Rb25 Flywheel Weight?

[car_fanatica]

Hey guys,

I've had a bit of a look around, but I can't seem to find a definitive answer.

Would appreciate something from the tech-heads preferably, but anything's good so long as it's accurate.

A couple of clients/friends are building a GQ Patrol for the SA Offroad Champs, and the vehicle is going to have a mid-mounted RB25 in it. Under the regs of the sport class they cannot use the standard motor, and would prefer to run a forced 6 cylinder instead of a V8, so the motor is going to compiled from an RB25/30 combination, as the motor must be < 3000cc.

More to the point, the car is being built to a spec is mindful of their budget & class.

That's not the current concern though, currently they'retrying to sniff out some information regarding the factory RB25 flywheel, because the motor was an automatic from a Stagea half-cut. How much does the factory flywheel weigh?

No need for suggestions on aftermarket options either, the guys are machinists amongst many things, and will be manufacturing most of the components themselves for the vehicle build.

While I'm here too.... This is unrelated to the topic title, but - What is the torque/power rating of the standard RB26/GTR transmission?

Cheers in advance for any help,

Rick.

[89CAL]

About 11kg from memory

[The Dan]

It is 10kg.

Some scales will say 9.9 but they are the ones my missus uses

[GTSBoy]

My RB20 one was high 9 kg range too, and they're basically the same flywheel. So I concur with Dan.

[car_fanatica]

Thanks guys, cheers for that!

[car_fanatica]

What about a standard RB26 Flywheel?

I'm going to assume they're physically larger, hence heavier?

[GTSBoy]

Why would you assume they're larger? I would have said they'd be about the same size. If anything, given the notional "performance" tag of the RB26, you'd expect its flywheel to be lighter, if anything.

[car_fanatica]

Not necessarily, things aren't always engineered from an aftermarket point of view, they're engineered to a torque rating.

Every manufacturer wants their vehicles to see out the warranty without paying out the nose for ongoing factory recalls, so things are always engineered or over-engineered to withstand a minimum specification.

The 'X' amount of extra power & torque from the 2.6 litre, plus the increased load on the drivetrain from an AWD format, means generally they'll install a larger clutch, to compensate for that. So the flywheel will be larger, respectively.

That doesn't necessarily mean it's heavier, of course.

But they could have just provided the same flywheel for all models/variants, but I don't know... that's why I'm here!

[GTSBoy]

Stronger clutch, yes. Bigger diameter, no. Therefore bigger flywheel, no.

Face it, the RB26 didn'tmake that much more torque than the 25, and not a whole lot more power. And the flywheel is almost the same (if not the same) between the piddly little RB20 and the 26.

A 10kg flywheel is overengineered by a factor of a bazzillion for an RB26.

(Yes, I am an engineer).

[The Dan]

They are the same

[car_fanatica]

Guys, thank you very much for your time!

I do find it interesting that they kept the same flywheel from RB20 through to RB26 though, on all models. Strange indeed.

But I guess they knew what they were doing, and that's all that matters.

See I hail from the Pulsar mob... SR20's are commonly used, and there is a distinct difference in the variants, from RWD to FWD/AWD and GTiR. GTiR is commonly known as the black sheep, because 99% of it is different to other SR variants, and thus usually not interchangeable. The flywheel & clutch is one of those things... Ours are around a 215mm clutch, and the GTiR is around 245mm. Then of course, the flywheels are different to compensate.

So I figured maybe there might be a difference between models in the same fashion, but obviously not.

All the same - I got the information I was after anyway, so thanks again guys!

Rick.

[The Dan]

The flywheels are not all the same, they are all the same weight and look the same.

None of this really matters though because if you were building a serious offroad competition car you wouldn't be using that cast iron grenade

[car_fanatica]

Yeah, too true.

That was the idea of finding out... Briant (the owner/builder) wants to machine one up from scratch, but simply wanted to compare the standard TB42DE flywheel, to the RB25DET they bought to throw in the car.

Most of this is R&D, because the RB motor will likely be copping the GQ's FS5R50A transmission. He's a machinist, so making the components is not an issue for him.

Thanks again Elite/Daniel.

Edited June 14, 2012 by car_fanatica

[The Dan]

Yeah no problem.

The RB25DE grenade has a shorter pin than the RB25DET grenade. Turbo models were nodular cast iron, non turbo models and RB30 flywheels are regular cast iron.

If you are going to be making torque/hp, you need to consider an aftermarket flywheel. NPC do the revsolution flywheels at 6.5kgs at approx $400-$450.

The worst thing for that setup is the weight of the car. There is a lot more load on the clutch and drivetrain so it's even more important to consider non-cast iron options when it comes to flywheels

[B-rice]

so just to be clear r33gtst flywheel is the same as r34gtt flywheel.?