Cooling system Q's, CFM on fans, dual fans

[Guest jcmcc89]

Anybody know the CFM of the stock fan vs the vtr? I'm trying to figure out if a spal fan would be of benefit on our bikes (mine is a 5g).

I've gone thru the whole cooling system and still see 245 occasionally in hot weather stop and go traffic- Although the VTR fan blade has stopped the heat runaway a good bit and works good up to about 85 deg.

Initially I was considering mounting a small spal puller fan to the outside of the right radiator to aid cooling, but I think two fans may be a bit too much of a load on the bike electrically, especially at low revs.

Now I'm playing with the idea of using a single spal to replace the stock fan. Simiiar to the vtr fan blade mod, but with a more efficient/powerful fan.

something like this for the right rad:

http://www.spalusa.com/store/main.aspx?p=itemdetail&item=30103018

something like this for the left rad:

http://www.spalusa.com/store/main.aspx?p=itemdetail&item=30103013

Humor me

[mello dude]

Interesting thoughts - I have also wondered about the CFMs of the stock. Occasionally I have seen fans of other vendors and its tough to compare with out knowing stock output. The spal you have marked for the left is 5.2 inch dia and the stock is 7 inch, so I dont think you would gain anything. There might be room to squeez the 4 incher on the right.

I hear the 6 gen rads have 8% more cooling and been wondering if that would fit. Or on the right side, look like there would be room for a wider custom raditator in that space. --- Then again some guys have added 3 row or 5 row oil coolers to bring the heat down. If I lived farther south I might be checking out options.

-On the crazy azz idea chart -- how 'bout a 9 inch fan, 839 CFM

http://www.summitrac...-ZFB9/?rtype=10

8" and 605 CFM

http://www.summitrac...-ZFB8/?rtype=10

[YoshiHNS]

Maybe someone at somebody's work has an airflow meter. I know we had one at my other co-op that came in handy all the time.

[mello dude]

^^^ There is a standard procedure for fans that uses a wind tunnel. The fan has to be setup properly and the test measures static presure vs CFM. I imagine it would cost some bucks to do it.

[Guest]

yeah i wasn't sure what size the OEM fan was.. too lazy to go down to the garage and measure . That 8" one seems promising; 605 cfm is quite a lot of air...

The other thing to consider with the aftermarket fans is that they will not flow as efficiently without a shroud. Some of the fans seem to have a small one built into the fan assembly, but who knows how that would change airflow characteristics.

I guess its all hearsay until someone pops in with the OEM fans CFM

[vfr350]

just a thought, can the OEM fan motor just be replaced with a motor that runs at a higher rpm?

[Guest]

That, too, may be a viable option. Maybe a fan motor from a different sportbike would be a similar fit with higher rpm??

The only problems I see with that is finding one that fits in the stock shroud, and also there may be a benefit to flow by changing shape, size, quantity, and profile of the fan blades.

[Guest]

Thought I'd update this thread with what I decided upon doing.

I ended up just replacing the motor on the left side leaving the VTR fan blade in place. There were too many variables/unknowns in going with a different main fan.

On the right radiator, I installed a PC case fan (< thats a link) on the outside as a puller. My intention was not to replace the OEM fan.The fan is rated at approx 100 cfm but is only rated at about .6 amps (~7-8 watts) draw. My thinking is that any air movement is better than none on the right side. My overall goal is to take some of the load off the main fan, without taxing the electrical system too much. There are plenty of different ways to go about setting something like this up- here is what I did.

Ideally, I would have liked for it to be hidden behind the fairing, but it rubbed ever so slightly when placed forward on the rad. By moving it back, it does not contact any part of the fairing. I grounded the fan to the fairing bracket to the far left of this picture.

No fairing to fan contact- fits with a good bit of room to spare.

Here is how I ended up mounting the switch. Just a quick bracket I made at work connected to one of the tank bolts. I really don't like the way this is mounted (very ugly) but it will do for now.

