HKS CAMs

[tribex]

hey fellas,

currently running computer, exhuast, i/c, dumpipes 1 bar boost

so far 257kw at rears,

upgrades on the way, considering camshafts and camgears, question is which camshafts, have decided to go with hks but which ones ???

the car is a street car driven regularly , so can we get cams now for stock turbo's that would also suit 2530's down the track??? or this wont work???

any advice appreciated...

[Sydneykid]

What engine/chassis is that tribex? What are your intended uses?

[tribex]

r33 gtr rb26dett 96,

microtech ecu, dump pipes, jasma exhaust, 1 bar boost,

maybe updating to 2530's in the future,

must be streetable,

cheers.

[meshmesh]

I'm also considering cams, to go with my GT2530's upgrade next week on the GTR. But was told by my tuner I'd be strectching the limit of the standard internals, with a cam upgrade. He did mention if we were to go down that path, to run 256~... but then I think you different lifts, and some require new spring..etc .. so confused. I'm thinking probably give it a miss for now?? I dunno :confused:?

Love to know what SK thinks also.

[OVL-747]

try Tighe Engineering (Tighe Cams) get some cams ground to match ur turbo , computer , boost selection etc.

grab a set of springs too while ur at it

[JAGR33]

I've been looking at this option too, but have been told that for the money spent, there is minimal gains.... Is this true??? (Assuming your gonna use them with 2530s or equivalent and stock bottom end)

[OVL-747]

cams , once dialled in , and matched to your other components (turbo , boost , computer etc etc) will make a world of difference.

definately grab a set of adj gears too.

[Gav]

I'll have a pair of HKS cams (264IN/272EX 10.2mm lift) installed in a month or so. These'll be teamed up with a pair of 25/40s on a HKS low mount manifold. Will post the dyno chart after tuning.

[tribex]

I'll have a pair of HKS cams (264IN/272EX 10.2mm lift) installed in a month or so.  These'll be teamed up with a pair of 25/40s on a HKS low mount manifold. Will post the dyno chart after tuning.

i'd be really interested in your results, power but also how much bottom end you loose .....if any

[Sydneykid]

Hi guys, it's been a while since we had a thread on camshafts. Camshaft upgrades need to be considered, not for the max power increase they give at one single rpm point, but for the improvement in average power over the rpm range that you intend to use. A few rules of thumb that I use;

If you intend to use 7,000 to 9,500 rpm, something around 272 to 288 degrees would be the go. For 5,500 to 8,000 rpm, around 260 to 272 and for 4,500 to 7,500 rpm then 248 to 260 is the go. That's a simplification, but you get the idea.

I should point out that you need to be realistic in your rpm choice, most people grossly overestimate their rpm usage and then are disappointed with the result.

So much for timing, now moving to lift. I have a personal philosophy that says go for the highest lift you can get with the timing as per above. You need to be aware that anything over 9.5 mm may require machining of the head to clear the lobes. It’s not a big job, a couple of minutes per lobe with the die grinder is all it takes. Can be done in the car, if you are careful with the swarf. In my opinion, anything over 10 mm will require upgrading the valve springs and changing to solid lifters in RB20/25’s.

Lastly, I never use camshafts that have a smaller PCD than standard, they put too much side load on the buckets. You can get offset followers, but why go to the expense when you can get standard PCD camshafts that don’t need them.

Hope that helps

[Gav]

i'd be really interested in your results, power but also how much bottom end you loose .....if any

Hoping to "have my cake and eat it too" with regards to the top end power as well as mid range torque.

Will be tuning primarily for mid range and to this end have focused on ensuring good exhaust flow via head porting, good terb manifolds and good exhaust (terb extensions, front pipes, "Jap spec" cat, good zaust) to help spoolup.

Have not scrimped on internals to allow reliable high revs as well as high boost if and when required.

The rest is now in the hands of Murphy, the engine builder and my tuner. :blah:

[JAGR33]

Hey sydneykid,

What cams (duration and lift) would you recommend for a GTR runing 2530s or equivaqlent?

Looking for more power in the 5500rpm to 8000rpm..

Would the power in the midrange be noticeable???

Should the valve springs be changed too??

Thanx in advance...

