Rb26/30 Build, Yet Another One... ;)

[Beer Baron]

it's funny. I haven't been convinced by the whole RB30 is better argument for a long time and it seems there is more and more anecdotal evidence to support a well built and tuned RB26 being just as good if not better than a RB30 apart for lazy overtaking on the road as no amount of tuning will give a 26 as much torque under 4,000rpm as the 30. over 4,000rpm the benefit of the 30 becomes questionable. in track cars I've seen 26/27 or even 28 seems to be the way to go. the 30s just don't seem to perform as well. case in point the 30 berry switched to in the advan 34. it's as good a 30 as you will find but doesn't do anything that much better than his 26 did really (except fry tyres as it hits boost). the only positive side of the 30's is they can be a lot cheaper to build. purely on block price with a 30 block being $0 and an N1 block being a few thousand right up to mega $$ for a GT block. even stock 26 blocks cost more.

for me, for a circuit car it will be RB26 or RB27 all the way. my 2 GTRs at the moment run 26 and a Jun 27 (with tomei rods and pistons) and they are both nice set-ups for what they are.

[Beer Baron]

BTW, Spa is an awesome track. I drove their last year just not long after you guys (I was there in september). you need to get into the brave pills though and keep up with those porsches! you can go way harder through eau rogue/radillion and same goes for blanchimont too. you were losing heaps of time just in those 2 spots. it's such a high speed circuit overall it takes some getting used to at first. I was waaay off the pace there in my first session probably more than I have been at any other new track I've been to as you need to recalibrate for corners that require little braking (even in high powered cars) and so many 4th/5th gear corners. probably my favourite track I've driven.

[sucram]

Engine size comes down to personal preference

One isnt necessarily better then the other, since both (and everything in between) can be built to do something similar

[Simonster]

Its interesting listening to views on the differing capacities. As this is a street car and my daily, the 3 litre is a no brainer-soooo much more torque, driveability compared to the 2.6 is just night and day. I like the fact it's like driving a v8. Getting into a 32 was not without problems, however now i wouldn't go back to a 2.6 in a GTR.

Still haven't been able to get it back to the dyno to try a few things but i'll post when i have. In the mean time, i hope to start the 2.6 build for my S13 soon as i haven't been on the for 2 years this july.

That said, be interested to hear from anyone that's changed to the CES dump/front pipe arrangement as i'm looking at that doing, but making them all a little longer.

[Marko R1]

I had xforce dumps and xforce front on my rb30, easiest way to get around it is extend your front pipes by 40mm just under the flange where it bolts to the dump pipes, it only cost me 150 bucks by a very reputable exhaust shop in syd who does all the plumbing for pacmans rotaries and many other drag and circuit cars

[R31Nismoid]

Regardless of compressor surge, drivers ability or any other factors such as even gear changing, it is evident that bernie's gtr is not gaining on nick's gtr on any straight in his vid.

Bernie - are both setups running the same boost level and have both been measured on the same dyno?

Comp surge is a massive issue though. It hurts the entire power output, boost build up between gears and so on if it's doing it consistently and it can do it even @ full throttle depending on where you are in the RPM range.

That 0.3 of a second delay is pretty critical when you think about how many times you are on/off the throttle over a lap.

It's not always super audible either depending on the setup.

[Beer Baron]

Engine size comes down to personal preference

One isnt necessarily better then the other, since both (and everything in between) can be built to do something similar

yeah I agree. it does come down to preference and you're right that can both be made to do similar things. having said that they do each have some basic 'characteristics' that set them apart.

Its interesting listening to views on the differing capacities. As this is a street car and my daily, the 3 litre is a no brainer-soooo much more torque, driveability compared to the 2.6 is just night and day. I like the fact it's like driving a v8. Getting into a 32 was not without problems, however now i wouldn't go back to a 2.6 in a GTR.

Still haven't been able to get it back to the dyno to try a few things but i'll post when i have. In the mean time, i hope to start the 2.6 build for my S13 soon as i haven't been on the for 2 years this july.

That said, be interested to hear from anyone that's changed to the CES dump/front pipe arrangement as i'm looking at that doing, but making them all a little longer.

