To Fan or Not to Fan

[evolution247]

Say, I am planning on coming back for a few rounds this season. I am curious what the rationale is behind removing the fans from race bikes? I've heard weight savings, but have yet to confirm if this is indeed the real reason people remove them. The bike I recently picked had them removed (as did my last race bike).

Given my pace, I don't think it would make a huge difference. :rofl

Thanks in advance for your feedback.

 

[afm199]

The weight savings is negligible. You get better airflow for cooling.

 

[Honey Badger]

No good reason other than weight savings, and I think for most of us, the better cooling on hot days is worth it. My race wiring harness eliminated the fan, but saw no reason to remove it before that...

 

[csik magnet]

Yeah, you get better airflow without a fan choking half the radiator. If you're cooking your engine during your races, consider pulling the fan off.
That said, I still have my fan installed so that I don't have to worry about overheating in the pits during those hot August days at Thunderhill. I want to steal a friend's idea and add a manual fan switch in parallel with the thermostat, he turns his on as soon as he pulls of course and claims his temps are ~180 by the time he reaches his pit.
I also have a different friend who started his race bike to warm up before being distracted helping another rider and left his bike idling in his pit (no fan). Helped him replace the head gasket on that. I don't think I'll be pulling my fan off anytime soon...

 

[stangmx13]

I removed the fan off my first race bike during a trackday in Utah. the bike ran 15F cooler in the next session. some bikes need the extra cooling more than others. if your lower isnt enclosed behind the front tire, u probably need the extra cooling.

theres no reason to keep the fan on a race bike. if u are sitting in the hot pit before a race, u went out too soon and your tires are cooling off . also, just turn the bike off.

Yeah, you get better airflow without a fan choking half the radiator. If you're cooking your engine during your races, consider pulling the fan off.
That said, I still have my fan installed so that I don't have to worry about overheating in the pits during those hot August days at Thunderhill. I want to steal a friend's idea and add a manual fan switch in parallel with the thermostat, he turns his on as soon as he pulls of course and claims his temps are ~180 by the time he reaches his pit.
I also have a different friend who started his race bike to warm up before being distracted helping another rider and left his bike idling in his pit (no fan). Helped him replace the head gasket on that. I don't think I'll be pulling my fan off anytime soon...

turning the fan off doesnt do squat as far as providing more cooling. the blades and the housing are still blocking airflow at track speeds.

 

[EastBayDave]

there's' always the oil cooler alternative...

but it's entirely dependent on where you ride & local conditions. If your facility is 109' in the summer, the fan stays. I'd add an oil cooler too...

If it's a foggy, cold Sears Point (say 64'), You might want to pull it just to get the engine up to temp. Again entirely dependent on conditions...

I'd leave it....

 

[evolution247]

Great intel folks. Okay, they stay off. I knew there was a rhyme or reason behind it, just wanted to be sure. Thanks again!:thumbup

 

[csik magnet]

I removed the fan off my first race bike during a trackday in Utah. the bike ran 15F cooler in the next session. some bikes need the extra cooling more than others. if your lower isnt enclosed behind the front tire, u probably need the extra cooling.

theres no reason to keep the fan on a race bike. if u are sitting in the hot pit before a race, u went out too soon and your tires are cooling off . also, just turn the bike off.

Yup, on track temps will definitely be lower without a fan blocking part of the rad. I still think it's good insurance to have though; for myself and I'll assume a lot of us here, the racebike is also the trackday bike and those events can have you sitting on grid waiting to go out / hanging out at the side of the track on a red flag / in 1 case I know of, leaving your bike unattended to cook itself while you go do something else (completely his fault, but a fan would have saved it). I'm a lot more precise about when I roll out for final call before a race than I am for "A group, 5 minutes". Yeah you can and should turn the bike off while you're waiting, but having a fan is one less thing to keep in your mental checklist.

turning the fan off doesnt do squat as far as providing more cooling. the blades and the housing are still blocking airflow at track speeds.

I've heard before that at speed, a running fan is more restrictive than a stationary one because you're now blocking flow across the entire fan surface area vs. just the areas obscured by the blades (and it will freewheel better when off). Can't speak to the truth of that though, I didn't do fluids in school. Either way, no fan is better.