To 30/26 Or Keep The 26?

[Lithium]

Q. i'm currently needing a rebuild, an only bn to one happy laps in the 5n a half years ive owned the car. An yes I do like to listen to my car sing to 8000 before changing gear n not running out of puff.

currently have a rb26, -5's n 270 cams. but as its my weekend driver (when its going) it can be a lil annoying with lag round town. Im glad someone pointed out some of the head aches of a 30/26. I know drag 32/26's will happily rev to 9000+ but a purpose built. I'm not after super quick laptimes...

I know a 30/26 would fix down low problems, but worried what the difference is from 6000-8000rpm, as ive spent time in an xr6 turbo, an no lag is great, but just got more boring towards the limiter the harder u revved it instead of getting more exciting, didn't seem right. an maybe I should get out more an go to more skyline meets, but how bad can a 30/26 sound

Any RB30 with typical mods you would do to a RB26 (built motor) will happily spin to 8000rpm - one with your turbos may fall over in the 7000rpm range because it is a bigger motor and those turbos are small for it, not because it can't... you just need to feed it more air The sound stuff is just a single guy trolling, RB30s do sound different... some might say they sound BETTER, they definitely don't sound bad.... at all.

The concerns people have about big torque breaking transmission stuff is also bollux - if you are REALLY worried you can limit peak torque by dropping boost back... the motor will give the same torque delivery as an RB26 with less boost, so less overall strain on the system but still better off-boost torque and better driveability, and no extra wear on the transmission. The bonus about the extra displacement is you can do everything equal or better - but you can use it how you want, its just that most people want to go for the bigger overall torque/power numbers you can make.

If you want what you had with the RB26 but more driveable, just hold back on boost

[Country Cruzin]

Thanks for that, you've answered my question well

[XGTRX]

Has anyone got any evidence that a 26/30 is fast around a track. With similar power levels of course.

And I am not trolling as suggested just have an opinion....26s do sound better and a lot of vl boys agree. But each to their own.

[Mick_o]

VL boys also think dose sounds good lol

[Shoota_77]

Yeah not a strong fan base to quote....

I haven't seen too many VL's rip out their 30's in favour of a 26.....

With your example above ("with similar power levels") it's not a relevant argument. What is a relevant argument is "with the same mods" which would presumably lead to the 30 being more powerful and obviously higher torque. But even if they did have similar power levels the 30 will still have more torque regardless due to the lower stroke so longer period of time the power is being made per cycle.

At the end of the day a well set up 26 is more than adequate for 90% of the population. Some people are brilliant drivers and can easily handle/use the extra power/torque then you've got dicks like me that can't drive for shit and just think they need more power. Plus it's just a little bit different, it's about pushing the boundaries of what's possible. If we all did the same thing the world and car scene would be a very boring place...

[ido09s]

Its all about how its built if you ask me.

Put a high powered motor in a poorly setup car and its going to be slow. Put a lower powered engine in a well setup car and its likely to be faster.

Yes, torque is great, but at the end of the day its not worth having if you cant use it.

Perfect example is my old mate Frosty's Mazda 3. Extremely well setup track car with minimal engine mods. Most Eastern Creek track days he would get out in this car and play with the likes of E46 M3's and so forth. The only time they beat him was down the straight. As soon as turn one came up he was all over their ass again and ready to pass them at turn 2. All the torque in the world that the E46 made was not going to help them against this Mazda 3 because it used everything extremely well.

Obviously it was part driver, but most people would not believe that a $150k M3 would be slower through the twisties than a $20k Mazda 3

If i was the OP, put the motor back in and sort the chassis out and suspension. Get it sorted and worry about the motor when it needs attention.

[sky30]

Has anyone got any evidence that a 26/30 is fast around a track. With similar power levels of course.

And I am not trolling as suggested just have an opinion....26s do sound better and a lot of vl boys agree. But each to their own.

As i said earlier, mark berry went from rb26 to rb30 in his world time attack car.

Do you think he would do the swap to go slower?

[ido09s]

Mark doesnt even race the car at these events anymore does he?

Edited November 19, 2013 by ido09s

[sky30]

Not sure if he still races these days

[XGTRX]

So no-one has any track times data then...interesting.

Ido09s thank you. My point all along. A well setup GTR with a built 26 with 350kw is more than capable without the headache of a 26/30 conversion for the average 12 event a year jo blow. And if driven correctly will be bullet proof.

