GTR cam into gtst ???

[Sydneykid]

Sorry MIC33R, I did not measure up the RB25DE cams and I haven't seen any figures for them floating around. I believe those numbers are for Series 2 RB25DET, my understanding is that Series 1 cams are a little more aggressive.

Regardless, using Meg's numbers, the GTR exhaust cams are a little less aggressive in the timing, 240 versus 236, but the lift is higher by 0.78 mm. The GTR overlap at 125 would show a benefit from the adjustable pulleys on a RB25 (the standard cam is 117).

So I reckon changing the exhaust cam would be worthwhile because you can use an adjustable pulley to maximise the overlap, but only for a 5 to 8 rwkw gain.

Since the car is boosted, I don't believe the GTR inlet cam would show as much gain, particularly since the VVT will not function. So you might loose enough mid range to offset any top end gain you get. I would like to someone try it though, I'd be interested in the results.

As matlowth posted, you would have to use GTR valve springs with GTR cams.

Hope that adds to the discussion.

[dojobi]

Thanks for the info, Sydneykid. I think I might pass on the cam upgrade then. If I had the time and the cash I would have bought all of them, installed and compared them on the dyno.

Cheers,

Michael

[DAMQIK GTS-T]

Originally posted by Sydneykid

Series 1 RB25DE cams are quite a bit more agressive in both timing and lift, I reckon they would be a better bet than GTR ones.  Plus you can use the hydraulic buckets.  But you still have the VVT problem, as the N/A engines don't have VVT.

We used these cams in the RB30ET/RB25DE hybrid for 475 bhp on the engine dyno in our old GTR, so they are certainly OK at that level.

Hope that helps.

I'll be interested in the results.

Hi Sydneykid,

The RB25de Cam's that I have are VVT,(I have the complete engine sitting on my garage floor) Its a series 1 R33 RB25 DE with VVT.

I also belive from looking at the cams that any cam put into a head that is equipped with vvt would work, as the vvt only advances and retards the cam by moving the pully which is spring loaded so it moves back again. There is no shifting the cam back and forth to a different set of lobes like honda engines.

Dose this sound right?

Im going to try the N/A cam's this weekend will post results.

Regards Damqik.

[DAMQIK GTS-T]

Well I pulled out my cams and found no difference between them and the N/A ones (Mesured them with a micrometer).

very dissapointed, however I found out what the VVT dose.

its oil pressure feed and simply moves the intake cam pully about 2 deg when the soilnoid is powered by the ecu.

I also got my tappet covers polished whilst they are off and I painted the coil cover.

Damqik

[Warpspeed]

Are you sure its only two degrees, hardly seems worthwhile. Most other VVT systems that I know of shift things 15 to 20 crankshaft degrees.

[DAMQIK GTS-T]

No I'm not sure but it only moves a few mm

definitely dosn't move 15 to 20 deg tho