If you are planning on doing this mod, please don't forget circuit protection. I have my 3a fuse (straight off the battery) and switch on the positive side in the event something does short out- everything won't go up in smoke . Also, remember to solder and heatshrink any connections/terminals for reliability and safety!

Total investment for this little project is about 25 bucks. I know the PC fan will likely burn out with lots of bad weather riding, but they're very versatile being so small. Also, at about 10 bucks each it won't break the bank replacing one. I also purposefully overbuilt the circuit (8A max) in case I decide to get a small SPAL or heavier duty case fan down the road (check this one out- 250+ cfm)

Also- please excuse the messy garage

[mello dude]

Interesting setup - tried it out yet?

[Guest]

only played with it a little today. I turned on the secondary fan right when the main fan turned on and the temps did seem to come down faster than before (although I never really measured this time previously). I will update with more info as I get it.

[Guest]

I completely forgot I'd made this thread.

So far this setup has made a huge difference for cooling in stop and go. What sold me on this setup was a recent stint of Chicago stop and go traffic in 108 degree heat. I was stuck in traffic for over an hour on the interstate and the coolant temp stayed below 240. I also put in a fresh mix of ~60/30/10 percentage of water/coolant/water wetter which helped lower temps too.

To put that in comparison: the stock cooling system (fresh coolant, new tstat, OEM fan) would routinely hit over 250 even in only moderate traffic in under 90 degree weather.

Overall the only things I would change with this setup is the fan to a waterproof sealed unit but I don't know if I'd ever be able to find one slim enough to fit under the fairing. Also the switch is ugly but that's just cosmetic ;-)

[AnikMankar]

are you using this as a fan (push) or as an exhaust (pull) ?

[Guest]

Its setup as a puller.

As a pusher, it would counteract the airflow as the bike moves forward leaving the radiator to bake (just like the VFR fan blade).

[Mohawk]

"Overall the only things I would change with this setup is the fan to a waterproof sealed unit but I don't know if I'd ever be able to find one slim enough to fit under the fairing. Also the switch is ugly but that's just cosmetic ;-)"

Check out the CBR600/1000 fans, they use two fans, a bigger one & a smaller one. the smaller one would fit where your PC fan is.

I used a high velocity PC fan, but fitted it inside the right rad at the front, there is just enough space to squeeze it in. I have wired it in parallel with the stock fan with VTR blade.

I may add a second one as per your one & rig it up with a seperate supply via a relay, so they trip in with the standard fan. These do make a huge difference to the temperature of the system & the speed at which iot sheds heat is massively improved just with the one I have added, with two it would be even quicker.

[speedracer2235]

I reversed the polarity on my oem fan and added an inline switch. As long as I turn the fan on by 195deg in most cases the trafficy ride home seems to almost never hit 228deg. Never could understand why Honda did the air flow they did. When I first bought the bike in 06 it would bake itself and me on the afternoon ride home.

[Auspanglish]

I've seen that solution before but with two PC pullers on the outside of the RHS rad... makes a dif.

[Guest]

The relay for auto on/off is a good idea. I set mine up this way to keep things simple.

I think I might change my setup to activate the secondary fan with the primary once I install the Fuzeblock that is in the mail. That will eliminate the ugly switch and clean up the wiring a bit while also making it impossible to leave on accidently :-p

Dual pc fans would be great, too, but could those cause excess power draw? (especially at idle)

[Guest]

Interesting idea with the PC fan. I'm sure myself or one of my geeky cohorts has one laying around, and I've sure got spare wiring and switches laying about, would be easy enough to try it out.

Though about the physical mounting, was it just done with zip ties to the plastic "shield"?

Also, one thing to remember about fans is that just because they are rated at a certain CFM, you have to ask (for lack of a better way to phrase this, partially due to PUI) "at what load". In other words, think about an air compressor. They have two ratings for CFM, one at 40 PSI and one at 90 PSI (usually). A PC fan may be rated at a certain "resistance" to air being pulled through it, as I suspect the effort to pull a the same volume of air through a radiator is higher than for a PC case.

