Exhast valves

[xctasy]

I need better quality exhast valves to cope with extreme lean conditions on my early log head. I've got the option of both American (0.3100" +/- 0.0005") and Australian (0.3440"+/-0.0005") valve guide sizes, and think I might have to go to the bigger Aussie valve guide size to remove exhast valve heat. I'm looking at the stock 1.388 sizes, or maybee the 144 intake or Ferra 1.5" exhast

I've done some significant study, and some suggestions I've been given are to go to sodium cooled exhast valves. I'm a little worried, as I've seen some big damage when these items have been dropped.

 

[rbohm]

8) yes sodium cooled exhaust valves can cause a lot of damage if they break. but usually if you stay with quality manufacturers, you mitigate the large majority of the issues of breakage. manley products come to mind. but remember that even the best can have a minor flaw that goes unnoticed and can cause problems. larger stems and stainless steel construction do well even in some extreme circumstances.

 

[CNC-Dude]

If your exhaust temps are that extreme, you might need to look at going with an Inconel material for you valve. Thats what the material of choice is for the Top Fuel and nitro burning engines use, also for other extreme turbo and supercharger builds as well.

 

[bubba22349]

I used the sodium exhausts in my 427 FE late 1960's had no trouble but I have also seen some damage done by them in the big truck FE's a time or two (high milage ones). My thoughts are that there would less as the vale stem got bigger, of corse then the valves weight goes up too, I should think that quality should be much better now days also. Good luck

 

[xctasy]

I'd like info on the US Ferra and Crower sodium filled exhast valves as a replacement for unleaded fuel exhast vlaves under extreme lean or high temperature condtions on the rich scale. Its a dimension verses operation temperature issue. As others have said, for the price of the Sodiums I can get Ferrea Inconel valves; they are good for 3000 degree F EGTs, but when a sodium filled valve is compared with the same dimensional valve without sodium, a heat difference of 80 to 150 degree is reported at valve head circle as well as at the critical point where the valve stem and head radius intersects.

I'm keen to run sodium cooled now, because I haven't ever thought the need untill I looked at lean running torchdowns and some durability issues that most hi performance engine makers eliminate by limiting boost via turbo exhast size or sofening some tunning parameter so the car defualts to a normal 12.5 to 15.2:1 air fuel ratio. They do happen, and it used to be common Merceades Benz, Austin Rover and Lotus practice for there hiperforamnce engines to meet the 300 hour WOT tests.

I use other types of non Ford valves in my non cross flow FAZER engines, as they are only turbo or supercharged engines that are EEC5 EFI which copy the stock Aussie Ford F6 Typhoon fuel delivery specifications, and aren't under lean running conditions. But I've noticed that Skyline GTR rb26dett's, SIT WRX Imprezia's and anything Japnes and turbo charged will run conventional iron guides, or full bronze, but not K lined. And that the clearances are loose, with 0.2755" guides running in at 0.004"

I've done a lot of research into lean running these engines, and when subject to avaition syle leans outs, very reliable passenger car engines like Subarus no longer like lean mixtures due to the small valve guide diameter. Adding sodium cooling should really be done with much bigger valve guide diamaters so the sodium exhast valves never snap, only bend. Those I've talked to had said its more than likely a sodium cooled valve will take out a piston if they do disintergrate...whereas a dropped conventional valve will not often be a promise that the pistons and bores will be scrap.

The FE/FT sodium cooled valves look close to some of the old Aussie 250 exhast valves in terms of valve guide size, and I'm interested in going up a guide size, perhaps to LA Mopar, and getting the best security I can. I'm talking about running an engine in a very psychotic manner, at once either very lean, or then running a huge amount of water injection under very rich conditions.

 

[CNC-Dude]

I've done some significant study, and some suggestions I've been given are to go to sodium cooled exhast valves. I'm a little worried, as I've seen some big damage when these items have been dropped.

That is a good likelyhood if used for any kind of applications where high RPM and/or high valve spring pressure are used. I have cut open some sodium filled valves before, and on a stem as thin as you will be running, the wall thickness is only .060" or less. So you don't have any strength there to compensate for much abuse. I would stick with an Inconel valve and be able to sleep at night.

 

[xctasy]

I've done some significant study, and some suggestions I've been given are to go to sodium cooled exhast valves. I'm a little worried, as I've seen some big damage when these items have been dropped.

That is a good likelyhood if used for any kind of applications where high RPM and/or high valve spring pressure are used. I have cut open some sodium filled valves before, and on a stem as thin as you will be running, the wall thickness is only .060" or less. So you don't have any strength there to compensate for much abuse. I would stick with an Inconel valve and be able to sleep at night.

I need sodium cooled exhast valves since I'll be running leaner than 22:1 air fuel at part throttle, and I run water injection, which never reduces the exhast valve temperature because it liberates hydrogen when squirted into the air fuel mix. The exhast valve becomes a detonation point, and I have to reduce its temperature. So a stock or really good solid valve of whatever material in non sodium won't buy my wife a new hat.

Lets see, stock US log heads are 5/16 or 0.3100", where as stock non 221/260 SBF, and all Cleveland, Lima and Chevy Big Blocks run at 25 thou under 11/32. Then the big guns (and Aussie Hemi Valiant Sixes) run 11/32, and if someone has riffle drilled them to 0.22375 to get enough sodium in them with a 6o thou wall thickness, then that's the same as a smaller than 7 mm valve guide.

