| Author | Message | ||
     Benm2 |
Does anyone have any experience with beryllium copper valve seats in a Buell head? They've got a very high coefficient of thermal conductivity, and I was wondering if anyone has tried them. The theory is that it allows the exhaust valve to stay cooler (but it will transfer more heat to the head) | ||
| Torqd |
Benm2... Nallin has used them....check with him... | ||
| Pammy |
Beryllium, It's not worth the health hazards.  | ||
| Blake |
Ben, The heat will get to the head no matter what, it has to get out somehow. Better conductivity through the seats just means that the same heat flow can be achieved with a lower temperature differential between valve and seat. So if they are available, and if you are having trouble with your valves overheating, then the beryllium-copper might be a good idea. Beryllium-copper is also much much stiffer than the stock seats, which could effect sealing performance. Beryllium-copper is 33% stiffer than even steel. | ||
| Benm2 |
Huh? I'm not sure I understand what you're saying. C172 Beryllium Copper alloy has an elastic modulus of 19.6Mpsi, versus approximately 30Mpsi for carbon steel. Did you mean straight Be? The question was with regards to a few theories: 1. Larger valve seating surfaces (valve-to-seat interface)improve heat transfer of exhaust valve heat to the head, but also impede flow. 2. Exhaust valves get really hot, and that heat may affect the valve guide clearances & sealing characteritics. Also, hot valve can distort and cause other problems. I know that the valve will get hot anyway, but I figured that improving the heat flow away from the valve could improve performance (and maybe reliability) during continuous high-rpm running. If the exhuast valve generally ran cooler, it could also reduce the engine's tendency to "ping" by removing the valve as a potential source of "hotspots". When the heads finally come off my bike, I want to have a plan. This seems like an idea that might have some merit, and I wanted to know if anyone else tried it. Was thinking about thermal barrier coatings on the pistons too... Ben | ||
| Blake |
Ben, I may well be wrong, I was thinking that the BeCu with which I'm familiar had a modulus of 40M psi. Maybe I am confusing BeCu with pure Be. I don't have my reference books in reach. Apparently, Nallin Racing sometimes uses BeCu seats. Give them a call if you are serious about using such exotic parts. My main concern however would be that if your stock engine pings, that is a symptom of the real problem; there is something else amiss that needs rectified. Either it is over-lean (carburetor problem or intake leak), the timing is too advanced, spark plugs are too hot, the VOES is malfunctioning, you have a buildup of carbon in the combustion chamber, the fuel is inferior, or you are lugging the engine. I suggest rigorously attacking the problem rather than the symptom. Can you describe the specific scenario(s) when you notice your engine is pinging? | ||
| Pammy |
You can use thermal barrier coatings on the valve, in the exhaust port, the combustion chamber and the exhaust pipe as well. | ||
| Benm2 |
I saw some heads done with thermal barrier coatings inside the combustion chamber; I wondered (they were pictures) how they blended the coating into the valve seat (coating after machining?). They hadn't done the exhaust port, and I had wondered why not; I figured there was something I didn't know. It seemed to make sense (reducing exhaust heat transfer to an air cooled head seems like a good idea). Blake, the bike "pinged" when it got hot, its previous life was commuting in Philadelphia traffic, and it did it at low rpm. The only reason I want to use CuBe valve seats is 'cuase I think they're neat. I'm an engineer, I can't help myself.  | ||
| Steveshakeshaft |
Benm2- "I'm an engineer, I can't help myself" Keep fixing it till it breaks Ben! LOL! Steve steve_s@ukbeg.com www.ukbeg.com | ||
| Blake |
Okay, were getting closer to understanding your pinging problem. Can you describe specifically what you mean by "low rpm", is that taking off in 1st gear, or accelerating from 3,000 to 4,000 rpm in any gear, rolling open the throttle from 55 mph in high gear...? Also, has the bike always exhibited the pinging at low rpm or did it develop and or worsen with time? Steve, It's half the fun isn't it?  | ||
| Steveshakeshaft |
