Cooling system improvement ?

[Mohawk]

I've tried a search & not found anything interesting. So, has anyone upgraded the cooling system on a 5th gen or reconfigured it for a better performance ?

 

Since adding the TBR system last year & combined with all the other mods, it seems to run a fair bit warmer than stock. Now this was suppressed to some degree when I had a PC3 due to the excessive amount of fuel that it pumped in the midrange. Plus Honda seemed to program it rich in the top end, again I feel to assist cooling. I've proved this with a separate AFR sensor/gauge & run an MTB to set the fuelling now.

 

So I'm looking for ways to improve the cooling & wondered if anyone has done anything already ?

 

Options are to increase radiator size, or reconfigure the rads to be serial flow rather than parallel, I'll be lloking at changing the fan system this winter & using radiator ducting to improve flow throgh the rads on the move.

I'll also be upgrading the oil cooler system, to hopefully improve that area too.

 

Any sensible input is welcome.  Thanks

 

 

 

[hellindustries]

• I've read that some have used a VTR fan as it pushes air out from behind the rad, instead of pulling as it does in stock config. Also fits perfectly.
• Maybe increase fan speed?
• Only one rad has a fan at all, but that may be due to internal clearance. Maybe if you move some bits around you could fit a second fan? I don't know if that's be practical, however....
• I guess you could also change the temperature sensor so that the fan/s come on sooner, or install a manual switch.
• If you want to go the ducting route; You may end up having to make new fairing holes or getting quite severe on the changes. Really depends how far you want to go and how much you're prepared to spend.
• Larger rads may also be an option, as you suggested, space permitting.
• Would increasing the coolant flow rate/pressure be an option at all?
• If you haven't already; Consider wrapping your exhaust system and/or installing heat shielding to keep thermal bleed to a minimum
• You may also be able to fit an extra rad down low at the front behind the pipes for the the forward two cylinders, though that's almost pure speculation on my part, and i have no idea how practical it may be.

[GleninAus]

You can gain up to 10% more cooling efficiency by changing coolant to something like "water wetter". Actual water is the most efficient but the engine will rot and if you live in a place that gets to freezing temperature you trade efficiency for no freeze and with the other side of that coin,  no  boil. The Honda has a quite high glycol mix of 50/50 making it inefficient but durable with a 120C + boiling point with the fan cut in at 108C .

 

I think all  mods are kinda hard to measure for effectiveness when it comes down to a really hot day stuck in a traffic nightmare travelling at walking pace. You can't even measure eg: 20 degrees  difference on a Dyno as using a dyno means using a fan to keep the engine cool in testing.

 

A mod that I did to my Ducati St4 ( it really hates traffic and makes me pay miserably for putting it there) was to replace the plastic fan blades with a metal blade.  This I could test. it was about 10% faster at reducing fan start (108C) to  fan off (98C) time.

 

Haven't seen this mod for the Honda so maybe worth looking at.

 

[mello dude]

As mentioned above the VTR fan could be a good trade for the 5th gen depending on your riding profile. The stocker is likely more effective in the 0 to 10mph range, but the VTR is much better at 10mph +. ( I am running the VTR blade) 

The 6th gen radiators are 15% larger(so I have read) and would be an easy drop in to a 5th, with minor trimming. There is a thread about this but I havent been able to find it.   

[RVFR]

15% you say Hmm ?  then this VTR fan blade,   Double interesting.   Does these VTR blade fit the stock VFR fan motor?  Guess I could google it ;)

[keef]

Front mount radiator, and drop the oil cooler down low.

I've used a slightly modded TLR top rad which was so effective i was going to drop the oil cooler entirely. And this is in aus where a heatwave is 40*, not just high 20's.

Instead, i made a narrower custom rad, so kept the SP1 oil cooler.

The TLR rad should fit in between the fairings, it was (from memory) 450mm wide.

A bit too wide for my streetfighter, but will be hidden inside your fairings.

