Landracing Forum
Tech Information => Technical Discussion => Topic started by: fordboy628 on July 23, 2014, 05:25:13 PM
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To anyone searching this thread,
I've deleted all of my original content on this older thread. Sorry for any inconvenience this may cause you.
:dhorse:
Fordboy
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This looks like it will be an interesting subject. It is nice of you to take the time to type it up.
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I just wish that this was being dealt with a much younger more SUPPLE mind--- :-o I feel a brain stretch coming on---lol
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One of the best books I ever read was Waddell Wilson's book on assembling each of the big three stock car engines. It's hugely dated and only dealt with those three specific engines, but he emphasized over and over the importance of measuring everything several times and checking all clearances before ever doing the final assembly. He also emphasized the fact that it should take a good amount of time to put a good racing engine together. The philosophy works!
Pete
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He also emphasized the fact that it should take a good amount of time to put a good racing engine together. The philosophy works!
Pete
Engines are funny, in that if you're moderately competent, you can usually screw one together and it will likely work.
But there is no "one thing" that makes for a good race engine.
I'm still an amateur at putting together an engine, which makes me inherently slow, but going slow s l o w l y uncovers the problems. This often leads you to taking it apart, which gets you better at putting it back together again.
And then there are the questions that come up that you don't know are questions.
Measuring everything is important, but I've discovered, under Mark's tutelage, that things you wouldn't instinctively measure for a simple re-build of a stock engine are often the critical items that you must measure for a race engine.
The work of others, regardless of their competence, expertise or experience, are often the things that need the closest scrutiny.
Yes, it's time consuming. To do it right, you may have to skip an event - which I learned is a better proposition than doing it wrong and gnashing your teeth all the way home. Seat time is fun, but only in a proper running ride.
Mark's made me a believer in dyno testing - for 2 reasons:
A. You can dial in a tune much easier on an exposed engine in an air conditioned shop than you can bent over under a tarp on the salt in 95 degree heat.
B. It's better to solve the problems at home, where you have all the resources and contacts at your disposal to deal with them, rather than 1600 miles away, where you're at the mercy of a late running UPS truck.
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There are a few things that can be done.
Radius and polish the lower edges of a new set of keepers. This will reduce the amount and magnitude of stress risers.
Check the valve spring tension and replace weak springs. This type of failure can be attributed to valve float. The valve slams onto the seat rather than following the cam and gently closing. This puts a shock load through the valve, springs, keepers, etc.
Calm down with the right foot.
Reduce the number of load cycles. Limit the runs down the track to the minimum needed to do the job.
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Wow! Very well written and lots of little details covered! One thing that wasn't mentioned for the longevity of a race engine is just time it's actually rotating. I'm still with the thinking of going through the lights, push in the clutch and kill the engine . Using the engine for slowing and stopping puts wear and stress on parts that could have been used for MORE passes under power! I see guys do that all the time and don't understand their thinking. Plus if you shut it right off, you can look at the plugs and see what's going on. This is just my opinion...
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Cubic Money, common sense (brad has a good idea), more cubic money.
reapply cubic money as necessary.
am i a smart ass? maybe . . . no offense intended.
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Bike racing can be done at reasonable cost...until you crash.
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Saltrat has definitely "been there". :-D
A quote from the guy that ran the Mercedes DTM operation was that if you had enough money it still wasn't enough!.
If it was cheap everyone would be doing it.
I'm not a designer but a good assembler (I hope) and cleaning before assembly is most important.
I wash the stuff, chase threads, blow out all the holes and just keep going until there is no residue.
Having a good mentor also helps. :-D
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On the subject of busted keepers...
Years ago the valve head seperated from the stem on a Honda engine I built. Others were having the same problem. After-the-fact investigations pointed to annealed valve springs as the culprits. Honda tend to rum hot and their design and metallurgy was not the best at that time. What I learned was to check valve free length, compressed length, and tension at every tear down. This includes checking new springs.
Another thing to look for when a keeper breaks is pack length. Is the valve spring fully compressed, or packed, at any time? This can break a keeper.
Spring harmonics can be a problem. This is when the natural frequency of the spring matches the frequency of the cyclic external loads. Surging can occur through the spring and it creates additional forces on the valve train. The preferred valve spring setup for my engines is a two spring setup with the inner and outer springs wound in different directions. What I am trying to do is have a spring setup where, if there is surge in one spring, there is not in the other.
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A) 4 valve cylinder heads flow pretty well at low lifts, but there are some modest increases that can be gained with careful work.