I think your assessment is pretty right too. For a street car a 30 makes a lot of sense. they do make the faster road car. I mean we are not spending much time above 5,500rpm on the street and that's where the 26 shines. the 30 shines in that range up to 5,000or 6,000rpm.

and of course there are bad RB30s our there and bad 26s too. many people doing 30s seem to be on a tighter budget so we haven't seen as many 'maximum effort' RB30s as we have RB26s.

I still love my 26s though and not sure I'd have a 30. I would consider one for a road car with the odd weekend trackday thrown in for sure. but I just love the howl of the 26 and that certainly does get lost in the 30 somehow.

[N1GTR]

Wow this argument is silly.

Come on guys, really, its been shown already that a 30 will rev, they dont drop off in the top rpm, they just don't feel like a slingshot like the 2.6 as the power is a smoother delivery (eg pulls from down low).

Agreed with BB though shame most people are not spending the time, effort and money on 30's and are happy with a basic effort build (funny though, the comments even someone with a basic effort build will say over their old engines but im not getting into that).

RIPS has done stacks of development and good on him for pushing forward with it. Whats his rail car down to? Surely thats got to be close to, if not THE the quickest RB on the planet.

While im at it; As far as comparisons go, you wont find a closer set of GTR's spec wise than Pauls and mine (in my old setup), I wont even say what I think of the difference, his posts are enough that anyone can see the result

[Beer Baron]

I'm not arguing with anyone. I don't think anyone is arguing? it's just a simple discussion and I think many people would agree RB30 is not the be all, end all of RB engine development. Depending on what you want to use your car for there may be better options out there.

as I said above I don't dispute the RB30 has advantages over a similar spec RB26, but people forget there are some negatives too and in certain conditions the RB26 may have some advantages of it's own. if that weren't true everyone would be running 6L engines by now. there is so much more to engine behaviour than just it's capacity. stuff like rod/stroke ratio, harmonics, piston speeds, rod length, bore/stroke ratio all make up an engines characteristics.

I'm not saying RB30s are no good. they make for a great engine and get fantastic results especially with larger twins and singles that are otherwise not good packages on a 26. but at the same time there are plenty of good 26 packages out there too.

[Marko R1]

Wow this argument is silly.

Come on guys, really, its been shown already that a 30 will rev, they dont drop off in the top rpm, they just don't feel like a slingshot like the 2.6 as the power is a smoother delivery (eg pulls from down low).

Agreed with BB though shame most people are not spending the time, effort and money on 30's and are happy with a basic effort build (funny though, the comments even someone with a basic effort build will say over their old engines but im not getting into that).

RIPS has done stacks of development and good on him for pushing forward with it. Whats his rail car down to? Surely thats got to be close to, if not THE the quickest RB on the planet.

While im at it; As far as comparisons go, you wont find a closer set of GTR's spec wise than Pauls and mine (in my old setup), I wont even say what I think of the difference, his posts are enough that anyone can see the result

paul was very impressed with my setup as well & it comes down to personal preference...ive had both engines & i know that i wouldnt build another rb30 for my own reasons which are similar to what you read in this thread & well aligned to other ppl's opinions as well (such as beer baron), simple as that!

rips is the king when it comes to rb30's - no doubt.

[Marko R1]

I'm not arguing with anyone. I don't think anyone is arguing? it's just a simple discussion and I think many people would agree RB30 is not the be all, end all of RB engine development. Depending on what you want to use your car for there may be better options out there.

as I said above I don't dispute the RB30 has advantages over a similar spec RB26, but people forget there are some negatives too and in certain conditions the RB26 may have some advantages of it's own. if that weren't true everyone would be running 6L engines by now. there is so much more to engine behaviour than just it's capacity. stuff like rod/stroke ratio, harmonics, piston speeds, rod length, bore/stroke ratio all make up an engines characteristics.

I'm not saying RB30s are no good. they make for a great engine and get fantastic results especially with larger twins and singles that are otherwise not good packages on a 26. but at the same time there are plenty of good 26 packages out there too.

good post beer baron im on your wavelength.

look at motogp, when they switched to 4 stroke they dropped from 1000cc to 880cc & now 800cc and they keep getting quicker every year, similar to f1!

rb30 you cant beat for the street if u want effortless power, why did i sell my engine after all & not keep it for my next gtr?

[R31Nismoid]

You would have to be the king of mad-hatter analogies Marko.