Blake, your right. But I have to say (yet again) how brilliant it is to be able to Brainstorm with folks from across the whole world on sites like this. Wow! Wish I could've done it in the 70's when I had the 2 str Yamaha's on every horizontal surface. Like Homer Simpson says, "the internet is cool, you can even get it on computers these days". He's right, ofcourse. Steve steve_s@ukbeg.com http://www.ukbeg.com | ||
| Benm2 |
Blake, thanks for the help but you're offering to solve a problem I don't care about anymore. The bike got REALLY hot, sitting in stopped traffic three-lanes wide with an outside temperature of 98 degrees, idling. Miles of clutch-slipping hell, running just off idle, sweating profusely (but still better than car). Just a few disgruntled knocks as the clutch came out for a few feet of movement. The bike pinged cause I abused it. Thought about fitting the X1 fan kit (ugly as it may be) before the bike left streetbike land. Now, its moot. To the engineer, the glass in neither half empty or half full, its improperly designed. | ||
| Blake |
Gotcha. No problemo existo. That's good to know. Heck, fuel injected automobiles do the same thing. | ||
| Flapjack |
Ben with regards to thermal barrier coating cylinder heads it is for sure a good thing. Coating the chamber, valve faces & piston dome can increase performance. Tuning can be more aggressive and more compression may be run because the proper barrier coating will provide resistance to detonation. Coating the intake and exhaust ports with various coatings will also impact performance. A coated chamber,valve face & dome combo reduces the amount of heat escaping during the power stroke which means more energy available to push down on the piston. Thermal barrier coatings woek in several ways: to keep heat in,move heat over the surface to reduce hot spots, reflect heat to shrouded areas, and because it retains less residual heat from combustion it transfers less heat to the incoming charge. These features combined lead increased power. reduced operating temperatures, reduced detonation, and possible increases in fuel economy and reduced emissions. By transferring less heat to the incoming charge detonation is reduced , as pre ignition which is a cause of detonation, is reduced. By allowing the heat of combustion to be more efficiently used, the fuel charge is better combusted allowing more compression. By accelerating the burn rate of fuel mix, throuhg better heat management, less timing is needed in order to have the optimum burn occur at TDC. Coating the ports will help flow and provives additional thermal benefits. Coating the intake port reduces fuel drop out while insulating the incoming charge from heat of the head. Coating the exhaust port with a thermal barrier can improve flow by creating a very slick surface , while reducing the amount of heat transfered to the head from the hot exhaust gasses. In our shop we usually rough in the seats before coating and do our final seat work after the heads are coated. The angles on our seats are bare metal cut on a Serdi. Dyno tests performed by Briggs & Stratton to determine the effects of various weights and volumes of oil in their engines are very interesting. Average HP 5.86, head temp 454f.and oil temp 206f. The head and piston were then coated with a ceramic bases thermal barrier coating and the test rerun. The results: average HP 6.54, head temp 391f, oil temp 168f. Thats a 10% increase in HP with a 14% reduction in cylinder head temp and a 19% reduction in oil temp. | ||
| Benm2 |
Flap, thanks. Dyno results are most useful, aren't they? I was thinking that with finite resources, the best buell race engine should be made to be the most reliable race engine. Keeping the engine cooler seems to be a good thing to try, as I'm guessing it would reduce cylinder distortion & oil breakdown. I thought that CuBe valve seats would help keep the valve/chamber cooler on the exhaust side, and that heads done with both would be "the ultimate". My ultimate 'on paper' engine would include these things plus: 1. N4 cams 2. Solid lifters 3. roller rockers 4. Ti intake valves (stock size), but stronger springs on intake an exh. 5. millenium cylinders 6. ported heads 7. forged pistons, machined to match cyl squish band, 11:1 8. 7000-rpm ignition, single-fire 9. HSR42 10. Buell race exh I'd hope for close to 100hp, but more importantly I'd have an engine that would be slightly lighter, would run cooler, and would have some over-rev (missed shift) durability built in. If I still had money left, I'd spend it making the bike lighter. | ||
