RB20 - Cams for Torque

[JH32]

Since I'm going with a big turbo ... I'm going to be after some torque generating cams.

Which would be better for an RB20 .... 256deg or 264?

Cheers

[Roy]

What are the specs of your T67?

[JH32]

I'm not sure .. I bought it from Clint32 on these forums.

I think it has an 8cm^2 exhaust housing

I've been advised that I should perhaps be going for cams that will generate torque rather than power as I'm going to need all the low down grunt I can get

[DCIEVE]

anyone? im in the same situation

[RS500]

why don't u see how the turbo goes first, and then look into cams if u feel u need them?

[Roy]

Tuning costs?... give me another week to get another RB20 into my thing and ill see how i do with the baby TD06 properly tuned... if the cams arrive before the engine gets bolted in then it will all go in at once saving me the costs for another tune...if the cars is back together begfore i get the cams then ill be able to give you a before and after.

[Cubes]

Is it the rebuilt TO4E Clint made 243rwkw on ~17psi?

[CerealKiller]

i'm interested too as I'm going for response rather than power.

[JH32]

RS500: As Roy said, tuning costs. I thought if I just get the cams to start with then I can do the valve springs etc and get that side of things out of the way. But then again I guess tuning costs = dyno time so it's probably not too expensive the second time round to get a retune.

Joel: I dont think so. It's a T67 that he had in addition to his TO4E. I'm not sure if he put the T67 on or not though.

[BoOsTeD_RB26]

James,

Don't plan on changing the valve springs unless you have intentions of taking the head off.

I've heard its mega money. Just wait until you rebuild it, and then when you get the head serviced and/or ported or whatever, do them then

[DoughBoy]

The cam selection for using hydraulic followers are all small lift, and won't require non-standard springs.

Cams for torque... where do you want the torque to be in the rev range? If low-end, use the standard ones. If you want more torque higher in the rev range use 264's or 272's - this would complement the turbo alot better than trying to compensate for lack of low rpm boost with standard cams. Although larger duration cams would probably assist low rpm torque as well, as they aren't aimed at reduced emissions al la std jobs.

Running an aftermarket exhaust manifold (re: a good, proven one, not a hack job) will give you a big gain in off-boost torque and driveability, as well as a throaty exhaust note.

Short version - get the largest you can get your hands on. 264 or 272 would be awesome!

[JH32]

Hi Doughboy thanks very much for the reply

What about something slightly smaller than the 264s, like 256s?

And I wouldnt need to change the valvesprings then ?

[DoughBoy]

You would only need to change the valvesprings to accomodate either:

a) higher revs

B) higher lift cams

Really you should be designing the engine to work together as a package, that will produce peak results within a specific rev range to suit your purposes.

The turbo, cams, gearing, head flow, manifolds can all be juggled to work well for a specific target - since you've already nomiated the rev range the engine will be in (by buying that turbo) you have to make the rest of the components fall into line. Mismatched components are a comprimise, they can work well together but it's not optimal.

Having said that, I'm sure even the standard cams would work with that turbo, so anything larger is a bonus.

[JH32]

Oh ok, cheers heaps for the info!

Much appreciated !!

Do you know what the lift is on the standard RB20 cams ?

[DoughBoy]

8.xx, there's a (probably incorrect) chart on the Tomei site that's been pasted into Joel's RB30 pdf guide.

[JH32]

Cool, thanks mate !

[RS500]

JiMiH,

fyi, the lift on the inlet/exhaust cams for the RB20DET are 7.8mm for both.

http://www.tomei-p.co.jp/_2003web-catalogu...haft-specs.html

[JH32]

Cheers!