[XKLABA]

And yet it will still be slower then a "well setup" GTR with a 2630 and 350kws just from seer response the extra 431cc gives not to mention the extra torque you get from the extra leverage from the longer stroke crank, as for sounds better, horse shit if your worried about sound buy a MX6 with an exhaust, they sound more like a 26 then a 26 does

How on earth can you sit there and say there is no benefit from a 30 in daily duties, same tech on more capacity is always going to be better

Better response
Better torque
Better fuel economy
And all with less strain on motor
And further once setup if you blow one you can buy a complete running motor for $100, I did, find me a running 26 for less then $2500

The only drama with the 30 is clearance top and bottom but again once setup that no longer an issue

Then there was the need comment, whats need got to do with a 350kw GTR, that is ALL WANT, the want to go faster, gearbox longevity is as much as driving style as outright power, and as I've said before those of us that want push that far know that doing the drive line is enevatable, I've seen GTRs blow boxes with less then 350kw, the BSM car did a few, OS and PPG, when it was in IP with around 300kw

So OP needs to decided HIS end goal and build for that, if all he wants is faster then go the 30, if he is worried about sound and drive line leave is stock or find HIS own happy medium

My 32 is my happy setup, 293rwkw and an 11.1 for a daily drive it is an absolute ball to drive and IMO the perfect alrounder, my 34 on the other hand is all about speed and lap times and that is why it has a 30 in it and should make north of 450awkw on its current setup

[C4a0s]

found this RB30DET

dont think there is an absolute good or bad just a matter of preference..

personally i'd stick to the RB26DETT..its not THAT bad...esp if Mine's can make theirs so fast too rite? Mine's Skyline

[XKLABA]

ok, wikipedia compairs stock vs stock and a stock 26 will piss all over a stock 30 plain and simple as there is no factory twin cam 30 with ITBs and twin turbos, stock the 26 has the tech in it, put that tech on a 30 and that changes

the mines car is fast comaired to what, a stock car yes but put in up against the Hi Octane R34 and see how it goes

[XGTRX]

And yet it will still be slower then a "well setup" GTR with a 2630 and 350kws just from seer response the extra 431cc gives not to mention the extra torque you get from the extra leverage from the longer stroke crank, as for sounds better, horse shit if your worried about sound buy a MX6 with an exhaust, they sound more like a 26 then a 26 does

How on earth can you sit there and say there is no benefit from a 30 in daily duties, same tech on more capacity is always going to be better

Better response

Better torque

Better fuel economy

And all with less strain on motor

And further once setup if you blow one you can buy a complete running motor for $100, I did, find me a running 26 for less then $2500

The only drama with the 30 is clearance top and bottom but again once setup that no longer an issue

Then there was the need comment, whats need got to do with a 350kw GTR, that is ALL WANT, the want to go faster, gearbox longevity is as much as driving style as outright power, and as I've said before those of us that want push that far know that doing the drive line is enevatable, I've seen GTRs blow boxes with less then 350kw, the BSM car did a few, OS and PPG, when it was in IP with around 300kw

So OP needs to decided HIS end goal and build for that, if all he wants is faster then go the 30, if he is worried about sound and drive line leave is stock or find HIS own happy medium

My 32 is my happy setup, 293rwkw and an 11.1 for a daily drive it is an absolute ball to drive and IMO the perfect alrounder, my 34 on the other hand is all about speed and lap times and that is why it has a 30 in it and should make north of 450awkw on its current setup

Is your car quicker around the track now? No-one seems to be able to quote any evidence.

Never said there is no advantage in a 26/30 of course there is due to the torque coming in earlier etc etc, so don't know what gave you that impression.

Your comment on response is interesting. I find my daily 26 responsive enough from 3800rpm which I am happy with and swapping cogs at 7000-7500 rpm I don't fall off peak boost...if I want response from 2000rpm I will go back to driving my clubby but I love revving out my 26 that's why I drive it,

fuel economy??? you've got to be kidding right?

As far as pushing the limits, a 26 is more than capable of running 8sec 1/4 mile, don't need a 26/30 for this and those 30s running quicker are rumoured to be cracking blocks that's why they are starting to use patrol blocks. And even so they try to reduce torque because they lose traction mid track. Circuit is all to do with setup and driver.

The reason why I quote 350kw is because 300-350kw seem to be the 26s sweet spot in a GTR for a nice daily and track event car with great reliability. Yeah and I also know of many 350+ kw 26 gtrs which get a lot more abuse than mine that 10years on and they are still running strong, standard 5 speed gearbox and all.

