RB20 vs Rb25 vs RB26.

[JD74]

Back on topic......

Wanna be poor (and careful by fear of breakage) ? build a '26.

Wanna drive it like you stole it and not care ? build a '20 or '25.

[Velders]

LS1 ftw

(you think I'm joking)

Thats a stupid idea. I cant imagine why someone would want a lighter engine with just as much aftermarket support, torque for days, and better fuel economy (better that my gtr anyway). What a silly thing to say.
Oh I guess I should add reliability too, who wants that.

[NismoS-tune]

Suddenly, I think I figured out what to do with my silver surfer! I've been too busy to sell it and I don't owe anything on it... Maybe an LS1 would be a good project!!!

[RABBIT]

26's are for people with small penises.

[JD74]

26's are for people with small penises.

That's probably the stupidest thing you have posted on this forum.

I'll leave it at that.

[DrMango]

If you're worried about oil issues, get an accusump or some other oil accumulator. The self priming ones for startup are pretty kickass. When my rb20 is set for a rebuild, there's definitely one going in my car.

im interested in this. im in the middle s of a rebuild so im looking for any stop gaurds to needing a second rebuild any time sonon...

Kyle

[Skym]

JD74, please don't quote me on this -

The owner of the R32GTS-T owned a N1 R34GTR and he said the R32GTS-T was quicker and cheaper to run.

Here's his N1 R34GTR -





His R32 GTS-T -











After hitting a fence and going into I think was a field -



Exactly, RB26 doesn't get onto full boost until later in the rpm's 3800-4000 rpm where it can accelerate better if car is lighter (racetrim) and R32 GTS-T gets onto full boost at 2500-2800rpm with a GTS chassis that's lighter than GTR chassis.

These Targa cars are restricted by rulebook to stock engine, stock turbo's that came with engine and only allowed a few mods like ECU, suspension, etc. As you probably already know a N1 GTR has bigger turbo's and can produce 455ps quite easily but weigh alot (200kg or so more) compared to R32 GTS-T. HP makes up for the extra weight.

I gather it's power to weight, as he said his R32 GTS-T had similar power to weight figure to the GTR's (he roughly knows the awkw of the other GTR's). I think it's the handling and the way the engine builds full boost earlier, weight of car that makes his R32 GTS-T quick out of corners.

It's not the only GTR or Porsche they have passed. Also he said there are few guys now building similar spec R32 GTS-T's.

R32 RB20DET is very impressive for a stock engine package that alot of people dump and fit bigger capacity, heavier engine like RB26 or RB30 or bigger turbo that comes onto full boost at higher rpm's.

[Terrh]

I've seen as many blown up 25's and 20's as I have 26's.

They all blow up. They're all 10+ year old motors.

Comparing stock cars to modified cars is retarded. My RB20 is faster than a 26! Not really. Do the same things to the 26 and you'll see the difference lol. Displacement is king. There's no way around it. Go for a ride in a turbo v8 running 7PSI and you'll be floored by the sheer power it has.


Those oil pressure ignition cut switches IMO are a waste of money. You have to set them at some sort of oil pressure below what you'd see at a hot idle. (say, 20psi) - and having only 25psi at 7000RPM means a dead motor. Besides, if the oil pressure dropped - it's probably too late now anyways.

[RHDskyline]

there is no replacement for displacement.


That was true, it is true, and it will always be true

[JD74]

Exactly, RB26 doesn't get onto full boost until later in the rpm's 3800-4000 rpm where it can accelerate better if car is lighter (racetrim) and R32 GTS-T gets onto full boost at 2500-2800rpm with a GTS chassis that's lighter than GTR chassis.

That makes sense, but you have to admit - the GTS driver drives the car WAY deeper into the corners (when he catches the GTR) and does a much better job at keeping the motor spinning in a proper power band.

The driver of the GTR could have done a better job.

[Skym]

This videoclip shows what the R32GTR is capable of in tight corners with a good driver -

http://www.youtube.com/watch?v=DbEx7uY0b0k&feature=related

Terrh, the engine in the N1 R34GTR is N1 spec (factory spec racecar) with stock RB26 engine (modified cam timing, modified engine internals) and "bigger" N1 turbo's (steel exhaust wheels), so is already capable of more hp than stock RB20DET engine in a R32 GTS-T. Like I said above, they are both restricted by the rulebook to stock engines, etc. But it's impressive that the R32 GTS-T is quicker with similar mods and stock RB20DET engine. Even in modified trim, up until a certain hp level, they are even.

