ESE's works engine tuner

[senso]

Regarding the plated iron liners, I can also confirm that, I have one CRM cylinder that is chrome plated, its much harder than the iron that composes the cylinder, and every machine shop that I take it to bore it out want to charge me twice, because has they say the chrome chews up the boring bars they use for the iron liners.

Never rode with that cylinder, but it should have a bit less drag than a iron liner.

[peewee]

smitty im not worried much about heat transfer or lack there of, with a plated iron bore. for drag racing with methanol i dont think it will matter much. my reason for plating the bore is so i can always use standard readily available pistons. plus when you have a ton of hours devoted to porting the cylinders you want to keep it intact as long as possible.

[husaberg]

Did you consider silver? Great heat conductor, much better than copper. You know the old saying "Speed costs money; how fast do you want to go? "

.

Ages and ages ago I posted that the works Nortons actually had silver alloy heads.......
Yes I realise your post was in mirth........

[Ocean1]

Ocean, even though my iron sleeve is to be shrink-fitted in place, don't you think a plating of heat-conductive material on the O.D. of the iron sleeve would help move those BTUs along? One advantage might be that if you had to press a sleeve OUT, a copper of silver plated surface would help enough that you could slightly increase the tightness of the shrink fit . . ???

I remember sleeving an alloy cylinder many years ago and deciding a taper fit was a good idea. By the time I'd worked out the maximum shrink the cylinder would take without exceeding the materials' elastic limit I needed a new cylinder. It worked OK, but on striping it much later I found the liner wasn't anywhere near as tight as it had been, presumably the many heat cycles since had some effect in relieving some of the stress in the alloy...

I'm not now in a position where I've got the sort of constraints that would require me to use an iron liner in an alloy cylinder for competition, so it's not a problem that keeps me awake at nights. If you're considering plating the outside of a liner for thermal continuity then why not just use a silver thermal paste? If it's a water cooled application and you've got room maybe make it a wet liner?

[seattle smitty]

The idea of the taper being that the upper half of the sleeve and cylinder are running hotter and expand more, right? I was thinking of that too. But why not try to draw the heat out of the aluminum (upper cylinder) faster so that it's not trying to expand itself away from the sleeve? Okay, there's a water jacket; okay, we look at pumps and flow-rates and radiator capacity and such. But it evidently is not enough to just put water in and take it out. The coldest water would seem to need to be DIRECTED at the hottest regions, so that it is moving fast and scrubbing off steam bubbles as they form. And if cooling fins work on air-cooled engines by increasing the radiating surface area of the hot parts, some form of fins INside a watercooled engine, doubling or tripling the surface area of the metal over and around the exhaust port ought to do some good in engines prone to problems there. Similarly, as TeeZee and I have been telling each other in a PM, those cylinder head inserts he has shown us in photos have room for at least one good cooling fin, that might nearly double the area exposed to coolant. Then maybe you could run a hotter plug, a little less likely to foul . . . .

And if we find we have over-cooled an engine, just "tip the can" (add some nitro)!!

[Ocean1]

The idea of the taper being that the upper half of the sleeve and cylinder are running hotter and expand more, right?

The idea of the taper was a slightly misguided attempt to get a tighter fit than I thought I'd achieve from a simple interference fit on a parallel liner. Misguided because I thought I could get enough pressure to begin to get some actual mechanical bonding between the two surfaces. I didn't. Turns out the limit was the strength of the cylinder, which you could exceed either way.

I did get there with just a couple of ton on the press, though.

[TZ350]

Well todays attempt to ride the first EFI 2T to compete in and finish an actual race did not turn out so well. The bike ran better and stayed strong all day but the throttle response was not good enough to race. Such a small area on the graph, such a large effect on the track.



The technical high light of the day was seeing this very cleaver idea for adding some heat sinking to the crank cases. On the clutch side the copper extends into the clutch/crank case area where it is bathed in oil. A very neat and effective way to add some extra cooling.

Another great day of racing in the sunshine at Mt Wgtn. After round 4 I suggested that a "sub-30 second lap on a 50cc bike is looking distinctly possible". And at his next serious attempt, Nathanael Diprose has done it. I must extend my congratulations to Nathanael for his 29.831-second lap in F5 race 1 today. I'd be even happier if I wasn't the poor sod in second place watching him disappear into the distance.

Mylaps: http://www.mylaps.com/en/events/1108317

Tim

[Frits Overmars]

Makers of small aircraft cylinders tend to be the experts at plating now, though there's a difference in that their cylinder liners are alloy steel."

Define small aircraft cylinders, Smitty. I was able to contribute a bit to the design of the 6,5 cc (.40 cubic inch to you) MB40 engines that have ruled F3D pylon racing for the past 15 years or so. My first concern was to get rid of those ridiculous sleeves altogether and switch to hard-chromed alu cylinders.
It worked; they just don 't wear out at all. And the pistons are happy too; finally they have got a relatively cool surface to lean against.

Frits has said he doesn't like iron sleeves

I never said that; I said that I hate any form of sleeve: iron, steel, alu, unobtainium, whatever.