| Blake |
Flap, "Dyno tests performed by Briggs & Stratton to determine the effects of various weights and volumes of oil in their engines are very interesting. Average HP 5.86, head temp 454f.and oil temp 206f. The head and piston were then coated with a ceramic based thermal barrier coating and the test rerun. The results: average HP 6.54, head temp 391f, oil temp 168f. Thats a 10% increase in HP with a 14% reduction in cylinder head temp and a 19% reduction in oil temp." I'm confused. Was the oil used the same viscosity and at the same level in both tests? Also, how thick are the coatings on the piston and head surfaces? What affect might that have on compression ratio and thus power? If the coating technology is as wonderful as your dyno results make it sound, why aren't automobile manufacturers using it in their engines. After all, more power means more efficiency, means better fuel mileage, and that is something they are VERY eager to improve is it not? I have more questions but maybe we need a new topic? Blake | ||
| Steveshakeshaft |
I share your scepticism Blake. I've many questions. I asked the UK agents for this stuff (Cam Coat) for information to some questions and got no reply. Doesn't inspire confidence in me. | ||
| Benm2 |
Check the old roadracing world article on the pro thunder buell. It was using thermal coatings on the pistons. The car companies aren't using metal-matrix composite pushrods either, or titanium valves. Car engines are built to be cheap & reliable. | ||
| Blake |
Ben, I think the high compression Pro Thunder bikes use the thermal barrier to protect against melting a piston. Insulating a surface against excessive heat is the legitimate use of thermal barrier coating technology. It is another thing completely to claim a 10% increase in engine efficiency (power output). I don't see that as a legitimate claim wrt thermal barrier coatings. Do you? | ||
| Used_96_s1 |
Huh? I'm not sure I understand what you're saying. C172 Beryllium Copper alloy has an elastic modulus of 19.6Mpsi, versus approximately 30Mpsi for carbon steel. Did you mean straight Be? Rigidity and modulus of elasticity should not be confused. Of course steel has a higher moudulus of elasticity; it is the most elastic substance known to man, that's why it works so well for springs. | ||
| 1320 |
I'm not real up on the subject of coatings but I do know that Nascar vehicles use 2 separate types of coatings on their pistons..1 for the domes and a different 1 for the skirts.. Maybe Bubba can shed some light on this as Don Tilley also uses this approach with all of his race bikes??? | ||
| Firemanjim |
1320,get hold of Flapjack,he has a hi-performance coating business.He did a bunch of stuff to the piston,head,cyl on my son's Derbi for Bonneville. | ||
| Flapjack |
Joe, There are 2 coatings for piston domes. The first is a ceramic based thermal barrier designed for normally asperated engines. The second is a cermet based thermal barrier coating designed to be used on engines runned forced induction,nitrous oxide,hi volumes of fuel,or corrosive fuels such as nitro or alcohol. Both coatings work by drastically reducing heat soak into the piston,reflecting heat back into the chamber thus increasing chamber efficiency. The combustion chamber surface and valve faces should also be coated to gain maximum benefit. The intake port can also be coated with a different coating to help insulate the incoming charge from the heat of the head and aid in fuel suspension. The exhaust port can be coated with another thermal barrier to reduce heat transfer to the head and keep exhaust velocity high. There are a number of coatings that we apply to piston skirts depending on the intended use of the engine. All are variatiations of a permanantly bonded extreme pressure dry film lubricant that attracts oil, reduces friction thus allowing the use of less piston to wall clearance resulitng in less piston rock and better ring seal. Just about every part in the engine can be coated with a specific coating resulting in increased power and or reliability. | ||
| Panic |
"it is the most elastic substance known to man" Perhaps known to man if the man were Andrew Carnegie. However: silicon nitride balls (used in ball bearings) have 50% higher modulus of elasticity than steel. | ||
| Blake |
Ever check the modulus of the best graphite fiber? Only three plus times the modulus of steel. What is the modulus of diamond? |