 

Or you could put a third rad in like highside, but that would mean a bit heavier, and your bike has been on a serious diet. A single rad and coolant weighs less than 3 rads and coolant.

[Mohawk]

Thanks all, it's not really a fan related thing, I did all of those way back when tuning the bike, so it has a VTR fan blade & yes it cools much quicker when in traffic. I already have a fan on the front half of the right rad as well & this also helps reduce temps much quicker in traffic. I also have a lower temp fan switch which worked great under my old setup, where the bike used to run at a constant 79C, fan would come on at 92C & off at 82C, which was perfect. Like everything else you will always suffer in traffic.

 

The concern I'm trying to address is cooling on the move ! The bike now runs at a constant 84-86C which is fine, but the current fan switch never goes off if it comes on !  The bike also gets up to 90C much quicker when you stop if the ambient temps are high for the UK, so the fan comes on much more now than it used to.  I've ordered a higher temp fan switch with a narrower range, to see if the bike can maintain cooling efficiency on its own (I can't find the original Honda one). This should come on at 95C & off at 90C so if the bike can stay below 95C on the move then that will help.

 

i've read up on cooling efficiency & the various cooling mixes, from what I've read water wetter works great as a corrosion inhibitor for water only cooling, the real reason it's sold, it does not appear to improve the cooling properties of antifreeze mixes. I do have a feezing issue where I live, So I intend to reduce antifreeze level to 30% giving a greater percentage of water & thus a higher cooling efficiency.

 

My next thoughts were to add ducting to ensure the rads get a good air flow on the move. This winter I will strip & deep clean the rads. May look at 6th gen rads or a custom additional rad to replace the cross rad pipe above the oil cooler. I intend to fit a larger oil cooler too. The best place for fans is on the back of the rads pulling air through, this cause low pressure air in the rads which is cooler, they also allow better airflow to the rads as its uninterrupted. But due to the side mount rads it's a bad place to have them in a crash as they will try to crush the rads if the bike goes down. 

 

I spoke to to the designer of the Vyrus race bike which has a front swingarm, so no place for the rads, he placed them where the belly pan is on a normal fairing as side mount rads & the air enters through the centre of the fairing & this causes a high pressure area, then exits through the rad due to pressure differential. Their wind tunnel testing showed this was more efficient than front mounting the same area of radiator by reducing the frontal area drag & the air flow through the rads is more even with the side mounts.

 

another thing I'm looking at it re working the right rad, so the hose from the thermostat goes straight into the right rads rear end, then coolant flows up through the rad to the front, then across to the left rad. This will increase the fluid velocity through the rads which is supposed to increase their efficiency.

 

Thanks for the ideas & comments.

 

 

[Vee-Ef-Ar]

When I finally get around to rebuilding the 98 I was contemplating on doing a mod I've seen on VFR800P bikes in Japan. It involves cutting the fairing to create a larger opening for the radiator.

 

[adeyren]

10 hours ago, Mohawk said:

I've tried a search & not found anything interesting. So, has anyone upgraded the cooling system on a 5th gen or reconfigured it for a better performance ?

 

Since adding the TBR system last year & combined with all the other mods, it seems to run a fair bit warmer than stock. Now this was suppressed to some degree when I had a PC3 due to the excessive amount of fuel that it pumped in the midrange. Plus Honda seemed to program it rich in the top end, again I feel to assist cooling. I've proved this with a separate AFR sensor/gauge & run an MTB to set the fuelling now.

 

So I'm looking for ways to improve the cooling & wondered if anyone has done anything already ?

 

Options are to increase radiator size, or reconfigure the rads to be serial flow rather than parallel, I'll be lloking at changing the fan system this winter & using radiator ducting to improve flow throgh the rads on the move.

I'll also be upgrading the oil cooler system, to hopefully improve that area too.