2) "Dogleg" ports are not the ideal. But you probably don't get to fix that.
d) Small increases of size and % of valve throat diameter can dramatically alter the flow.
z) Concentrate your efforts on the lift range that gives the best gains.
Aren't these statements common knowledge among engine builders and racers in general?
DW
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I'll take a stack of spreadsheets over a box of shiny, unusable parts any day.
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I'll take a stack of spreadsheets over a box of shiny, unusable parts any day.
Shiny? Hell sometimes our parts looked like :-o Scoria
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Mark, what is your opinion on ceramics? The engine is a twin cylinder Triumph with air/oil cooling. This is what I was planning to do and the reasons. Am I correct in my thinking? The exhaust tracts, piston crowns, and combustion chambers will be ceramic coated to reduce the rate of combustion heat transmission to the engine structure. This way, I hope to keep the engine a bit cooler since it has a hard time shedding heat. The intake tracts will be ceramic coated and the intake valves polymer coated to reduce the rate of heat transmission from the engine to the intake charge. By doing this, I hope to maintain intake charge density. I am not sure if anything needs to be done to the exhaust valves.
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One has to weigh the supposed heat transfer benefits versus the cost and worry of possible ceramic chips flying around in the engine. While the notion of ceramic coating to resist heat transfer is attractive intuitively, when one does a heat transfer calculation with and without a necessarily very thin ceramic coating, it turns out that the transfer rate is only minimally affected.
Has anyone ever seen documented test results that show the heat transfer rates are, in fact, significantly reduced?
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In the late 70s I was running a twin turbo 270 GMC in my '32. I had Jahans cast pistons and a poorly designed intake. Which was tough on pistons. I was also working in the tool room in the plasma spray Dept. of a large airline overhaul facility. I sprayed my piston tops with the same ceramic as they were using on the burner cans. Worked well for me. Good forged pistons worked better. But as observed, the ceramic worked well in that circumstance.
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IntObs;
I was under the impression that a significant portion of the ceramic coating advantage was its reflecting of the radiant heat of combustion.
Regards, Neil Tucson, AZ
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What Neil says may have some implications. Will the ceramic coating raise the combustion temps enough to require adjustments to the tune, like higher octane fuel or a couple of degrees of retard on the timing?.
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Hey, Wobbly -
Part of the last iteration of the Grenade included coating the pistons.
Because we notched the piston to accept an exhaust valve that extended deeper into the combustion chamber, and the original piston head thickness was getting a tad thin in that area, my chief concern was to protect the piston from additional heat build up. There were enough other changes made that I can't reasonably say that the piston coating was a contributing factor toward power production, but it did provide some additional peace of mind for me.
In addition to an ever-so-slight increase in CR, and the same fuel for the dyno work in both sets of tests, the total advance timing remained the same, although as I recall, I was able to kick in an additional bit of advance in the midrange.
Granted, we were using 118 octane, and we were not running any boost.
Total timing was 36 degrees advance.
Your mileage may vary, but I'm one of those heretics who believe that durability is a performance factor. :wink:
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Well it is Christmas time again. Time to share some development information as my Christmas gift to everyone.
WARNING: You supply your own brain cooling . . . . . . I recommend a chilled and fermented beverage . . . . . . .
This is a real world example/sample of why: "It's Complicated" AND, why: You need to Test, Test, Test.
This is some development data collected from some sample Subaru EJ25, DOHC, 4 valve per cylinder heads. Some of the data was collected from differing samples, some data was collected from samples modified as described below. I'm going to post the data, graphs and comments, in order sequentially, so you can use the screen zoom feature to examine the data more closely. Try using a zoom % of 200/250% to be able to clearly read the data on the individual pages. I might have to add a second posting to complete all the pages and data, but here goes.
The premise was to document the data, starting with the baseline of a stock cylinder head with stock valves, so that differing performance modifications could be evaluated. Some data sets have varying numbers of samples, as shown below. My own opinion is that more data samples equates to better data averaging, but I ended up using what the client was able to provide. Some data is withheld. Valves were tested to .55" lift to determine the "port limit". The cams used have only .46"/.48" gross lift.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20101%20001_zpsv0my0hmg.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20101%20001_zpsv0my0hmg.jpg.html)
Test 101: Stock head with stock valves. Notice the flow difference on exhaust between the 2 cylinders. On Subarus, one exhaust port is centered between the valves of the cylinder, one is offset, inline with one valve and the other valve's port has a "dogleg".
