Fans /airflow / techies wanted

[soullad]

Just another angle ........why not mount a fan, say computer sized, to force air directly over the exhaust cowl exit area. The power for which could be fed from say the nearby brake switch permanent live?
It would make sense to use the large cowl retaining bolt as the fixing for this bracket and actually design / make this a cooling "fin" itself. This bolt must be a hot spot on the cylinder cowl so be a great place to help additionally cool. It would be protected by the splash plate from the elements and just constantly run whenever the engine runs.
RE. the venturi effect - its worth noting that the diameter of any ducting used should ideally progressively decrease in size along its length, to a critical opening size - so speeding up air flow, increasing its effect and therefore cooling etc - note size of inglenook fireplaces and chimney tops. Also steam engines used this system to great effect to draw air in thru the firebox.

I also like the idea of a large duct thats bolted from below the leggies that forms a tube / cone around the frame tube and forces air over the exhaust region. Heh surely its all gotta help? Apologies if im talking to the converted or teaching folk to suck eggs

[RICSPEED]

Also steam engines used this system to great effect to draw air in thru the firebox.

i said i wasn't going to mention steam engines

[156 D]

I thought i would just answer Dan`s post in reply to my own on the previous page.......If your just talking racing ...then this will not apply as every racer should know what he is doing with his ignition set up and so this event would not arise... but it can happen to all those road going scoots if perhaps the ignition has slipped back for some reason perhaps not quite on topic but nevertheless one reason to have proper efficient cooling or ducting.......

Below is a quote from another forum about Retarded Ignition.....it is a well known fact that this condition causes overheating of the engine... especially the exhaust near to the head...the reason for this is that apart from the combustion being late and after TDC the flame front extends out into the exhaust port and will severely heat the manifold and due to conduction the heat will spread both ways into the components of the engine and further along the exhaust or silencer....the combustion time is a lot slower with a retarded ignition thus allowing the heat build up....it is a very serious engine situation with dire consequences if not noticed and corrected............

Quote: "Back to Discussion Summary Page
Discussion Title: Effects of retarded ignition timing

eswaroop 2004-04-08 19:55:00

Effects of retarded ignition timing

Hi,

Can somebody throw light on the effects of retarded ignition timing? First of all I am assuming retarded means for example, changing from 12 BTDC to 10 BTDC..

What are the symptoms?

Thanks
es
--------------------------------------------------------------------------------
eswaroop 2004-04-10 17:14:00
any idea what is happening?
Here is what I know till date. The car runs okay for the first 15
minutes or so and then the performance and mileage drop drastically.
It seems to limp around even if I floor the pedal.


The ignition timing advance is 10 degrees during idle ( must be
between 11 and 13 according to the honda diagnostics unit).

The spark plugs are blackened (sooty, so rich mixture)

The o2 sensor is shifting between .1 and .89 volts, but quickly enough
or not - I dont know..

The car revs smoothly, too smoothly than it ever did earlier in fact
(maybe sign of retarded timing)

I think the exhaust is heating up a lot more than usual (again sign of
retarded timing?) :flaming:

Drives okay for around first 15 minutes, then acceleration and
response declines drastically as I drive longer, mileage also suffers.

What could be wrong??

thanks," end Quote

156 D

[Markus]

I run a full sized Piaggio Skipper flywheel on an machined down Lambetta flywheel - in in combination with modified crowlings of course. I belive the volume of air that flowl arround the barrel has much increased compared with an AF flywheel. You can feel it if you hold you hand infront of the air oputlet of the cylinder crowlings. I don't know if the engenine ancutally runs cooler, but I hope so.

Maybe I'll check the maximum surface temperatures with thermachrom pens on a very boring day.

[soullad]

Markus - any pics fella?

[rossi46]

So basically you would end up with something that looked like the deloren (sorry about spelling) from the film back to the future but it would run cool as a cucumber and would keep cool and not seize at high speeds tuned to death...mmmmmm ..? yes I could live with that..while they all would laugh/take the p155 Id be blowing by them sat at the road side ringing the AA...Yep still live with that...

There was a very nice scooter (can't remember the make) in scootering a little while back where the guy had done a lot of this sort of thing really nicely - You really didn't notice what was different. It sounded like he worked in F1 (all the ducts were bespoke and carbon fibre )

Well on that score where`s Rossi46...Come on matey how do you differ heat and draw in cooler air on them rally cars..and yes I know there water cooled BUT you still must need to draw extra cooler air at the temps them beasts must run at..

Basically for the intercooler system, which just a large radiator that has hot air flowing through it from the turbo, this is fitted at the front of the car were the air hits it cools the inlet charge and vents the exchanged hot air out of a duct fitted into the bonnet.

The same goes for the radiator cold air comes onto the radiator cools the water and then the hot that has gone through the radiator is then vented out of the sides of the front bumper.

I have a simple scoop fitted to my flywheel cowling which directs extra air into the flywheel, it did make a small difference to EGT, but I have not had time to vent the cowling, my plan is to vent from the back of the cowling at the base of the cylinder, with a small duct which will be hit bay the air flow while riding causing a vacuum which in turn will draw out the air at the same time, the problem is getting the angle correct for maximum suction.

Hopefully I wil get some time soon to have a go and try and borrow some test equipment from work to see if the temp is dropping around the cylinder.

[Andy Pickering]

Remember seeing that rossi46 on the pics update thats why I mentioned you mate ..Had a conversation with the engineer who does a lot of the maintence of our plant today and brought up my ideas regarding air flow and ducts and how I could harnes it to improve the cooling of an old air cooled lambretta.....When he stoped laughing :flaming: ...He said wye aye man just get a f@@king motorbike ye tart (geordie)...Ye right oh, been there done that...Right what he said basically in great depth was what Sean/Ric/Dan/Me/Jason and many others regarding ducts and in particular the venturer thingy you guys where on about and I gave him my drawings on it, hes taking it away to have a play and some ideas from his past experiences..so Ill see what he comes back with...Ive asked him to look at 2 areas the cowling and An idea I have about turning the toolbox into a wind catcher (vent toolbox door) plus using the scoop much the same as rossi`s scooby`s..

[carlos fandango]

Oh i give up
8 pages
76 replies
583 views
And still no one can answer my question
I feel like slitting my wrists with a piece of steel shaped into a duct/scoop

[sean brady scooters]

oh ........go on then ....remind us........what was your question exactly..........?
i promise my next responce will be for you only...............

[sean brady scooters]

here goes matey
Q1.........................dont know
Q2..........................impossible,i would think
Q3.......................not sure
Q4........................Maximise the greatest amount of the coolest air available..........from exterior of panel work as is poss........
and also increase exit side of hot air area...............

hows that........?