Getting ready to build a VVT head up and would like to use +1 SS Supertech intake valves with Inconel +1 exhausts. Stock VVT cams @ >20PSI EFR, ST heavy doubles, 93 octane straight gas, roadcourse endurance.

Seems many people had problems in the last couple years with them and cant find the Manleys some talk about.

Has the cause been found and are they fixed, or was it a bad batch? Installation error?

 

Also curious

 

I really thought this would get more response?

Calling Emilio, Savington, Hornetball, Godless Commie, Curly, rleete, 18psi, Tntuba, Leafy, TurboTim. ext....

Or should it be in the race prep section?

 

The last set of Supertech Intakes I used lasted a full season. It is my understanding, that after feedback provided by a few of us, that ST reversed some changes in their manufacturing process.

I have been using Manly valves since though and have had no issues.

I will say that the way I got the STs to live was to run a wider seat, fresh guides and A LOT of seat pressure.

 

Would you mind sharing where you got Manleys that fit? Not listed that I could find. Can PM if you prefer?

 

Summit Racing has them listed with an estimated ship date of Monday.

 

Thank you. Noticed those but for some reason Manley doesn't list them as for a VVT head?
Going to give Manley a call Monday as they do not catalog the exhaust in "Extremealloy" which I can assume is there proprietary Inconel?

 

Spoke with Manley today, they only offer the Inconel with 5.96mm and 7mm stems. Seemed to think the 5.96 would not properly fit keepers?
They can turn down the 7mm stems to fit retainers and keepers but ends up being $73 per valve.
So why are the Supertech so long?

 

Last set I used were the “stellite” faced ones. They lasted 6 hours and had signs of wear. Hand delivered then to martin at st and that was the last time I will ever use the intake valves from them.

I built a Frankenstein intake valve and spring setup with bp/4g63/b16/f22 parts. So far so good, but I don’t have enough hours on it for a final stamp of approval.

 

Why not get something good like SI or Ferrera...

 

i tried some SI ones a few years back they didnt last much longer than the supertechs.

Ferrea doesnt have an ots valve for the bp, but a nissan valve with a toyota keeper in a mazda retainer could work so long as you are using a SUB setup and measure spring pressure/shim as needed as the keeper groove is about 1mm higher.

 

I wouldn't put any faith into Summit Racing's estimated dates. I once ordered an exhaust flex pipe and the ship date kept being pushed further out just about weekly. After a few months I cancelled the order and dug one up elsewhere.

 

As far I know ST does not manufacture any of their products. The valves are most likely made by SI.

 

I've never had an issue with their ship dates correlating to when they actually ship and I spend about 10 grand a year with them. They are in Atlanta and if I order parts they have in stock before 8pm, I usually have them the next day

 

The only time I've had issues with Summit like Jesse mentions was a dropship.

 

I've posted severaql times now on the big thread on the valve issue that FM has +1 inconel intakes, I don't know about stds.. This up coming season well be my 4 th one on these intake valves with no rebuilding of the head. I just did a comp. check and leak down on the engine and the comp was 200 across the head and leak down was 1 1/2 to 2 % on all cyl. I used to not get a full season out of my intakes. I don't know why force inducted people are still screwing around with SS intakes.

 

I believe those are ST/SI valves. Intake valves don't usually have issues. Personally I would run stock or SST intakes and 1+ inconel exhaust.

 

https://www.flyinmiata.com/inconel-1...ake-valve.html READ the thread on intake valve problems and you well see this has been talked to death and the high HP people have tried combinations of springs, added shims, different seat cuts and so forth with varying results. These have been in for 3 seasons now without having to be redone with heavy double springs which the SS valves lasted less then a full season with the same springs. The issue is not heat, it is wear on the seat face of the valve from pressure allowing the valve to bounce. Yes they are ST for both.

 

Do you have a link to the thread on intake valves? I wonder how production engines that run 20-30psi of boost last for 10yrs and 150kmi on steel intake valves. Maybe high rate springs with a high seat pressure and a wider seat face.

 

https://www.miataturbo.net/race-prep...ing-out-82462/ You aren't running 20 to 30 psi for any length of time like on a road course track .and you damn sure aren't running around making 30 psi on the streets for any length of time. As you well see it has been discussed to death. I'm just giving a sure fire solution that has been tested on a track car that has the **** driven out of it and they have held up for 3 seasons with not needing to be renewed. If you want to go another way, have at it. As I said all kinds of things have been tried by a lot of people that are very smart. i'm done here as this has been talked to death and I was just posting my results and others have had the same results.