As far as th hi octane GTR, we are talking a whole different level but still as far as I know evos are still kicking arse....but not relevant here anyway.

Each to their own mate but I am yet to see enough evidence, ie track time, to suggest an indisputable advantage of throwing out the 26 in favour of a 26/30.

[Lithium]

I know a few people who have gone from RB26 to RB30 in track cars, and they have all ended up going quicker - I haven't mentioned any of them because going to an RB30 (or even an RB28 really) is usually part of a list of things often done when someone is taking it to the next level, and I anticipate the natural (and understandable) comments that the time reduced, or at least a certain amount of it can be attributed to the other bits. The fact it is normally part of the "taking it to the next level" bit has to be worth something, though.

[XKLABA]

Is your car quicker around the track now? No-one seems to be able to quote any evidence.

Never said there is no advantage in a 26/30 of course there is due to the torque coming in earlier etc etc, so don't know what gave you that impression.

Your comment on response is interesting. I find my daily 26 responsive enough from 3800rpm which I am happy with and swapping cogs at 7000-7500 rpm I don't fall off peak boost...if I want response from 2000rpm I will go back to driving my clubby but I love revving out my 26 that's why I drive it,

fuel economy??? you've got to be kidding right?

As far as pushing the limits, a 26 is more than capable of running 8sec 1/4 mile, don't need a 26/30 for this and those 30s running quicker are rumoured to be cracking blocks that's why they are starting to use patrol blocks. And even so they try to reduce torque because they lose traction mid track. Circuit is all to do with setup and driver.

The reason why I quote 350kw is because 300-350kw seem to be the 26s sweet spot in a GTR for a nice daily and track event car with great reliability. Yeah and I also know of many 350+ kw 26 gtrs which get a lot more abuse than mine that 10years on and they are still running strong, standard 5 speed gearbox and all.

As far as th hi octane GTR, we are talking a whole different level but still as far as I know evos are still kicking arse....but not relevant here anyway.

Each to their own mate but I am yet to see enough evidence, ie track time, to suggest an indisputable advantage of throwing out the 26 in favour of a 26/30.

I certainly didn't go to a 30 to go slower, and as Lith said no one does just the 30 to improve lap times, it is almost always part of a bigger build with turbo cams intercooler exhaust etc, like mine, so evidence of them been quicker directly from the increase in CCs would be rear, but if you can't comprehend that a 30 is going to give better response and a more drivable setup that is naturally going to be quicker then what can we say

if you agree there is a benifit to going a 30 why are we having this discussion ?

why is my comment about a 30 been better response wise interesting, when you push near 450cc every cycle that is a puck load more air and more air means it will pressurize the exhaust manifold quicker and force the turbos to spin sooner, that is just commonsense

my 32 makes positive boost pressure from before 2000rpm and will drive hard from 2000rpm all the way to 7500 no dramas at all so I don't have to drive a dressed up commodore to get that response and it runs 11.1

when I first did my 34 the only things that changed is the 30 and the turbos went from -7s to RSs, everything else was the same even the tune and since the 30 pushed the RSs the same as the 2.6 pushed the -7s I was able to drive it for 6 months with out tuning it until I changed the exhaust, and yeah it used LESS fuel driving around normally on a non tuned setup, exhuast temps where the same as before and the knock never went over 4-5 on the commander, and it only registered that on startup

so how many 2.6s are running 8s and how many 30s are and how many 2.6s are actually 30s but won't tell you that, whats need got to do with it, simple fact of the matter is the 30 WILL ALWAYS, on the same setup, be nicer/easier to drive on and off the track, be more responsive, and have to work less hard to move 1500kgs of car and there fore use less fuel, both 2.6s and 30s split blocks it is a risk you take when move on from factory power on a cast iron block

instead of reducing torque they should look at increasing traction and they will go faster, it is a drag car after all

350kw on a 30 will be a sweeter spot then the 2.6 with 350kws, better on and off the track, I didn't bring up the Mines car but since it was there needs to be a reference to compair it to, it is faster then a stock car yes but I'd say slower then the Hi Octane car so what do we compair it to

I'll say this, after driving an untuned 30 I'll never build a 2.6 again, as much as I wouldn't build a 30 block again it will be a 3ltrs, no ifs or buts, drive one and you'll understand why

[XGTRX]

Again put up some lap times that indisputably show it's worth the change.

