Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Engine Performance (https://www.miataturbo.net/engine-performance-56/)
-   -   Worried about valve float... but not from RPM (https://www.miataturbo.net/engine-performance-56/worried-about-valve-float-but-not-rpm-107734/)

offatooth 12-23-2022 08:17 AM

Worried about valve float... but not from RPM
 
Hi all,
LONG time lurker, first time poster. Thanks to all of the great knowledge here, I have been reaping the rewards of my 93 with a 99 drivetrain, built bottom end, and kraken turbo kit at about 18psi.
Built last winter with Manley H-Beams and 8.6:1 Supertechs, and an MS3 no one was able to convince me at the time to make any valvetrain upgrades to the head, so I gave it nothing more than a full refresh with factory seals, a clean, and and valve lash.
Well, building season is back and we picked up a low mileage (70k) rear ended 2001. My main goal here is to utilize the 6 speed as I believe the 5 to be the weakest link on my drivetrain, and the VVT Head.
After pulling the head, it was as clean as expected with that mileage, and I was prepared to throw it on as is. Bit hard to stomach swamping a rebuilt head with one that's got some miles, but time is a non issue so I can work it over later for the cost of a head gasket.

Now to the point, with the added drivetrain stoutness I want to go above my current 18PSI. I am not built for, nor do I see the benefit of going past 7000 rpm. In fact my fuel cut is set to 6500 as my fuel table is set to 6800 (crazy I know but the linearity and resolution of my VE Table has been of huge benefit) Now... when looking at aftermarket valve spring options, they are all marketed around RPM, but with a 1^2 valve area, I am effectively going to a see a min seat pressure of up to 20-25 pounds less than an NA application.

So... Has anyone here actually experienced valve float? or seen wear on the valves that would indicate such? Would VVT tuning be greatly effected by even a mild increase (56# ST single option)?

Thank you beautiful community!

sixshooter 12-23-2022 01:08 PM

Future-proof your world by going with the light doubles. And, yes, the boost makes it harder to close the intake valves. Most people don't pay attention to that.


All times are GMT -4. The time now is 02:36 AM.


© 2024 MH Sub I, LLC dba Internet Brands