 

Any sensible input is welcome.  Thanks

 

 

 

Mohawk, you thought of changing the Honda fan for a Spal fan? Shifts a lot more air than standard. Just fitted twin 5" Spals to my Bird, difference in cooling is markedly better. Birds are notorious for running hot in traffic now she doesn't suffer at all. I think a single 5" shifts approx 360 cfm. Merlin do a range as well but not sure on the specs. https://www.merlinmotorsport.co.uk/p/electric-radiator-cooling-fan-6-5-inch-diameter-rad-fan-65

[VFROZ]

I've replaced the right side radiator with a 6th gen, it is 2 rows higher from memory and has better shaped tanks to ease flow.

It only needed some trimming to the inner fairing to fit.

My next step was to replace the fan side radiator with a 6th, but haven't found one at the right price yet.

I've also added a fan switch override that I use in traffic lights as it gets to near 90*C, it stops it from run away temps.

I have been looking for a larger oil cooler which I think is a must for Australia as I ride in over 40*C temps sometimes, but again haven't found one at the right price.

A better fan is by far the best option, but I'm still looking for something that will fit.

 

 

[Mohawk]

1 hour ago, Vee-Ef-Ar said:

When I finally get around to rebuilding the 98 I was contemplating on doing a mod I've seen on VFR800P bikes in Japan. It involves cutting the fairing to create a larger opening for the radiator.

 

 

I think you will find this (and most of the answers so far) was to facilitate better cooling when stationary or at low speeds. The side rads use pressure differential to pull air through the rads, so larger opening will be less efficient at speed, due to the reduced pressure differential. I'm looking to improve the cooling at speed, in traffic the current fans work fine.

 

Another option is adding some vortex generators in front of the fairing openings to reduce the pressure outside the opening & further enhance the pressure differential. I'm thinking that the original front indicators did this to some degree above the top opening, but I have no referen es for this, just my expectation from the aerodynamics.

 

[VFROZ]

Then I would try the 6th gen rads, 8% more capacity as on my picture above.

[keef]

I'll say it again, a front mount rad. If a numpty like me can make it work, it'll be a piece of cake for you, Mohawk. 

TLR and SV650 have been made to work on mine and paladin reeds. 

If you wanted to get super fancy, TLR top rad which usually connects to a lower rad. You could connect it to a water cooled oil cooler thing, like toro used in his supercharger kit, or that is on a heap of modern bikes. 

[deltaboxii]

Hey Mo,

 

I swapped out my 2 row oil cooler that was standard on the 5th gen with an RC51 oil cooler.  it is substantially larger.  Temps under normal cruising are in the 190 F range now, as opposed to the 200-210 F range before.

 

Go with the '00-'01 RC51 oil cooler as it has the correct bend on the ports.  Don't double o ring them, cut and weld the correct ends on.  i dont trust "double o rings".

 

I was trying to post pics but it wont let me for some reason.  There are quite a few threads on this topic, and I believe there are some pics of the conversion in my build thread on my Gen 5.5

 

Installing the RC51 oil cooler was pretty simple and straightforward on the 5th gen.  For my next trick, I am going to try to install one on my 6th gen.  That should prove to be a challenge because of how the stock oil cooler is positioned under the front fairing (great idea Honda- put it where there is no air flow).  So I will need to watch the clearance with the front fender.  I would prefer to move it where the 5th gen oil cooler is positioned for more air flow. 

[JZH]

Found on UK eBay ( 252441514058 ):

 

 

They claim a 30% cooling improvement (cough, cough)...

 

Do you feel lucky?

 

Ciao,

[mello dude]

12 hours ago, RVFR said:

15% you say Hmm ?  then this VTR fan blade,   Double interesting.   Does these VTR blade fit the stock VFR fan motor?  Guess I could google it ;)

 

The VTR fan is a drop in to the OEM VFR fan motor. Unbolt stock, bolt in the other. Easy...

[adeyren]

2 hours ago, JZH said:

Found on UK eBay ( 252441514058 ):

 

 

They claim a 30% cooling improvement (cough, cough)...

 

Do you feel lucky?

