Steel pistons...

lcrken said:

Actually, a Commando engine can be made to run quite happily at 12:1 +,
<snippo>
, and run on high octane race gas. Not very practical for our regular street bikes.
Ken

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Yes, running on current pump gas is rather a different proposition.

Heck, it could probably happily run on 18:1 on alcohol, if you could figure out how to squeeze it that much.
But again, running it on the street on pump gas is different...

hobot said:

As no oil jet coolled steel pistons in our sights if ya enjoy the delights of Norton torque of a responsive tuned-set up engine then its likely often lightly detonating in a good way. Online is spare on references but studying Engine Masters and early air coolled engine studies reveals its more common than expected. Dig deeper here.
http://www.google.com/url?sa=t&rct=j&q= ... 9352,d.aWw

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Thanks for the article above. Excellent info.
Confirms my thoughts.
Ta.

texasSlick said:

<snip>
With higher allowable piston temps, higher engine temps can be tolerated, and will result in increased fuel economy

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There is a very finite limit to how much hotter a Commando could be run. ?
Getting the valves beyond too hot is probably not going to last very long.

Performance engines have all sorts of tricks to extra cooling for the valves,
including lots of metal around the valve guides, and oil cooling around the valve guides.
And more of them, to spread the heat load.
Not to mention water cooling.....
All not very applicable to Commandos ?

One of the advances over the years is in the various types of coatings that can be applied. If ceramic can be reliably made to be as effective as the claims, then perhaps the thermal question is a non issue.

Whether that can be made to work in old engine designs, already taken to what are currently thought of as limits, remains to be seen.

Many years ago, someone (big well funded company) built some engines which had pretty much everything inside the combustion area ceramic coated. This worked very well in the CI variant, not so well in the petrol version - to close to detonation too often - but I am reasonably sure it was before the advent of electronic FI.


Pistons run in cylinders - any info on the type of running surface on the piston and/or bore?

Exht valve heat is often the limiting heat detonation factor in air cooled engines and one reason blown Peel retrained the stock size exht for more seat area heat flow vs its heated mass compared to larger valve. Should not matter to Notons big valve that just suck on intake stroke.

The definition of entropy is different depending on whether you are British or American. I was taught that entropy is 'the amount of disorder in the universe'. American and British textbooks on thermodynamics differ by use of a minus sign in different places. I think it is because God-fearing Americans think he created order out of disorder, and the uniform ground state is disorder.

I'd be more impressed with the idea of steel pistons if you could find them in any modern competition engines. Surely if they were an improvement, we would have seen them in F1, Nascar, Motogp, etc. Great for long life, relatively low rpm diesel engines, but not much potential for our Nortons.

Ken

I would think the benefits in a Norton motor would be large.

You could then run a nice short piston with tight clearances.

Yes the diesel engines using them have oil cooling but so do the aluminum pistons in a high output diesel. I suspect you could do without the cooling provisions in a Norton motor if they were tuned similar to a engine with an aluminum piston.

The big problem is the cost of machining billet steel pistons or designing steel forging dies in a Norton size.

We wonder though what is termed 'light' in regard to these pistons.
Diesels often had very heavy pistons, so even in 'light' form they may not be, compared to stock Commando alloy ones ?
The big chunky nature of Commando pistons may mean there is not much gain in steeling them ?

Numbers, we need to see numbers !

acotrel said:

The definition of entropy is different depending on whether you are British or American. I was taught that entropy is 'the amount of disorder in the universe'. American and British textbooks on thermodynamics differ by use of a minus sign in different places. I think it is because God-fearing Americans think he created order out of disorder, and the uniform ground state is disorder.

Click to expand...

A quick google search fails to find any mention of these divergent ways of counting disorder Alan. ?
This seems to be your own personal interpretation ?
As was mentioned previously on the same point when discussed here.

We could go into numbers and details. But we digress, muchly....

lcrken said:

... we would have seen them in F1, Nascar, Motogp, etc.

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No, they all specify AL-based piston materials. Same reason why you don't see CFC or MMC or any other interesting piston material in any of these series.


Tim

* detonation* occurs AFTER spark ignition and is herad as a knock while US-ping/UK-plink is herad on PRE-ignition and is more potentially fast destructive than detonation. So wonder how often Commandos may be running in tolerated detonation yet not destructive pre-ignition especially the hotted up ones given the spurs, Not particularly good long term practice any more than not conserving very soft compound tires but can be so so worth it for a while in the end, In the end we are limited to hydrocarbon fuel which can not take the heat of really efficiently combustion engine. I suppose a steel piston Norton would make a decent low term lawnmower engine if if had a fan blowing over it and limited to 3600 rpm, in british racing green with yellow wheels.

Ceramic miss firing V6 clattering out raw head ports
[videohttps://www.youtube.com/watch?v=sAk5tc_gpmo][/video]

Trouble with cermaics at decent efficient CRs and temps.
Shashank Sakleshpur Nagaraja, Student at SUT Written 30 Aug, 2014
5 upvotes by Quora User, Quora User, Giri Venkatraman, Priyatosh Mitra, (more)
Thanks for A2A. Ceramic cylinders can be used in high temperature applications. However, ceramic is very brittle. We have worked on carbon pistons in ceramic cylinder. The coefficient of friction between these two materials were found to be very less and hence, the mechanical efficiency was high in such a engine. We also tried out the same at higher compression ratio in order to obtain higher thermal efficiency and found that pre-ignition was a major drawback factor above compression ratio of 12.

So, would we expect to see either pre-ignition or detonation in our COMMANDO engines Steve ?
Given octane fuel of the rating they were designed for....

I've driven an iron engine V8, briefly, on low octane fuel - when nothing else was available.
Had to switch it off by putting it in gear against the brakes, the key did nothing....

Commando engine had a fairly advanced combustion chamber for its day,
even if technology and ignition systems (and DOHC and FI) has moved on considerably since then.

i go back to 1940 trucks trackers cars and traveled central america with diesel like gasoline in 58 chevy wagon pulling trailer in desert to Mt conditions plus later ran the snot of my own cars so know the diesel knock and clatter that may blow engine apart or even run away on oil leak fuel no spark needed. Peel will be pinging & Bang prone so snooping some years on risky optimal power states. Pre-Ping or Post-Bang is a sliding scale when might occur but the best power makers will have some of each for some intervals of maximum out put. The common denominator for piston materials to octane is the heat flow and fuel temperature tolerance. I know a way to get one piece light weight steel piston-rod with crank center support not using bearings but may still need oil jets to get away with it long. There is a way to get most of the oil slung out of rod journals to hit piston bottoms on down strokes w/o altering oil system and is common feature in lugging lawn mowers.