what rb25det cams to get?

[trunks_phil]

Hey i need some help with ordering Poncams for my rb25det. what one do i order? i got a series 2 rb25det with the silver cas.

http://www.frsport.com/Tomei-143020-PonCam-Intake---Exhaust-Camshafts-Set-RB25DET-Series-1_p_16782.html

or

http://www.frsport.com/Tomei-143050-PonCam-Intake---Exhaust-Camshafts-Set-RB25DET-Series-2_p_16791.html

i read somewhere on the net where it says series 2 cams refer to the neo. so i'm kinda confused .
i got the rb25det series 2 with the built in ignitor in the coils.

[BrodyGoble]

Correct, if you have the silver CAS it accepts a semi circle drive type which means you need the s1 poncams. The s2 poncams have a star shaped drive which need the newer black neo CAS.

I have an s2 rb25 and I made this same mistake unfortunately, it's misleading! Had to track down a neo CAS to get it to work.

[trunks_phil]

Thx for the info .What one are u running 256?

[BrodyGoble]

Yes, 256/8.5's

[Skym]

R33 Series 2, R34 NEO = Hitachi CAS (has a black cover over it)
R33 Series 1, R32 GTR, R32 GTS-T, R33 GTR = Mitsubishi CAS (same CAS)

On Series 2 R33 RB25DET they moved igniters from ignition module on back of engine to each coilpack (why the ignition module is smaller on Series 2 R33 RB25DET) and changed ECU programming, etc to suit. That's so can shut coilpacks off via ECU when checking for a failed coilpack, instead of removing coilpack cover, unplugging each coilpack while engine is idling to find faulty coilpack that doesn't affect idle. Same coilpack setup is used on R34 NEO RB25DET.

Poncams work with stock valve springs, stock ports, stock valves, stock intake manifold, stock exhaust manifold, mild turbo upgrade.

Poncams are similar to factory cam regrinds (copy of factory cams), but using new blanks (more aggressive profile on lobes). With regrinds they used to weld onto lobes, regrind lobes to shape (to increase the lift), but was an unreliable way.

These days they just grind a bit off base circle of lobes on stock cams (play with duration of cam for more hp) -

http://www.capella.co.nz/sites/kelford.co.nz/regrinds/

To know what goes into selecting cams, have to look at this (what a cam manufacturer asks for and engine builder supplies the info) -

https://www.capella.co.nz/sites/kelford.co.nz/design-shop/

Basically cams match powerband that's created by turbo (where turbo reaches full boost, peak hp), intake manifolds, port sizes, etc.

[BenOswald]

I got Kelford 270's and love em. Streetable but pretty nasty when you get them breathing!

[trunks_phil]

Need some advice I just recently bought some cams off a member .poncams 256 for rb25det but the intake one says its for a rb20det? I was told this will work but I would have to lose vvt? I got cam gears to adjust timing . so would adjusting timing be better off and losing the vvt . cams are only 256 with 8.5 lift

[DRIVER_R32]

would the rb25det neo with stock turbo turned up with blitz dsbc and stage 1 upgrades be enough for the poncams skym?
or does it require a higher a/r turbine

[Skym]

Keep VVT, as can get good hp, torque gains and it helps to spool turbo earlier with rpm.

Cams are usually upgraded when fit a bigger turbo (cams + richer ECU tune produce more exhaust gas at lower rpm to help spool a bigger turbo), equal exhaust aftermarket exhaust manifold, opened up exhaust from turbo.

Stock cams suit stock turbo or hybrid stock turbo. But some do upgrade to Poncams when boosting up stock turbo's on GTR, S15 (with extractors), S14 (with extractors), etc.

[DRIVER_R32]

okay so poncam overrides/disables vvt, i thought maybe it was engineered to work with "vct" for skylines though.

[trunks_phil]

Only the rb25det 256 poncam intake side will let u keep vvt

[DRIVER_R32]

but does the intake stay open as the piston starts to compress, then close.

or does the valve close as the psiton reaches bdc?

i dont want to push air back out into the runners

[BenOswald]

I have Kelford 270 degree cams stock lift, direct drop in. Not compatible with VCT. I love them very street able and flow huge amounts of air. I'd highly recommend them.

[RWD_GTR]

funny this thread is 1st in discussion. i just recently installed my cams to find out they were for r34 with the hitachi cas.

[BrianV8]

I have a brand new set of Tomei Type A valve springs to go with your cams. PM me if your interested

http://forums.gtrcanada.com/parts-sale/58464-bnib-acl-tomei-manley-arp-n1-cp-much-more-rb25-rb26.html