Modified Rb20 Vs Stock Rb25

[Col-GTSX]

The only people that will tell you an RB20 is any good are the owners that are either in denial or haven't seen the light of the larger displacement RB motors.

RB20 was probally good for the jap taxi's though

<{POST_SNAPBACK}>

HAHAHAHA :lol: Thats magic....

WHat i was trying to say... Alfter owning the following

* 2 x Rb20det

* 2 x Rb25det

* 1 x Rb26dett

I have to say the 26 was fun but fairly expensive to modify (back when i owned one in 1999 parts for a 25 were half the price as for a 26)... But the 25 is so cheap to open up and modify with 26 bits anyway...

I still think the more cubes the better but as a medium i like the 25 the best.

[r32skyline_89]

Stay with the rb20. bore it to 2.4lt and your nearly at rb25 anyhow. cheap power. rb20s good for 400hp you dont really need too much more than that, spend your bucks on a good computer and tunning along with strong internal work and guarenteed a reliable 400hp car. and if its and every day driver thats what you want RELIABLE

[Roy]

The only people that will tell you an RB20 is any good are the owners that are either in denial or haven't seen the light of the larger displacement RB motors.

<{POST_SNAPBACK}>

LOL..anyone in their right mind would agree....but then when you consider economics and registration, well lets just say that my car sneaks into the 12s, is reasonably quick at the track, and im making reasonable power reliably on a std motor.

How much to get 240-250rwkws out of an RB25 and installed in an R32 GTST....remembering that 4,500 to redline my car makes something like 223rwks average power (from memory)

Its not the greatest setup by any means, but considering its a std $600 motor, and the gearbox appears happy the last 20,000kms with the current turbo...well to do an RB25 with gearbox, to make 15kws more peak power?????

Admittedly it probably will make double the power at 3,800rpm which is huge difference on the street...but i dont speed and have never been booked so as long as im able to keep it on the boil above 4,200rpm on the track then im happy...and slightly more wealthy.

Would my turbo setup be quicker on an RB25 or RB30, no doubt, but im only after a fun car that is reasonably quick...not the quickest car as i cant afford to raise the bar any higher

[TTT]

I hate it when Roy speaks logically.

[Gts-t]

People who say rb20 are shit are those that:

Cant use gears correctly. and wants to drive around at 1000rpm

Have only driven one with a stock turbo

Or have owned one in a r31, or drive a whale ie 33 or 34 that really does need a 2.5 to move its heavy ass.

Anyone with 220rwkw from a hks 2530 in a 1300ish kg r32 will tell you all about the 110mph it will generate easily on the 1/4 mile. Add that to lightweight wheels and flywheel and you have a highly responsive car that will walk away from a a lightly modded or stock as per the thread rb25 in a r31/3/4

The 2.5 has always been a joke, its either 2 or 3. 2.5 must be the most boring motor on the planet, not to mention the most likely to break.

For example there are plenty or sr20 equiped cars that will whip a stock or mild or wild rb25.

Basically if u cant drive get a 2.5, if you can get the 2.0 and a bolt on turbo

Also fuel consumption should be 25% worse with a 2.5 considering its fueling 25% more engine the whole time.....

[TTT]

so going by your theory, the rb26dett is even worse than the rb20.

is that right?

anyway, these RB20 is better than RB25 threads are just stupid.

each to their own.

Roy and his love for his car is easy to see.

no problems around town cause he is a law obiding citizen.

his car needs 4200rpmish to get fun.

on the street that is not going to happen.

so he can potter along and then go crazy on the track.

but me personally, I can't stand the lazy feeling of the RB20.

and will go straight to 30 when I can.

especially when my one weighs the same as a GTR but with only the 20 in there.

[Gts-t]

so going by your theory, the rb26dett is even worse than the rb20.

is that right?

anyway, these RB20 is better than RB25 threads are just stupid.

each to their own.

Roy and his love for his car is easy to see.

no problems around town cause he is a law obiding citizen.

his car needs 4200rpmish to get fun.

on the street that is not going to happen.

so he can potter along and then go crazy on the track.

but me personally, I can't stand the lazy feeling of the RB20.

and will go straight to 30 when I can.

especially when my one weighs the same as a GTR but with only the 20 in there.

<{POST_SNAPBACK}>

Nah i didnt include it for the obvious reason its tops. Besides the fact i havent driven one. I agree each to there own but there is still no arguing with the smoothness of the rb20, that said im planning a 26/30, lol.

