Cam Choice For 500Kw Rb26

[Tyranus]

As title states i need help picking out a correct cam choice for engine setup. Im about to dump a whole lot of money and i want to make sure im doing the right mods by getting the correct advice from people who have been down this path before.. The engine is getting pulled out this week for its overhaul and the heads are getting sent off to be ported.

Now i originally planed to go with HKS Step 2 cam's (272/280 10.2) but i dont want to confirm this purchase without asking you guys first.

What are my options?

Apexi V-Max 280 ?

HKS Step 2?

Custom made?

Im about to purchase Ferrea 1mm oversized valves and retainers. I already have HKS Cam gears and Step 2 Valve springs (could sell these off depending on feedback i get from you.)

Any suggestions? I plan on running 30+ psi, my goal is to achieve full boost before 6000rpm would be a great achievement if i get it by 5,500rpm. Power goal is 500kw at the wheels.

Thanks guys.

Edited October 8, 2012 by Tyranus

[Tyranus]

The turbo im using is a T51R SPL 1.00 AR.

Edited October 8, 2012 by Tyranus

[KiwiRS4T]

If you can get some recommendations for a good cam grinder in your area (or anywhere really) he should be able to make a cam to suit your requirements (not just 500kw but street, track, drag or a combination) for a better price than HKS etc.

[Lithium]

What fuel are you intending on running? What displacement will the engine be, and what kind of dyno are you aiming at 500kw @ wheels on?

A mate is running Jun 280deg with 11.35mm lift (and a reasonable amount of headwork) on intake and exhaust on a stock stroke RB26 with the same turbo you are running - with that setup it is making 1bar (on the dyno) at around 6000rpm and "over 500rwkw" on pump gas and while it takes some time to get wound up, the car is surprisingly responsive once the engine and turbo are on steam - though the engine really wants 8000+rpm to give its best. Unless you have an RB30 in there I can't see you making full boost near 5,500rpm.

[Tyranus]

The car will be mainly used for drag, 1/4 mile and rolling starts. So you think custom is the way to go ?

[Tyranus]

What fuel are you intending on running? What displacement will the engine be, and what kind of dyno are you aiming at 500kw @ wheels on?

A mate is running Jun 280deg with 11.35mm lift (and a reasonable amount of headwork) on intake and exhaust on a stock stroke RB26 with the same turbo you are running - with that setup it is making 1bar (on the dyno) at around 6000rpm and "over 500rwkw" on pump gas and while it takes some time to get wound up, the car is surprisingly responsive once the engine and turbo are on steam - though the engine really wants 8000+rpm to give its best. Unless you have an RB30 in there I can't see you making full boost near 5,500rpm.

The engine will remain as an RB26 when i eventually buy a nitto stroker kit which a long way down the track.

I will be using E85, ID2000cc injectors, surge tank etc all the usual fuel mods for big power.

Do you have a dyno sheet ?

[bigmikespec]

I am going through this at the moment. Best you work with the guy porting your head to determine what would work best.

If you got low turbine back pressure and a lot of porting; got with big duration and big lift.

[rob82]

I would be more worried with block integrity than cam choice.

I think you could achieve that power with a smaller turbo and a well setup engine on e85. (gtx35r, 10:1comp and around 256deg cams at 10mm lift)

[Tyranus]

Had a chat with my tuner he reckons i should get custom made cam's 280's 11.50 lift he also thinks 290's would be to big for my application.. any opinions ?

[bigmikespec]

Had a chat with my tuner he reckons i should get custom made cam's 280's 11.50 lift he also thinks 290's would be to big for my application.. any opinions ?

There are off the shelf cams available in that size; depends on what you want to do with the engine/car.

[Tyranus]

Well the mech is telling me that custom cams are billet made so they are stronger etc, where jap ones are cast iron this is what he says. What do you think about the 290 cams ? Car will be a weekend warrior. Will be taken to the 1/4 drags will be driven on rolling start "fun" times on private roads and will see prob a few track days here and there. Not after world breaking times on the race track just wana get the feel of the car on the race track.

[bigmikespec]

Well the mech is telling me that custom cams are billet made so they are stronger etc, where jap ones are cast iron this is what he says. What do you think about the 290 cams ? Car will be a weekend warrior. Will be taken to the 1/4 drags will be driven on rolling start "fun" times on private roads and will see prob a few track days here and there. Not after world breaking times on the race track just wana get the feel of the car on the race track.

Ok fair enough... you could make them hollow too if you were ambitious; not sure on his machine capability but if you could gun drill the whole thing that would be cool.

Don't know man, try them out... if you got significant head porting and a 1:1 ratio (or better) boost to exhaust manifold back pressure then go 290's. But if you are not designing the system for low turbine back pressure then forget it.

[BMYHOE]

dont forget the bigger cams you go the lower the CR will be. make sure the engine builder calculates the CR before any parts are ordered.

instead of shaving head to raise the CR get some custom pistons made up.

you need 9.5:1-10:1 CR with e85

[Tyranus]

Cheers Mike,

Im getting heads + in/ex manifolds all CnC ported.. so its nothing super crazy but it will be alot better than stock. Im also going to give the HKS manifold a crack aswell as it came with the kit.. I might upgrade to a 6boost manifold if the HKS one f**ks up.

The head will have all the usual Ferrea bits and pieces as i want the car to rev upto 9k to fully utilize the size of and power of this turbo.

[BMYHOE]

if the car is going to be registered i would go a max of 272's...

[Tyranus]

dont forget the bigger cams you go the lower the CR will be. make sure the engine builder calculates the CR before any parts are ordered.

instead of shaving head to raise the CR get some custom pistons made up.

you need 9.5:1-10:1 CR with e85

I will tell him that thanks mate.

[Tyranus]

if the car is going to be registered i would go a max of 272's...

Why's that ?

[BMYHOE]

Why's that ?

no doubt you will be using a 4inch exhaust & with cams like your talking 280's/290's you will not be able to drive on the street with much comfort of knowing every single person can hear you and the gate hasnt even cracked yet...

272's will easily do the job with that turbo & the supporting mods you have.. look at the Rb26 / Rb30 threads..

[bigmikespec]

Forget high compression if you want big boost... waste of time. The small amount of hp you will make lower off boost will not offset the amount you could make by winding the boost up further and not having any issues.

Lower compression and no quench for big power and high boost.

[UWISSH!]

no doubt you will be using a 4inch exhaust & with cams like your talking 280's/290's you will not be able to drive on the street with much comfort of knowing every single person can hear you and the gate hasnt even cracked yet...

272's will easily do the job with that turbo & the supporting mods you have.. look at the Rb26 / Rb30 threads..

this

i have hks 272 10.25* in/ex cams 1mm oversize valves, retainers, porting , the lot

i have the same turbo and have a full 4" exhaust, its lumpy as, not quiet at all, draws alot of looks from people close by/ across the street.

i wouldnt want to go any bigger for the street

with this set up my redline is 9250, n wants to keep going.

full boost at 6000rpm

for your power level just run e85, 28-30 psi and you will make well over 500kw, i wouldnt worry to much bout the cam choice