To 30/26 Or Keep The 26?

[XKLABA]

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.

yeah ok what ever guy, I'll just correct you on what you think you know about my cars, it was -7s on my 34 with cams injectors etc etc and yeah it made more power then my 32 but yet ran an 11.8 against 11.1 for the 32 so that proves power isn't everything, the 800rpm increase was a change of cams not bottom end and it was the car came on boost 800rpm sooner, was easier to drive/more powerful off boost and was still holding 20 psi at 8000 and with a leaking rear manifold to turbo gasket and shite tyres, stock brakes and suspension I still managed 1.09 around wakefield

as for the 30 swap there isn't a result for that yet as it hasn't been tuned, I've only just finished the supporting mods for it and it doesn't get tuned till the end of next week, then we will see the advantage of a 30

OP asked for opinions so heres mine, if your 2.6 isn't broke use it, if it does stroke it

Oh I remember you now, your the guy that posts alot of shit without any evidence you even own a GTR except your user name

[XKLABA]

I think there's lots of oxygen in the old can't beat cubic inches argument though forced induction changes the playing field significantly . yes and no, tech changes that field, look at the little honda motors, that said put the same tech and boost at a bigger displacement and it will always be better

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 .

I remember watching or reading some thing about the making of the R32 GTR and from what I remember it was going to have a RB25 but when they finished the car it was to heavy to be competitive in that class so they inceased the stroke and lifted the piston pin hieght to increased the engine capacity by 70cc over 2.5ltrs, everthing else you've said is exactly why I built a 30

[whatsisname]

It comes as no surprise manufacturers use displacement when they want to improve engine performance from one model series to the next. The only exceptions are when a manufacturer opts for forced induction over a previous naturally aspirated engine, and even then in time they may increase the capacity of the forced induction unit later in the model cycle.

Mazda: SP20 2L- SP23 2.3L - SP25 2.5L

Subaru: 2L - 2.5L

Nissan: RB20DET - RB25DET / CA18DET - SR20DET / RB26DETT - VR38DETT

GM/GMH: 5.7L - 6.0 - 6.2 etc.

Ferrari: 348 - 355 - 360 - 430 - 458

Porsche 911: 2L - 2.2 - 2.4 - 2.7 - 3.0 - 3.2 - 3.6 - 3.8 - 4.0

Regardless of the engine, forced induction or naturally aspirated, there really is no replacement for displacement.

[Tyranus]

RB30 without a doubt is a better base to start off with if you want a power house. Like i said before i wouldnt swap the RB26 for a 30 if my gt-r was going to be a mildly modified daily. Ive stroked my 26 to a 28 due to going big single otherwise i would had stayed with the 26 if i were going to keep the twins.

All the money you would need to spend on a 26/30 could be spent on other areas of the car likes brakes/wheels/suspension etc.

Edited November 20, 2013 by Tyranus

[XGTRX]

 

yeah ok what ever guy, I'll just correct you on what you think you know about my cars, it was -7s on my 34 with cams injectors etc etc and yeah it made more power then my 32 but yet ran an 11.8 against 11.1 for the 32 so that proves power isn't everything, the 800rpm increase was a change of cams not bottom end and it was the car came on boost 800rpm sooner, was easier to drive/more powerful off boost and was still holding 20 psi at 8000 and with a leaking rear manifold to turbo gasket and shite tyres, stock brakes and suspension I still managed 1.09 around wakefield

 

 

Oh I remember you now, your the guy that posts alot of shit without any evidence you even own a GTR except your user name

So you're agreeing that you putting cams on a -7 setup made your car slower and a pig to drive.....funny people have been reporting this for 10+ years and there are results to support this NOT a favourable setup.

Yeah you're right I don't own a GTR and all my experiences are pretend fantasy world delusions. Grow up mate. Don't try to discredit me because we have a difference of opinion.

[Piggaz]

So you're agreeing that you putting cams on a -7 setup made your car slower and a pig to drive.....funny people have been reporting this for 10+ years and there are results to support this NOT a favourable setup.

Yeah you're right I don't own a GTR and all my experiences are pretend fantasy world delusions. Grow up mate. Don't try to discredit me because we have a difference of opinion.

So, putting cams in a basic setup like the one mentioned above is a bad idea because it may push the curve to the right a tad, but putting a bigger engine in the car which will push the curve to the left is also bad?

[C4a0s]

just to summarize...

putting in a RB30 requires more supporting mods..meaning u cant just use those existing on ur RB26 else it'll perform worse?

so...maybe to some, it boils down to cost effectiveness and/or purpose. no right or wrong... as long as it fulfils ur requirements and wallets.

chill guys

[sky30]

Xgtrx,

If i put a rb20 in my gtr, is it going to be faster than a rb26?

[Ben C34]

So, putting cams in a basic setup like the one mentioned above is a bad idea because it may push the curve to the right a tad, but putting a bigger engine in the car which will push the curve to the left is also bad?

Because Internet argument.

[XGTRX]

It comes as no surprise manufacturers use displacement when they want to improve engine performance from one model series to the next. The only exceptions are when a manufacturer opts for forced induction over a previous naturally aspirated engine, and even then in time they may increase the capacity of the forced induction unit later in the model cycle.

Mazda: SP20 2L- SP23 2.3L - SP25 2.5L

Subaru: 2L - 2.5L

Nissan: RB20DET - RB25DET / CA18DET - SR20DET / RB26DETT - VR38DETT

GM/GMH: 5.7L - 6.0 - 6.2 etc.