Again, never did any form of fluid mechanics or anything, and I'm fueled tonight by the King of Beers. But if it makes a difference in the real world, that's all that should matter. After all, the only difference between theory and reality is that in theory there is no difference, and in reality, there is.

Cheers!

[Guest]

Might be a bit late to the party, but I have been looking at this fan:

http://shop.perma-cool.com/19127-Std-Electric-Fan-7-2200-CFM-19127.htm

I have seen it for cheaper elsewhere, but I contacted them regarding the amp draw, etc... Basically it 3A constant and 9A on startup. From things I have read on the forums, it looks like the stock fan draws 9A constant.

Even though you would lose 80% of the claimed 2200CFM by switching it to a pusher style (if you replaced the OEM fan with it), the load on the electrical would be far less. Never a bad thing with these bikes.

Thoughts?

[spacetiger]

Have you considered other alternatives to your coolant such as Evans Waterless Engine Coolant. It has some good properties to include a much higher operating range with a high boiling point (180 C or 356 F). You could run upwards of 250 F on occasions and never boil over. A big plus is that you never have to flush the system and there is no risk for corrosion (because there is no water in the system) but it is expensive.

There are also coolant additives that help the efficiency of water based coolants. Here is a good article on them that is worth reading.

Jerry

[Guest]

Yeah, I've read those. This was purely on the thought of aftermarket CFM's vs. stock fan. Putting a higher flowing, lower amp drawing fan to replace the stock one seems to solve 2 issues at once: Less amp draw and more air flow.

But yes, better coolant is always a good idea.

[Guest]

Has anyone tried that waterless stuff? I am not a huge believer in boutique fluids/chemicals. I tend to abide by the early and often rule of maintenance with more "bang for the buck" grade fluids. I just like the idea of being able to top off what I need to with supplies from a walmart or gas station.

Regarding that 7" fan, how do you know you will lose 80% efficiency by using it as a pusher? Not calling bullshit- maybe you know an equation or rule of thumb that I dont. Without knowing what cfm the stocker is rated at it would be difficult to tell if it would make a difference without mocking one up and running homebrew testing. Interesting thoughts :)

[Veefer800Canuck]

Jerry, the Evans product has too high of a specific gravity to circulate through the VFRs cooling system. I tried it in my bike with a perfectly functioning cooling system, and burped the air out 100%, and the bike would simply overheat. I fiddled with it for 6 hours to no avail. It circulated through the return hose from the thermostat housing back down to the water pump, but would never move through the side mounted radiators no matter what RPM or anything else. And the bike was on its side stand, rad cap at the highest point, burped and burped until there was zero air in the system. No joy.

I think the VFRs cooling system is too long with too many bends, and the water pump does not have a large enough impeller or the internal clearances are too great.

As soon as I drained the system, flushed it with water, and refilled with Dex-cool, it worked perfectly. No change of components nor technique on my part. And the bike has been running happily on that Dex-cool for years now.

[Guest]

Has anyone tried that waterless stuff? I am not a huge believer in boutique fluids/chemicals. I tend to abide by the early and often rule of maintenance with more "bang for the buck" grade fluids. I just like the idea of being able to top off what I need to with supplies from a walmart or gas station.

Regarding that 7" fan, how do you know you will lose 80% efficiency by using it as a pusher? Not calling bullshit- maybe you know an equation or rule of thumb that I dont. Without knowing what cfm the stocker is rated at it would be difficult to tell if it would make a difference without mocking one up and running homebrew testing. Interesting thoughts :)

You wouldn't lose 80% efficiency, you would lose 20%. It would only be 80% efficient, can't remember if that's what I said earlier, but that's what I meant. Most pusher/pullers will lose about 20% of their airflow if you go to a pusher type set-up. Not entirely sure why, probably has to do with the motor. Even so, that 7 incher would be pushing 1760 CFM approx. It's a pretty safe bet that the stocker doesn't even come close to that.