[Guest two.06l]

tomei 260 with 9.15 lift would be ideal if correctly dialled in

[Russco]

Sydneykid, you made an interesting point about avoiding cams with a smaller PCD than standard - any brands fall into this category (or any that you recommend?).

Why do some people run say, a 264 inlet & a 272 exhaust cam as opposed to run a pair of 264 cams??

[Warpspeed]

If you only change one cam, change the exhaust cam. A longer duration exhaust will open up the middle and top end without losing any low end torque. It is possible to go fairly radical on the exhaust side without getting into too much trouble. A lot of guys just retard the exhaust cam a few degrees and that is a low cost option, but what it really wants is more exhaust duration. The stock cam was designed for light throttle fuel economy and idle emissions, very important to Nissan. If you are more the full throttle type of driver, more exhaust duration is going to make a big difference.

The inlet cam requires a whole lot more thought. As you add more and more duration, at first the whole curve lifts for a really mild upgrade. As you go more radical, the low end falls away faster than the top end gains. So really give some thought as to if this is going to be a good thing. Finally a really long duration inlet cam can lose you power everywhere unless everything else is upgraded for sufficiently high RPM and airflow.

In brief, there are more gains to be had on the exhaust side than on the inlet side from a camshaft change, and the inlet side is what can get you into trouble if you go too far.

Remember also that if your engine is not making good low end torque it is not going to be putting out much low end exhaust flow. The turbo is not going to spool as hard, so if you want a tractable engine do not overcam it.

Hint........an exhaust cam fits into either side of the head because it has the little tang to drive the optical sensor. An inlet cam can only be used as an inlet cam. So if you decide to experiment with some different duration cams, buy all exhaust cams if you can.

[meshmesh]

SK & Warpspeed,

Thanks for your input, I'm now more educated, but even more confused. I think it's fair to say that amongst us here, the general objective is a cam selection suitable for a Street "GTR" with HKS 2530's. I guess, it goes without saying this would also assume the car have the standard upgades eg: fuel pump, injectors, cam gears, computer, and so on.

Based on that...

1. What cam & lift specs do you think would suit best for the following rpm ranges as quoted by SK...eg:

a) 4500 - 7500

B) 5500 - 8000

The mines R34N1, states the following cam specs for their car. It looks like they have 2 different settings one's a stage 1 & the other is a stage 2. Can you elaborate a little on these & would they be suitable for us.

IN 252°/lift 9.1mm

IN 260°/lift 10.2mm

EX 252°/lift 9.1mm

EX 252°/lift 9.5mm

EDIT:

Forgot to mention, using stock GTR internals, would this be pushing them to their limits..?

Thanks

mesh

[Warpspeed]

Meshmesh,

Sydneykid has offered some excellent advice (as usual), and I have tried to explain what effects you might expect, and what to do if the results do not meet your expectations.

But really it is an impossible question to give a definite answer to. The mines figures sound pretty reasonable as well.

Suppose you could buy six different hypothetical camshaft packages for your engine, and they gave the following results.

Cam A +10% @ 4500 RPM

+ 5% @ 7000 RPM

Cam B +2% @ 4500 RPM

+10% @ 7500 RPM

Cam C -10% @ 4500 RPM

+ 15% @ 8000 RPM

Cam D -25% @ 4500 RPM

+20% @ 8000 RPM

Cam E -40% @ 4500 RPM

+22% @ 8200 RPM

Cam F -65% @ 4500 RPM

+27% @ 9000 RPM

Now someone asks which is the best one to get ?

If you were a conservative sort of bloke Cam A might look pretty good with the best overall gain everywhere.

But demon Freddie the local drag racer says Cam F is the only possible choice, and he would get a G or an H if he could find one.

So which really IS the best cam ?

[meshmesh]

Thanks Warpspeed, my ignorance is showing here...

I just would have thought, that along your journey's you would have come across a particular set up for "what I would think" the common Street GTR with HKS2530's.

[Guest two.06l]

i run 260 tomei 9.15 and they are a great match for 2530 turbos on a street engine hi octane in syd has these cams in stock.make sure they are dialled in properly ie. with vernier cam sprockets.

[Warpspeed]

meshmesh, I would say something in the 256 to 260 range would suit you fine.