RB26 camshafts in RB20??

[Roy]

It's my understanding solid lifter cams won't work in hydraulic lifter engines as the profile shape is different.

...yeh im listening, can you elaborate on how the profile is different?

I cant see there being any real effect especially at under 7,400rpm. Fair enough the valve springs may be a bit different due to the difference between sold v hydraulic lifters.Also the solid cams in order to have higher lift over same duration must have a higher ramp rate then RB20 hydraulics.......but i dont know, just thinking/guessing

Dont hydraulic lifter engine normally run higher spring rates then sold lifters? So is it safe to assume that putting a solid lifter cam in a hydraulic application is safer / will work better then hydraulic cam into sold lifter engine?

Excuse me if not using the proper terms...its been 4 years since i passed MOMs :Oops:

The RB20 has 240deg - 7.8mm lift intake & 240deg - 7.8mm lift exhaust

The RB26 has 240deg - 8.5mm lift intake & 236deg - 8.2mm lift exhaust

So any increase in power will come from the increase in lift, not duration

[bbenny]

it all depends on lift as to whether they work with hydro lifters or not.

i think there is a 0.9mm increase in lift with the GTR cams over std, but i think anything over 9.5mm (not 100% if its exactly 9.5) and the hydraulic lifters need to be changed to a solid lifter kit.

[Roy]

Of interest is that Tomei make the following cams, and are abolt in affair using std hydraulic lifters and RB20DET valvesprings:

256° / 8.50 inlet (PONCAM)

260° / 8.50 exhaust (PONCAM)

So from a mechanics (dont tell me i have to digout my mechanics of machine texts from uni) i suppose you could have an issue with increasing lift without the duration as the valve velocities would increase, which is perhaps why the above Tomei cams work with the std RB20 valvetrane.... then again we are perhaps makign a mountain out of an ant mound considering the physics of it all.

[Clint32]

i used tomei springs in my rb25 and that suit up to 8.8 lift from memory, so the rb20 would be very similar i would say, i used a rb26 exh cam to get the max lift with more duration so i would like to know any diff between solid and hyd lift cams

[Sydneykid]

The old solid versus hydraulics question, there's a blast from the Chevy past. :Bang:

When the follower fills with oil it is SOLID, not compressible, so the effect on the valve (open and close) is exactly the same. The only real difference occurs as the oil is moving into and out of the follower, simplistically, when the valve is closed.

The "filling up with oil rapidly enough" is worth noting as this is why the rpm limit for hydraulic followers is lower than for solids. They, what is called colloquially called, pump down ie; the oil level gradually falls as it can't get in fast enough to hold the follower at full extension. Thus the clearances get large and the follower start to knock.

So, provided the followers don't leak oil pressure and fill up with oil rapidly enough, then there is basically no difference between a current generation of hydraulic follower and a solid follower.

This of course was not the case with the Chevy, the lifters leaked, the oil was slow moving, the oil itself was not so good. So "hydraulic" cams had softer ramp rates than "solid" cams to allow time for the oil to flow. :dump:

Time has moved on and the dinosaurs are gone, well from my garage anyway.

[rsx84]

OK i've been following this thread for a while and are thinking of doing the swap but it seems to have hit a snag, i'll be doing some other mods at the same time and was asking what would be the salution to the idle problem? example, the ECU does it need a swap to after market or a rechip or maybe a piggy back system.. any surgestions/help....

[Roy]

... i'll be doing some other mods at the same time and was asking what would be the solution to the idle problem?

My suggestion is if you are goin gto install the cams get a flexible management system first... then after the car is set up a nd running properly with new management then intall the cams.

I did the cams, AFM, cam gears and ECU in the one hit and workshop is having trouble getting the thing running, could be a completely unrelated problems (coincidence) or could be a combination of issues arising from all the parts bolted on in one hit....so unless you gave done the GTR cam swap before, (or your workshop), then id suggest small bites as it makes everyones life easier, if not a little more expensive.

[WazR32GTSt]

My suggestion is if you are goin gto install the cams get a flexible management system first... then after the car is set up a nd running properly with new management then intall the cams.  

I did the cams, AFM, cam gears and ECU in the one hit and workshop is having trouble getting the thing running, could be a completely unrelated problems (coincidence) or could be a combination of issues arising from all the parts bolted on in one hit....so unless you gave done the GTR cam swap before, (or your workshop), then id suggest small bites as it makes everyones life easier, if not a little more expensive.

top quality advice...

i'd agree and say the 'little bites at a time' method of trying one thing before the next (rather than everything at once) is much more effective at diagnosing problems that generally arise. unless you are going to a top workshop that specialises in skylines then most mechanics will shake their head if you swapped alot and they can't get it to work - if only we lived in japan where skylines are the equivilent of commodores/falcons and mechanics know them inside-out!

[Sydneykid]

tif only we lived in japan where skylines are the equivilent of commodores/falcons and mechanics know them inside-out!

Ho ho ho, you couldn't afford to pay them. Mechanics in Japan charge like brain surgeons. That's why everything has to be bolt on.

[jaik]

I was contemplating doing GTR Cams, Gears, GTR injectors all at once on my Cefiro because a friend of mine does alot with Nissan ECU tuning (Makes bulk SR daughterboards etc *another top aussie export product!*) and I figured it would be cheaper for dyno time to do it all at once (Can get the tune done for free). I was also going to start off with a base Mines map aswell.

