Cam Selection

[Turbz_13]

how ya going guys,

just wondering how ya decide on a set of cams for ya car. if there is like a guide on how each different duration would affect the car, i was told that there is a book for v8, when people are looking at cam selection. just wondering if there is anything like this for imports, or more so rb engines, even more specific, rb26's?!?!

thanks guys

James

[Turbz_13]

surely someone can point me in the right direction??? i know everyone is going to have a different opinion. i woiuld have thought this would have been a large interest point with building up hi po rb26's

[STR8E180]

need some more info dude

cant reali just recommend a cam with out knowing specs its very important u match the size of ur cams to the size of turbo ur using

by looking at ur signature it only looks like ur running R34 GTR twins so i would go stage 1 but if ur planing on changing the turbo's to some thing bigger later on down the track then thats a different story

Edited December 3, 2008 by STR8E180

[Turbz_13]

i am running 34 gtr ceramic turbos atm, but im looking at either the garrett gt2860r -5(the hks gt-rs equivilent?) or a garrett t04z/r(would you know the part number by off chance for that turbo mate?) upgrade.

i was looking for a nice lumpy idle, good mid range response right thro to the top end say 8500rpm. specially caus ethese turbos are bigger than stockies

[Piggaz]

If it's any help im running 270 @ 10.25 on a 2.8 Twin GT - RS's motor.

[PM-R33]

As a rough guide, the larger the duration on the cams, the higher in the rev range it moves the powerband/peak torque.

Edited December 4, 2008 by PM-R33

[Turbz_13]

is there any beinift in using different duration in the in and ex sides? as i hav seen some hipo gtr's in japan running the different durations on each side

i was looking around the 260ish-270ish but wasnt really sure on how this would help me with what i wanted, so i thought i better ask!!

i have a built motor, with 20thou over. so slightly over the stock capacity, if this can help. also i have a set of adjustable cam gears on the car but havnt been dialed in yet, waiting for the cams.

how would the car react with the cams in on the r34 gtr turbos? b4 i start plaing around with my turbo set up???

also what kinda lift can the stock head gear handle, and when should i start replacing the springs and other componentry???

cheers

James

Edited December 4, 2008 by Turbz_13

[discopotato03]

Need more info like what future mods your going to do to that engine .

Many think that Tomei Poncams are a good bolt on (in) and they seem to work well .

Personally I would stay away from wild cams in a mechanically std road engine because they aren't driven at high revs for long enough to make them worth the grief .

Your call but I don't see a lot of value in a lumpy "idle" , it's usually a sign of bad tuning or reversion and by nature these are not what I call desirable characteristics .

If you had financial and time freedoms I think a well ported head and mild cams would give good all round results but cams alone get you part of the way there .

I'd look at Poncams , cheers A .

[Shaun O]

I think when choosing cams you need to take everything into consideration

Rev Limit

Gear Ratios

--These come together, to find where you're at on your upshift

Turbo

Cams

Combining all these, best turbo for early spool to bring you all the way to your rev limit

You may not need a high rev limit if you're upshifts bring you to a sweet spot so you can opt for an earlier spooling turbo

Then based on where that sweet spot is, cams with duration to suit that rev range

I would do that for track anyway, drag and stuff would probably be a bit different

I think this post gives a good fairly general guide of durations

http://www.skylinesaustralia.com/forums/in...t&p=4002120

The answer on duration depends on what RPM range you are targetting, be realistic. If you intend to use 7,000 to 9,500 rpm, something around 272 to 288 degrees would be the go. For 5,500 to 8,000 rpm, around 260 to 272 and for 4,500 to 7,500 rpm then 248 to 260 is the go. That's a simplification, but you get the idea. As for lift, once I know the effective rpm range, I then choose the highest lift I can for that duration. What valve springs you are using will also determine the maximum lift.

Cheers

Gary

[STATUS]

good mid and lumpy idle is an oxymoron.... lumpy idle is caused by big lift long duration cams....all designed for top end hp

[KB240RB]

Ive got a Built SR20 in one of my S13's revving to 9krpm with T67 turbo and i run Tomei 270's. Idle is somewhat lumpy but nothin too bad. Powerband is strongest from 5k-8500rpm. I imagine the 270's for the RB will be similar.

http://www.youtube.com/watch?v=syNqwlcebrw

[Turbz_13]

all good, i know what im going to use. have looked at many rb26 that are running similar or same turbos as what i am looking at, goign to use the same kinda cam these guys have all used.