Ocean has pointed out my concern, the thermal barrier between sleeve and cylinder. My dumb-welder understanding is that this junction would have some resistance to heat transfer even if you pressed an aluminum sleeve into a tight-fitting aluminum cylinder; in other words, the discontinuity itself is a big issue, not just the lower heat transfer through cast iron.

You've got that absolutely right, Smitty.

don't you think a plating of heat-conductive material on the O.D. of the iron sleeve would help move those BTUs along?

Do you think adding another layer of whatever between sleeve and cylinder will improve conduction? Only if it's a good conductor and the contact between the sleeve and the cylinder was imperfect to begin with. But then you will probably have that same problem with your added layer.

The high light of the day was seeing this very cleaver idea for adding some heat from the exhaust pipe to the crank cases.

Fixed that for ye .

Here is a picture of my little German friend (116 kg) winning a 50 cc aircooled race by keeping his 'porcupine' engine cool while the competition looses one-third of their power during the race. It is amazing how even the cooling fins on the ignition cover get extremely hot. Just don't touch the fins on the clutch cover.

[Frits Overmars]

as TeeZee and I have been telling each other in a PM, those cylinder head inserts he has shown us in photos have room for at least one good cooling fin

Or two. Front and side views of a double-finned insert and cover:

And if we find we have over-cooled an engine...

You won't. You can't.

[seattle smitty]

(For some reason, my computer won't bring up that photo, just endlessly indicates it is loading).

By small aircraft engine makers I meant outfits like Lycoming, though I do not diminish anything that can be learned from model airplane racing (quite a few older outboard racers have flown in control-line speed and combat meets, including Jim Hallum who engineered that Anzani outboard I've referred here; Jim's planes had pulse jets and went 150mph in the early Fifties)(at 80, Jim has returned to flying some of his slower ones).

However, a current top-level outboard racer and engineer/machinist who does lots of paid engine-building and boat-building for others, in talking about today's Rossi and VRP methanol-burning outboards states that the Nikasil plating in these engines is only good for 15-20 heats . . . and our heats are very short sprints, say about 5 miles per heat, average. He suggests that serious racers keep spare cylinders, and cycle them through the re-plating service on a schedule that gets you fresh cylinders in time for the Nationals race. Add to that Jan Thiel's observation that his re-plated cylinders were never as fast as before.

[husaberg]

(For some reason, my computer won't bring up that photo, just endlessly indicates it is loading).

.

Right click on the inmage then save it to your computer. Then open it out of your computer file, Since i went to Windows 8 point whatever, I can't bring up PNG files off a message board , no idea why either. I guess its a Browser setting issue.

[F5 Dave]

Yeah I must try Firefox again

[wobbly]

Re the question about plating a cast liner - i have done this on several builds all for the same reason, to keep the same piston size
for the life of the engine.
The first was done by Millenium, the others by NZ Cylinders, all have worked out just fine,with a couple of silly seizures and no damage to the bore at all.

The other issue for comment is cylinder head cooling.
Mr Thiel gave us one really "cool" pointer about keeping the plug body temp under control, by allowing water close to the threads.
But in theoretical terms we dont want to cool the chamber surface, as this increases the temp delta, and simply pulls heat out of the expanding
combustion charge - throwing away Hp.
So what we dont want to do is add fins to the back side of the chamber and allow the water to cool that area more.
Without simply giving away a really successful secret, what we do want to cool as effectively as possible is the squish band area, to keep the end gases away from
the killer deto heat range.
TeeZee does it by having a copper fin connected directly to the squish in the head, so think about applying Jans plug body water cooling idea to the squish area only.
Then add another method for keeping heat in the combustion charge and ceramic coat the inside of the chamber only.

[Frits Overmars]

a current top-level outboard racer and engineer/machinist who does lots of paid engine-building and boat-building for others, in talking about today's Rossi and VRP methanol-burning outboards states that the Nikasil plating in these engines is only good for 15-20 heats . . . and our heats are very short sprints, say about 5 miles per heat.

The nikasil plating that I know is also good for 15 heats, a heat being three days of practising followed by a Grand Prix, maybe 600 km per weekend, 15 times a year.
Not on cool-running methanol but on hot-burning petrol. Were do you boat people get your nikasiling done, Smitty?

[Haufen]

The other issue for comment is cylinder head cooling.
Mr Thiel gave us one really "cool" pointer about keeping the plug body temp under control, by allowing water close to the threads.
But in theoretical terms we dont want to cool the chamber surface, as this increases the temp delta, and simply pulls heat out of the expanding
combustion charge - throwing away Hp.
So what we dont want to do is add fins to the back side of the chamber and allow the water to cool that area more.
Without simply giving away a really successful secret, what we do want to cool as effectively as possible is the squish band area, to keep the end gases away from
the killer deto heat range.
TeeZee does it by having a copper fin connected directly to the squish in the head, so think about applying Jans plug body water cooling idea to the squish area only.
Then add another method for keeping heat in the combustion charge and ceramic coat the inside of the chamber only.

Thanks for the tip, wob. What's the minimum wall thickness for a dome you'd recommend in the plug and squish area?