My car with a 2530 is perfect for the street, generates boost almost as fast as the stocker, the difference is hardly noticeable. I think roy went a little over size for the 20 but perhaps not, it all comes down to what you personally think is fun or exciting to drive. I would love to drive roys for comparison looking at his dyno chats he has heaps more over 6000 than me.

my 2c, Mick

[Roy]

Like i said, if i had the money to build up a larger RB## then i would. Building one up only to have it let go at the track because of bad luck is another story all together...

Thing is even with a bigger RB i would go for a similar power delivery as to what i have now. I would obviously like it to be a little more responsive..say 200rwkws at 4,000rpm...but i dont want too much mid range torque stressing the tyres as i dont have too much finesse with the throttle

Dyno plots are only guides, but this is a spreadsheet i made up to compare my different sized exhaust housings...and comparing it to some other setups including std RB25s the gap isnt that large that i feel the compulsion to change. If it blew up and i could get an RB25/30 in the car for the same price, no doubt thats what i would be doing.

PS..its possible that the rolling diameter of the tyre i was running on the dyno is a little out for the road speed to rpm calculation, but at worse it may be 150-200rpm out (i got the circumference of the Dunlop webiste so if its wrong blame them )

[BHDave]

I'm lazy, i like my rb25 r32 for the simple fact that i don't need to change out of 4th all that often once i'm moving. I'll get an rb30 when i want to pull away in 4th

[Roy]

BHDave...but to be fair, i was looking at your T300 setup and my RB20 actually has more midrange, and almost matches it up top, and basically equals your peak power figure with less boost.

So any RB is only as good as the balance of parts thrown at it?!?!?!?!

[BHDave]

Yeah, i noticed that, except i get boost about 800rpm sooner on the street than the dyno.

Not taking anything away from yours, as the change in exhaust housing seems to have made a huge difference. My response with the rb20 and highflow was only marginally worse than what your's has (and nowhere near the top end) and the bottom end / midrange was non existant compared to my current setup.

Edited January 6, 2006 by BHDave

[Savage Bliss]

You know what??? Call me Judas... but.... 2JZ HAHAHA... :lol:

[Roy]

Yeah, i noticed that, except i get boost about 800rpm sooner on the street than the dyno.

<{POST_SNAPBACK}>

...at the end of the day you do all your driving on the street at 3,000rpm +/- 1,000rpm, and at 3,000rpm an RB25 would have twice the power of an RB20...you just cant make up for that lull if you are driving through that rpm trying to have a bit of a squirt on the street....which is part of the reason my car to many is a dog on the street

[BHDave]

That was the main reason i ditched the 20. I used to drive my car alot for work and once the bigger turbo went on it was just unbearable for me.

[Nathan_G1]

i was happy with my RB20, was cranking 180rwkw with great spool. but the bigger turbo u add the more mid-low torque u loose which isnt wat i wanted to do seeing that i wanted to drift it. i also didnt wanna crank out near 9g's or more for an RB24 overhaul. in the end its up to the owner if he wants to remain with his RB20 or if he bites the bullet and cranks an RB25 in it. coz with that light weight and a bigger engine itl b better

[predator]

That's what i think too.. ok at lower levels. Soon as you get some power going through, the lag just gets nasty and you then have to spend more money on cams, or camgears, careful turbo matching, etc to get what back you're losing down low.

But again, if you need to drive slowly around the streets (i.e. VIC) it doesn't matter if its slow down low or anywhere else. But I live in QLD .. and the roads are pretty open here and a lot more freedom.

Anyhow, had a mildly modded rb25, got a mildly modded rb20, getting another rb25 .. from experience I know what does it for me.

[Jamezilla]

I use to own a GTR, and the simple fact is i have driven a R32 with RB20 and TD06 POWAH...and there is no comparison.

The GTR kicked its ass

But said R32 still blows the doors off every Vic RB25

PS - I love using other peoples ID...signed Roy

[Nathan_G1]

thank god im from S.A, coz u aint gonna blow this guys doors off mate........actually u probly will coz i most likely wont get traction till 5th

[BreathLess]

i read somewhere that the R32 gts25 has the same weight as a R33 gts25 so does that mean the frame of the car weight the same. the weight was 1360 for both cars. so the only weight gain is from the lower power of the Rb20

[wheels_24]

I was in the same boat my RB20 went i me and i was stuck with the same problem weither to build it back up again or buy a RB25. In the end i just rebuilt as i was happy with the power i was getting before the problems with it, so i got some aries forgies and got my machanic to rebuild her for me and i couldn't be happier, i am same as roy just like crusin around town and if i want to have fun i have to take it up to about 4200rpm. But remember i have a new recondition engine that should be good for say 150,000km (lets hope) were if you buy a secondhand motor in 6 months down the track after warrenty runs out you might be in the same boat again and have to engines that are no good, that was my worry