Please dispell a myth...

[Ebola 33-t]

Got this from HPI no. 24:

"With the R33 GTS25t, there is more chance than most that long term thrashing by a previous owner, particularly if the engine is modified, can cause big problems.

The reason for this is the RB25DET's propensity for both detonation and engine fatigue. I have seen too many break blocks (yes, split the wide open), throw conrods and smash ring lands off pistons. For some reason, the RB25 seems to have nowhere near the durability of the RB20. For peace of mind, it is important that the R33 you import is one in stock or at least near stock condition."


My skyline is heavily modified by a previous owner, i guess this is a bit of a shock to read. But i think they mean by "previously modified", as in no internal work being done. Which makes sense. But i have been lead to believe that the conrods especially were really good on the RB25DET's so it is a slight cause for concern...

You're comments please

[tarmac_terror]

rofl

Luv it when magazines run these stereotypical statements that seem to suggest things like this.

RB25 is more prone to detonation due to higher compression. I imagine winding the boost up to levels that a RB20 might cope with would cause some issues in the short to medium term.
What they fail to think about or write about is the huge number of R33s that were subjected to high quality modifications in Japan and in other countries.

Detonation is not something that just happens because it is an RB25....the engine is irrelevant. Detonation is likely to occur as a result of other factors e.g. excessive intake air temp. So a R33 running say 13psi boost on standard intercooler etc would be (opinion) running at or close to the point of detonation. Add a decent front mount cooler which should reduce temps by a big amount and that same 13psi would probably be doing no harm.

Heat isnt the only factor, compression is another, timing yet another and overall tuning is a huge factor too.

The moral of the story is that well considered and executed modifications to RB25 are no more detrimental than to any other forced induction engine.......the key to that is WELL CONSIDERED AND EXECUTED!

[Ebola 33-t]

Cheers Tarmac terror,

So essentially what you're saying is that, broken conrods and split blocks is the result of detonation 9/10, rather than running too much horsepower, in a well tuned and sufficiently cooled engine?

[moondog]

Ken Nomura's R34 25GTt would seem from the listed modifications to have no internal mods to its RB25DET, but is happily running something over 500hp with all its bolt-ons. Drifting, mind you, so running bloody hard without breaking. There's nothing inherently wrong or weak about the RB25DET

[1viadrft]

All RB series motors are built tough... that magazine is rubbish!

[MurcielagoFun]

Actually, the RB 25 motor does not hold well under high stress. The RB 26 is the motor to have.

[1viadrft]

Hmmm... that is strange b'cus I was under the impression that all the RB motors shared the same block...

[moondog]

Originally Posted by MurcielagoFun

Actually, the RB 25 motor does not hold well under high stress.

And you're basing that on what?

You don't get much more "high stress" for an engine than a season of 500HP D1 drifting - and like I said, Ken Nomura's R34 (with an RB25DET) lists no internal mods to the engine.