Some new thought about 5th Gen summertime cooling...

Today I was putting the fairings back on my '99 5th Gen for the first time after installing the "New 5th/6th Gen Header".  Doing this required a bit of modification to the fairing's chin insert due to the slight mis-alignment in the design (vs. the bend of original Honda headers) of the #4 cylinder header. 

While doing the necessary work to accommodate this little header problem I started thinking about the hot-weather temperature behavior of my 5th Gen.  I was in the process of applying some extra heat-reflecting aluminum tape to the inner surface of the fairing's chin insert as an extra effort to prevent the new headers from melting the plastic. 

Then, when I was installing the newly-modified chin insert into the fairings I happened to look up at the large radiator-to-radiator coolant connector tube (the one that connects the 2 radiator drains back into the bike's water pump).  The idea/realization hit me that this radiator-to-radiator connector tube is probably the most unfortunate piece of engineering in the cooling system (maybe even the worst part in the entire bike?).  I understand that the Honda engineers had no choice in the design because they had to connect the bike's 2 radiator drain outlets back to the water pump and they had nowhere else to go with the tube but right behind the cylinder #2 and #4 header pipes. 

The transfer of radiant heat from the header pipes onto this radiator drain outlet connector tube has got to be pretty substantial.

The bike's right-hand radiator is trying to do its job of rejecting to the atmosphere as much heat as possible from the coolant, but then its return flow of coolant has to travel through a tube that is being actively heated by the radiant heat coming off the header pipes.  This has to be a factor in the overall heat load that the bike experiences, but how large of a contribution the headers are making is an unknown at this point.

So now I'm thinking about experimenting with this situation by adding a heat-reflecting Hose Shroud to cover the radiator drain connector tube.

[image: Screen%20Shot%202019-07-08%20at%205.48.3]

[image: Screen%20Shot%202019-07-08%20at%206.36.3]

[image: Screen%20Shot%202019-07-08%20at%206.37.5]

And because this product comes in a 3 foot long length (which I won't need all of that length to cover the radiator drain connector tube) I might also use the leftover length of this shroud to cover the other radiator connector cross tube, the one that connects the 2 radiator inflow ports located at the top of each radiator.  While this tube doesn't pass close by the exhaust headers like the drain connector tube does, it does travel above the forward cylinder head which probably creates a pretty hot radiant heat environment, especially when the bike is moving slowly or sitting stopped.

Testing my theory about the radiant heat effect of the exhaust headers will be easy as this shroud uses velcro to hold it on.  So it will be easy to install it and then remove it again for comparison rides to see if it makes a noticeable difference in how the cooling system behaves.

My opinion is that any heat gain by this hose will be minimal at best if any at all. 

Air is a really bad and inefficient heat transfer medium, rubber is nearly as bad. 

It is nothing compared to the liquid  to metal heat transfer inside the heads. 

Nothing much will fix the design issues with the 5 and 6G. 

The best solution would be a second fan on the right radiator, but no space there. 

Also fans are hopeless at pushing air through a radiator, they do a lot more sucking. 

1 hour ago, VFROZ

My opinion is that any heat gain by this hose will be minimal at best if any at all. 

Air is a really bad and inefficient heat transfer medium, rubber is nearly as bad. 

I was talking about radiant heating, which occurs regardless of the atmosphere (it doesn't even need an atmosphere at all), so I'm not sure how air is factoring into your thoughts on this idea.

I don't believe that the length of rubber hose linking the two radiator drains is a great conductor, but it is in close proximity to the #4 and #2 header pipes and they definitely radiate a lot of heat, so that piece of hose is almost certainly adding heat to the situation. 

Yes but the radiated heat is tranfered by the surrounding air, and the coolant is moving pretty fast.

I was head or R & D at an airconditioning manufacturer in a past job, and have worked on high end airconditioning design for may years.

A lot of my work revolved around air movement, fan design and heat transfer.

I don't think you would be able to measure the amount of heat gain to the coolant by that hose.

I'm not trying to discourage you from trying it, just giving you my educated opinion.

