Cooling 100cc Class
 

I've not needed to duct airflow before, but finishing my Wild Hare 35%, I think I should. Location of head and holes in cowl front look very direct, so I think I have to manage "exit area". I'm not running canisters, so was thinking of opening both exit holes at the rear of the canister "tunnel", and putting a 45* one inch deflector in front of that opening. The rear of the tunnel is angled, so between it and the deflector, I'm thinking I'll have pretty good "ducting".

Question - should I still open up more area under the fuse?? Thoughts?

RE: Cooling 100cc Class
 

Hey Bob
Which Wildhare? I have the 35% Extra and the 35% Edge. On the Extra I did put a baffle on the cowl and opened up the 2 bays behind the landing gear and it's been working great. On the Edge I haven't baffled it yet but I did open up the raised portion on the bottom of the cowl, plus the 2 bays in front of the gear.

RE: Cooling 100cc Class
 

On my 62cc Extra 260 the bottom of the fuse is sloped making the whole area a low pressure area, so I just opened the end of the can's tunnel and it's worked great with no issues for about 2 years now.

RE: Cooling 100cc Class
 

I have the 35% 300, long hatch. What you did is what I was thinking, except I thought maybe an external deflector would create additional low pressure area to help. The pic from Soarrich looks exactly like I'll end up with if I open the two bays.
Thanks guys!

RE: Cooling 100cc Class
 

If you put houshold air vent louvres in that opening, you will have an excellent low pressure zone. Just a large opening always is uncertain. Sometimes it works, sometimes it won't, depending on very small airflow path fluctuations. With louvres, it will create a low pressure zone for sure, as well as create a larger pressure difference.
More pressure difference is better cooling.
With aircooled gas engines, there is no such thing as too much cooling, because the temperature difference needed for heat transfer must be a lot larger than with liquid cooled engines.
Engines run best with their temperature at about 150F. That is extremely hard to achieve with air cooling in our meagerly finned engines, so we are already happy if temperatures stay below 350F. At that temperature the engine is less happy though, and rewards you with shorter time intervals between overhauls.

RE: Cooling 100cc Class
 

You might fine this interesting.

http://www.supercoolprops.com/articl...delengines.php

RE: Cooling 100cc Class
 

Pe,

My notes and experiments have consistenly shown that our engines do quite well up to 148c. After that point they have, with every size engine tested, shown an rpm fall off to some extent due to a reduction in pumping efficiency. Less than 85 to 100c they don't atomize fuel as well as they should. They will handle higher temps for sure but 148c seems to be the max they will maintain max output.

RE: Cooling 100cc Class
 

The MVVS liquid cooled engine runs between 60C and 85C. As a result, it has 5% more power than the aircooled prosport, all other things being equal. I do not think there is a fuel atomizing or evaporation problem in cooler running engines. In cold engines maybe, but 60C is not cold. Gas evaporates from -18C and up. At 87C all is in vapour state, but that happens during the compression stroke and subsequent combustion when the charge is heated evenly. Before that, only the charge that contacted the engine walls received heat, so most of the atomized gas had no chance to evaporate at all.