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20102%20001_zpsf8n2psvr.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20102%20001_zpsf8n2psvr.jpg.html)
Test 102: Different Stock head with 1mm oversize valves, both intake and exhaust. Re-worked valve seat angles. Note the pronounced difference in flow for the "dogleg" port.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20102%20002_zps5iviwoth.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20102%20002_zps5iviwoth.jpg.html)
Comparison data for Test 101 Vs Test 102 with flow differences in cfm and %. The client was disappointed with the results, but it was pretty much what I expected. Some decent gains @ low/mid lifts, peak flow unchanged. Well, the ports were not enlarged, so no improvement in peak flow.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20103%20001_zpsev2ufquj.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20103%20001_zpsev2ufquj.jpg.html)
Test 103: CNC ported head with stock valves. This combination was tested because the client thought that CNC porting would improve the flow without the valve size change.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20103%20002_zpspb8wchhy.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20103%20002_zpspb8wchhy.jpg.html)
The flow data for Test 103.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20103%20003_zps8aijg3t8.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20103%20003_zps8aijg3t8.jpg.html)
Comparison data for Test 101 Vs Test 103 with flow differences in cfm and %. The client was disappointed with the results again, because the flow gains were only small/modest through most of the lift curve. My conclusion was that the stock valves are too small to be effective in the CNC ported head.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20104%20001_zpstmt2eedi.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20104%20001_zpstmt2eedi.jpg.html)
Test 104: CNC ported heads with 1mm oversize aftermarket valves. Re-worked valve seat angles. Note that there are still differences in exhaust flow in the "dogleg" exhaust ports.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20104%20002_zps1kcskcq0.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20104%20002_zps1kcskcq0.jpg.html)
The flow data for Test 104.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20104%20003_zpsridhru9v.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20104%20003_zpsridhru9v.jpg.html)
Comparison data for Test 101 Vs Test 104 with flow differences in cfm and %. The client was now happy with the results, because the flow gains were substantial pretty much throughout the lift curve. My conclusion was that this combination had further potential, particularly on the exhaust side of the CNC ported head.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20105%20001_zpstfjzwaih.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20105%20001_zpstfjzwaih.jpg.html)
Test 105: As for Test 104, BUT, minimum throat diameter increased .014" on intakes, .015" on exhausts. No other changes to CNC ported heads with 1mm oversize aftermarket valves. Note that there are still differences in exhaust flow in the "dogleg" exhaust ports.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20105%20002_zpsx0hqyhe5.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20105%20002_zpsx0hqyhe5.jpg.html)
The flow data for Test 105.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20105%20003_zpswgrinjiv.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20105%20003_zpswgrinjiv.jpg.html)
Comparison data for Test 101 Vs Test 105 with flow differences in cfm and %. The client was now very happy with the results, because the flow gains were substantial throughout the lift curve. At this point I was pretty satisfied as well, although I still think that the intake might be "slightly" too large on throat diameter. Significant double digit gains on exhaust, throughout the lift curve.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20106%20001_zpsoujwei2e.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20106%20001_zpsoujwei2e.jpg.html)
Averaged flow comparison graph between Test 104 and Test 105.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20106%20002_zpsiqlkivpc.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20106%20002_zpsiqlkivpc.jpg.html)
The averaged flow data for the comparison between Test 104 and Test 105.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20107%20001_zpsln8rtmpn.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20107%20001_zpsln8rtmpn.jpg.html)
Averaged flow comparison graph between Tests 101, 104 and 105. So from start to finish.
(http://i1267.photobucket.com/albums/jj549/fordboy628/Subaru%20107%20002_zpspmbvyjwd.jpg) (http://s1267.photobucket.com/user/fordboy628/media/Subaru%20107%20002_zpspmbvyjwd.jpg.html)
Balance of the averaged flow data for the comparison between Tests 101, 104 and 105.
Conclusions:
A) 4 valve cylinder heads flow pretty well at low lifts, but there are some modest increases that can be gained with careful work.
2) "Dogleg" ports are not the ideal. But you probably don't get to fix that.
d) Small increases of size and % of valve throat diameter can dramatically alter the flow.
z) Concentrate your efforts on the lift range that gives the best gains.
So, once again, work carefully, thoroughly AND, Test, Test, Test.
Chris and Bo, once I get some more time, I will modify this post and add some numbers and %'s for valve throat diameters for the various tests. These numbers might be of interest to others as well.
