Topic: Air Cooling Duct for Zero SR/S/DS (Read 3447 times)

StephentheEE · « **on:** January 22, 2016, 09:27:20 AM »

A few days ago I posted some photos of a sheet-metal air duct I made for my 2014 SR on the Zero Motorcycles Owner's Group on Facebook. By popular request I am presenting a project summary here.

**Please note that I have placed links to all the project photos on Imgur. They are physically too large to show in-line.**

The standard Zero S/SR/DS places the air-cooled motor directly behind the battery pack. The battery pack does an admirable job of blocking almost all airflow across the motor fins. Consequently many riders will experience overheating issues when riding at high speeds for extended periods. Especially so if you happen to live in Tucson, AZ, with 40+ Celsius summers

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My primary goal was to create some kind of air duct that would at least get a little air moving across the motor. The finished product had to be removable, minimally visually intrusive, and reasonably sturdy. In that regard my design worked well. The airflow is not optimal, but it's better than almost nothing at all.

I created my design from 20 gauge galvanized steel sheet metal. I used a jigsaw to cut out the flat pattern shown below. I apologize for the sloppy dimensioning, I am only an EE after all

After cutting out the flat pattern, I folded it as shown below to form the air duct.

I used M4-0.7 8mm long screws and nuts to fasten the two small triangle "ears" at the 45 degree bend. This is necessary for stiffening the folded duct. A more enterprising individual would weld these ears in place. I should also point out the three holes I drilled at the rear 45 degree bend to allow water to drain out.

The next step was to drill holes in the bottom belly pan from the motorcycle to fasten the duct. The air duct hooks over the rear edge of the belly pan. Once positioned, I drilled and tapped M4-0.7 threads using the air duct mounting holes as a reference.

I coated the air duct with three coats of Rustoleum Professional metal primer and three coats Rustoleum Professional flat black for a solid finish. Once well cured, I fastened it to the bottom pan with M4-0.7 8mm long screws and Loctite blue.

Then, it was simply time to bolt the whole shebang back on the bike and admire the work. By the way, I found that I had to wrestle the ground wire for the 110VAC charging jack around to clear the air duct.

So the big question is, does it work? I have not yet conducted any kind of controlled experiment to give a definite answer. I can state anecdotally that it seems to have shaved anywhere from 5-10 Celsius when riding on the highway. Naturally, the duct is much more effective at higher speeds. We'll see how it handles on the track at Arroyo Seco Raceway in New Mexico this weekend.

Do be aware that if you make this for your own bike, you'll lose about 2 cm clearance. Additionally, it could be easily damaged by stones and debris and such. Not a good idea if you're going offroad. Of course, it can also be removed pretty easily if you don't like it

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Possible improvements would include a larger duct height (from 2 cm as shown), a smooth bend at the rear end rather than 45 degrees, and additional ducts/tubes directing air towards the top of the motor. I'm welcome to suggestions.

NEW2elec · « **Reply #1 on:** January 22, 2016, 09:59:52 AM »

We had been talking about something like this since before the 2016's came out but you actually made one. Can't wait to see how well it works for you. Way to hit a home run on your first post welcome aboard!

laramie LC4 · « **Reply #2 on:** January 22, 2016, 10:05:02 AM »

tucson? been kinda cold for my tastes lately.

Erasmo · « **Reply #3 on:** January 22, 2016, 02:36:23 PM »

Looks good!

MostlyBonkers · « **Reply #4 on:** January 22, 2016, 02:51:30 PM »

Bloody hell, that's amazing! [emoji4]

rayivers · « **Reply #5 on:** January 22, 2016, 09:16:14 PM »

Great work! The diagram is excellent - anyone could take that to a good sheet-metal shop and have one of these made. It looks like this would work on a bunch of other Zeros too, perhaps with a tweak or two.

On the SR, it seems to me like one lower front side cover should extend completely to the frame rails in every direction, with a large intake opening in front (the other side cover remaining as-is). This would eliminate still-air pockets in the battery & motor areas with the bike in motion, and also push a fair amount of air sideways across the motor which the cooling fins should fully utilize.

Ray

Richard230 · « **Reply #6 on:** January 22, 2016, 09:36:38 PM »

Just keep in mind that the duct will not do anything for the bike's aerodynamics and it will take a little more power to travel each mile after the bike is modified.

MrDude_1 · « **Reply #7 on:** January 22, 2016, 10:07:49 PM »

Quote from: Richard230 on January 22, 2016, 09:36:38 PM

Just keep in mind that the duct will not do anything for the bike's aerodynamics and it will take a little more power to travel each mile after the bike is modified.

