Two-stage fan modification

Hello all!

I know how much we all love getting our nuts roasted by our bikes, so I thought I'd post my recent "win" in the parts sourcing game!

I'm about to order the parts I need to add a fan onto the RHS radiator of my 5th gen (this will also be of interest to the 6th genners).

Until a couple of days ago I was thinking of putting in a thermistor instead of the fan switch, and using PWM control (read: expensive and requiring development time). However, I've now found that there's a dual-stage thermofan switch with the required M16x1.5 thread! It's a Facet 7.5665:

7.5665

I've contacted a few companies who sell them, and the only company who has returned my email is:

Auto Agencies in New Zealand:
Auto Agencies

They're willing to freight to Australia. Who knows about elsewhere, but you never know...

Anyway, the tech detail is:
* The right thread to screw straight into a 5th gen (maybe a 6th gen too - can someone confirm?).
* Stage 1 temps: On 95'C, off 85'C (203f - 185f)
* Stage 2 temps: On 102'C, off 97'C (216f - 206f)
(switching points aren't perfect, but the first stage is better than the EOM single-stage switching points)

I'm waiting to see if it needs relays, or if it's ok to switch the OEM fan (and a non OEM fan) directly. Watch this space for details...

I'll post at a later date with the full details of the modification (ie: extra fan(s), wiring diagram, relays if needed, voltage limiting for extra fan(s), instructions, photos, etc). The biggest trouble is that I'll have to wait until the Australian summer to report the full effect.

Cheers,
Danny

PS: I already have the VTR1000 fan mod, so this is for seriously hot days in traffic...

 

Looks interesting.
As for the 6th gen switch, it is also a M16x1.5

 

I've ordered the switch. Also got other goodies on their way: relays, high flow fan, fan grille, and a couple of high-current diodes (to drop the voltage to a safe level for the fan).

Here's the fan I've bought:
http://item.mobileweb.ebay.com.au/viewitem?itemId=180758652926

It's a 120mm case fan, 25mm thick, 175CFM, rated to 13.8V (hence the diodes to use in series to bring the voltage down a bit).

More details when I have more to show...

 

I used a nissan sunny one, comes on at 92C on my gauge & off at 78C perfect, bike has never got hot since, even when sitting idling. That said temps ahve NOT been hot here, but was good in 20C ambient a couple of weeks back idling in traffic ! Costs peanuts from any local Nissan dealer, I'm sure there is one local to you

 

The two-stage switch I've found is for a Nissan Primera P10 2.0 diesel. It seems that Nissan likes M16x1.5 fan switches...

I thought about using a lower temp single stage switch, but the engineer in me said "you know you want something trickier than that!" I'm going for just one extra fan for now, but I'll design the system to cope with adding a second one to the right hand side. Going to mount the fan on the outside so it's easier to install.

 

Well good luck with that. I have a high spped PC 120mm fan on the front inside of the right rad & a VTR1000 fan blade on the VFR left fan. The right fan is wired in parallel with the left, so they both suck from the front & expel to the outside, i.e. the same as when you are moving. The single temp fan means you don't need a two stage one as the temp never gets high enough to activate the second stage ! If you add the right fan whilst the left one is sucking, it will not be very effective, as the left fan will be blowing hot air into the void inside the fairing front & then the right fan will suck that hot air through the right rad !

 

I fail to see the logic in this, so maybe somebody should explain it to me. If Honda engineers would have deemed some other fan type/function was called for, I'm sure they would have designed the bike with it instead. Seems to me just a large amount of time and money spent fixing a problem that isn't really a problem.

 

Hmm, bean counters & emissions regs, do not suit all environments. Running an engine close to maximum heat soak at idle is NOT a good idea. The best temperature for an ICE is approx 80c at all times. The max is approx 110c. The closer the engine gets to max temp when stopped the more it wears & the closer you will get to seizing it if you then goose it. Honda designed it to run quite hot to pass emission regs, so long as it outlasts the warranty, manufacturersdon't care !!!

You are free to run it as it comes & if you are happy so be it. But some of us are not.

 

By that logic, we should just not worry about the crappy wiring that our bikes came with as well, since it was deemed appropriate that the gauge of wiring used was sufficient.
I'll be open to new ideas and suggestions that help cool the bike when the temps hit 100+ and the humidity is 95%+.

 

I agree with Mohawk and Talon on the logic of modifying the fans. Also, the OEM system works well on some bikes, and poorly on others (especially in weather conditions that Japan doesn't experience). There's obvious bike to bike and environmental variation that they haven't accounted for in their design.

Just to clear up the confusion about the intended direction of my second fan: it will draw air from "inside" and blow it out the side.

I've chosen sucker configuration for ease of installation and cleaning (blower can clog up the fins more easily, and needs the fan to be removed to clean them). I'll use some foam sealing tape to make sure the fan actually sucks air through the radiator (instead of sucking it from the sides).

 

Maybe you shoulda been Honda Engineers.....

 

Hehehe... Perhaps it's a good time for me to say that I'm an automotive engineer, and my job is to find and fix other engineers' f***-ups...

 

And just to add I'm an ex REME mechanic, who often had to work with less than ideally designed equipment, field modification is the norm, rather than the exception !

 

Looks like we're the right people for the job! Let the modifications begin!... when the parts arrive...

 

LOL, sounds like you guys are EXACTLY the right guys for the job!! I wish you good luck.

 

So are you going to make the stock fan stage one and the add on right fan stage two or vise versa where as the right fan begins cooling and then the main left fan kicks on if the temp continues to raise. Just wondering which way you think would work better?

 

I'm a Customs Broker with a minor in shade tree mechanics, does that count? :wink:

 

I plan to do one of the following options:

1: Left then right
2: Series then parallel (both low speed then both high speed)

I have the parts coming for both options, so maybe I'll try one, try the other, then decide which works best.

 

Happy dance!!!

I've started receiving the parts! Here's the dual stage switch:

 

It's been almost an entire day... I expected better progress. :tongue: