RB26 Build Question - Valve Springs

[drew6]

I'm rebuilding my RB26 and at the moment plan to use the stock cams (Atleast for now)... Their actaully not a bad spec at all really.

Anyway, my question is do the OEM valve springs experience any sort of valve float at high rpms? I understand that even the larger aftermarket cams are able to use the OEM springs so I am not concered about that - really just the valve floating issue. I would like to be safe into the 9-10k area.

Thanks.

[cobrAA]

good question. i would like to know too!

[GTRADDICT]

10k Rev GTR in moncton! awsome!! Should come by McLaughlin ave. for a ride lol
I don't know, but the springs may have some fatigue in them (20+ years or hot/cold cycle)
And if you plan to run that high RPM I think you will have to get cams that are more top end oriented... If you get money to make it rev that fast, you have money for cams and springs! Shout out if ever you need help.
Nick

[bizzle]

The OEM valve springs are not designed to rev into 9-10K. You might get away with an accidental over rev to that range here and there or things might break on the first over rev. I personally would not be revving a stock motor past 7800-8000rpm at the most. Are you rebuilding with brand new OEM valve springs or just re-using your existing stuff? If you are planning reusing what you have to keep in mind that they have been thru some abuse already.

[MarusGTR]

10k Rev GTR in moncton! awsome!! Should come by McLaughlin ave. for a ride lol
I don't know, but the springs may have some fatigue in them (20+ years or hot/cold cycle)
And if you plan to run that high RPM I think you will have to get cams that are more top end oriented... If you get money to make it rev that fast, you have money for cams and springs! Shout out if ever you need help.
Nick

What about me? I want a ride too!

Edit: ...and bizzle makes a good point, the spring rate is set for maximum energy release at stock redline plus a safety factor. After 20 years of fatigue cycles I wouldn't risk it. It would be possible to crunch approximate spring rate degradation with the mileage, cam duration/lift and spring geometry, but it's not worth it lol.

[GTRADDICT]

What about me? I want a ride too!

Hey!! Shut up. You already have your godzilla lol

[drew6]

Thanks for the inputs. The reason I ask is because I read some stuff on the british boards about people using the OEM springs for high reving engines (although now I can't seem to find the thread...)

The reason I'm keeping the stock cams for now is because I plan to use N1 turbos for the break in and some tuning. I also plan to see what these turbos can do.. I'm interested in pushing them. After that I'm going in for some bigger turbos and hence a higher rpm range. I'll change the cams out then. I'm not going to pull the head to do it so I'm going to need to put springs in now if I'm going to do it.

The engine is not stock... If it was 9-10k would certainly be out of the question. (and pointless)

[MarusGTR]

Hey!! Shut up. You already have your godzilla lol

And it's not going past 7500RPM anytime soon!

BTW, you shut up, I let you drive her, don't start whinin' if you don't want me to cut you off

Speaking of which I'm not sure if I should service the waterpump, belts and idle pulleys this summer... I sure could use some help if I save up enough money. That, among lots of other things. I'm going to take a full month off research during the summer and dedicate it to servicing the GTR if you're interested. I just need, oh you know, a decent garage and tools...

[DJ]

Reving to 9-10k... you'll need some extensive headwork .Make sure you get your bottom end sorted out with proper oil system mods.

Whats the point of reving to 9-10k anyways? Why dont you aim for usable power in the lower revs unless you want to slap a gt45 on the 26 and not have fun at all till you get boost at like 7k.

[NismoS-tune]

There was a guy in alberta who had a built engine with stock springs. I forget what RPM he went to but they floated and cause damaged when 1 caught. I don't think it was major but still couldn't run and had to get the head taken off. Anyways, springs are cheap. You can get Supertech or Ferrea springs for less than $400 that are better than OEM. Tomei would be the expensive type but Ferrea are better I heard.

I'm rebuilding my RB26 and at the moment plan to use the stock cams (Atleast for now)... Their actaully not a bad spec at all really.

Anyway, my question is do the OEM valve springs experience any sort of valve float at high rpms? I understand that even the larger aftermarket cams are able to use the OEM springs so I am not concered about that - really just the valve floating issue. I would like to be safe into the 9-10k area.

Thanks.

[NismoS-tune]

Stock head (and everything in it) is good for 500whp. If you don't really want to do springs and other head work now, may as well wait on cams. If you're pulling the head for work, do it all at once.

I personally watched a stock headed gtr get 500+whp and it wasn't a crazy build.

doesn't really matter which turbos you use for break in if you simply disconnected the wastegate actuators and run no boost. Works fine, then you can reconnect your wastegate actuators on the dyno. I've changed turbos with the engine in place, it sucks. Why not do it while the engine is out, unless it's not coming out which then I'd say, why do it twice

Thanks for the inputs. The reason I ask is because I read some stuff on the british boards about people using the OEM springs for high reving engines (although now I can't seem to find the thread...)

The reason I'm keeping the stock cams for now is because I plan to use N1 turbos for the break in and some tuning. I also plan to see what these turbos can do.. I'm interested in pushing them. After that I'm going in for some bigger turbos and hence a higher rpm range. I'll change the cams out then. I'm not going to pull the head to do it so I'm going to need to put springs in now if I'm going to do it.

The engine is not stock... If it was 9-10k would certainly be out of the question. (and pointless)

[drew6]

To answer everyones concerns:

1. Oil control issues are corrected.
2. Head will not be stock. It will be reworked.
3. I will not be removing the head or engine to change the cams when I do switch turbos and cams. They are both something you can in car.
4. 2.6L is such a small engine. If your going to make big power 9-10k is the only way to go.. I'm not afraid of trading off some bottom end.

So... it appears that no one has any first hand experience with floating the valves.

Thanks for the help.

[NismoS-tune]

There's a GTRC member that had valve float with his 800hp turbos. I'd have to find his name..

As for big power, we're talking more than 550whp right so since you can afford to build a big power car, you should change everything from springs to valves to oil pan, just cause you can What kind of engine internals do you have?

To answer everyones concerns:

1. Oil control issues are corrected.
2. Head will not be stock. It will be reworked.
3. I will not be removing the head or engine to change the cams when I do switch turbos and cams. They are both something you can in car.
4. 2.6L is such a small engine. If your going to make big power 9-10k is the only way to go.. I'm not afraid of trading off some bottom end.

So... it appears that no one has any first hand experience with floating the valves.

Thanks for the help.

[drew6]

As for big power, we're talking more than 550whp right so since you can afford to build a big power car, you should change everything from springs to valves to oil pan, just cause you can What kind of engine internals do you have?

Hahah. At first I thought you were serious about this... Trust me, I'm not made of money.

I'm will be running CP pistons with Crower rods.

[NismoS-tune]

Semi serious. You don't need cams for medium power like 500whp. It helps with making it easier but not necessary if you want to spend that elsewhere.

Hahah. At first I thought you were serious about this... Trust me, I'm not made of money.

I'm will be running CP pistons with Crower rods.