Tomei Poncams Installed ! Hmmm power...

[GTS-t VSPEC]

Dave, With stock cams peak power is at 8000rpm. My exhaust is very hi-flowing;)

[rev210]

Lukevl ,

what do you reckon of GTS-t VSPEC's cam choice?

[GTS-t VSPEC]

Dave/lukevl, As you can see, even with the stock cams it wasn't falling off as much as I would have expected. I kept the stock cams in so long just to see what power we could get out of them. They seem to have done very well.

[meshmesh]

Dave/lukevl, As you can see, even with the stock cams it wasn't falling off as much as I would have expected. I kept the stock cams in so long just to see what power we could get out of them. They seem to have done very well.

WOW.......What car is that on?

[rev210]

I'd expect a very large increas in power over that. The torque will up a great deal.

[GTS-t VSPEC]

Mesh, Just a RB25, standard head and cams.

Dave, The only reason the torque drops off is cause we trailed the boost off as my fuel pump couldn't keep up, else it would stay pretty much straight across the page.

[lukevl]

The cams are a good choice. I don't see anything wrong with them although I would use more lift. But with more lift you will need to machine the head. I have 9.9 mm of lift on STD base circle and the head needs machining to fit the lobes in

Paul - Do you have the @ 0.050" figures?

[GTS-t VSPEC]

Sorry lukevl, your speaking to a cams dunce, but I can get ND4SPD to check the figures as he'll be putting them in.

These are NVCS cams, and as such haven't been able to find anything with higher lift, due in part to the hydraulic lifters.

[Trust33]

Because they use hydraulics the lift isn't as aggressive as you get with solid lifters, but there the biggest I could find. 270duration  8.9mm lift. Shouldn't require any machining, and we're just putting a set of performance valve springs in to cope with high revs, 8.5k:D

What valve springs have you chosen?

Is that 8.5k spent on the engine?

[Sydneykid]

i think in the case of the tomei poncams, sydneykid said that cam gears aren't necessary because tomei got the timing spot on. In the case of having normal cams in the rb25, cam gears in the series 1 rb25dets alot of ppl have seen nice improvements.

Great thread guys.

I just need to clear something up here, I have used the Tomei 256/260 Poncams in 2 X RB25's, one Neo in an R34GTT and one non Neo in an R33 GTST. Neither of them benefitted from having an adjustable exhaust camshaft pulley, they both made their best average power at zero degrees adjustment. The Poncams work very well with the VVT, I kept it, so no adjustable inlet camshaft pulley.

This has not been my experience with GTR's, they ALWAYS benefit from adjustable inlet and exhaust camshaft pulleys. The more extensive the mods, the more they benefit and no two engines are the same.

Hope that clarifies:cheers:

[GTS-t VSPEC]

What valve springs have you chosen?

Is that 8.5k spent on the engine?

The 8.5k, is 8500rpm. There performance valve springs that we've ordered, to cope with the higher lift and high rpm, will find out off SST-Steve which manufacturer there from.

I have an adjustable exhaust cam gear, with the stock cams we found zero to be the best, will see what the apexi cams dial in at best.

[Skyrine-Dave]

what sort of cams would be good on an RB30DET using an RB25DET head with NO!! VCT.. its been welded up.

I take it that with the hydraulic lifters i'm limited to ~8.5mm lift.

I am worried if i get a set of Tomei poncams they wont be 'ideal' for me as they are designed to work WITH VCT... but i dont/wont be running that...

anyone shed some light for me?

[Ronin 09]

Will be interested to see the results - exactly what I am planning with my ausgtr in december...

[Gradenko]

what sort of cams would be good on an RB30DET using an RB25DET head with NO!! VCT.. its been welded up.

I've been looking at cams for a similar application. You're right in that we're limited for lift since they're for hydraulic lifters. I think we're down to HKS 256/256 or 256/264 at 8.8mm lift, or Apexi 250/250 or 250/260 or 260/260 at 8.9mm lift. I'm leaning towards Apexi 8.9mm of some duration for similar reasons as vspec - the lift. We won't need as high duration cams as vspec because we won't be reving anywhere near 8.5k.

[Sydneykid]

I've been looking at cams for a similar application. You're right in that we're limited for lift since they're for hydraulic lifters. I think we're down to HKS 256/256 or 256/264 at 8.8mm lift, or Apexi 250/250 or 250/260 or 260/260 at 8.9mm lift. I'm leaning towards Apexi 8.9mm of some duration for similar reasons as vspec - the lift. We won't need as high duration cams as vspec because we won't be reving anywhere near 8.5k.

I have found the Tomies to be superior to both of those brands in RB25DET's.:cheers

[GTS-t VSPEC]

Superior in what regard? From the fact that you can drop them in without adjustment? Or other reasons?

[rev210]

On the lift side of things the HKS cams for the RB25det do go as high as 9mm of lift @ 264deg duration, at least on the exhaust side. I put one of these in the old R33 gtst.

[Trust33]

On the lift side of things the HKS cams for the RB25det do go as high as 9mm of lift @ 264deg duration, at least on the exhaust side. I put one of these in the old R33 gtst.

And did you have valve spring issues.Or was it fine and dandy??

What is the cost of valve springs and whats it like to install a set while the cams are out.Does it interfere with the valves when trying to install valve springs?

:flower:

[Skyrine-Dave]

I have found the Tomies to be superior to both of those brands in RB25DET's.:cheers

Yeah but SK he was talking about an RB30/31DET

what are your thoughts on cams for an RB30/31DET with NO VCT?

[rev210]

And did you have valve spring issues.Or was it fine and dandy??

What is the cost of valve springs and whats it like to install a set while the cams are out.Does it interfere with the valves when trying to install valve springs?

:flower:

No spring issues. My engine was set to develop a nice fat power band up to 7500rpm. I had only the aftermarket exhaust cam and a factory spec inlet cam.