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cams for an rb25det

gtstvp

By gtstvp,
in Engines & Forced Induction

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gtstvp Apprentice

gtstvp

Posted
Posted

im looking for cams for my rb25 and was just after some recomendations from people who have changed theirs.

im looking at tomei poncams (256 grind) for both exhaust and intake.

im currently running 1 bar of boost through a stock internal motor that has a gt30/40 turbo and autronic smc ecu. its making 302rwhp.

any help would be great

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Bullant47 Community Regular

Bullant47

Posted
Posted

I know that a lot of guys swear by the Tomai Poncams but i was advised that the HKS 256 IN and 264EX are a little more powerful and still retain the VVT. I went the HKS route and after a minor hickup being sent the wrong HKS EXH Cam from Japan with the wrong CAS fitting (R34 CAS), I must say i am very happy now and the car is making good power around 260kw at the rear wheels.

Ian

Bass Junky Grand Master

Bass Junky

Posted
Posted

R32, R33 or R34.

The Tomei Poncams are designed to work perfectly with the single stage VVT in the R33 and the constantly variable in the R34.

The 260 degrees ones are often spoken about as the best to buy.

That's what I have my eyes on to answer the question once and for all about the power gains on a stock turbo.

BASS OUT

SLY33 Mentor

SLY33

Posted
Posted

fresh: are you serious?!

cams and head gasket is my next move too, SK backs the 260 poncams strongly, so thats a good indication.

Ive also heard to go HKS 256in and 264 ex. What is the advantage of doing this as opposed to 260in and ex?? Can anyone say which route is better?!

SLY33 Mentor

SLY33

Posted
Posted

fresh: are you serious?!

cams are my next move too, SK backs the 260 poncams strongly, so thats a good indication.

Ive also heard to go HKS 256in and 264 ex. What is the advantage of doing this as opposed to 260in and ex?? Can anyone say which route is better?!

Bass, how much do you love your buddy club P1s!? I just put a set on, great rims, bargain price.

Sydneykid Grand Master

Sydneykid

Posted
Posted
SK, what stops us from throwing in a solid setup to replace the hydraulic?  As with my old torrie we simply through in a solid profile and solid lifters and ditched the hydraulic stuff!

You have to change everything, valves, springs, followers, seats, guides, retainers and collets. They are all different dimensions to allow for the extra thickness required for the hydraulic followers.

Last time I added it up, it was much cheaper to buy an RB26 top end.:D

jnr32r Proficient

jnr32r

Posted
Posted
You have to change everything, valves, springs, followers, seats, guides, retainers and collets.  They are all different dimensions to allow for the extra thickness required for the hydraulic followers.

Last time I added it up, it was much cheaper to buy an RB26 top end.:D

So wouldnt this apply to the GTR cams in a RB20/25... = cant be done without changing all that?

Sydneykid Grand Master

Sydneykid

Posted
Posted
So wouldnt this apply to the GTR cams in a RB20/25... = cant be done without changing all that?

Some explanation required............

RB25's have VVT and RB26's don't.

But RB20's don't have VVT, so you CAN use RB26 cams in an RB20.

But that wasn't the question....

The question was can you simply swap over the followers from hydraulic to solid

And the answer was no, you have to swap everything.

Hope that clarifies:cheers:

Sydneykid Grand Master

Sydneykid

Posted
Posted
couple more things SK, when adding a set of poncams, im guessing you want to use new lifters too?  and how are original 1994 stock valve springs going to fare, is it wise to throw some new springs in while your there?

thanks!

Personally I am not a fan of standard RB vlave springs, even new they are a bit soft for my liking. That said their quality is OK, they don't seem to soften off much. Poncams are designed to work with standard everything else, so I haven't heard of anyone with a problem.:rofl:

HypeR33 Mentor

HypeR33

Posted
Posted

Hi Guys,

I have a question on this too. I am ooking at 256 degree/8.8mm lift HKS cams IN & Exh. Is it better to run a 264/9 Exh cam with 256/8.8 In? to run with a GT30R turbo.

Will this also require new springs?

Thanks

Bullant47 Community Regular

Bullant47

Posted
Posted
Hi Guys,

I have a question on this too. I am ooking at 256 degree/8.8mm lift HKS cams IN & Exh. Is it better to run a 264/9 Exh cam with 256/8.8 In? to run with a GT30R turbo.

Will this also require new springs?

Thanks

It's fine to run 256/8.8mm lift IN and 264/9.0mm lift EX. Thats the way i have my R33 GTS-t setup. 264/ 9.0mm EX still retains VVT. When you install them make sure you coat all the journals and bearings with "mollybond" yellow tube, and rev to constant 2000 RPM for 15 minuites to break in the cams. It's not necessary to install new springs with these cams.

Ian

HypeR33 Mentor

HypeR33

Posted
Posted
It's fine to run 256/8.8mm lift IN and 264/9.0mm lift EX. Thats the way i have my R33 GTS-t setup. 264/ 9.0mm EX still retains VVT. When you install them make sure you coat all the journals and bearings with "mollybond" yellow tube, and rev to constant 2000 RPM for 15 minuites to break in the cams. It's not necessary to install new springs with these cams.

Ian

Cool thanks for that!! :cheers:

Looks like I will follow that route then :) The rev limiter on mine has been removed. Is it a safer option to install new sturdier springs to allow higher revs? Is there anything else that needs to be done to allow higher revs safely? Not astromonomical revs...just a bit higher. It seems to rev over 8500 comfortably without valve bounce. I was told that it had internal work done on it when i bought it, but someone else listened to the exhaust note and said that it still had standard cams.

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