Worth Changing Cams?

[joeyjoejoejuniorshabadoo]

It's on a dyno.

What some testing did down here was find that cars looked better on the graph, but on the circuit they were slower.

Hence a lot of Racepace cars all went back to stock cams, a few had poncams etc.

this^ is why i still havent cammed my car... after speaking to benno he advised against it, and gave me a fair few examples

anything that kills on/off response is going to slow the car overall imho

it's just so tempting when i see soo many graphs that look better tho

[PM-R33]

Like I said with mine, it's a bit hard to exactly discuss in this conversation due to having head work done at the same time.

But without a doubt, the difference after it was EASILY noticable with an increase of power every where. Didn't even need to look at a dyno graph to know it and every person I took for a drive after wards was very impressed with the difference.

I dont think response increases, but midrange power will, the top end wont increase on a smaller turbo eg. Phils GTRS because they are already at max airflow on a stock RB25, a bigger turbo that can flow more air will show gains in the top end.

So throwing some cames at a stock turbo Rb25 will give you nothing apart from a lighter wallet.

Imo I would not change the cams unless I had a .82 GT3076 or larger turbo on the car.

Exactly right. On a stock turbo or really any smaller than mine it's a bit of a waste. Hell even mine would benefit from a larger turbo - one day.

factory cams are high performane,huge job changing cams and for the amount of work the difference will not be great,I know someone who tried and was a major headache and disappointing finish,he regretted doing it.

I hardly call RB25 cams as high performance. If you are handy in the garage it really aint that huge of a job. I have had my cams in and out probably half a dozen times times swapping from stock to HKS, HKS to stock, stock to Poncams etc. If you can rig it up so you don't take the timing belt off like some people do it's even easier. I never did it that way though.

Any way, here's the old graph I posted up back in the day, take from it what you will:

Also most of the guys in this thread are talking about RB25 cam changes where as others seem to be talking about RB26 cam changes without saying so. These are completely different heads so please specify what you are talking about to keep things accurate.

[R31Nismoid]

a few of the cars were 2heads, not many.

mine ran stock items too, same with guilt-toy.

[335]

If you add aftermarket cams to a RB25, will that take away the VCT?

I have a RB25 that I am going to put into my R32 but it has a Greddy foward facing plenum on it. I read that it takes away midrange.

Will putting cams in help bring back some lost midrange?

[boostn0199]

If you add aftermarket cams to a RB25, will that take away the VCT?

I have a RB25 that I am going to put into my R32 but it has a Greddy foward facing plenum on it. I read that it takes away midrange.

Will putting cams in help bring back some lost midrange?

Just drop in some poncams and only get adjustable cam gear for the exhuast so you can keep vct and tune the exhuast side.

[hypergear]

Not point getting cam gear for stock turbo. How ever it would help to smooth out the power curve with a larger turbos, but not necessarily adding power to top end.

[zebra]

How does adjusting a cam gear smooth out a power curve? it just shifts it left or right

[hypergear]

Not an exact "shift". More of removing power from upper rpms and adding them to the lower rpms. Comparing to stock cam gears, you get more power down mid-low and less power mid-top, While all peaks at similar spot.

[skyline2148]

So for the RB25 any suggestions for upgrades? and are the PONCAMs considered mild? i'm looking to do the cams but i'm not sure if it's still worth it after having read the above, this due to the stock turbo.

[GT-T 1998]

The short answer is no.

Unless you have a fairly big turbo GT3076 and up they dont make much difference.

I remember a few years ago on here, a bloke put some Tomei poncams in his Stock turboed 34 GT-T and lost power everywhere in the rev range, even after It was tuned to within an inch of its life.

Roy also went backwards changing to Apexi cams in his angry RB20

ive got a gt3076 garret on my rb25det neo

does that mean its worth while changing my cam shafts aswell as cam gears :s confused

[wolverine]

I have 260 degree poncams on the Stagea which fattened up the midrange. There is was no discernible loss down low.

If I could have my time again I would choose the 252 degree poncams as they come with the extra lift but would probably remove the slight lumpiness at idle.

You shouldn't need cams gears as the best results seem to come at 0 deg.

[AngryRB]

I was told to use the cam gears if the motor was stock, but if using poncams which i have then all id do is make it laggier and get a bit extra at the top end, not to mention the stuffing around on the dyno and extra $$ to set up.

With mild cams you can still have a lumpy idle, the idle mixture just gets played with to make it lumpy, i chose to have it mostly smooth...

Edited September 30, 2012 by SliverS2