What on earth does a race bike capacity & lap time have to do with what are mostly street cars, 26 vs 30 debate?

There are so many other factors like weight, aero, tyres, brakes etc

[Marko R1]

You would have to be the king of mad-hatter analogies Marko.

What on earth does a race bike capacity & lap time have to do with what are mostly street cars, 26 vs 30 debate?

There are so many other factors like weight, aero, tyres, brakes etc

the discussion here is 'capacity' hence the comparison between road bike engines & car engines (the principle is the same, right?) - not tyres, stickers or anything else that you suggest...unless im on the wrong page lol

yes i do like my analogies, puts things into perspective for most ppl

[Marko R1]

this thread is way off track, sorry simon

although, as it turns out - a great debate!

[sucram]

Meh once he tells how his engine fitted it will be back on track ;-)

I dont think MGP ever raced 880cc. Just 500cc 2 stroke, 1k, now 800cc and back to 1k next year.

I know where your coming from tho, its like the 600cc vs 1000cc shit fights on bike forums

[Marko R1]

Meh once he tells how his engine fitted it will be back on track ;-)

I dont think MGP ever raced 880cc. Just 500cc 2 stroke, 1k, now 800cc and back to 1k next year.

I know where your coming from tho, its like the 600cc vs 1000cc shit fights on bike forums

the time i spent on gixxer.com & kwaka forums - to clear the muddy waters on bikes, you cant go past a 1000cc...nothing better than lifting the front wheel on power & doing over 200km/h

[sucram]

The only road bike I seen that could do that was a mates 08 r1 with a 40 shot

I still prefer 600 on the track, 1000 on the road

[FineLine]

Until you've lived with a 30 for a while you will not appreciate the advantages of the engine. It simply wins in every department.

Yes its easier to fry tyres but its also easier to not fry tyres. The larger engine gives you far more control and can deliver the power in a more linear fashion just by throttle control. Theres also plenty of evidence around to shoot down the myth that the 30 cant rev. There is simply no need to make it rev to make most people's target goals so why lean on it if you dont have to. The exponential loads on an engine as revs increase make it a no brainer to keep the revs as low as possible to make the required power.

The built 25/26 does sound amazing up in the rev range, the howl of a well tuned example still makes me wet and I'll bet I am not the only one who can pick it a mile away sight unseen. The smaller rb literally howls as beer baron stated. How many times have you beeen sitting in a restauraunt or similar and stopped half way through mid sentence because you heard that unmistakeable sound. The good news for the forklift lovers is they give nothing away in the noise department. Come sit in my shed and listen to the deep rumble of a lumpy cam driven rb 30, It is pure porn. It doesnt howl on wot, It literally roars. The day it stops making the hair stand up on the back of my neck is the day I'll give it away.

Baron the reason why we dont all drive 5 and 6 litre powered cars is because we drive skylines. Fitting a 30 is a no brainer compared to doing a v8 conversion. Its so easy in comparison its almost cheating.

I'll never dis the 25/26 but given the opportunity I would take the twin cam 30 every time.

[Marko R1]

The only road bike I seen that could do that was a mates 08 r1 with a 40 shot

I still prefer 600 on the track, 1000 on the road

yeah the r1's have always been a bit soft when it comes to power - the gixxer however is a demon!

for me, 1000 for both scenario's

[Marko R1]

over 4,000rpm the benefit of the 30 becomes questionable.

i agree & have experienced this with my rb26 & rb30 as once you are in the sweet spot, the tables turn & it falls in the favour of an rb26...for example, when i had my rb30, due to the early boost i found myself shifting @ 7krpm as anything above that wasn't beneficial & my engine could rev to 9.5krpm (i saw it on the dyno). if i compared the power band of both, rb26 won in this dept. for some reason, the rb30 did not feel as revvy & free revving was much slower as well.

in track cars I've seen 26/27 or even 28 seems to be the way to go. the 30s just don't seem to perform as well. case in point the 30 berry switched to in the advan 34. it's as good a 30 as you will find but doesn't do anything that much better than his 26 did really (except fry tyres as it hits boost).

the youtube clips show mark's car very well & should consider entering drift competitions what a burnout beast!

yeah ive heard he hasn't been doing as well as expected with the rb30.