Rb26 Or Rb 30

[SimonR32]

i dont have them, he posted them somewhere on here ages ago...

[shanef]

ok ill actually bite on this one...

rb20 has 3000rpm of useable boost and rb30 has only 2400rpm!!! RB20 WINS!!!

if you actually have a look at both your graphs you would actually find that the rb20 would turn out to be faster motor for the car

good graphs to compare rb26 vs rb30 are busters rb30 with 51kai and mine or r32gts rb26's with t04z, all are making similar power with very similar rev/power bands

the 30 would have loads more midrange though, and itd carry that peak power (or similar) right to redline. so say redline on the 20 was 7500 and on the 30 it was also 7500, the 20 would only have a peak power band of 1000rpm, whereas the 30 would have a peak powerband of 2900rpm

i dont understand the way ur thinking about that

[SimonR32]

RB20 170rwhp+ between 4700-7700rpm = 3000rpm

RB30 170rwhp+ between 3500-6000rpm= 2500rpm

we will call that a win to the RB20

RB20 230rwhp+ between 5750-7500rpm = 1750rpm

RB30 230rwhp+ between 4400-5800rpm = 1400rpm

another win to the mighty short stroke machine

and dont give me the sh1t about the rb30 will last longer because of the revs bullshit, a rb20 will never die haha

Edited March 4, 2009 by Cerbera

[R31Nismoid]

ok ill actually bite on this one...

rb20 has 3000rpm of useable boost and rb30 has only 2400rpm!!! RB20 WINS!!!

if you actually have a look at both your graphs you would actually find that the rb20 would turn out to be faster motor for the car

good graphs to compare rb26 vs rb30 are busters rb30 with 51kai and mine or r32gts rb26's with t04z, all are making similar power with very similar rev/power bands

I was thinking similar re: RB30/20

the 30 would have loads more midrange though, and itd carry that peak power (or similar) right to redline. so say redline on the 20 was 7500 and on the 30 it was also 7500, the 20 would only have a peak power band of 1000rpm, whereas the 30 would have a peak powerband of 2900rpm

i dont understand the way ur thinking about that

Ah ye but by half the arguments in this thing, if your never below 3500rpm then why the need for power below it?

Not that i neccesarily agree, but it goes against what a few others have been saying so far here.

Not sure how its a peak power band though, the torque would be dropping off, how much depends...

Its all argumentative of course

[SimonR32]

oh my god

r31nismoid agress with me

*goes and slits wrists

haha

[TiTAN]

Why not compare AL's 30 with GT3076 vs someones RB26 GT-SS setup? both setups will result in ~320-330kw.

[bradsm87]

I'd go a JUN 2.7L crank with custom rods and 88mm pistons in an RB30 block. Best of both worlds. 2.75L for a bit more down low than an RB26 and high rod to stroke ratio to just KEEP ON REVING!

[N1GTR]

88mm bore? Thats not leaving much safety margin...

[shanef]

88mm bore? Thats not leaving much safety margin...

yeh, like none

[bubba]

ok ill actually bite on this one...

rb20 has 3000rpm of useable boost and rb30 has only 2400rpm!!! RB20 WINS!!!

if you actually have a look at both your graphs you would actually find that the rb20 would turn out to be faster motor for the car

good graphs to compare rb26 vs rb30 are busters rb30 with 51kai and mine or r32gts rb26's with t04z, all are making similar power with very similar rev/power bands

The RB30 only gets revved to 5500-6000rpm at the moment as the turbo is WAY too small, that's still at least 3000rpm of usable power..

the 30 would have loads more midrange though, and itd carry that peak power (or similar) right to redline. so say redline on the 20 was 7500 and on the 30 it was also 7500, the 20 would only have a peak power band of 1000rpm, whereas the 30 would have a peak powerband of 2900rpm

i dont understand the way ur thinking about that

Limiter is set to 6800rpm but never gets hit as the power drops off rather dramatically after 5800rpmish

RB20 170rwhp+ between 4700-7700rpm = 3000rpm

RB30 170rwhp+ between 3500-6000rpm= 2500rpm

we will call that a win to the RB20

RB20 230rwhp+ between 5750-7500rpm = 1750rpm

RB30 230rwhp+ between 4400-5800rpm = 1400rpm

another win to the mighty short stroke machine

and dont give me the sh1t about the rb30 will last longer because of the revs bullshit, a rb20 will never die haha

It was a direct comparison between spool and peak power.. anything else is pointless because the turbo is so undersized for the engine. If the turbo was big enough to let me reach redline then the RB30 would win in your above comparisons.

GT35R will be on soon.. unfortunately I don't have an RB20 that I can strap it to aswell and do some more testing

Oh and an RB20 will die.. didn't adams' die? yes it lasted quite some time making the power it did! but it still died! but anything will die with enough abuse..

P.S. yes the RB20 was faster (due to not being able to wind it out in each gear) but that was countered by making use of the extra torque with some 3.9 gears. The RB30 is an alround nicer engine to drive on the street though.

