Exhaust Valves to consider

[leet]

Do MNGSX a favor and keep your bullshit arguments out of HIS thread.

You want to discuss valves? Fine. Keep the insults out of this forum, merely point out WHY someone is incorrect and provide proof.

We ALL know burldude has some rather 'crazy' ideas by now. None of us are going to change his mind (obviously).

There is NO sense getting a proper discussion locked.

 

[98spydert]

Do MNGSX a favor and keep your bullshit arguments out of HIS thread.

You want to discuss valves? Fine. Keep the insults out of this forum, merely point out WHY someone is incorrect and provide proof.

We ALL know burldude has some rather 'crazy' ideas by now. None of us are going to change his mind (obviously).

There is NO sense getting a proper discussion locked.

So you continue to fuel it?

You want to discuss valves? Fine. ..., merely point out WHY someone is incorrect and provide proof.

Did your post have anything to do with ^^^ What makes you so special, let the mods do their jobs. The report button is there for future "problems" and there's even a box where you can type your complaint. Enjoy

 

[leet]

Excuse me?

I fuel nothing, I'm merely trying to get things back on track.

I merely figured people might be mature enough to calm themselves down without having to get moderators involved.

I guess I was wrong.

 

[Mirage2LTurbo]

Excuse me?

I fuel nothing, I'm merely trying to get things back on track.

I merely figured people might be mature enough to calm themselves down without having to get moderators involved.

I guess I was wrong.

Next time it's some other n00b or someone asking for help, and burldude replies with some other brilliant idea of his, I'll handle myself more appropriatly.

I think I speak for a lot of people (atleast the ones I know) when I say we are tired of people like him, both on and off the boards.

I'm done with this line of posting.

I don't see any advantages to go with Sodium filled valves, I've seen them used on some OEM motors, but never seen any proven results with them. My stainless steel valves work, but I only got them because that's all I knew at the time I had the head built. I'd be interested to see some more talk about this Na stuff

 

[silverbulletAWD]

I'm running SS valves right now to. They're definately holding up well to my abuse. I also bought them at a time when I thought they were the best but now I know a bit more and one of my concerns is reducing parisitic loss. I've never weighed a SS valve against a stocker but I would dare to bet they are a bit heavier. Multiply that by 16 and it could become substantial. I realize sacrifices must be made but if sodium filled valves are now a feasible option it's time someone answers my standing question. Will a sodium-filled valve disipate heat better than or equal to a SS valve can resist it? If this proves true than I'm in because I believe there is some weight to be saved. This winter I will build a new head and if no one knows the answer then I'll find out myself what these things will hold up to.

As far as Titanium goes, I had no idea it would make a poor valve material I thought alot of big time race engines ran them. I know NASCAR does (Which really doesn't say alot to me). Are they only good for NA apps.? Could someone please prove this to me? Possibly by supplying some kind of MSDS form that displays a melting point or something?

Andy

 

[Defiant]

it's time someone answers my standing question. Will a sodium-filled valve disipate heat better than or equal to a SS valve can resist it?

It's not a matter of dissipation, it's one of transferrence. Exhaust valves are mostly cooled by conducting heat out through the valve seat at the sealing face (some by the incoming intake charge, which is the primary cooler for the intake valves), and through the oil to the guide from the stem. Sodium-filled transfer more out of the head by shaking the molten sodium up from the face of the valve to the root of the stem at the back of the face. Stainless will endure more heat and hold it as a poor conductor, sodium-filled will transfer more away and run cooler. Look at the pictures around here of the glowing turbo manifolds, and guess what color your stainless valves are running.

There's some things you just don't want to think about as the car's cruising along at 4K or so. And then think about a Formula One or racing motorcycle motor at 18K. It's a miracle that any of this stuff works.

 

[gixrman]

How about HPCoatings?
www.HPCoatings.com

www.performancecoatings.com has pricing

www.ferrea.com/valvestech.php has good tech info

 

[silverbulletAWD]

It's not a matter of dissipation, it's one of transferrence. Exhaust valves are mostly cooled by conducting heat out through the valve seat at the sealing face (some by the incoming intake charge, which is the primary cooler for the intake valves), and through the oil to the guide from the stem. Sodium-filled transfer more out of the head by shaking the molten sodium up from the face of the valve to the root of the stem at the back of the face. Stainless will endure more heat and hold it as a poor conductor, sodium-filled will transfer more away and run cooler. Look at the pictures around here of the glowing turbo manifolds, and guess what color your stainless valves are running.

