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Adjustable Exhaust Cam Gear For Rb25det

vidospace
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vidospace Mentor

vidospace

Posted
Posted

I have a brand new adjustable Cam gear that I was going to put on my previous car, but I now have a R34 GTT. The question I have is, the car is basically stock and will shortly be getting the timing belt changed. I want to know if it is worth putting my adjustable cam gear on while the belt is off.

Should I be installing my one cam gear on the exhaust or the intake (I have heard you only need the exhaust) or should I be buying another one and doing both?

What sort of advantages would there be to having an adjustable cam in the future if I had a turbo upgrade, exhaust, SAFC, and FMIC?

Or should I sell it and forget the whole thing?

PM-R33 Grand Master

PM-R33

Posted
Posted

There was a really good article in the latest HPI magazine on cam gears and wether they are worth it or not. I myself don't have one on my car so i don't want to agree or disagree wether they are worth it or not. The exhaust cam gear if installed, will have to be adjusted a degree at a time on a dyno to see if there will be any difference in top end, midrange or wherever. You adjust the cam gear by one degree, do a run and see how it went, if it made more midrange or something, u would adjust it another degree and see if it made things better or worse. On stock cams it might not make much of a difference, maybe 1-5rwkw. On aftermarket cams however they are extremely good at getting the most out of ur cams to have them adjusted to the best spot that you want to be making power at, and u may gain a significant improvement in power.

On a basically stock car like yourself, you may use up an hour or two on the dyno, pay $200 or so dollars in dyno time and maybe gain a couple of killowatts that you probably wont notice......up too you wether you think its worth it...

My 2c worth, feel free to correct me if i am wrong or have missed something.

Phil

Bass Junky Grand Master

Bass Junky

Posted
Posted (edited)

Hey guys,

I've done this on my car, and there is very little difference really. R34 GTT

I spent a lot of money on a dyno to have this properly installed and tuned. They actually changed the gear ON the dyno so as not to upset the straps and get 100% accurate results.

As you can see by the graph below, the difference was marginal if not non-existent.

As for after market Cams, my Poncams are actually designed to run the best at 0 degrees. Tomei make them to be best at 0 so that you can just bolt them in.

I still have the adjustable cam gear on my car, but it's set at 0.

BASS OUT

post-6399-1180612845_thumb.jpg

Edited by Bass Junky
Marco-R34GTT Grand Master

Marco-R34GTT

Posted
Posted

Basically, keep your cam gear/s tho...

Just do the bigger mods first, like ecu, fmic, cai, exhaust and a few engine tweeks (plugs, leads & coils if it blows your skirt up) and then go to the camshaft/camgear combo... You will get a lot more scope from them a cut a major portion of dyno time, which = saved $$$$'s...

siddr20 Grand Master

siddr20

Posted
Posted (edited)

I had a few friends who put adjustable cam gear (exhaust side) on.. n gained 10kw extra!!

Also comes down to the tuner!!

Most workshops will charge anywhere from 70-100 bucks an hour.

So go into a workshop and ask roughly how long it will take!!

edit: talkin about labour costs!!

not dyno time etc..

Edited by siddr20
WRRR Rising Star

WRRR

Posted
Posted

If your timing belt is off you have nothing to lose in putting the adjustable cam gear on. It is literally a few bolts - about 3 minutes off and on.

If you add the other bits later you can then play with cam timing on the next tune.

In my opinion even with stock cams adjusting cam timing is of benefit if you are trying to maximise output/driveability.

tridentt150v Grand Master

tridentt150v

Posted
Posted

Adjustable cam gear on std cams = power increase with dyno time. Best benefit can be had if you have a pfc, front mount etc etc etc.

Adjustable cam on tomei cams = no benefit cos Tomei's work best at 0 degrees.

vidospace Mentor

vidospace

Posted
  • Author
Posted

Yeah thanks all. I guess I will get it put on when I get the belt changed. I plan on getting a FMIC and SAFC + fuel pump installed later on, but before then I will just set it to 0 but install it with the belt anyway. I only paid $70 for it so there isnt much to loose (less rolling resistance because it is alloy?)

rev210 Grand Master

rev210

Posted
Posted

If you aren't carefull when installing the cam gear on an old stock rubber belt you can end up stretching the belt, it may have already stretched over time. If you don't re-dial the cams afterwards you are likely to find that the magical 4 degrees isn't working, you might need 6 or so.

The 4 deg general rule applies to the R33's. R34 GTT Neo Rb25's have a solid lifter cam setup as opposed to the RB25's in R33's, they also have a different profile on inlet and exhaust cams. Making for some potential differences in timings and effects on moving the exhaust cams overlap around.

As for larger profile cams, you can always change the shape of the power curve by setting them at different timings. It it typical to be able to fatten the bottom end at the expense of peak power and any number of other variations. Having the option of setting the timing is a good thing for this reason.

  • 2 months later...
R338OY Veteran

R338OY

Posted
Posted

I only have the stock cam gears on my RB25, but i reckon until you'd completed the first basic mods there really isn't much point to chucking on the exhaust cam gear. only do it if you're gonna change the timing belt cause it'll save time for later.

:D

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