Cooling improvements

[dickie]

Yes, I see what you mean mickyork. It would be tricky to get air to circulate around the lower parts the barrel with vertical fins though. You could design some really elaborate arrangement with some spiralling etc as someone else suggested.

I'd struggle to achieve that in my garage with some thin plate and pop rivets though

What you suggest definitely has merit but unfortunately for most of us, we're not in the position to pursue these kind of things; Ron Moss, Richard Taylor etc have shown that it can be done though.

All that said, the couple of people who's work I've plagiarised have put their overly tuned 50 year old utilitarian 'peds through some pretty severe testing using just these cowling enhancements.

[Triffid]

What are people's thoughts on coating the cylinder and head with black paint of the type table for bbq's? I've still got some Hermetite Bike Pot Black in my cellar specifically for bike engines. On the tin it says it contains 'added graphite for cooler running'.

[Warkton Tornado No.1]

This thread is an interesting one as it recognises that we can attempt to make DIY improvements to our machines. Nonetheless, we shouldn't lose sight of the fact that the OEM concept apparently still does achieve some measure of cooling, specifically in the instance of the twin cylinder engines.

The S1 to S3 single cylinder cowling is only a close fit on the fan side as it reaches the head, presumably speeding up the velocity of the forced air in that area. That said, the original remit was for cooling a cast iron cylinder (poor heat transmission) as well as the alloy head (much better heat shedding)

The two stroke engine does use the cylinder head as a heat sink, but many of us do not take advantage of that principal by having a practicable squish. However, the cylinder is hottest around the exhaust port area. Current Group Four racers scoop air onto the hottest side of the cylinder but also have cylinder heads with vertical fins. That system works well as there are no obstructions to the throughput of air, as with the toolbox/air filter box in place. They also use Avgas, which runs cooler than petrol, the trade-off being less power.

I imagine that in a scenario where I was building a really powerful, yet civilised air cooled engine with little compromise in terms of cash & ideas, then scooping air would be a serious consideration augmented by a thermostatically controlled fan of some kind pulling air over the top end whilst sat in traffic etc. The hot air would then be routed out toward the back, or through the dummy GP louvres(!)

All 'ducting' would be in alloy, glass fibre or Kevlar.

Dream on.....

[Bilko]

Great thread and a blimmin good read.

[Fast n Furious]

What are people's thoughts on coating the cylinder and head with black paint of the type table for bbq's? I've still got some Hermetite Bike Pot Black in my cellar specifically for bike engines. On the tin it says it contains 'added graphite for cooler running'.

Technically, yes. A matt black finish would be best. By how much is difficult to gauge. Suffice as to say, doing so will not make it worse.

What if the cooling part of our cylinders and heads looked like this?
Just need a 3D aluminium printer.

Ideal heat sink.jpg

[Bilko]

Still on cooling, but has anyone tried a finned exhaust clamp, like these?

I think it was Jarv from Norwich, who spoke about these years ago.



If I thought they would help and there was enough space I'd try one.

[ULC Soulagent]

Wonder if it’s a take on the flying Kettles exhaust collar, although not sure if it was was aesthetic reason or had a purpose since it was an water cooled engine

[vegansydney]

What are people's thoughts on coating the cylinder and head with black paint of the type table for bbq's? I've still got some Hermetite Bike Pot Black in my cellar specifically for bike engines. On the tin it says it contains 'added graphite for cooler running'.

I've been trying to convince my ceramic / powdercoater to coat a cylinder with Cerakote heat dissipating black for over 3 years. I'm curious to see if it would have any real world effect on temperatures. Although he regularly does them on HD motorcycle cylinders, he believes that fins on a Lambretta cylinders are too close together to get adequate coverage.

[coaster]

Wonder if it’s a take on the flying Kettles exhaust collar, although not sure if it was was aesthetic reason or had a purpose since it was an water cooled engine

Standard fittment to pretty much all British bikes in the 60's. Would make access to the flange studs a bit awkward on a lambretta

[coaster]

One thing that hasnt been mentioned in terms of air flow through the cowlings is that its normal practice to have the air intake in an area of high pressure and the outlet in an area of lower pressure. I have no idea whats going on pressure wise on a Lambretta traveling at speed but have often wondered of the splash plate might play a psrt in creating a low pressure zone around the bottom of the cylinder housing and thus aid air being sucked out as well as forced in? Maybe, maybe not, maybe there wasnt much science involved

[dickie]

maybe there wasnt much science involved

This bit, I think. Really hard to model and well beyond my capabilities, but you certianly can create a high pressure zone at the inlet by using a scoop as F&F has done. I think I'll copy this too.

I just love a bit of plagiarism, I do.

[Warkton Tornado No.1]

Any viable suggestions to cooling improvements are welcome, but the necessity can often be due to an inadequate tailpipe diameter. IMHO, aiding cooling is a logical step & something Some of us will endeavour to improve/augment, but there is often a 'conflict of interests' if the exhaust is nor, erm, exhausting well enough

Larger tailpipes, or bleeds, tend to result in sacrificing low down torque, but the current trend of box exhausts with 'pipes less than 25 mm bore on a 200+ 'developed' engine is going to cause heat build-up & consequent premature range.

[MickYork]

Hmmm, possibly.....but aren't the RM Clubmans renowned for torque yet have probably the largest tailpipe ?

[dickie]

Hmmm, possibly.....but aren't the RM Clubmans renowned for torque yet have probably the largest tailpipe ?

Yes, but I think they lose out to bgm etc below about 5000ish.

I've got an empty (gutted) bgm on my piston ported 175, but I'm building a reed tuned rt230 with rm clubman for the reason that wt1 states.

[Warkton Tornado No.1]

Out of the current batch of mass produced 'clubman' exhausts, it is worth considering just why some require supplementary mufflers. My understanding is that Gori, Ancillotti & some AF's have them because their tailpipes are not so restrictive.

A smaller tailpipe may well increase torque but it is also an easier (cheaper) way for the noise to be limited. That is definitely also going to cause heat build-up.

In many circumstances, such as a local run in convoy or blasting around town, an engine may not suffer. The problems will arise when that same engine is subject to a long hard slog, two up with luggage & the rider plods along in top (however many gears are fitted!) oblivious to the function of the engine speed fan & it's capability.

Then, when problems arise, as they are most likely bound to, it will be a case of 'dodgy fuel' & not 'operator error'

Anyway, it is no desire of mine to detract from the worthwhile discussion concerning better top end cooling & hope that can continue

[MickYork]

Another thought to stick in the mix.....with higher rev's you'll get more air circulating (fan going quicker), so if two engines are running at the same speed would the shorter geared engine run cooler than the taller one ?

One problem we have is that temp' gauges are inconsistent between different scooters. Sensors are placed in different positions which means it's hard to say if one scooter is running hotter than another, regardless of what the gauge reads.

[johnnyjarvis]

How about a flanged flexible hose. Thinking of fitting one behind the louvres on my toolbox door, i could also fit one to my air scoop. Run the hose down the front of my tank ( Diablo ) and position the hose to direct the air were it would most benefit.

[gizmo]

I bought a few items from Steve Richards aka Streetweasle and the results where a drop of 20* on my CHT gauge. Also there was no change in temp from my EGT even when powering up hills

Is this what Casa have now done with there new cooling fan?
I like this idea.
Cheers Shane.

Just having a flick through old posts in my dinner break and out of curiosity. Any updates on these ideas making any significant improvements. Anyone with a casa cooler find it beneficial for the outlay