RB26 in GTR is quick once you modify the engine to higher hp levels and lighten the chassis to racespec, there's no doubting that. But RB26 needs more hp to move the heavier 4wd GTR chassis that loses alot of hp to wheels compared to RB20DET that moves a lighter rwd chassis and has less drivetrain loss.

GTR would be better in wet weather with similar power to weight, as it can keep up the pace with 4wd. That's why they call it allround supercar, as it can produce the result's when ground is dry or wet.

A good example of RB26 engine with single turbo in lightened R32 GTS-T chassis at 2:40 -

http://www.youtube.com/watch?v=a5uRmQhVJp4

Good combination if you want reliable stockish engine (like N1 engine) with 460hp, like in a 24 hour race.

[Terrh]

drive a GTR in 2WD mode in the dry. It's ******* useless. Even on the stock turbos, hello 3rd gear wheelspin. and 4th if you're using the gas pedal cornering.

GTR's EXPLODE out of corners like nothing 2wd can even dream of. the AWD system isn't optimized for wet use, it's designed to haul ass in the dry.

GTR's only have more drivetrain loss when the torque is actually moving foreward, and it's not a very high loss system.

my stock turbo'd (R32 ceramics) went 11.5 in the 1/4 mile and did things at deals gap and on the street that a GTS could only dream of. There's no comparison between the two at anything even resembling stock. What's the fastest stock turbo'd GTS run? I bet it's not even in the same leauge, nevermind the same ballpark.

[Andrewc]

http://www.accusump.com/accusump_tech.html#whatis

This explains the accusump, for the money they're worth it imo.
Basically if your oil pressure drops below a set level, it dumps extra oil into the system to keep the pressure constant. They also store oil pressure on shutdown so you have full pressure on starting.

[Skym]

Semislicks or slicks and good suspension helps with wheelspin. Also the way the engine is tuned (cam timing) in rwd can make a big difference, as found this out with a S15 that was tuned this way to maximise grip at lower rpm's on semislicks but wheelspins at higher rpm's (gives it away as to how they set the cam timing). Also if shocks are stuffed, can cause excessive wheelspin, even with a RB20DET in R32GTS-T.

That's true, at Nurburgring they had buttons on the dash to reset 4wd, ABS for wet weather on N1 R34GTR prototype.

That R32GTR in videoclip above shows what R32GTR can do on a tight course.

From what I understand from the videoclip I saw, the way the Gibson R32 GTR's were setup, is the 4wd helps in slower corners to rocket from corner to corner, but was rwd at high speeds. Could be one of the reasons why it struggled on a tight circuit due to big loss of hp at the wheels in 4wd split. The other is the you can jab throttle with RB20DET powered GTS-R which helps to narrow the gap in corners where the R32GTR has to slow down and keep a constant speed (you lose lap time due to slowing down in corners which was the achilles heel of the RB26 engine and is why GTR now has a V6 which helps with lateral balance, corner speed). Little characteristics of the way the car drives that I've noticed that helped the RB20DET powered GTS-R to catch up to Cossies, R32GTR's, V8 powered Ford Falcon's, etc.

The R32 GTS-T with RB20DET produces fullboost, peak torque lower in the rpm's which helps to pull out of corners quicker. Also R32 GTS-T has 4.36:1 diffhead which matches the quicker spooling setup and helps with low rpm acceleration. R34GTR is geared to topspeed with higher ratio diffhead's (3.45:1?) which doesn't help at lower speeds, lower rpm's. Needs 4.11:1 R33 GTR diffhead's with HKS 25/30 turbo, etc, which is a popular upgrade for R34GTR.

My guess would be roughly mid 13sec on street tyres with the 200rwkw (268 rwhp) that which this R32 GTS-T was producing with stock turbo at 14.7psi and street tyres. He might have been running semislicks which helps alot with grip, so maybe high 12sec 1/4 (on a prepped / grippy dragstrip or grippy road).

Also Group-A R32GTR needs to stretch it's legs on the straight's to make use of the extra hp, which was it's advantage at Bathurst, etc.

[love_boost]

That's probably the stupidest thing you have posted on this forum.

I'll leave it at that.

lol.
well i am just trying to get at my 350-400whp goal the cheapest and most safest way, considering the 26 can make around 350rwhp with just higher boost tune and supporting boltons (which i pretty much have now anyway.) i think it may be smarter.

or i could spend 1000 dollars less and get a RB25. not only that to get the same whp goal out of a 20 or 25 you would think a bigger turbo would spool later on? im sure full boost in a GT32 or TDO6 20G wouldnt come on until around 3400?

thats why i kinda gave thought to the RB26, and there is alot of room for improvement once i get outta highschool. Not only that i think a RWD RB26 would be pretty crazy as is in a GTS with just bolt ons.