ESE's works engine tuner

**Bren_chch** · 2nd March 2009, 19:50

Originally Posted by TZ350

We think this could be a real problem and we are looking at gold plating the copper combustion chamber to try and retain its reflective properties.
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farken hard out!!! u coming to the BOB this year, i wanna see/hear this mad machine!

**koba** · 2nd March 2009, 20:37

Originally Posted by TZ350

We think this could be a real problem and we are looking at gold plating the copper combustion chamber to try and retain its reflective properties.
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On old fella I know who knows alot about these things said look at silver too.

**TZ350** · 2nd March 2009, 21:07

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Thomas points out that ceramic coating the exhaust port tract has the same sort of problems as wraping the header pipe. It allows over heating of the fresh charge drawn into the pipe then this overheated mixture is pushed back into the cylinder by the returning pressure wave in the pipe. The over heated mixture in the combustion chamber then limits performance..

We have been looking at making a copper insert that fits in the exhaust port which draws the heat out to its own set of fins thereby reducing the cooling load on the barrel and heat transfer into the head. But converting the idea into a practical solution is proving difficult.

All I want is to be able to improve the (air) cooling so I can lean the mixture a little and recover some power, is that to much to ask from the

God of Speed?
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**TZ350** · 2nd March 2009, 21:14

Originally Posted by Bren_chch

farken hard out!!! u coming to the BOB this year, i wanna see/hear this mad machine!

We would love too! I have to get work to find an excuse for me to be in the South Island then. So I can tow the bikes down and the others can fly. When is the BoB this year?

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**TZ350** · 2nd March 2009, 21:16

Originally Posted by koba

On old fella I know who knows alot about these things said look at silver too.

Silver might be more pratical from a cost point of view, but wouldn't it tarnish with the heat?

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**TZ350** · 2nd March 2009, 21:23

Originally Posted by koba

On old fella I know who knows alot about these things said look at silver too.

Silver might be more pratical from a cost point of view, but wouldn't it tarnish with the heat?

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**speedpro** · 2nd March 2009, 22:01

What about aluminium. It polishes nicely and doesn't seem to tarnish in a 2-stroke chamber and it should be a pretty good price.

**TZ350** · 2nd March 2009, 22:09

Originally Posted by speedpro

What about aluminium. It polishes nicely and doesn't seem to tarnish in a 2-stroke chamber and it should be a pretty good price.

Could this be why the factory uses aluminium?

this hotting up business is real hard to do!

**SS90** · 2nd March 2009, 23:16

hmmmmmmmmm

**SS90** · 2nd March 2009, 23:32

Sorry to pull back on the topic a bit, but I was looking at the photo's of the seizure marks on your piston, and would like to suggest that there is a good chance that the cam grind is not too far wrong for your air cooled engine. True, a Piston designed for a Liquid cooled engine, has less Cam grind (less of an egg shape), due to the fact that the thrust face of the piston is subject to less heat expansion, but, in my experience, you only have to pay particular attention to the piston to bore clearance.

What is the clearance you use when honing the new cylinder to size?

What is interesting to note, is that (from what you describe, and what is evident in the picture), there are 4 even seizure marks that would correspond with the pressure points on the side of the cylinder, where the studs run.

I believe they are 8mm studs.

Due to the fact that the engine is in a high state of tune, as you have clearly established, extreme amounts of heat are thereby generated...... The original expansion amount of the cylinder (particularly in regards to height) is well and truly exceeded.

Therefore, the 8mm bolts, in my opinion, are causing the cylinder to "squash", as the studs, do not expand the same amount as the cylinder.

Basically, when hot, the cylinder goes "hour glass shape".

This, coupled with, possibly, incorrect piston clearance would cause this problem.

One solution would be to use thinner studs (7mm are hard to come by, but are available), or, as the Japanese did in some bigger 4 stroke engines, use "waisted studs", where the studs tapers in in the middle, allowing for more elastisity of the studs..........

If I am right, then this (more clearance, thinner studs) would decrease the temperature of the engine somewhat.

There are literally hundreds of thousands of modified high powered air cooled two stroke engines in use today using pistons designed for liquid cooled engines that have no seizure problems.

Also, a piston that seizes because of the incorrect cam grind, does not seize on all 4 stud points, it seizes on the thrust face (because if the cam grind was too small to suit the heat of the air cooled cylinder, the first part to touch would be the thrust face, not the stud pressure points.......... (think about it)...... That's because of heat... the very thing you are battling!)

Remember that a cast iron lined cylinder is 30% more efficient at displacing heat than a cast iron one, and a Nigusil (or similar) coated cast aluminum cylinder is 30% more again than that (approximately), and there are plenty of examples of cast iron cylinders 125-133cc that can be modified to put out more than 22HP (marginally though), for example Mallossi Small frame Vespa Cylinders (although they are force fed air via a fan and shroud) Can be modified (alot) to put out 23 HP or so, but they do not suffer from excessive heat related power fading, due to the fact that the guys doing this have VERY carefully designed exhaust systems, that maintain a more constant combustion chamber temperature, (and yes, the fan), also a big consideration is again, compression ratio..... TO FINISH FIRST, FIRST YOU MUST FINISH, and with an air cooled motor, there is always going to be a compromise in relation to cooling vs power.

Also, what is your primary compression ratio?

I see you are familiar with Gordon Jennings writings.... he points out (and you have touched on this subject much earlier on) that the suggested (and this is backed up by the Japanese engineer Fujio Nagao) that primary compression ratio's over 1.5:1 give "little to no advantage", and also, the pumping losses are increased!

I realise that you have lowered the ratio with things like the chamfering of the intake side of the crank web, but have you measured the ratio at any time? It could be worthwhile at some stage.

Maybe it is actually lower that 1.5:1

If this is that case, increasing it would improve overall efficiency, and therefore lower overall temperature.

A more efficient engine is simply a cooler engine.

Although, it should also be noted that Gordon Jennings points out.....

" deficiency in air delivery due to a crankcase volume too great for a given engine speed is fairly well compensated by properly tuned intake and exhaust pipes"

I seriously would look at the design of the exhaust as another option to lower overall engine temperature as well.

**koba** · 3rd March 2009, 06:10

Not sure on the logic behind the silver, but the guy who said it tends to be right on weird shit I don't understand.

Onthe stud subject Volkswagen switched from 8mm studs to 7 or maybe even 6mm studs when they upped the flow of the heads and they stopped the cases cracking from un-even expansion.

**F5 Dave** · 3rd March 2009, 08:40

Well i think irrespective of the plating on the inside you should definitely gold plate the outside of the head.

YoYo, boys in the hood check out my bling bling [& so on & so forth] A few medallions worn outside your leathers, well, you could be the badest Ho talkin Homie at the track. Word.