Valve Float?....... Next Step?

[BEN 0]

I've recently converted my skyline to united e85.

Had the car tuned and the result was 410hp at 18psi.

The tuner had stated that he couldn't put any more boost in because of valve float.

So I had some performance springs valve springs installed.

Had the car retuned and the result was 437hp at 23/22psi

The tuner had stated that the car still had valve float above this level.

He asked what springs installed and commented that they're not up to the task and had seen many customers have similar problems.

Raising the boost would not effect the power curve and estimated power figure not reached.

I'm disappointed with the situation and would like to know what you guys think?

Should I change springs again?

Should I change dyno operator?

Is this a below average outcome for my setup?

Is this valve floating?

Mods include but not limited too:

Garrett Gt3076r t3 .70 comp .82ar ex wg

3.5 inch exhaust

100mm thick cooler 3in piping

China ffp

Standard throttle body

Walbro 460

Id1000

Mls head gasket

Wolf 3d v5

[BEN 0]

Had a graph of a pressure drop test they did in the dyno to check for restrictions only 1psi drop

[Blackkers]

What engine?

[GTSBoy]

I would have thought that >300 rwkW on a 3076 on E85 was getting close to the full potential of the turbo.

I would wait for the advice of others with more experience with those turbos before taking anything I said about it to heart though.

The other thing that occurs to me, now that you have posted up those dyno charts, is that there doesn't seem to be any giveaway of valve float showing up in the curves. Usually when they start to float you at least see some sort of upset in the curve. I'd be asking your tuner what signs or behaviours he is using to tell him that it's floating.

[BEN 0]

It's a rb25 series 1

I agree that the curve doesn't show a typical valve float situation.

The tuner stated that as he tried adding boost in the higher rpm range the curve stayed the same as you can see in the graph.

He said swapping the springs for supertech would fix it and show a big increase in power.

I'm just skeptical having already spent a bit of coin.

Edited February 6, 2015 by BEN 0

[Kinkstaah]

I was of the impression that the GT series tend to, well.. die in the ass after about 22-23PSI on a RB

In other words moar boost = no moar power.

This was the impression I got when reading about the GT3076 when compared to GTX3076, in that the GTX series continue making power under more boost after the GT series has stopped making gains.

[r32-25t]

Have you had the head reconditioned at any point in It's life?

[BEN 0]

Yeah head reconditioned when gasket and studs installed. No porting done.

Had the springs installed with the head on.

[r32-25t]

There is a good chance that the valve seats have been cut and all the japanese branded valve springs don't have enough tension if the seats have been cut. i have seen this issue arise on 3 different RB engines (2x26s and a 25) all 3 upgraded to super tech to fix the issue and have shown great results

[BEN 0]

That's very interesting Brett, thanks for you input.

If you can remember, how big were the gains on the setups you seen?

Would changing to higher lift camshafts help with the spring situation?

[BEN 0]

Who has big boost setups on rb25 with hydraulic lifters? And what springs do you use?

[r32-25t]

Higher lift would make it worse, one car was bad enough he couldn't get it to rev cleanly, it was almost as if it was hitting a rev limiter at random spots in the rev range. Changed springs and pulled over 450kw at the wheels

[Piggaz]

  On 06/02/2015 at 7:01 AM, BEN 0 said:

That's very interesting Brett, thanks for you input.

If you can remember, how big were the gains on the setups you seen?

Would changing to higher lift camshafts help with the spring situation?

How big of gains regarding what exactly?

As Brett said, shoving higher lift bump sticks in there won't be doing any favours unless you get a decent spring in there.

[BEN 0]

Was just trying to gauge the difference in performance by changing the springs.

Just need to weigh up the options with my goals. Would like to reach 500hp.

Replace springs and retune

Replace springs and cams and retune

Replace springs and turbo to GTX

???

[r32-25t]

Out of those options your biggest gains would be made from springs turbo and retune

[BEN 0]

I see, if there is a better option feel free to let me know.

The tuner recommended super tech, from doing a search it seems they only make a single spring to suit hydraulic rb25

part no. SPRK-2081/rb25

Ferrea do a dual spring for hydraulic with slightly better specs

part no. S10112-24

Would either of this be the right choice?

[Piggaz]

What camshaft have you got in there? I highly doubt you'll need a duel spring!

If you keep it at say 20% throttle, will it rev out to 7000 rpm without it doing it's thing?

If you give it more boost, does it do it's "thing" earlier?

[r32-25t]

Personally I've only used the supertech and had good results so I stick to them. That not saying they ferrea aren't good, I've just never used them

[BEN 0]

Standard camshafts

I can't notice anything driving it, I believe the tuner has turned it down as not to damage anything.

His words were he'd seen the same situation many times before with this brand of spring.

[Scott Black]

Could you shim the spring without it binding to increase tension/ preload