All I have heard is opinions on how much faster the 26/30 SHOULD be around a track....I have looked myself and can't find any, so until I find data that there are SIGNIFICANT advantages to change a 26 to a 26/30 on a daily that sees 12 track days a year then as far as I am concerned it's not worth it...and if well setup will continue to be a force on the track.

As for the 34 on -7s I remember it had cams in it and produced more power than the 32 you have...I think it's you....from what I know you just moved the sweet spot up by 800rpm...not the best setup for circuit as the -7 would quickly run out of puff and torque would come on too late to take advantage of their lower rpm efficiency.

And yes I know of many people using 26s and running 8-9 sec quarters. A guy in qld had the fastest 26 running 7.5 from memory. And yes there is word that the mattouks like others are using patrol blocks to run more boost, so not true rb 30s

As for everything else...well lets just agree that we disagree on what we think is a better car to drive on the street and many people that I let drive it love it and rave about the performance and characteristics of the 26 and yes these are people with vls, ss, supras, 200s street cars that many run 9-10 secs quarters and know how to throw a car around a track.

No disrespect to you or your opinions but I have driven and been in many 30s and 26/30s....great engines....but if I wanted all torque down low I would drive my v8 but I don't and I love driving a 26 that is very comfortable driving around under boost in peak hour and is very rewarding at 4000+rpm when I want to play.

But each to their own...all good.

[fatz]

this thead is gold!

[discopotato03]

I think there's lots of oxygen in the old can't beat cubic inches argument though forced induction changes the playing field significantly .

I'd say that saying came from the states in decades gone by where fuel was cheap and big V8s were everywhere .

My take is that more cubes makes everything easier because you need less revs to achieve the same thing and the increase in low rev part throttle torque is often directly proportional to the capacity increase . We know full well why Nissan went with 2568cc and it had nothing to do with making a GTR a nice all round road car .

I don't know for sure but I think the RB25 and 26 blocks are externally the same dimensions as the RB20 that they'd had for a while before the GTR saw the light of day . I don't think either 25 or 26 are exactly ideal bottom ends and the blocks could have been taller and their rods longer . From this perspective the RB30 is better because the bore stroke and rod stroke ratios are better , the 26 combination is the least desirable IMO and stroking their std height block makes the situation worse again . This is not to say those combinations don't work its just that they're not exactly ideal .

Look at the apps RB30s went into and its hard to deny they wanted more torque in a lower state of tune - read cheaper to manufacture and sell single cam types . I think Japan and NZ had SOHC RB20s and we got SOHC 30s in R31s/VLs and ST Patrols . VLTS had 30ETs in a really soft state of tune and getting the 155 odd crank wasps up to 209 would have been a walk in the park with a half decent IC CR increase and something a bit better than a small series Garrett T3 .

A 3L factory R32 GTR making the same 209 kw should have had more linear power delivery than 2568cc versions and I think would have pleased more people who bought them . Not everybody gets off on reach for the sky rev counters and boost gauges and a road car that "feels" peaky takes more effort to drive if you want it to pull well everywhere .

Gearboxes , they are a problem in road cars given a big bootfull of revs because strong enough shafts gears and syncro hubs have a lot of inertia and convincing everything to slow down at change time can be difficult . I knew a feller that tried dragging a VLT with an RB26 and the std wide ratio VLT box and it would never change gears properly . If you don't want to go to dog boxes closer ratios and more torque at less revs is an advantage .

Anyway I agree with Lithium in that reducing the state of tune (boost) is the way to torque limit a larger engine , this doesn't alter the RB30s ability to out muscle an RB26 at 1-3000 revs and pull higher gears down there .

Ultimately high revs is where wear and tear are so if you can in theory make the same power at less revs then the engine should have a longer useful life between rebuilds if serviced properly and not abused . Better fuel consumption from not having to boot it everywhere is a bonus . Some of you may laugh at fuel consumption woes but try driving that hotted up GTR everywhere and living with the fuel bills . I think the consumption killer is having to dump extra fuel in every time the engine goes into boost , if it made adequate part throttle torque and the turbos were sized not to spool every time you breathed on the go pedal it's easier to get acceptable consumption .

Anyhow blame the Grp A regs and the weight class Nissan wanted to race the GTR in .

A .

[Lithium]

So reading through all these posts objectively - in summary of straight facts technically the RB26 is not a bad donk but the RB30 is still equal or better at virtually everything, however when it comes down to taste some people like the way the RB26 sounds over the RB30. I guess what that means is the RB30 is clearly better but you can't knock anyone for wanting to stay with the RB26