 

Ciao,

Put one of these (similar, )http://www.ebay.co.uk/itm/FOR-Honda-CBR1100XX-Blackbird-Fuel-Injected-1997-2008-ALUMINUM-RADIATOR-/152060263063?hash=item23677f7a97:g:pgkAAOSwKfVXFYaq along with the Spal fans and did make a big difference. Should imagine it will on the VFR.

[CandyRedRC46]

http://www.honda-rc51.de/Parts_price_list.htm#Radiator Air-Scoops

[Mohawk]

Thanks CR, yeah I found the scoops for RC51 + VTR1000's which both suffer from heat soak or lack of airflow when used on track, where low gears, high revs when combined with technical low speed track layout means lots of heat but little cooling.

 

The Trackday I just did, was in 33C ambient and over 50c track temperature, when I tried to up my pace once I'd learned the track using lower gears/higher revs, the bike went into melt down mode. Average speed on my best lap was 61mph, so you can imagine how tight & slow the track was. Thus was the worst scenario for my cooling issue. Even with both fans on, the temp reached 108C & I it started dribbling excess coolant from the overflow, I have a minimal sized expansion tank !

 

But I feel a combination of the ideas above will cure it.

 

 

[keef]

The fan never came on when i was running the TLR rad, slow stop start traffic, or high speed track day work.

Before i wired in my fans on my smaller custom front mount, it was close to overheating (well, close to spewing coolant out teh expansion tank)in slow traffic when it didn't have airflow - this was riding to a track day.

But actually on track, it was running around 95*, and this was a hot sydney track day, so similar temps to the above.

 

The TLR rad ran cooler than my new one, but was uglier.

 

[Mohawk]

So I can't run a front mount rad, due to my ramair inlet being where it wants to live. Further research implies that the parallel radiator setup is considered the best, so I'll leave that. I'll give the rads outside a deep clean & see if that helps. Plus I'll upgrade the oil cooler. I might upgrade the electric water pump if the stuff above fails.

[deltaboxii]

Here is my newest plan.  Unfortunately I can't take credit for it.  Kevin @ Fatty's Cycles in Fortville IN (the wrench behind my Gen 5.5 coming to life) actually proposed it to me.  We looked at the space available in my 6th gen and we are concerned that a larger oil cooler such as the RC51s will interfere with the fork travel.  That would be a very bad thing.  So I don't think the answer on a 6th gen is the RC51 cooler.

 

Fattys works on sportbikes, drag bikes, heavily modified Harleys (I thought i wasted money well) but alot of racing quads as well, and their racers have had success with inline coolers.  From reading the quad forums (scary), racers have noted temp drops of 5-7 degrees in engine temps after running one of these.

 

http://www.modquad.com/product/2-inline-super-cooler-en-2-3/

 

The easiest and (*probably-disclaimer- I am not an engineer with a PhD in fluid dynamics) most effective place to install it would be the upper central hose connecting the radiators, by the horn.  These are about 3 inches long and would be easy to fit here.  Plenty of open air flow as well.

 

For those of you that love to see the numbers, they even sell coolers with a gauge on them.

 

Not only are these cheap, but they are much easier to install than another larger oil cooler.  For the 6th gen, with really tight packaging and no room for a larger oil cooler where the stocker is mounted, then this could be a good solution.  On my '01 5th gen, its getting one of these plus the RC51 oil cooler that worked so well on my Hybrid 5.5.

 

More research to follow.

[jhenley17]

Hm... Wonder if I can fit that between the rads on my 8th.

[deltaboxii]

Got a pic of the cooling system on the 8th?  not very familiar with the 8th gen.  Although at some point if I ever wear out my 6th gen that's what i will be getting.

[Mohawk]

I have come across those, but all the. Ones I've found seem to be smaller bore, or very short. I already added alloy pipe to replace the cross rad pipe & the pipe for thermostat to rad cap. I'm looking into the possibility of replacing the cross rad pipe with a custom rad. Basic check shows the gap to be approx 330mm & I could probably squeeze in a 140mm deep rad & still keep my ramair intake.