:cheers: :cheers: :cheers:
Fordboy
While we hang onto every word, Chilled and fermented ain't a world wide phenomena. Some LSR wannabeees like the Scotch, Mexican and other concoctions. Forgive me for being "partly' raised by Canadians who termed beer "Beaver Piss". I swear the Hard Tack runs better that the 4.3% fermented stuff. Whoever won a race on Miller Lite. Alky, that's the stuff. :cheers:
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While we hang onto every word, Chilled and fermented ain't a world wide phenomena. Some LSR wannabeees like the Scotch, Mexican and other concoctions. Forgive me for being "partly' raised by Canadians who termed beer "Beaver Plymouth". I swear the Hard Tack runs better that the 4.3% fermented stuff. Whoever won a race on Miller Lite. Alky, that's the stuff. :cheers:
There is a universal sentiment which I embrace -
Stay hydrated. :wink:
:cheers:
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Oh, a basic question. Was the engine named "Grenade" after it was run with the ceramic coatings?
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Oh, a basic question. Was the engine named "Grenade" after it was run with the ceramic coatings?
I named it that long before the first bolt was turned. Gratefully, it never lived up to its namesake! :wink:
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My thoughts were build what ever it was to go just a little bit farther than a 1/4 mile :-D. So I looked to what was needed to be competitive in off shore boat racing and used those parts... Worked pretty good so far.
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Oh, a basic question. Was the engine named "Grenade" after it was run with the ceramic coatings?
I named it that long before the first bolt was turned. Gratefully, it never lived up to its namesake! :wink:
Wasn't there an old drag racing car called "The Jade Grenade"?
Regards, Neil Tucson, AZ
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That name "Calico Coatings"has been mentioned several times when discussing coatings. I will get their advice and send the parts there.
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Neil, It still shows up at the "Cackle Fest" at the California Hot Rod Reunion. They fired it up under the check in area at one of the big motels as a promotion one evening on 100% Nitro. A few of the un-initiated were standing, albeit momentarily, over the headers. You've never seen so many people scatter so fast. Beautiful car and worth seeing.
Doug :cheers: :cheers: :cheers:
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Thanks, Doug. I had not heard of it in years.
Regards, Neil Tucson, AZ
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Wobbly,
I think you would be well served to do a bit more research and fact-finding before just hauling off and sending your parts for coating. In perusing the Calico web site, it appears they only have one application suitable for the combustion chamber, and it is a “metal-ceramic” material. That is, it is aluminum with some ceramic mixed in. Not a whole lot different than your existing aluminum parts and it is dubious that it would restrict heat transfer to any extent.
They show no physical properties for the material nor heat transfer performance. They seem to be a coating shop that deals mostly with anti-friction and anti-corrosion coatings which probably do about what they claim, but insulating coatings don’t seem to be in their repertoire.
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IntObs;
I was under the impression that a significant portion of the ceramic coating advantage was its reflecting of the radiant heat of combustion.
Regards, Neil Tucson, AZ
These guys want to help me with coating. Check them out Neil.
http://td.co.za/
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Thanks, Mike- will do.
Regards, Neil Tucson, AZ
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Mike:
From TD Coating website with regard to their ceramic/thermal materials:
“These coatings can take very high flash temperatures well over 1000°C. Due to the coatings thin nature (25 microns) it is not a solution for efficient sustained thermal insulation..”
Neil:
Some while back you raised the question of reflectivity contributing to possible reduction of heat transfer. I did not ignore your point as this was an aspect I had not considered, and since have done some reading and consulting of knowledgeable individuals. The upshot of this is that yes, a portion of the incident thermal radiation may be reflected, depending on the reflectivity of the material, but practically, with gasses being essentially transparent to thermal radiation, it just gets reflected to the surrounding surfaces over and over until absorbed. Net result is a minimal insulating effect.
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Mike:
From TD Coating website with regard to their ceramic/thermal materials:
“These coatings can take very high flash temperatures well over 1000°C. Due to the coatings thin nature (25 microns) it is not a solution for efficient sustained thermal insulation..”
Neil:
Some while back you raised the question of reflectivity contributing to possible reduction of heat transfer. I did not ignore your point as this was an aspect I had not considered, and since have done some reading and consulting of knowledgeable individuals. The upshot of this is that yes, a portion of the incident thermal radiation may be reflected, depending on the reflectivity of the material, but practically, with gasses being essentially transparent to thermal radiation, it just gets reflected to the surrounding surfaces over and over until absorbed. Net result is a minimal insulating effect.