2 hours ago, VFROZ

Yes but the radiated heat is tranfered by the surrounding air.

Air conditioning systems and forced-air heating systems are convection.  I'm talking about thermal radiation.

Thermal radiation is one of the three principal mechanisms of heat transfer. It entails the emission of a spectrum of electromagnetic radiation due to an object's temperature.

The interplay of energy exchange by thermal radiation is characterized by the following equation:

The type of heat transfer you keep referring to is convection, which is defined as: heat transfer due to the bulk movement of molecules within fluids such as gases and liquids.

Thermal Radiation is why spacecraft need to have cooling systems in place, the Sun's radiant heat passes through the vacuum of space (no air out there) and hits the spacecraft and heats up the surfaces.  Lots of heat transferred without any air involved.  

I'm sure you're both right. As it simply velcros in place, it can't hurt, can it? What about pipe wrapping the headers, too, to keep the heat in the pipe?

48 minutes ago, GreginDenver

Air conditioning systems and forced-air heating systems are convection.  I'm talking about thermal radiation.

Thermal radiation is one of the three principal mechanisms of heat transfer. It entails the emission of a spectrum of electromagnetic radiation due to an object's temperature.

The interplay of energy exchange by thermal radiation is characterized by the following equation:

[image: \alpha +\rho +\tau =1.\,]  In this equation [image: \alpha \,] represents the spectral absorption component, [image: \rho \,] represents the spectral reflection component and [image: \tau \,] represents the spectral transmission component (you'll note that this equation does not include anything about air or atmosphere).

The type of heat transfer you keep referring to is convection, which is defined as: heat transfer due to the bulk movement of molecules within fluids such as gases and liquids.

Thermal Radiation is why spacecraft need to have cooling systems in place, the Sun's radiant heat passes through the vacuum of space (no air out there) and hits the spacecraft and heats up the surfaces.  Lots of heat transferred without any air involved.  

Every town’s got one. 

You know what every town needs though?

A front mount radiator. 

You could always do this 👍😎

Works a treat.

[image: 6B4DE43B-BD9F-4916-AC9C-5E2CEE8C4350.thumb.jpeg.f7efffcded974fc6cf8c7b81010b3942.jpeg]

[image: 379CB7F9-73CB-4A72-876A-A3512CDFE19C.thumb.jpeg.e682a5494e422a2f512034e320bb3806.jpeg]

Same both sides oem fan is long gone these are IP67 rated fans & the combined FPM is 50% more than the OEM fan & both suck air outwards through the rads. I have 90C thermal switch which resets at 80C. Works great. Plus if one fan dies there are 3 others still working. 

Just needs a little sculpting of the outlet vents where they cross the fan frames. This is not visible from outside.

Have fun. 

Mohawk, 7/9/2019 at 4:28 AM

You could always do this 👍😎

Works a treat.

[image: 6B4DE43B-BD9F-4916-AC9C-5E2CEE8C4350.thumb.jpeg.f7efffcded974fc6cf8c7b81010b3942.jpeg]

[image: 379CB7F9-73CB-4A72-876A-A3512CDFE19C.thumb.jpeg.e682a5494e422a2f512034e320bb3806.jpeg]

Same both sides oem fan is long gone these are IP67 rated fans & the combined FPM is 50% more than the OEM fan & both suck air outwards through the rads. I have 90C thermal switch which resets at 80C. Works great. Plus if one fan dies there are 3 others still working. 

Just needs a little sculpting of the outlet vents where they cross the fan frames. This is not visible from outside.

Have fun. 

You managed to get those under the fairing and make it look relatively stock eh? Niiiice! Puller fans are always more effective, without a doubt, and having fans on both radiators has got to really drop the heat in a hurry.

Can you show a picture of the fairings back on the bike to see how the fans are exposed. Thanks

:lurk:

Be sure to let us know if you experience a heat reduction from the saddle.

When peeps ask if riding in a leather suit gets warm in the summer heat I reply "It like wearing a sauna while sitting on a hot oven".