So I guess, aside from the International Trucks 0.433 monsters, the thickest valve guides are 3/8" nominal 0.3725" Chrysler ones. I could go up to 1/2" if I use rated plane valves.13/32 used to be a common Lycomming size, then they shot up to 7/16 and then half an inch to avoid valve failure due to high EGT.

Doing a calculation taking the center void of the hollow part out of just a 11/32 sodium valve

11/32 is 0.092788 sq in
take off 0.039312 sq in
Effective guide size is 0.053476 sq in, or 0.26096, or a 6.63 mm valve guide, not good enough for a single exhaust valve in a hard-charging Ford 200 or 250.

CNC dude, I get your point. If its four valve per cylinder, and Nissan GTR, not a problem, but that lack of stem root area becomes a failure root where the valve head and stem interplay on bigger valves like ours.

If I used a Mopar valve cut down, but with a 0.3725" guide and riffle drilled it for 60 thou wall clearance, I'd get 0.051061 off the 0.10896, or a 0.27154", or 6.894 mm valve. Still a bit too small

A later 289 cubic inch aviation, non ground power unit 0-290 exhaust valve, or a cut down Lycomming 1.75" sodium filled 0-320 valve has a 0.50" stem diameter. If it had 60 thou wall thickness, I'd have an effective
area of 0.19631-0.11339, which would be a 0.3250" guide, better than stock.

In 7/16 form, they can be cut down to about 1.40 to 1.45", with an effective diameter which might be 0.15030-0.07916, or 0.30099", 7.645mm. That might be pretty good compared to other options. The same issues exist with the sodium filled exhaust valves in aviation, with most guys wanting to replace there 0-290 and 0-320 exhaust valves with nuclear bomb proof 56 to 60 International truck AS2215 austentic steel, 40 rockwell 1.812" 0.433" guide items, if they could get away with it.

The sodium form an aircraft will probably be where I head. If I run a forged piston, sodium exhaust valve with a thick bronze guide to conduct the heat away and a nice cylinder sleeve to really pull the heat away from the engine, I should be able to run higher compression and run it leaner without a destructive torch-down. Nimonic and Inconel sodium cooled exhaust valve are around too.

As for damage, even with the best exhaust valves in the business, they still drop heads. This is page 3 of Nick from Calagary, his 0-540 J1A5D made it home without its lolly on the stick in one cylinder...

See http://maulepilots.org/forums/viewtopic ... c&start=30

In some very rare cases the heads just fly out the exhaust, but more often, they get reintroduced into the intake manifold. Alfa Romeos never seam to loose there sodium valves, but for Lancia Stratos and Ferrari pilots, embedding into the cylinders is much more common until 1982, when everything went quattrovale and solid stainless exhausts.

 

[xctasy]

Since I don't want to use Inconel since the spot temperature is higher than the sodium cooled items, I've found some nice 0.3909" diameter sodium filled Daimler Benz exhaust valves ex the fabled M110 series twin cam 280 E W123/280SE W126, but they are only a nominal 1.347", but they are 5.177" long, and able to take 1.900" installed heights and 0.550 thou lifts at the valve.

Problem is at 1.570 for a plain intake and 1.347 for an exhaust, they are kind small, but they have a huge valve guide, and look like they could take a huge amount of heat. They are smaller than the stock 200 early engines valve sizes.

A common fix to the awful low length stock valves which restrict valve movement to 0.490 at best is the longer 1.78/1.50 253/308 Holden valve, which is 5.16" tall, and this allows a proper valve spring. There are no sodium options with this.

There are plenty of 1.75 O290/O320 Lycoming air plane valves around that can be cut down off the back of the Cesna 2000+ hour airplane TBO service schedules, they have nice big valve guides.
Reputedly, some 67 318 Mopar truck engines got sodium exhaust valves in 0.375" sizes.

International SV series engines in 392 cubic inch Trucks too had 427 FE style 1.734"sodium exhausts, 5.479" long, 0.4145" stem diameter.

http://www.mgexp.com/phorum/read.php?40,94274

See http://www.binderplanet.com/forums/show ... hp?t=62039

All the 1962 to 1967 262 engines in things such as f600 Ford trucks got 1.925/1.6" valves with 3/8 (0.375") valves, with a good 5.11" valve length to take some lift, but nothing sodium.

The FE 427 has the 1.733" sodium exhaust valve in 5.43" length. The iron log heads have something of a problem with exhaust valve seat to water jacket space, so if I have to use a stellite valve insert, it doesn't leave much space. The FE design team did the 144-170 small six design, and it shares a lot of the rocker gear and combustion parameters, despite the size difference. When the big block Chev Rat came out, the 427FE and 429 Lima revisions started to use common valve retainers and rocker gear, so Chevy Big block springs, keepers and retainers retrofit

Since our needs also included a higher-rpm range than the stock IH valve springs could handle, Wilson Bros. did some checking and found that springs and retainers designed for a big-block Chevy would work just fine. These provided a seat pressure of 95 psi and an open pressure of 280 psi. See http://www.off-road.com/trucks-4x4/392- ... 19285.html

The search continues. 1.88 and 1.45" will fit, but below .500" lift flow drops off over 1.74" valve size on closed chamber 200 log heads, and above 1.65", the available chamber size goes up. and compression ratio drops when you have to de-shroud the chamber walls for better gas-flow. If you don't do that, gas-flow drops.