Ferrari: 348 - 355 - 360 - 430 - 458

Porsche 911: 2L - 2.2 - 2.4 - 2.7 - 3.0 - 3.2 - 3.6 - 3.8 - 4.0

Regardless of the engine, forced induction or naturally aspirated, there really is no replacement for displacement.

Yeah and then you turn up to one of their track days with a GTR with a 300kw 26 and decimate them all....as has happened many times before. And the thing that's amazing is that after 20 years a lightly tuned well sorted GTR can be driven to a track compete with current supercars and drive home. Or that a highly tuned 26 can stand toe to toe with 7 litre turbo charged LSX in a straight line. 26 must be substandard then.

[Piggaz]

Xgtrx,

If i put a rb20 in my gtr, is it going to be faster than a rb26?

Destroke it. RB 08. 31 mm stroke. Sound better too.

[XGTRX]

So, putting cams in a basic setup like the one mentioned above is a bad idea because it may push the curve to the right a tad, but putting a bigger engine in the car which will push the curve to the left is also bad?

No it's great but doesn't mean it's vastly superior to a well sorted car with less cubes. That's my point.

Its like having a cam that comes in at 4000rpm on an na ls and having a 2000rpm converter, it would be a slug but put a 4000rpm converter in it and it's very efficient.

[sky30]

Destroke it. RB 08. 31 mm stroke. Sound better too.

RB08 would be crazy fast then.

[XKLABA]

some dudes need to learn to read, IT CAME ON BOOST 800RPM SOONER with 250s then it did with 260s, so how does the better response make it slower, it wasn't it was faster, my 32 is just very well sorted given it is basically stock, the 34 hadn't quite got there and I didn't get to drag it on that setup before spinning a big end and bending a crank which is why it now has a 30

the wrong cams will make your car worse the right cams will make your car better, you just gotta know what your doing and not just copy what some dude on the computer did, instead look at what people have done and see what happened and decide for your self what works

I don't need to discredit you, your doing a good job of showing what you don't know all by your self, but it is you that keeps asking for evidence and I haven't seen any thing about anything from you yet, just alot of typing

I'll take it the supporting mods comment was at me and will respond with, no not cause of the 30 but cause I want to see 450+awkw, limited by turbos, the car happily drove around for 6 months with all the old supporting mods but they won't like the power goal and so when the new computer got here they got upgraded to help assist my goal

my stand is this, take two cars one 26 and one 30, same car same mods same setup same tune same same, the 30 is always going to be nicer to drive and faster to race

RB08dett, lol for sure, my 1ltr ninja revs to 13,000rpm maybe I should put that in my car

[C4a0s]

I'll take it the supporting mods comment was at me and will respond with, no not cause of the 30 but cause I want to see 450+awkw, limited by turbos, the car happily drove around for 6 months with all the old supporting mods but they won't like the power goal and so when the new computer got here they got upgraded to help assist my goal

my stand is this, take two cars one 26 and one 30, same car same mods same setup same tune same same, the 30 is always going to be nicer to drive and faster to race

thanks for clarifying

cost wise.. how much was it to build the RB30?

[XKLABA]

thanks for clarifying

cost wise.. how much was it to build the RB30?

just the engine to fit a GTR ?,

I went for the best of most every thing so my cost was higher then most but I knew what I wanted to end up with, and for the average build not needed

running RB30 $100

forged pistons and rods $ 2000 landed

preping the crank $500

adapter plate including required machining just shy of $3000, I used the Platinum Racing one because it bolts to the girdle as well as the block, I've seen normal steel ones for around $800 no machining required

Nitto oil pump and N1 water pump $1500

machining for over size pistons and bottom end assembly $1500

then say $1000 for miscellaneous like gaskets oil water feeds for turbos, oil restrictors bearings etc

I made 8mm spacers for the subframe and cause I have the long CES dump pipes they didn't have to be modified

really the only thing different to building the 30 instead of the 26 is the adapter plate, every thing else is much of a muchness and once its in and setup rebuilding a broken one is the same as a 26 except replacing the crank and/or block, complete running motor $100-$300

In total for my whole build, hahaha more then I care to tell my wife

[C4a0s]

the adapter plate is the scary part...$3000...ouch

[sky30]

My adapter plate was $450, plus bit of time for me to drill and tap holes to fit

[XKLABA]

My adapter plate is the dearest one there is and when I brought it I didn't know the amount of machining involved, $1250 for adapter kit, $1700 for machining

the girdle had 5thuo taking off it then torqued down

then they had to machine the top of the girdle at a set distance from the block

then drill and tap a dozen bolt holes in the girdle for the adapter to bolt to

then line bore

then drill and tap the holes in the bolt for bigger bolts in the block

none of which is required with normal steel one like sky30 uses, they bolt straight up with no machining

$450 is cheap the best I found was around $800 for a kit with all the bolts needed, where did you get it from

the one I have

http://www.hioctanedirect.com/index.php?main_page=product_info&cPath=67_88&products_id=1338&zenid=q99cn7eg0qtdsbad43tq8jbvk0

the normal one

http://www.hioctanedirect.com/index.php?main_page=product_info&cPath=67_88&products_id=1369

[ido09s]

I dont know how quickly the guy plans on upgrading the turbo, but a customs from Unigroup, also a member on here, is planning to upgrade his T04Z to a 6766. It sounds like he will be running the same turbo as ours only it will be a 26 versus a dirty 30 with a 25 head.

Hopefully he does it some time soon so i will see if i can get a dyno graph of the 2 cars to compare the difference in power and torque