Jump to content
SAU Community

Recommended Posts

Rang the guys at UE today. A new set of injectors are in the car. It hasn't been ran up under load yet so we don't know if thats the issue. Tomorrow we will know. I have a funny feeling its a valve spring. Stupid car!

Rang the guys at UE today. A new set of injectors are in the car. It hasn't been ran up under load yet so we don't know if thats the issue. Tomorrow we will know. I have a funny feeling its a valve spring. Stupid car!

I wouldn't think it's a valve spring because you say it only does it when loaded up .. A dud valve spring & it would be rooted everywhere .

I wouldn't think it's a valve spring because you say it only does it when loaded up .. A dud valve spring & it would be rooted everywhere .

At 19 psi it happens at 7000 RPM

at 26 is happens at 5000 RPM off

at half throttle we can turn it to 8500.

More pressure behind the valve forcing it open? I'm sure the ramp rates of these cams are not helping the situation haha.

I had a miss with my other gtr and the cause was a faulty coil pack (what do u expect after 20yrs of abuse). Splitfires fixed that.

However, your above post throws my theory out as it definitely sounds more mechanical. I agree with u paul but its not an educated guess.

I had a miss with my other gtr and the cause was a faulty coil pack (what do u expect after 20yrs of abuse). Splitfires fixed that.

However, your above post throws my theory out as it definitely sounds more mechanical. I agree with u paul but its not an educated guess.

Definately not coils. Borrowed Joey's set which did 430 ish 2 hours before hand.

At 19 psi it happens at 7000 RPM

at 26 is happens at 5000 RPM off

at half throttle we can turn it to 8500.

More pressure behind the valve forcing it open? I'm sure the ramp rates of these cams are not helping the situation haha.

Wasn't this a freshly built head with new springs etc ..

Hmm it's strange alright but I would still think if a spring was off you would still encounter problems at 8500 rpm .. But it doesn't do it at partial throttle.

Wasn't this a freshly built head with new springs etc ..

Hmm it's strange alright but I would still think if a spring was off you would still encounter problems at 8500 rpm .. But it doesn't do it at partial throttle.

Everything in the head was brand new. The springs are HKS step 2's. Maybe due to the fast closing of the valve it's just enough to cause issue with higher boost at higher RPM?

Shim the valve springs. They need more seat pressure!

What Sean said . I tried looking for the spring pressures on HKS step 2's , but can't find figures .

It would seem you may have a much too aggressive profile for the springs .

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • It was roughly 3.5 hours.    car went in around 11:00 and I was done around 2:30 He did the initial runs, install the BC and then Nistune install and tune.  The best part was sitting in the lobby and hearing the skyline on full throttle at the dyno 😂😂
    • Glad it all went smooth. How long did the tuning process take?
    • Yeah that was kind of the same feedback my tuner gave me.  the boost tee is until I can sort out my plan for the electronic boost controller and what I’d get, where I’d mount the dash etc.  I’m happy with this until I can figure it out. Not a big fan of the A-pillar gauges. I’d like to get a clean install of the boost gauge - something digital like GFB.  Something like that might fit neatly where the ashtray is and look clean. I feel like replacing the OEM triple gauge is a bit extreme for a weekender like my skyline. And it’s not making crazy power to need all the additional sensors/gauges. 
    • I'm about to swap my box to Tremec T56 Magnum F & initially thinking of re-using my DCS twin plate (can get it re centred for the bigger spline) but it's been called out the box will be noisy (rattle) as the clutch is unsprung.  So I'm doing as much research as possible. I'm not so worried about holding the power as I'll go the track version which on paper will hold the maybe 1000hp I make. It's the longevity I worry about. DCS told me they don't use a sprung centre as it's just something that can break. The uni clutch has a very complicated sprung centre. Any one had or heard about any issues with it failing? Thanks in advance.
    • Auto is at least 10% (from my real, actual experience with different torque converters and manual on the same setup) ~185rwkw at 11.6psi (peak!) is entirely what one would expect without a FMIC or anything else on the intake, it does bleed off towards the higher RPM so it's what, 9psi there? Note: There is nothing that can be done about this with a manual boost tee. If you want to hold it steady and gain more top end, well - You will need electronic boost control.....
×
×
  • Create New...