Rb26 Vs Rb26/30

[Gts-t]

I have a R32 gtst and have been thinking about which motor would suit the standard diff ratio best.

That is a RB26 with a 8000rpm rev limit

OR

a RB26/30 with a 7000rpm rev limit

either motor will run the gcg manifold, tial 44 ext gate, and correctly sized garrett turbo to push either motors STOCK bottom end to its reliable limit. Engine may also run mild cams in the future if its of any interest.

On a side note from what i can work out reliably a stock RB26 bottom end should be limited to 450bhp and a RB30 stock bottom end to 475bhp.

BUT as far as i can see most people are putting out 300+awkw in gtrs and alot of people putting out over 290ish rwkw (475bhp) from their RB30 stock bottom ends.

So do most people just over tune there motors and wait for them to break or are these reliable limits i talk of somewhat BS. I doubt they are.

I think everyone has a different opinion about what reliably actually is though

Edited April 30, 2006 by 26GTS

[R31Nismoid]

Well over the past 18months

RB26 @ 330rwkw (stock) slowly degraded.

They dont take that punishment forever. It has taken a while to die, extensive high RPM track work.

But no "stock" motor is bulletproof

[TTT]

to look at the first part of your question about which engien suits the stock diff (which is what 4.3:1 ??), you'd need to say what is the main use for your car?

I always thought that such a short diff ratio the R32 has, the RB30 would be pretty useless since all that torque would result in constant wheel spin, but SK says that it can all be tuned via the boost controller and suspension and it would be driveable.

personally I'd prefer a VL style (3.7:1) tall ratio with a 3L engine.

what do the gtr's have? 4.1:1?

second part of your questions has too many variables and opinions so I'll stay right out of that one..

[Gts-t]

Well over the past 18months

RB26 @ 330rwkw (stock) slowly degraded.

They dont take that punishment forever. It has taken a while to die, extensive high RPM track work.

But no "stock" motor is bulletproof

R31 nismoid

Yeah that is what im noticing people are tuning 300+ rwkw out of them in they usually die in a matter of 2 years or less. I am not very interested in tuning past a reliable limit just for the sake of an extra 50BHP or so.

GTST

My car is used for st and track, it is set up for fastest track (grip) times. When its all said and done i will be prepard to change diff ratios if the stock 4.3 isnt to flash. I too am worried about the extra tourque turning into tyresmoke, however on the flip side im worried a 26 might be shown the door by a 26/30.

Maybe i should just PM SK

i know there are some smart guys on here though when it comes to diff ratios and thought id pick their brains a little.

Anyone who has driven a rb26 with 300-350 wkw for over two years id be interested to hear from. Also im not talking about just to work and back, i mean those who have given their motor a fair work out too.

BTW im not talking about any dumb shit like holding it on limiters, or driving it when temps are in unsafe zones etc.

Thanks guys

[TTT]

I just wanna get taken for a spin in SK's car when done.

stripped R32 gtst powered by some 650 odd hp RB31det goodness.

and a car owned by someone who is what you'd call a suspension specialist of some sort..

I'll bring spare pants.. I promise..

[azzr32]

if your spending all that money on a rebuild i dont know why you would wanna try keep the standard diff??

it wont last long anyway depending what your doing with it.

plus i wouldnt be choosing what motor to build by what will suit your diff.

choose a motor that will fit your budget, and what its going to be used for.

[R31Nismoid]

ive only shimmed my diff, and it so far lasted a solid 6 months no issues in my HR31.

I have no intention of putting an aftermarket diff into it either so i dont think the 32 diff would be much different

Being a 32 gts-t, its a super light car. A 26/30 will move some serious mumbo in such a light shell.

Should be some good replies as the diff ratio thing interests me aswell with my car and the RB26 going in

[Duncan]

what is wrong with the gts4 4.4:1 diff? just as strong as the gtr diff but a shorter ratio.

only possible downside is increase highway fuel consumption since its reving 10% higher.

And considering the comparable prices of an rb30 an rb26 bottom end, why on earth would you take an rb26?

[Gts-t]

what is wrong with the gts4 4.4:1 diff? just as strong as the gtr diff but a shorter ratio.

only possible downside is increase highway fuel consumption since its reving 10% higher.

And considering the comparable prices of an rb30 an rb26 bottom end, why on earth would you take an rb26?

Thanks for the replies,

duncan: i would have thought i would want a ratio numerically lower ie 4.1, 3.9 to help a motor with significantly more power and toque than the RB20 i have now put its power to the ground. Also the cost of either bottom end doesnt worry me it might be 3k but at the end of the day id rather get whatever is going to perform better. Even if this means it takes me more time and effort to build a RB30 than to just buy a RB26 and put it in.

About choosing a motor around the standard diff i kinda think somewhat along the lines of R31nismoid, that is that teh standard one perform pretty well when in good condition etc. However it is almost inevitable taht i will buy a nismo mech 1.5 way in the future anyway. I am unsure of what ratio it comes as or what it is available in. About the only part of my car i havent played with is the diff so im somewhat a newb

I should ask SK what he mainly runs in his car, i say mainly because u know the lucky bugger probably changes the rations depending on cuicruit. Or maybe not, either way i like to talk it up

Hope this thread gets some replies, there should be a few guys on here running rb26 or 26/30 in gtst's who have changed their diffs be that ratios or to aftermarket mech ones where the ratio has changed from stock.

Cheers

Edited May 1, 2006 by 26GTS

[TTT]

like I said, as a "street" car, with an RB30det, I personally would prefer a VL commondore style tall gears...3.7:1

I just think it would make the best use of the torque the engine puts out.

circuit, drag, drift I would say you would not want that sort of ratio.