P.P.S. the 30 is also a LOT better for big smokey burnouts, which is afterall, the most important thing

Edited March 4, 2009 by bubba

[PM-R33]

Pfft RB20's don't die, what a load of shit.

I can gauarntee if the RB30DET was available from factory in a GTR half of these arguments wouldn't exist. It's just the fact it's in a VL which puts people off (and i dont blame them, it puts me off aswell, however i can look past that and look at a block for what it is...a BLOCK! There is more to an engine than just the block).

Hell if half you people are so against saying "you have a RB30 under the bonnet", simple fix, don't tell people. Not many people can notice the extra height in the engine bay, so for all they know, you have a huge HP RB25/RB26.

It would be interesting to see whether some one that was so "RB26 pure" could actually tell if a car was a RB30/26. I could bet they wouldn't and would probably just say "Wow this thing has a lot more torque/response than mine!"

Not saying you can't build a RB26 to have as much torque, not at all, Dirt has proved this, however look how much experience he has and how much time and money he would have put into development. For 90% of engine builders around the country, they couldn't come close to potential of a RB30DET.

My 2 cents.

Edited March 4, 2009 by PM-R33

[SLAPS]

Drop a GT35r or larger on an built RB20 vs a built rb30 and lets do the same comparison.

The RB30 is a much nicer, more forgiving and easy machine to drive and get power down out of corners out at the track compared to the small motors.

[SimonR32]

i know the turbo is too small for the dirty 30 but you brought it up as a example, i was just showing that capacity isnt always the be all and end all of the argument

the most impressive graph i have seen from a rb30det is al's 3076r which is very impressive, nothing else has really tickled my pickle as you can always find a rb26 making similar torque/power but with only 86% of the capacity

dont get me wrong 30's are great but they should be 15% better than 26's

[shanef]

this has bene said alot lately but i'll say it again. the head makes the power, so u cant really fairly compare a std head with a modified head

[Swiper the Fox]

this has bene said alot lately but i'll say it again. the head makes the power, so u cant really fairly compare a std head with a modified head

Great post Shane....

Example, our RB26 had a torque curve like an upside-down ice cream cone once we went from 2530's to GT-RS's...not even 9500rpm off the limiter launches would stop it from bogging and being a pig to race. Do you think that if we bolted on an RB30 bottom end it would have fixed it...no way.

Soon as we did the head it transformed it into a car that had a big flat torque curve from a peak at 4500rpm all the way to the 9500rpm redline.

Same thing happened with another car is was involved with that used the same style head as mine...it moved the whole torque curve 1000rpm earlier and kept it flat in the top-end without falling off.

There's more to these engines than simply bolting on a bigger bottom end.

Edited March 4, 2009 by DiRTgarage

[T04GTR]

ok, well il build one and put my s372 turbo on im sure that would be pretty solid

and besides it would be cheaper for me than buying another turbo if its to laggy

[SLAPS]

i know the turbo is too small for the dirty 30 but you brought it up as a example, i was just showing that capacity isnt always the be all and end all of the argument

the most impressive graph i have seen from a rb30det is al's 3076r which is very impressive, nothing else has really tickled my pickle as you can always find a rb26 making similar torque/power but with only 86% of the capacity

dont get me wrong 30's are great but they should be 15% better than 26's

I've never seen an rb26 get near the torque of an rb30 on the dyno I run on and there has been a a lot of rb30's and rb25s on that dyno running upwards of 500rwkw.

Regardless. A dyno sheet doesn't reflect the throttle response, drive ability and power produced in the lower gears. Its like night and day and I would say so more so than 15%.

The larger motor spools the turbo easier in the lower less loaded faster reving gears.

More boost is made combined with the additional displacement and the motor feels like its making considerably more than 15% power compared to the rb25 in the same low gear.

Get in to a well sorted rb30 (head cams etc) and similar sorted rb25/26 and youll realise how little dyno sheet comparisons mean when looking at different capacities and gearing etc.

Obviously as Dirt stated you can't just bolt on a bottom end and hope for the best. It must be well sorted otherwise rpm will suffer.

Edited March 4, 2009 by TheRogue

[PM-R33]

Exactly right, dyno sheets don't tell ANYTHING bout the way the car drives on the street other than whether the power comes on like a light switch at high rpm's.

[bradsm87]

88mm bore? Thats not leaving much safety margin...

OK my bad. Use the 87mm pistons that come with the stroker kit then.

[Mr Jollwah]

i know the turbo is too small for the dirty 30 but you brought it up as a example, i was just showing that capacity isnt always the be all and end all of the argument

the most impressive graph i have seen from a rb30det is al's 3076r which is very impressive, nothing else has really tickled my pickle as you can always find a rb26 making similar torque/power but with only 86% of the capacity

dont get me wrong 30's are great but they should be 15% better than 26's

Is that similar PEAK torque and power or average peak torque and power.

No capacity is not the be all and end all, but volumetric efficiency is so if your playing with a larger volume then all else being equal the larger engine will produce a higher average and overall power and torque figure.

Doesn't really matter as this is a pointless "horse for a course" argument really.