IO;
Yes, the heat of combustion is reflected off the coating on top of the piston and it is absorbed by the combustion chamber and valve faces. How much of that heat is absorbed is determined by the geometry and emissivity of those surfaces. True- some heat is reflected rather than absorbed but not much. What is reflected back to the piston crown is again reflected efficiently by the coating and the whole cycle repeats at a far lower level until it reaches equilibrium.
If its melting point were not so low, gold would be an ideal heat reflecting coating since its emissivity in the infrared is so low. That's why most spacecraft are wrapped in gold coated Mylar foil to reflect solar radiation.
The point is that the heat reflectance of the coating reduces the temperature of the piston crown compared to an uncoated piston.
Regards, Neil Tucson, AZ
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In his 1976 book "The Chevrolet Racing engine", Bill Jenkins had this comment: "The last procedure (after bead blasting the dome- my addition) is an application of Sperex VHT white paint to the dome surface followed by a 8-10 hour heat bake with infrared lamps. This is, more or less, a shield to provide faster heat buildup when the car is leaving the line. On the dynamometer we haven't found any power increase from this technique after the heat has stabilized. We know that an engine which as been assembled with bright , shiny, new combustion chambers requires a different "tune up" setting until the chambers have become coated with a fine carbon layer. The VHT paint acts similar to a thin carbon layer and helps promote carbon build up. Without using the paint it takes 6-10 hard passes before we can get back to our race tune-up. By using the paint we can go straight from the shop to the strip with a brand new motor, fire the engine, and hit the first pass with our race tune-up. The carbon buildup , incidentally, is very important in a drag engine. It acts as a head dam or absorption layer inside the chamber and on the head of the piston. During operation it reaches glowing-hot temperatures and assists heat buildup in the chambers during initial full throttle application- quickening response in the first few , ultra-critical feet of the race. "
There is some more but the above covers the topic here.
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Mike:
From TD Coating website with regard to their ceramic/thermal materials:
“These coatings can take very high flash temperatures well over 1000°C. Due to the coatings thin nature (25 microns) it is not a solution for efficient sustained thermal insulation..”
Neil:
Some while back you raised the question of reflectivity contributing to possible reduction of heat transfer. I did not ignore your point as this was an aspect I had not considered, and since have done some reading and consulting of knowledgeable individuals. The upshot of this is that yes, a portion of the incident thermal radiation may be reflected, depending on the reflectivity of the material, but practically, with gasses being essentially transparent to thermal radiation, it just gets reflected to the surrounding surfaces over and over until absorbed. Net result is a minimal insulating effect.
IO;
Yes, the heat of combustion is reflected off the coating on top of the piston and it is absorbed by the combustion chamber and valve faces. How much of that heat is absorbed is determined by the geometry and emissivity of those surfaces. True- some heat is reflected rather than absorbed but not much. What is reflected back to the piston crown is again reflected efficiently by the coating and the whole cycle repeats at a far lower level until it reaches equilibrium.
If its melting point were not so low, gold would be an ideal heat reflecting coating since its emissivity in the infrared is so low. That's why most spacecraft are wrapped in gold coated Mylar foil to reflect solar radiation.
The point is that the heat reflectance of the coating reduces the temperature of the piston crown compared to an uncoated piston.
Regards, Neil Tucson, AZ
What's your take on the combustion chamber material ie cast iron vs Aluminum?. Thanks. :cheers:
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Thanks for your insight. I think I'll be OK. :cheers:
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Should just add, aluminum carries away more heat so it can solve some detonation problems. But usually engine builders respond to this with even more compression... so... you're back where you started.
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Right now I figured out my piston demand at 28 inches per crank degree using PipeMax. I know the cam lift per degree and have flows at 28 inches. Now I am trying to figure out if the flow past the valves is equal to piston demand throughout the intake cycle. Somehow I need to factor lag into these calks. It is being done by hand and it is driving me nuts. Paying $99 to get software to do this is a bargain. Old Wobbles put in his order.
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:-D Yeah, people,----- can't wait to start me learnin un stuff..... :mrgreen:
Really hope there are another 48 thrifty people out there!
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The head is being flow tested and the machinist is trying to get that last little bit of flow. He give me charts of flows at 28 inches vs valve lift for the intake and exhaust. It looks like I also need "throttle cfm @1.5 inches Hg" and "Reference Bore Diameter - inch" according to the Horsepower Chain book. I do not have the program, yet. Is there more info than these two added items that I need from the flow testing?
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This weekend I will open the program and figure out exactly what they need. The download came in on today's e-mails.