Help!! My Intake Valves Keep Wearing Out!
04-02-2018, 11:29 PM
#223
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I'm running way more than that and rev to 8400. The last set that came out of the motor had 2 seasons on them and looked brand new. Prior to that....I was lucky to get 9 or 10 events out of a set.
The Miata bucket has more surface are than a small block Chevy V8 lifter and they run over 150psi on the seat. You aren't going to hurt the bucket or the cam by running 100-120 PSI on the seat. You just need to make sure you aren't in coil bind and that you have retainer to valve stem clearance.
Every single time we went up in seat pressure, the valves lived longer and the motor made more power.
I have a set of custom Pacaloy springs from PAC, they have made all the difference in the world in my valve-train longevity.
The idea that you need to run light spring pressures to avoid "resistance" is just flat false.
The Miata bucket has more surface are than a small block Chevy V8 lifter and they run over 150psi on the seat. You aren't going to hurt the bucket or the cam by running 100-120 PSI on the seat. You just need to make sure you aren't in coil bind and that you have retainer to valve stem clearance.
Every single time we went up in seat pressure, the valves lived longer and the motor made more power.
I have a set of custom Pacaloy springs from PAC, they have made all the difference in the world in my valve-train longevity.
The idea that you need to run light spring pressures to avoid "resistance" is just flat false.
Last edited by TNTUBA; 04-02-2018 at 11:43 PM.
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04-03-2018, 11:15 AM
#226
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Pictures of the failure mode are earlier in this thread here:
https://www.miataturbo.net/race-prep...2/#post1194012
https://www.miataturbo.net/race-prep...2/#post1194012
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04-03-2018, 12:29 PM
#228
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Pictures of the failure mode are earlier in this thread here:
https://www.miataturbo.net/race-prep...2/#post1194012
https://www.miataturbo.net/race-prep...2/#post1194012
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04-03-2018, 12:33 PM
#229
I'm running way more than that and rev to 8400. The last set that came out of the motor had 2 seasons on them and looked brand new. Prior to that....I was lucky to get 9 or 10 events out of a set.
The Miata bucket has more surface are than a small block Chevy V8 lifter and they run over 150psi on the seat. You aren't going to hurt the bucket or the cam by running 100-120 PSI on the seat. You just need to make sure you aren't in coil bind and that you have retainer to valve stem clearance.
Every single time we went up in seat pressure, the valves lived longer and the motor made more power.
I have a set of custom Pacaloy springs from PAC, they have made all the difference in the world in my valve-train longevity.
The idea that you need to run light spring pressures to avoid "resistance" is just flat false.
The Miata bucket has more surface are than a small block Chevy V8 lifter and they run over 150psi on the seat. You aren't going to hurt the bucket or the cam by running 100-120 PSI on the seat. You just need to make sure you aren't in coil bind and that you have retainer to valve stem clearance.
Every single time we went up in seat pressure, the valves lived longer and the motor made more power.
I have a set of custom Pacaloy springs from PAC, they have made all the difference in the world in my valve-train longevity.
The idea that you need to run light spring pressures to avoid "resistance" is just flat false.
I think the reluctance to increase pressure stems from their past experience running lower pressures in 4v motors. To your point it won’t really hurt going a bit over target. Going under clearly hurts durability. Both you and I run unique bump sticks so all bets are off anyway. I am running ST heavy doubles with 2 shims under intake. I forget actual pressure but from what I recall it was mid 80’s. Based on your comments I’ll target even higher next time around.
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04-13-2018, 11:00 PM
#230
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So the thought that high valve spring pressure is good is probably true in the turbo world. You need to think about what is happening. Most think with a long duration high lift cam big spring pressures are needed. Not true. I run 45 lbs on the seat on a .500" lift cam with 260 degree duration at .050"lift. Why the low pressure is because the ramp up is very gradual compared to even stock cams. Stock cams slam the valve open and closed. In a Turbo the valve spring is trying to control large intake charge pressure. In a NA those do not exist. And you run large overlap. If you don't get the valve closed positively it will bounce on the seat, in either NA or FI. So you turbo guys just have to live with the HP loss of big vale spring numbers. My last 1.6 SCCA FP engine only had slightly higher spring rates than stock and revved to 8300 rpm on stock lifters. I have never had a valve face problem with low spring pressures and lots of duration. You just need to look at the work you at doing.
