rb26 cams in rb20 with standard ECU works!

[WazR32GTSt]

sweet thanks mate...

am going to do a plug change and thought i'd check what my mechanic set the timing to while i'm at it

[BlueRB240]

So if the Stock GTR cams work in the RB20 could you use aftermarkets? Like HKS Step 1's? HKS web page with cam specs translated into egrish

R32,33 IN 264 degrees 8.7 110 degrees

EX 272 degrees 8.7 113 degrees

Rb20 IN 264 degrees 9.0 110 degrees

EX 264 degrees 9.0 115 degrees

[WazR32GTSt]

So if the Stock GTR cams work in the RB20 could you use aftermarkets? Like HKS Step 1's? HKS web page with cam specs translated into egrish  

R32,33 IN 264 degrees  8.7  110 degrees  

           EX 272 degrees  8.7  113 degrees  

Rb20 IN 264 degrees  9.0  110 degrees    

        EX 264 degrees  9.0  115 degrees  

i don't see why you couldn't? i think cams are generally for 'rb' engines so as to work in either rb20/25/26

just be wary that after a certain amount of lift, the rb20 head needs to be modified i think to accomodate the installation. can someone clarify this further?

[Sydneykid]

The GTR cams are a mild upgrade that don't cost too much. Good bang for your buck.

When you get into aftermarket cams the costs are substantially higher. Not just for cams themsleves, but valve springs, convert solid to hydraulic followers, machine head for lobe clearance etc. Suddenly it is not such good value as for the same money you can buy more effective upgrades.

Plus an RB20 is 2 litres and the larger cams you put in the more rev happy you needo be

[Roy]

The workshop where my car is claims the RB26 cams in Rb20 have been tried, and the result is ordinary... ie you lose power down low, and any top end increase seen with these cams isnt worth the trade off...not the expected result from a mild lift and duration increase. Also sighted concern over a solid lifter cam being used with hydraulic lifters.

So since they have my car, and they are advising against leaving the cams in, well im going to get them to take them out...for no other reason then if my engine dies after the tune, then i hadnt gone against their advice and they can be held more accountable.

Out of interest does anyone know if cams for sold lifter engines have a more aggressive cam lobe, whereby accelerating the valves open / closed any quicker then used for hydraulics...still having the same duration and total lift, but different gradient to fully open?

[R31 POWER]

The workshop where my car is claims the RB26 cams in Rb20 have been tried, and the result is ordinary... ie you lose power down low, and any top end increase seen with these cams isnt worth the trade off...not the expected result from a mild lift and duration increase

Can anyone verify that coz if i do the GTR cams I don't want to lose anymore down low power/torque :wassup:

Also sighted concern over a solid lifter cam being used with hydraulic lifters.

Good point,can that be promblematic later down the track?

[BlueRB240]

The GTR cams are a mild upgrade that don't cost too much.  Good bang for your buck.    

When you get into aftermarket cams the costs are substantially higher.  Not just for cams themsleves, but valve springs, convert solid to hydraulic followers, machine head for lobe clearance etc.  Suddenly it is not such good value as for the same money you can buy more effective upgrades.

Plus an RB20 is 2 litres and the larger cams you put in the more rev happy you needo be

Well in my case I'm in the USA. Finding stock GTR cams is like looking for a Unicorn. If I do find them there won't be a big diffrence in price vs Aftermarkets . I have some stuff already just looking down the road.Pics of the stuff I have so far for the RB20 I'm not too worried about the lost of low end power, just a trade off you have to live with for topend.

[browny]

http://www.newcovenant.com/speedcrafter/te.../camshaft/5.htm

[Cubes]

Roy,

The RB26 cams have a smaller duration but higher lift.

They obviously have a higher ramp rate though.

I wouldn't expect any loss in power down low.

[Roy]

BlueRB240 ... is that plenum for an RB20, looks neat!

Joel...are these figures right? The RB20 has 240deg - 7.8mm lift on both intake & exhaust , whilst the RB26 has 240deg - 8.5mm lift intake & 236deg - 8.2mm lift exhaust...is that right.

So yeh, the lift is really all thats really different between my R32 RB20DET cams and R33 GTR V-Spec cams. And even if the ramp rate was different, one would assume (i do a lot of that) that it becomes an issue as revs increase, not at idle or low revs (????)

Im over it now, ive only driven the car about 6 weeks this year, and it has cost me too much money (not alot compared to what most spend, but more then i lile spending)...just want to enjoy it again like i use to when it had the std turbo/injectors/ecu etc etc

[Cubes]

Yer thats right, well according to tomei.

http://www.tomei-p.co.jp/_2003web-catalogu...haft-specs.html

Whats considered the Vspec N1? (as per the above link) ???

Maybe the higher ramp rate is causing problem with air velocity due to the RB20's slower piston speed?!?!? Theories..

[Roy]

What causes NA cars with big cams to have poor vacuum at idle...too much lift? Could it be a vacuum thing at idle...i dont know?

[DoughBoy]

What causes NA cars with big cams to have poor vacuum at idle...too much lift? Could it be a vacuum thing at idle...i dont know?

Camshaft overlap - when the duration is large and/or the centerlines are too close together.

[Cubes]

Yer it is overlap.. Maybe the lack of piston speed in the RB20 (shorter stroke) isn't enough to create a decent air velocity hence fuel atomisation goes up the crap?!?!

Might start looking around to how ramp rate affects short stroke motors.

[Roy]

So any thoughts how these would work:

Tomei 256° / 8.50 inlet (PONCAM)

Tomei 260° / 8.50 exhaust (PONCAM)

on an RB20DET with a 420hp turbo...too big on the exhaust side, should i stick with 256 on inlet/exhaust.

Essentially if im not going to run GTR cams, i still want something to help beef up the mid-top end

[Cubes]

Roy,

Do u have an Engine simulator?

PM me if you want to have a fiddle with one.

[Angry]

as i own a R31 Rb20det ... cam duration being IN : 248deg and EX :240deg .. with 7.8mmlift

upgrading to the gtr IN : 240deg and EX : 236deg the 8.5mm lift .. will i actually gain anymore .. and is it possible to tune them with adjustable timing gears pacifically for more torque rather than top end power..

Well done to Waz on the successful setup ..sounds very promising for the other rb20 owners thats for sure

[bbenny]

well when i had the GTR cams in (apart from not holding idle) when i drove the car it was super laggy down low, and didnt come on very hard at high rpm... which is what R31 power is describing. there were no other issues with my engine as when i re-fitted the std cams the car was back to perfect running order

[WazR32GTSt]

i have not lost any power down low that's for sure... (had none to begin with anyway )

[Roy]

Woudl you be able to get the phone number of the mechanic that installed them... the workshop where my car is coudl be interested in speaking to them?