There's some things you just don't want to think about as the car's cruising along at 4K or so. And then think about a Formula One or racing motorcycle motor at 18K. It's a miracle that any of this stuff works.

Not that it really even matters..., but:

dis.si.pate - 1a : to break up and drive off (as a crowd) b : to cause to spread out or spead thin to the point of vanishing c : to lose (as heat or electricity) irrecoverably

I think you're right though, transfer is probably a better word.

But you still haven't answered my question. You've only explained what I already knew. I would like to know which valve is better. Or at least if sodium-filled is equivilant too SS. Because if it is than I will opt for the sufficient valve that also weighs less. Thanks.

Andy

 

[leet]

Possibly by supplying some kind of MSDS form that displays a melting point or something?

Andy

Titanium's melting point is 1800C, or 3272F.

 

[silverbulletAWD]

Wow, that's pretty high. Thanks.

OK, now, do you know it's density as opposed to the stainless used in the actual high quality valves? I would assume higher considering how hard it is but then again what would make it even more advantageous to the high dollar race motors? It must net a lighter valve or better heat transfer to be worth tripling the price spent. Or are there other properties that influence heat transfer that I'm not thinking of?

Andy

 

[Defiant]

But you still haven't answered my question. You've only explained what I already knew. I would like to know which valve is better.

Well, "better" carries with it a "when?" I'm sure that ounce-for-ounce, stainless valves will be stronger, if only because they aren't hollow. But protecting the valve from damage is the job of the cam's acceleration and deceleration ramps, and I'll wager that apart from being walloped by piston crowns during timing failure DSMs just don't much break valves. I'd call the sodium-filled "better" for their lighter weight and cooler running. And not just because I really liked my Alfa Duetto.
And I'm sure someone else can give a reasoned counterpoint to why stainless is "better".

 

[FireyIce01]

Well, "better" carries with it a "when?" I'm sure that ounce-for-ounce, stainless valves will be stronger, if only because they aren't hollow. But protecting the valve from damage is the job of the cam's acceleration and deceleration ramps, and I'll wager that apart from being walloped by piston crowns during timing failure DSMs just don't much break valves. I'd call the sodium-filled "better" for their lighter weight and cooler running. And not just because I really liked my Alfa Duetto.
And I'm sure someone else can give a reasoned counterpoint to why stainless is "better".

Well, this is just a completely random thought, but aluminum has a high rate of heat transfer and is fairly light... has anybody ever thought to make an aluminum valve? I know they couldn't stand up to the heat of the exhaust on their own, but for intake they're light and strong... anybody?

 

[Defiant]

Aluminum starts to go plastic at a bit over 400°. You'd never get the heads to stay on the stems.

 

[FireyIce01]

Aluminum starts to go plastic at a bit over 400°. You'd never get the heads to stay on the stems.

Then why does an aluminum head work?

 

[-red97rum-]

Then why does an aluminum head work?

I'd say because there is a lot more material in an aluminum head for the heat to "spread to" (dissipate) than a single valve. Then as the heat spreads throughout the head, the heat trasfers to coolant via coolant passages, makes it's way to the radiator..... and so on.

-Dustin

 

[silverbulletAWD]

Defiant, I think I'm with you on this one. The main concern I have is melting a valve in a unplanned and extra lean situation. Running 30+psi things can get ugly very quick so I'm just slightly concerned about the sodium-filled valves melting on me when I really need them to stay as a solid. I guess I'm just going to try them out on the new head and if they melt down in a reasonable situation I'll come back here and give everyone fair warning.

I think the problem we have here is that this option just become available so no one knows what these valves are good for. For so long everyone just ran stainless and quit there accepting the inherent heat transfer and weight issues. Now we have sodium fills at a very reasonable price and even though they've been around for almost half a century hi-perf. turbo engines and there demands have not. These were a big thing w/ V8's but what was the % ratio of those who were NA? Will they take the heat? I'm thinking, and hoping yes.

As for the aluminum valves, hahaha no.

Andy

 

[leet]

Wow, that's pretty high. Thanks.

OK, now, do you know it's density as opposed to the stainless used in the actual high quality valves? I would assume higher considering how hard it is but then again what would make it even more advantageous to the high dollar race motors? It must net a lighter valve or better heat transfer to be worth tripling the price spent. Or are there other properties that influence heat transfer that I'm not thinking of?

Andy

From what I can find, Stainless is barely more efficient when it comes to heat transfer.

Stainless also weighs roughly double what Titanium does.

