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Difference between RB20 & RB25?

elboro

By elboro,
in Engines & Forced Induction

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RedDrifter Experienced

RedDrifter

Posted
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I like this thread. I'm curious as to know where all the peak torque figures are for our RB20's sit at.

Would 5250RPM be too high for most of us or is it higher.  

The higher would be better for my setup.

I'm guessing my peak torque would be around 5000 to 6000 rpm.

Hopefully I will find out this week at the Ingham car show.

RedDrifter Experienced

RedDrifter

Posted
Posted

Just before 8000 rpm.

Ussusally about 7800 going from what my safc tells me.

I get 14psi buy 6000rpm.

The turbo is a little big for the RB20 i think.

It will make really good power but way in the rev range.

Would be more suited to an RB25 id say.

Oh well gota go with what I got now.

Phantom32 Experienced

Phantom32

Posted
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i recently did the converision for my car and i wholely agree with StarioTurbo - the rb25 has so much more low-end torque and is a whole lot smoother than the rb20.

I can do roundabouts in 3rd gear, don't have to downshift as often to pick up the pace and the car launches like no tomorow.

I would highly recommend the conversion to anyone. Engine + PFC = 200rwkws. Thats more than enough to have alot of fun with on the road.

I'm not sure, but would 200rwks out of an rb25 be equivalent to 220rwks out of an rb20? Due to engine capacity? I've been thinking about this one for a few days now....

Cubes Grand Master

Cubes

Posted
Posted

I often use 3rd for roundabouts when cruising. Speed, around 20-30kays exit speed. It accelerates easily from idle. Obviously just cruising, full throttle requires around 1700rpm on board otherwise it rattles the gearbox a little.

The 3ltr through the hills has removed the need for second gear.

I was recently playing around behind a R32 Rb20DET through the hills, he was flat stick through second in to third, I was much more relaxed simply accelerating out of 25kay hair pins in third.

Don't get me wrong it wasn't a full thrash, just a mild slow in fast out type drive. The safer way to drive. I've never been for hammering really hard in to corners on the street, its a receipt for disaster.

Roy Grand Master

Roy

Posted
Posted
...

I'm not sure, but would 200rwks out of an rb25 be equivalent to 220rwks out of an rb20?  Due to engine capacity?  I've been thinking about this one for a few days now....

A power rating is just that and makes no difference if its coming from a 1.8L, 2.0L or 2.5L, the torque charactoeristics and if the delivery is peaky may influence if one car is quicker....

Sure the RB25 transplant, especially with the RB25 gearbox is a good thing. The best street car i think i have been in was an R33 GTST with a 2530 setup, the thing was choice:)

BUT... me, i dont like playing around on the street. My car has plenty of punch to drive around day to day on the street...i can go round roundabouts in 3rd gear as well, i often do 2nd gear takes offs as well:) But i dont for a second think that this translates to my car having as much punch at 3,000rpm as a R32 with an RB25. But how quick do you want to go on the street, i can change gears at 2,500rpm and happily cruise along with traffic..often do. I can only ever go as quick as the car in front lets me.

An R32 GTST with a RB20 and turbo/ecu upgrade can easily pull mid to high 12s for the 1/4. That in my eyes is pretty quick. So can an RB25 powered R32 so there is no difference.

If you want to drive around in a gear higher then what is required...i dont understand why that hold so much appeal, but if you want to then go the RB25. As for smoothness and traction, my car hooks up perfectly with 235 rwkws in 2nd gear, doesnt wheelspin all that badly in 1st either...dont believe me :( Your welcome to drive it yourself It even has bald tyres at the moment.:)

By all means go and put an RB25 in the car if thats what you want to do (thats not what this discussion was about:)) ... and IM NOT SAYING RB20s ARE BETTER!!!!

All im saying is that you want a cheap / quick street car capable of 12sec qtrs then the RB20 will get the job done...if you want more then sure the RB20 aint the place to start...especially if you want a car that will storm out of corners on the street where your doing 35-40kms and hour...

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