Keep in mind that while accurate, merely moving your elbows around or sitting your head up higher would make a larger, equally immeasurable difference.

rayivers · « **Reply #8 on:** January 22, 2016, 10:46:51 PM »

Quote

Just keep in mind that the duct will not do anything for the bike's aerodynamics and it will take a little more power to travel each mile after the bike is modified.

I would use the existing Zero cover shape at the leading edge, cut away for air ingress - so aerodynamics would barely be affected, if at all. And who knows, there might even be some Zero owners out there who would trade a tiny bit more drag, and - as long as we're picking nits - weight, expense, and looks - for increased cooling.

Ray

StephentheEE · « **Reply #9 on:** January 23, 2016, 01:26:10 AM »

Quote from: rayivers on January 22, 2016, 09:16:14 PM

On the SR, it seems to me like one lower front side cover should extend completely to the frame rails in every direction, with a large intake opening in front (the other side cover remaining as-is). This would eliminate still-air pockets in the battery & motor areas with the bike in motion, and also push a fair amount of air sideways across the motor which the cooling fins should fully utilize.

That's an excellent idea. My first thought was to try to somehow catch airflow from around the side panels and direct it down and across the top of the motor fins, but I couldn't figure any way to do it without making the bike look like a wad of duct tape. I may still try adding some tubes or hoses and routing them underneath the "gas tank", if I can make enough room.

As for aerodynamic concerns, the bike is already has such high aerodynamic drag that this mod has basically zero effect. If I already had sport fairings, I might worry a little. Fairings would also reduce the motor's workload at high speeds and it would probably run cooler. Are you listening, Zero Motorcycles? We want sport fairings!

I will also be putting in a left hand rear brake soon. I will use a handlebar-mounted master cylinder and totally remove the foot brake master cylinder, with a hose straight from the handlebar to rear brake caliper. I'll probably make a project summary on this forum for that, as well.

Doug S · « **Reply #10 on:** January 23, 2016, 01:48:19 AM »

Quote from: rayivers on January 22, 2016, 09:16:14 PM

On the SR, it seems to me like one lower front side cover should extend completely to the frame rails in every direction, with a large intake opening in front (the other side cover remaining as-is). This would eliminate still-air pockets in the battery & motor areas with the bike in motion, and also push a fair amount of air sideways across the motor which the cooling fins should fully utilize.

Actually, I'd do pretty much the same thing on both sides, with a wide opening at front which narrows quickly to speed up the air. On one side re-direct the fast-moving air inward toward the motor area, and on the other guide it straight backward past that area. By Bernoulli's law, the fast air speeding by on one side would create a low-pressure zone, which would help move the air out from the motor area. If you want to get air moving through the motor cavity, you have to blow it in from one side and pull it out from the other.

rayivers · « **Reply #11 on:** January 23, 2016, 02:45:36 AM »

Even though I haven't really had any trouble with overheating, I've been giving it a lot of thought, just in case. It seems to me that a slight pressure rise on one side of the frame - ideally coupled with an equal pressure drop on the other side, perhaps using an internal fairing slipstream shooting by the opposite side of the motor, as Doug S mentioned - would automatically "duct" air through the motor area and battery perimeters (i.e., where it's needed the most) without any additional ductwork required. At the very least, a lot of hot air sitting around making things miserable would find a happy home elsewhere, and that right quick.

Here's one of my favorite-looking fairings...

... along with some doo-dads Airtech adds on to it:

Re the brake - I guess you could use a high-pressure hydraulic clutch setup?

Ray

Justin Andrews · « **Reply #12 on:** January 23, 2016, 03:43:13 PM »

Nice set of instructions Stephen, I think I might give this a go myself.

MrDude_1 · « **Reply #13 on:** January 25, 2016, 08:13:15 PM »

Because Imgur is not reliable to keep images for years, I put a copy of them on my webspace... and then made some resized ones to put inline.. (click them for larger pics)

Heres the whole first post with the images inline:

A few days ago I posted some photos of a sheet-metal air duct I made for my 2014 SR on the Zero Motorcycles Owner's Group on Facebook. By popular request I am presenting a project summary here.

The standard Zero S/SR/DS places the air-cooled motor directly behind the battery pack. The battery pack does an admirable job of blocking almost all airflow across the motor fins. Consequently many riders will experience overheating issues when riding at high speeds for extended periods. Especially so if you happen to live in Tucson, AZ, with 40+ Celsius summers