Cam Shaft Choice For Rb30/26

[Marko R1]

i priced up a set of jun springs or tomei ane they're $650 - these local springs are half the price!

[9krpm]

Shanef, do you have the rough prices on those psi and supertech springs?

Do you need to use their specific retainers with these springs?

[shanef]

i think the psi's were around $1200 for a set dont quote me, and the supertech's are USD$459 (they come with their own titanium retainers)

Depends how much ur spending/want to spend on the head, with the dual springs you'll need to get a custom inner seat made for the inner spring

[9krpm]

Thanks Shanef

[dorifticon]

Hi, I am just seeking some clarification on some of the info here about cam choices.

I am about to send my spare rb26 head out for porting and reconditioning etc. I will also be asking them to clearance the cam tunnel to accept bigger cams, and have budgeted to upgrade valve springs as per the comments on here. I am building a separate long motor with a 3.0 (realistically 3.1) bottom end to swap into my r32. Will be getting a fully balanced, forged etc bottom end from a shop and assembling myself.

In terms of the use, it will NOT be a daily driver, so off-boost response is not as crucial - however, I DO want my vaccuum assist to work from idle (ie brakes etc) w/o having a resevoir.

I have read on here that the 3.1 bottom end will "soak up" big cams, which intutiviely makes some sense - at the moment I am looking at either 272 or 280 duration, which provides lift in the region of 10-10.5 mm.

Is this ridiculous, unusable power for a 3.1? I would like to have boost on or before

4, 000 rpm. There will be inherent limits on revving out a big stroker motor. I also want working vacuum assist. As always, all advice or recommendations greatly appreciated.

[9krpm]

dorifticon, your power band will depends on which turbo you will use. You will still get vaccumm at idle with that setup.

[Marko R1]

i had a similar chat with dirtgarage about losing vacuum & braking power off-boost, could be very dangerous at times for a street car

im sure he can advise with his words of wisdom

...i just realised this is in the rb30 conversion group, he calls them 'forklift motors'...not much of a fan but i am

Edited May 15, 2009 by Marko R1

[dorifticon]

thanks, will wait any further feedback on loss of vaccuum.

My other queries relate to potential issues with valve-to-piston clearance using high-lift cams. Does anyone know at what lift the valves are at risk of hitting the pistons? I need to consider whether I want to raise the static compression ratio to compensate

for the lack of dynamic compression created by the big duration. Has anyone had any experience with using pistons with valve reliefs?

Finally, I am looking at having my porting work done by lewis engines in adelaide (very few choices in Canberra). Has anyone had any experience with them? feel free to shoot me a PM on that point.

[Marko R1]

perform a search on proengines, greg is very well priced with quick turnaround and everything he does is onsite and by 1 person so no middleman involved. has built way too many rb's and infact just about finished my 26/30.

ive seen my head porting which looks fantastic and is supplying flow bench testing with before v's after results...can i ask for more? others such as scooby have used the same workshop.

talk to greg about your setup, he can answer your q's mate