es?

And with a bitsa car there is a good chance its an NA R32 RB25 that has been turbo'd due to loom compatability etc

[GTSBoy]

This from Wikipedia

RB24S

Nissan RB24S engine, Carburettor, SOHC, used in the Latin American market Laurel Altima A31 (an export market name for the A31 Cefiro)

This is a very rare engine, as it was not produced for the Japanese domestic market. These were fitted to some left hand drive Nissan Cefiros exported from Japan new. Mechanically, the RB24S combines an RB30E head, RB25DE/DET block and RB20DE/DET crank with 34 mm height pistons. The resulting 86.0 mm bore and 69.7 mm stroke combined to form a 2,428 cc inline-six engine.

This engine used carburettors instead of the Nissan ECCS fuel injection system. It is able to rev harder than the RB25DE/DET (as it has the same stroke as the RB20DE/DET) as well as being almost the same displacement as the RB25DE/DET. A common modification is to fit a twin cam head from other RB series motors while retaining the carburettor set-up. The standard single cam form produced 141 PS at 5,000 rpm and 20.1 kgf·m (197 N·m) of torque at 3,000 rpm.

[Roy]

Yeh, will be interesting to know. What the guy was telling me made sense as the RB25 didnt really spring up in any Nissans until the R32 GTS25 which was a mid cycle thing from something like 92.

So means that Nissan were using the RB25 block in a car before the R32 in a late 80s export market car. Be interesting to know what sump is on them as I guess the RB26 was around so that is closer to RB25 family of blocks!?!??!

[GTSBoy]

Yeah. It's always been a bit of a conundrum. The only problem with the alternative path to RB24 is that it really takes an RB26 crank and a generous overbore to get it out of an RB20 block, and I don't see Nissan playing those games.

One thing to keep in mind....The A31 ran until 1994. It would have been easy for these RB24Ss to only turn up in the latter couple of years of the run.

[Roy]

That could coincide with the R32 RB25s and makes sense.

[StevenCJR31]

Weren't the factory RB24s SOHC and carbie?

RB24s actually use RB25/26 cranks so they are not actually using an RB20 crank and have the same stroke. They cant run the same bore so at 81-83mm bores thats where you lose the displacement

R32s did come with RB25s. They didnt have VCS and were NA with visually identical manifolds to an RB20 so ...

Also, RB25s head wont be able to be used on an RB24 bottom end. Not without loads of custom work so not going to happen so need to be RB20 based heads

[StevenCJR31]

intake manifolds visually same but different stud pattern and the na 25 has bigger ports

[RB34Medalist]

so would it be better that I just look for another RB25 block then?

[GTSBoy]

No, you can ignore what StevenCJR31 said, because it's not true.