Best Cams For Response

[DRIFTER]

i'm in the middle of building an rb26. do small aftermarket cams increase response, or should i stick with the standard cams?

[Busky2k]

Depends on what you mean by "response". If you are taking about earliest turbo spool, probably the stock cams if you are using stockish sized turbos.

[DRIFTER]

its a small single.

[archie01]

Standard cams

[DRIFTER]

thanks, any reasons, what cam timing specs do people recomend?

[rev210]

What rpm range / power are you chasing?

Power and torque wise the factory cams can be improved on, even with factory sized turbos.

[DRIFTER]

i'm hopeing for around 300kwatw, but i want the power as low down in the rev range as possible.

[R31Nismoid]

Stock cams with a cam gear

You'll need to play with it as there can be some good mindrange gains.

I'll be using stock cams for my gt-ss/rb26 as many others have before them

[rev210]

300rwkw with a low starting power band, definately requires cams to get the bet results.

256deg 9.15mm lift tomei's aren't shabby for what you are after.

[DRIFTER]

decisions decisions.

[rev210]

Here's a comparsion for you on stock turbos. Stock turbo's obviously work a little lower in the rpm range.

Standard R32 GTR cams & turbos

*(adjustable cam gears set to optimum low end boost response, 2deg adv intake & 4 deg retard exh)

* optimum AFR and ignition set on Power FC

Boost 12psi

rpm rwhp

3500 - 140

4000 - 180

4500 - 190

5000 - 220

average power = 183.75rwhp

Tomei 260deg intake and exhaust cams standard R32 GTR turbos

*(cams set for optimum low end response)

* AFR & ignition maps safe tune for old engine, so further improvements could be made (average up maybe another 20rwhp+)

Boost 10-11psi

rpm rwhp

3500 - 175

4000 - 200

4600 - 235

5000 - 265

average power = 218.75rwhp

So you can see that an average of more than 30hp can be gained in this lower area with cams that to be honest are a tad more suited to getting more air going in the higher rpm range. Obviously if your are dropping below 3500rpm on shifts you need to have a good look at your gearing ratios both gearbox and diff.

At higher airlfow requirements like those of a turbo aimed at 300rwkw, the right cams will shine even more.

You can also approach the exhaust or intake cams as sepparate proposals working together too, with someone who has the cam software to plug the numbers in. You can do some very interesting things in terms of engine characteristics if we had access to someone local who could do custom billet grinds. It beats the pants off buying the off the shelf tomei or other brand cams if you are after the optimum for a power curve you have in mind, particularly when you are doing things like porting the heads and you have some flow bench data to look at. When I checked last the issue was with the length of the RB cams for crow cams people to do billets, was a while ago though.

Hope that helps.

[700HP-GTR33]

Here's a comparsion for you on stock turbos. Stock turbo's obviously work a little lower in the rpm range.

Standard R32 GTR cams & turbos

*(adjustable cam gears set to optimum low end boost response, 2deg adv intake & 4 deg retard exh)

* optimum AFR and ignition set on Power FC

Boost 12psi

rpm rwhp

3500 - 140

4000 - 180

4500 - 190

5000 - 220

average power = 183.75rwhp

Tomei 260deg intake and exhaust cams standard R32 GTR turbos

*(cams set for optimum low end response)

* AFR & ignition maps safe tune for old engine, so further improvements could be made (average up maybe another 20rwhp+)

Boost 10-11psi

rpm rwhp

3500 - 175

4000 - 200

4600 - 235

5000 - 265

average power = 218.75rwhp

So you can see that an average of more than 30hp can be gained in this lower area with cams that to be honest are a tad more suited to getting more air going in the higher rpm range. Obviously if your are dropping below 3500rpm on shifts you need to have a good look at your gearing ratios both gearbox and diff.

At higher airlfow requirements like those of a turbo aimed at 300rwkw, the right cams will shine even more.

You can also approach the exhaust or intake cams as sepparate proposals working together too, with someone who has the cam software to plug the numbers in. You can do some very interesting things in terms of engine characteristics if we had access to someone local who could do custom billet grinds. It beats the pants off buying the off the shelf tomei or other brand cams if you are after the optimum for a power curve you have in mind, particularly when you are doing things like porting the heads and you have some flow bench data to look at. When I checked last the issue was with the length of the RB cams for crow cams people to do billets, was a while ago though.

Hope that helps.

Not being dis-respectfull

Poncams for gtr's...for road and track.

[The Alchemist]

I agree with REV210. Having worked on several GTRs with GT-SS some with std cams and some with TOMEI Poncams and tuned them as well the GTR with the TOMEI cams will win hands down in almost all respects. Well worth the money. Results like REV210 stated above agree with my experiences The most noticible thing is the torque holds dead flat almost to the redline whereas with the std cammed GTR the torque drops off over 6500rpm. These are the cams the GTR should have had from factory

[700HP-GTR33]

I agree with REV210. Having worked on several GTRs with GT-SS some with std cams and some with TOMEI Poncams and tuned them as well the GTR with the TOMEI cams will win hands down in almost all respects. Well worth the money. Results like REV210 stated above agree with my experiences The most noticible thing is the torque holds dead flat almost to the redline whereas with the std cammed GTR the torque drops off over 6500rpm. These are the cams the GTR should have had from factory

Just ordered mine.......

Would love to see how they are fitted.

I will need a re-tune aswell.

What else can be changed while you are fitting these?

[rev210]

while you change the cams do the retaining bolts for the cams. They have a habit of breaking as they cop a fair bit of fatigue when being torqued off and on. Tomei make some beefy ones. Also worth having a look at the valve springs etc. depending on what rpm etc you are going to see often and which cams you went for in terms of lift.

[GTS4-32]

my gts4 is lacking the torque before boost, response isnt the best. .

Do i need a tune-up or would the cams do the job?

Previous owner got 517nm out of it, should i be expecting alot more with better cams than i do now?

Im not to good with this sort of knowledge, any insight to clear it up 4 me would be great.

Cheers,

Steve.

[rev210]

Before boost torque can be improved on with smallish cams, turbo can be brought onto boost between 500rpm to 1000rpm sooner depending on what you have setup wise. If the turbo/s are large however you might consider a smaller unit if you like the low/mid range power to be sharper. There are a few ways to skin a cat as they say.

If its the physical time waiting for the turbo to get going the focus on reducing rotational inertia (from light weight pulleys to light forged rims) gives you a reduction in time taken without changing the rpm at which the turbo comes onto boost.

[GTS4-32]

So in other words if i want better response in the low/mid range area id be lookin for smaller cams. I have a gt2530 turbo in my 32, is that big enough?

[rev210]

For that turbo cams will help. Even 256 or 260's with 9mm lift will be better than stock.

[GTS4-32]

cool, thanks mate

Steve.