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12-19-2018, 01:19 AM
#231
Same old story
motor went low comp so I checked the lash and gone.
this go around new guides all around, st heavy doubles on the intake side only with the new harder stellite treatment. they probably lasted 6 hours at 10psi and 8100rpm.
the exhaust side look good with the light doubles
I’m fed up with this at this point. Looking at using oem rb26 valves and more spring shims unless you guys have something better in mind.
this go around new guides all around, st heavy doubles on the intake side only with the new harder stellite treatment. they probably lasted 6 hours at 10psi and 8100rpm.
the exhaust side look good with the light doubles
I’m fed up with this at this point. Looking at using oem rb26 valves and more spring shims unless you guys have something better in mind.
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12-21-2018, 01:00 AM
#232
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Well that sucks big time Twibs. I guess you need to try the high spring pressure setup as after talking to Jeremy yesterday I found out that ST doesn't think the inconel ones are justified and that the new stainless treated ones are the answer. Jeremy said he had not received enough feed back yet to know if the new treated ones are good. Twib__ please give Jeremy a call and give him your feed back. According to Jeremy ST dropped the inconel intakes without asking his opinion, it seems they thought the inconels were to expensive, 80 bucks more on a race motor, yeah right, and the new stainless ones should solve the problem, doesn't look like it's going too.
That's to bad because after talking to Jeremy I went out and did a compression and leak down test today. This is the second season on the iconels , thats roughly 18 tracks days of hard abuse in a fast car at 17 psi, 1:39.5 at Laguna on Rivals, so the car is driven hard. Anyway the compression was 200 on all 4 cyl., with really good leakdown figures, same as when built and at the end of last season. I didn't pull the valve cover this year as last winter I pulled the head as part of the deal with FM and the lash was as it was set and the valve seat faces looked perfect, no signs of cupping, so with the test results being so good this winter, I think it hasn't changed. I used to go about 6 track days and some would have zero lash. I have ST's heavy doubles and the stock single shim as I had with the stainless valves, Sounds like upping the pressure may solve this issue but I would rather run lighter pressure if possible. I am running a msm intake cam and you guys with your wild cams I wonder how many shims you can install before you coil bind, I would rather get the springs Eric has had success with. Anyway lets hope Jeremy can get ST to make the inconels again.
That's to bad because after talking to Jeremy I went out and did a compression and leak down test today. This is the second season on the iconels , thats roughly 18 tracks days of hard abuse in a fast car at 17 psi, 1:39.5 at Laguna on Rivals, so the car is driven hard. Anyway the compression was 200 on all 4 cyl., with really good leakdown figures, same as when built and at the end of last season. I didn't pull the valve cover this year as last winter I pulled the head as part of the deal with FM and the lash was as it was set and the valve seat faces looked perfect, no signs of cupping, so with the test results being so good this winter, I think it hasn't changed. I used to go about 6 track days and some would have zero lash. I have ST's heavy doubles and the stock single shim as I had with the stainless valves, Sounds like upping the pressure may solve this issue but I would rather run lighter pressure if possible. I am running a msm intake cam and you guys with your wild cams I wonder how many shims you can install before you coil bind, I would rather get the springs Eric has had success with. Anyway lets hope Jeremy can get ST to make the inconels again.
Last edited by jmann; 12-21-2018 at 12:30 PM.
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12-21-2018, 01:28 AM
#233
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I also debunk the idea that higher valve spring pressure loses power. If you turn my cams you'll get massive resistance as one of the lifters runs up a lobe but then all that energy gets returned on the down slope. I moved from Eibach springs to dual ST heavies and picked up power. I believe the heavier springs better control valve bounce on long duration cams, and actually I'd go as far as saying there is less wear to the cam because the valves are far better controlled.
