VTC vs. big cams. Which is better?

[chad b.]

I've been told that the largest cams you can run in an RB25 with out sacrificing the VTC is a 264. Is this true? Also, if it is, at what point do you make more power with larger cams and no VTC than with small cams with it hooked up? I would like to run 272's and adjustable cam gears, but if I can't do that and keep the VTC, would it be better to go with 264's and leave the stock cam gears and the VTC on it?


Turbo is a 6765, shooting for 550-600 whp range for street and drag.

[Cjmartz2k]

I'm not sure you really understand what VCT does, but BLUF, for your power level goal, ditch the VCT and get big cams.

[flatrate]

any pictures of the setup

[Joe]

I'm not sure you really understand what VCT does, but BLUF, for your power level goal, ditch the VCT and get big cams.

this.

[chad b.]

Yea, I called around today talking to a couple shops known for building these motors and also a friend of mine doing a similar swap with an RB25. Basically, the popular opinion is the VCT is only good with the stock intake cam (to make up for it's lack of duration and lift). If you plan on buying larger than stock cams, it's better to ditch the VCT and by a set of adjustable cam gears. After all, 26's don't have it and make a ton of power.

[StricNyne]

yeah, i am making around 400hp now with stock cams and upgraded springs, and i run vct, i am aiming for more hp once i retune for meth and more boost (15psi on hx35 currently) i think cams on rb25 are a waste cause they are expensive as hell and not many good sizes without doing the solid lifter conversion and if you do all that u shoulda bought a rb26 lol. i honestly ran without vct for a while and i am now running it again, havent dynoed with it but i made that 400 without it. look into kelford cams they made a good variety for the rb25 and check out bc as well

[chad b.]

I don't see why you can't run 272's with hydraulic lifters. DSM's and KA's have hydraulic lifters and you can run 272's in those. I'm gonna do some Kelford 272's and a spring/retainer set and call it a day.

BTW: Brian Crower is cheap garbage.

[Cjmartz2k]

BTW: Brian Crower is cheap garbage.

You seem to have a lot of strong opinions about certain brands and products. I've only heard or seen good things with Brian Crower products, but I'm curious; what bad experiences have you had with them?

[StricNyne]

also your going to have to machine the head to fit some cams in there of that size too man, i am sticking with my stock cams and i WILL make about 600hp on my setup, and if one day i ever blow motor, swapping it for a neo and still not touching the cams. I heard good things about BC though, why u dont like ? i know kelford cam used to make tomei cams in the usa for them, so its a qualit part

[RustspecS13]

Whats the big deal with not having big cams and VTC? A lot of new cars have a kind of VTC and you can run big cams with them. The 350z has intake and exhaust variable timing and I can't think of a limit to what they can handle.

Any one know how many degrees the VTC changes on the RB25?

~Alex

[StricNyne]

the problem is that no one makes them, first off the engine never came out in america so thats a big reason now, and its also been over 5 years since last version was made ( and that was solid lifters) regardless if u go over i think 254 u need to machine head, tomei makes drop in cams which are like 245 or something that use vtc but he wants a whole nother size

[chad b.]

The duration of the cam is not what will cause a need to machine the head, it's the lift. If you want to get a cam with 10mm or more of lift, then the head requires machining for lobes to clear head casting. Kelford makes 272's that are 9.3mm lift. That's why they say you can run them without and head modifications.

As for Brian Crower cams and valve train products. There have been several cams made by them that have made less than stock hp on dynos on a array of different cars. My last encounter with them was on my brothers 1G AWD DSM. BC 272's and a spring/retainer set was installed. 30 minutes later it dropped a valve. When talking to the owner of a mid 8 second 1G DSM and also the owner of a very reputable DSM shop, we were informed that this is typical. BC valve springs are no better than stock, their cams are machined horribly and usually cannot be properly degreed in no matter what ( also get on ka-t.org and search them out, a lot of disliking on BC over there ), and their valves blossom out at temps lower than what a stock valve would. Like I said, it's cheap junk. They're $400 cams. You get what you pay for.

[StricNyne]

yeah your right i said it backasswards my mind is fried lol. but i thought the magic number was 9mm not the 10mm for the lift
http://www.240sxmotoring.com/kerbca.html

those r the kelford cams, 800 bones same price as tomei with more options, and they used to make them for tomei so u know quality is there problem solved i would ask them if their larger cams operate with vtc i would imagine yes, and any good engine management should allow u to adjsut engagement of vtc ( my haltech does)

[chad b.]

I was told that any cam larger than stock would make more power without VTC. I know the Kelfords don't work with it, or so it says on their website. I'll get some adjustable cam gears and be done with it. I've heard of people running MSD windows switches and what not to control the VTC at different RPM's. I running AEM EMS.

[Carl H]

ditch vtc and toss in some rb20 spec upgraded cams with adjustable gears and go...its good for stock setup but will hinder power in the end.
check out what most supra guys do if they have a vvt-i head, they backstep to the non vvt-i head...least those going for big power.

[StricNyne]

hey carl i know rb20 is hydro lifter but their cams are drop in ?

[chad b.]

I ordered a set of Supertech springs and retainers yesterday. I guess next week I'll order a set of 272 Kelfords, then get the head to the machine shop for a freshen up.

[Carl H]

iirc, yes they are.
exhaust cams are identical pretty sure only difference is the intake doesnt have a port for the vtc cam feed.

[flatrate]

Deltacam has a tomei knock off grind available if you call them... ive debated trying them out but kinda skeptical

[StricNyne]

never heard of them link or ban

[flatrate]

Google delta cam... lazy a**

[chad b.]

sounds like delta-junk to me