.28~ pounds for 1 cubic inch of stainless
.162 for 1 cubic inch of Ti

 

[burldude]

Titanium is ,according to one study, the ninth most abundant metal in the earths crust . I have also heard that it is the second so who is to know . The cost comes from manufacturing .

 

[leet]

Hmm, alright.

I stand corrected

 

[91TSiGuy]

First of all, with titanium, I can share my experience of the titanium intake valves on Hondas CRF450 motocross bikes. Many of the guys have experience problems within less than one season, myself less than 2 because of little use, but the valves on these engines have been failing. The face on the valve which seals against the valve seat eventually began to indent causing almost no sealing and resulted in backfiring through the intake. This is on a 4 stroke motor, like ours, but of course it's being reved to 10k+ rpm. Now of course these are strictly racing bikes, and maintanence should be done regularly, but who really wants to replace intake valves every season? My point though is that althrough Nascar and other teams use titanium valves on their vehicles, you can be damn well sure that they replace them almost every race. Put ti valves on a DSM, and you're just asking for more unreliability.

Stock valves I feel are junk and should be replaced during your next head job. Freak accident or not, but this is what happend when one valve snapped on my last motor. The timing belt didn't jump, and only that cylinder had valve damages. Pieces of piston did manage to get stuck under other valves as well as pass through the exhaust destroying the turbine wheel.

http://www.personal.psu.edu/users/b/t/btb139/images/mycar/deadmotor/headprob2.JPG
http://www.personal.psu.edu/users/b/t/btb139/images/mycar/deadmotor/pistonprob1.JPG
http://www.personal.psu.edu/users/b/t/btb139/images/mycar/deadmotor/inspectcylindernicks.JPG

After that, I too feel the same way about wanting solid strong valves. I don't care about their weight, just so long as they don't destroy another built motor. You can save some valvetrain weight with ti retainers if one is that anal about it. Besides, 99% of you won't notice the difference in weight, or even be at the point where that is what is holding you back from breaking into the 9's or 8's.

 

[burldude]

Just for curiosity what material where you using for valve seats on these motocross bikes ?

Also how much area was making contact with the valve seat ? What about maximum revs ? Do motocross bikes have notoriously high exhaust temps ? I personally have seen titanium valves come out of a Nascar car . They look brand new when they come out with no signs of deformation and absolutly no sings of damage to seat area or gaulling on the stem . They hit 10 grand time after time . You can still read the writing on the valve after a race . Indenting is caused by bouncing ,stiffer springs would control that along with a helper spring to control the frequency .

So these are motocross bikes hitting 10,000 rpms + for the better part of the day (no a racing season) and this is being compared to a Dsm ? Thank you for sharing the info, I will go with a wider seat to help dissapate the heat . My head is on the way, I am going to hog this thing out so much

 

[91TSiGuy]

The valve seats I presume are stainless, although am not positive. Only the intake valves on those bikes were titanium. The exhaust are steel and have had no problems. Part of the reason the valves were indenting at the seat is due to high closing ramp of the cam, as well as the titanium content of that valve. (Bouncing would almost definitely result in piston to valve contact in these motors and at high rpm's so I don't know where you came up with that theory) Yamaha uses titanium valves on their bikes, however run a dohc design with 3 intakes rather than Honda's 2, and a slightly less agressive cam. One difference in those valves too is that they have less titanium content, making them more of a ti-alloy. The valve to seat contact area has been minimized to get the most out of the port size, so this area is less that what is found on our heads.

My point wasn't to compare motorcycle engines to car engines but rather materials used in the valves. Plus this thread is asking about exhaust valves specifically. As for still seeing the writing on the valves used in Nascar cars, that just shows how much use they are put through before being pulled. That and the fact they're using much higher quality gas than we get at the pumps.

The only way I would use a titanium valve would be if they were coated, providing a harder surface. Other than that, I don't see it being worth the cost or hassle.

 

[pinknuggit]

its not really the material that has an affect on valve face pitting, but rather the seat pressure.
Aggresive camshaft lobes with steep dropoff and high pressure springs will cause any valve to pit and seat to warp. There comes a point where you have to compromise between aggressive camshaft lobes with high lift and short duration (forced induction profile)or high pressure springs. Too much spring pressure with too much lift will definately destroy any valve face and seat, no matter what material.

oh, and someone earlier mentioned fords mercury filled 391 exhaust valves. When running hard, the exhaust valve stem will get too hot and destroy the valve guide. I've had to replace the guides in every single 391 head i've ever built.