Twibs, you shouldn't be having issues with the valve seats. I used to run oem RB26 intakes and I bashed them into the valve seats at only 8300 rpm. The valves were all rounded out. I rebuilt the engine with ST RB26 valves and upgraded to ST heavies and the valve train seems happy right up to 9000rpm now. Of coarse I'm not running boost, but my cam ramps are nasty.
Twibs, you shouldn't be having issues with the valve seats. I used to run oem RB26 intakes and I bashed them into the valve seats at only 8300 rpm. The valves were all rounded out. I rebuilt the engine with ST RB26 valves and upgraded to ST heavies and the valve train seems happy right up to 9000rpm now. Of coarse I'm not running boost, but my cam ramps are nasty.
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12-21-2018, 01:54 AM
#234
Martin at Supertech has been pretty useless he couldn’t confirm if the valves I had were stellite faced or not by the batch stamping even though I bought them 5 months after the switch to stellite. I’m pretty much done with them for valvetrain components.
I’d reallllly rather not deal with fm if at all possible.
Currently waiting for some 300zx valves to show up next week for test fitting and if it looks good I’ll be dropping in ferrea valves or oem Nissan 300zx valves and plan on custom springs with something like 100-110lb seat pressure.
300zx valves are 103.1mm long and 34mm at the head. So it should be a very close fit depending on the keeper groove location.
I’d reallllly rather not deal with fm if at all possible.
Currently waiting for some 300zx valves to show up next week for test fitting and if it looks good I’ll be dropping in ferrea valves or oem Nissan 300zx valves and plan on custom springs with something like 100-110lb seat pressure.
300zx valves are 103.1mm long and 34mm at the head. So it should be a very close fit depending on the keeper groove location.
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12-21-2018, 03:45 AM
#235
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I'm pretty sure all of the Nissan valve locks / retainers are the same taper angle as Mazdas so as long as you run the corresponding locks they will fit in the BP retainers. They can sit a bit higher or lower in the retainer though so you may need to add or remove some shims to keep the same spring tension.
I have run both OEM and Supertech RB26 intakes and I'm fitting SR20DE intakes and exhausts to my current head I'm building. The Nissan SR20DE valves are great because they are 2.15mm larger on the intakes and 1.65 larger on the exhausts plus you can generally get them for free if you ask around. Make sure you get the SR20DE not SR20DET exhausts because the turbo valves have a 7mm stem because they are sodium filled. Still might be worth running them on a turbo engine and getting the guides reamed to suit.
Also Nissan run the same size stems at 5.97mm for intakes and 5.94mm for exhaust valves. So they generally slide in to our valve guides nicely without any work. Also with the OEM Nissan valves, you can machine the valve lock grove in the valve itself to fit either the earlier or later BP lock shape. You can not machine the nitrided Supertech valves though, I've tried.
I have run both OEM and Supertech RB26 intakes and I'm fitting SR20DE intakes and exhausts to my current head I'm building. The Nissan SR20DE valves are great because they are 2.15mm larger on the intakes and 1.65 larger on the exhausts plus you can generally get them for free if you ask around. Make sure you get the SR20DE not SR20DET exhausts because the turbo valves have a 7mm stem because they are sodium filled. Still might be worth running them on a turbo engine and getting the guides reamed to suit.
Also Nissan run the same size stems at 5.97mm for intakes and 5.94mm for exhaust valves. So they generally slide in to our valve guides nicely without any work. Also with the OEM Nissan valves, you can machine the valve lock grove in the valve itself to fit either the earlier or later BP lock shape. You can not machine the nitrided Supertech valves though, I've tried.
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12-21-2018, 08:01 PM
#239
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Twibs I just talked to Willie at ST, that's who I dealt with a couple years ago when they made 8 valves to test. He said that Martin was talking to someone recently and he thought that it was probably you. He said they requested you to send them a valve so they can check the date code as I guess some got shipped out as stellite that weren't and they well stand good if that is the case. I asked why they quit making the inconel ones and he said because the stellite is harder then even inconel. So if you want, contact Willie, he said he would be glad to help you. He said they can still make the inconel ones but that they think the stellite if better . Keep us informed please as to what happens.
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