So perhaps no now? I would have presumed it would be rather common for people to do fuel stuff, cams & boost all at once to get good performance? Im hoping not to see any issues from screwing up the boost and putting in cams, but just getting the electronics for the injectors running shouldnt be too much of a drama either.

Crawl before running?

JK

[Roy]

Well, bringing this thread back from the dead. The GTR cams into RB20 has resulted in a dead engine. Dont read too much into that statement without reading all the post.

Like bbenny when my inlet cam went in it was a bit tight to turn the cam wheel by hand. With the timing belt back on i could turn the engine over easily by hand so didt think too much of the tightness.

Now it appears the car when trying to get tuned was skipping teeth on the belt, so me thinks DOH i rooted the timing belt/tensioner when playing with the engine. But it appears that the tightness in the inlet cam was enough resistance to encourage the 80,000kms timing belt and worn cam wheel to hop teeth.

And today im the proud owner of an engine with a bent inlet valve in cyl #1 , such as sad death for an engine that had been cained for 170,000kms and never skipped a beat...it deserved a warriors death screaming down the straight at Phillip Island at 1.5 bar with rods out the side of the block with me spinning/crashing/burning on my own engine oil. :flamed:

Not a rough 500rpm idle and cough...GAME OVER

So if doing this mod, if you notice any tightness in the inlet cam like bbebnny and i did, abandon the mod and see a professional, as to date no one can expalin to me why my inlet cam may be as tight as it is?

Oh and now have a set of R33 GTR V-Spec cams for sale :Oops: ...

[R31 POWER]

Ok WTF is going on,are people putting the cam cap thingys on backwards (I don't mean you Roy)

WazR32GTSt has his running,did you use the GTR cam caps?

[Roy]

Ok WTF is going on,are people putting the cam cap thingys on backwards (I don't mean you Roy)  

WazR32GTSt has his running,did you use the GTR cam caps?

LOL...Why not me, im the Hannibal Lechter of the DIY crew :Oops:

My cam journal/caps were 100% on the right way, all markings lined up correctly, at TDC the flank of the #1 cam lobe even appeared to be in the right position?!?! i dont know what else i could of visually checked to ensure everything was lined up correctly. And i was using RB20 caps, and the exhaust side was fine

I dont know but i suspect my problem has to do with the age / condition of my engine, it has seen over 3,000kms of track work and 170,000kms total. Even though i was amazed how clean the valve gear was it is old and i think it may be a lifter problem as the engine did have the occassional ticking when the car first started up when cold.

New head goes in this week, if the mechanic is adventurous after we get it running tuend with std cams may convince him to give the GTR cams a go in the other head and see how it goes...may be able to get some before after results with the TD06 so will show if the std cams hurt flow / performance on the RB20s.

[predator]

i can confirm it is the ECU flysky. because i checked and tried everything, there were no other causes. and SydneyKid has done several running a PFC with no problems and considerable gains. no probs with standard cams joel

adjusting any of the cams will probably cause it run poorly at idle, hence changing the cams with a stock ECU is probably not a great idea as the ignition timing is basically set for a stock cam combo afterall. That would make sense wouldn't it (?)

Even just with an exhaust camgear added on my old car to change things a little, i noticed the idle was a lot poorer, and more "lumpier".. stock ECU w/ S-AFC. Was fine to drive, but idle = goats. Wasn't absolutely terrible but in the mornings had some trouble and revs would jump all over the place at idle. With a proper aftermarket could probably tune it out I would imagine. Never got to find that out.

[Bl4cK32]

Shit Troy...i sold you the cam cap for yer head....i know what it was bad Karma my engine blew at 109,000 kms...must have carried over to yours....lol

Sorry to hear dude....

[jaik]

That is not good news! Did you compare the physicaly dimensions of the standard cams and the GTR cams? Both had issues with the inlet cams... very interesting...

Now im very weary of upgrading my cams, or atleast the Inlet cam (worth the hassle just putting in the exhaust one?)

Any further info you can provide us with?

Thanks

JK

[Sydneykid]

Hi Roy, I have been thinking about this camshaft tight in the bearings problem. I haven't seen it in an RB engine, but I have in other 6 cylinder DOHC engines. The camshafts are very looooong and I have found 2 that where not straight. Looks like they were in an engine that overheated or had the head torqued down incorrectly. This "bent" the camshafts and they went tight in the bearings.

We have had one of the race GTR's lock up an inlet camshaft which may or may not have been as a result of a "bent" camshaft. It is certainly "bent" now, but I can't tell if that was the cause of the problem or the result. So I am suspicious that RB's may not be immune from this problem.

So Roy, can I strongly suggest that you get the camshaft checked for straightness before you put it in another head. I am going to get the dial gauge out and check a set of RB26 cams that are destined for one of our RB20's. I will let you know what happens.

[rb25]

where do i buy dial gauges, verniers etc....

-rb25

[Roy]

You can get digital verniers from places like Jaycar / Dixk Smith. As for dial gauges, i think it may be best to go see your local engine / machine shop and get them to check for you, as to check the cam with a dial gauge you will need a jig/fixing to rotate the cam in?!?!?!

[aRCH]

Hey All,

Sorry to bump this thread up again but I've just purchased some R34 Nur spec gtr cams at a very very good price. I'm putting them aside for my new RB20 when I replace my current somewhat tired one.

Was just wondering if anyone knew of differences between the various gtr cams and if possible what differences I might find with the N1 cams.

I did a couple searches on the forums for gtr cam differences but couldn't find anything apart from a slight mention earlier in this thread.

Thanks for your help