Jump to content
SAU Community

Recommended Posts

hi every body just need some advice from people that know. iam running gt3040 powered rebuilt rb25 with gtr rods , wiseco forged pistons , tomei step 1 poncams and ported head. im running stock hydraulic lifters and valve springs. im wanting to rev the motor past 7000rpm to take advantage of the extra top end this gt3040 turbo gives me. whats a safe red line to have? thanks carl.

Link to comment
https://www.sau.com.au/forums/topic/114722-stock-valve-train-rev-limit/
Share on other sites

Mine was set to 8000rpm.

That was knowing full well it woould see the drag strip, and it did a few times :)

Stock head aswell, not even cam'd

So i cant see why you cant do the same if its still making power.

You have the rods & better bolts, so DO IT

Does anyone know for sure or has had experience when valve float has started to occur in the 25's with whatever modifications they have had done?

Im curious to know if it happens often or not at all, i have yet to see anyone complain about 25det and valve float. Ive heard its a problem in neo25's cause their springs are weaker then the previous models, is that true as well if anyone knows?

Well thats good to hear. Just that were upgrading the springs to some stronger Isky ones for the 25/30 just to make sure..we will be running around 22-25psi outta the 3540. Just wanted to check incase anyone had run into such problems before.

Ok so someone has run into problems...well our redline on the 25/30 will be 7k due to standard harmonic dampner, so with the stronger springs we should be good.

What turbo may i ask were you two running R31Nismoid/turbo87?

Edited by r33_racer

I also ran into valve float at about 21psi. It started around 4k according to my tuner.

That was on an HKS t300s turboed stock cam'ed s1 rb25 making about 240rwkw up top. I've got my rev limit pegged at 7300 more due to worries about the stock rods than the valve train.

im running tomei poncams step 1 252 degrees duration at stock 8.5mm lift. now wouldnt running these cams with stock lift enable me to run similar rev limit to if i had the stock cams still installed??? if im going to run 22psi on hi boost do i need to restrict revs to 7000rpm or can i go to 7300rpm ? without valve float any ideas people???

If installing pon cams I'd recommend upgrading the valve springs to gtr items. With stock lift I'd say you should be able to hit 7500 but you'l certainly find out. Didn't you have a gt 30 with nissan exhaust housing before or am I getting mixed up?

Cheers

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

    • I refreshed the OEM injectors with the kit and connected it up. It now ideals okay even with the IACV removed. Driving still has the same cutoff issue like the 550cc injectors so the issue is somewhere else. I bought FPG's Fuel Pump Hanger. I will be installing it next, but it is not as straightforward as I thought it was with my limited wiring knowledge and no instruction on the specific model I purchased (FPG-089). I also got the incorrect billet clamp as I could not find info on the OEM sizing.
    • Stop looking at the garage floor, and turn the radio up a bit louder if there's any strange noises...
    • No. Turbo shuffle and surge/flutter are not the same thing. Specifically, on a GTR, turbo shuffle has a definite meaning. On a GTR, the twin turbos are assumed to be the same thing and to operate the same way, exactly. In reality, they do not. Their exhaust sides are fed and exhaust a little differently, to each other. Their inlet sides are fed and exhausted a little differently, to each other. Consequently, when they are "working" they are often at slightly different points on the compressor map compared to each other. What this means, particularly when coming on boost, is that one of them will spool up and start producing extra flow compared to the other, which will put back pressure on that other compressor, which will push the operating point on that other compressor up (vertically). This will generally result in it bumping up against the surge line on the map, but even if it doesn't, it upsets the compressor and you get this surging shuffle back and forth between them That is "turbo shuffle" on a GTR. It is related to other flutter effects heard on other turbo systems, but it is a particular feature of the somewhat crappy outlet piping arrangement on RB26s. There are plenty of mods that have been attempted with varying levels of success. People have ground out and/or welded more material into the twin turbo pipe to try to prevent it. Extending the divider inside it works, removing material doesn't. There are aftermarket replacement twin turbo pipes available, and these exist pretty mush purely because of this shuffle problem.
    • You can temporarily* use lock collars to keep it in place until you can do the bushes, back the nuts off, slide them in, snug back up. *temporarily is often for ever
    • Thanks for the quick reply. To be clear, when you say turbo shuffle do you mean turbo flutter "stustustu" or referring to something else? I had thought they were the same thing. When I wrote the post my intention was to say it wasn't a flutter/compression surge sound. My understanding was that a flutter sound would be occurring when throttle is released, whereas I can keep the throttle in the same position for this noise
×
×
  • Create New...