Total CFM to cool bike. (Oil cooled) | GTAMotorcycle.com

Total CFM to cool bike. (Oil cooled)

ANDRASTA

ANDRASTA

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Hello,


I am designing a cooling system for my 90 GSXR 1100 ( Oil Cooled). I am just wondering if anyone knows how many CFM approximately I would need to keep the bikes temp steady or at least bring it down? It has a few modifications like higher compression, Jet kit, Ported head, full exhaust etc.


I know for example alot of Italian bikes run twin Spal fans ( 5.2") that pull approx 350cfm each but, they are water cooled bikes. The way its going, I can most likely fit 2X250cfm fans right now without too much issue but I still need to do some measuring. My oil cooler looks curved, much like that of a Yamaha R1 if I had to describe it.

I also do not know how the heat dissipation compares with oil vs water??


Im just trying to decide on going with a single large fan or small twin fans placed on the far edges of the cooler right under the inlet pipes??


If anyone has experience with heating/cooling/engineering feel free to chime in!!


What you guys think??
 
Couple of thoughts:

- how much is your bike overheating by? Before going down the fan route, perhaps just changing the viscosity of the oil you use may help bring the temps down? Higher weight maybe?
- if you are going to install fans, are you going to manually trip them or hook it up to a thermometer? You don't want to cool the oil too much that it doesn't reach proper operating temperature.
- if you don't install a thermometer, I've heard of some guys installing automatic switches attached to brake lights, neutral gear, etc., so if you're stopped in traffic the fans come on. Just a thought...
 
Add a secondary oil cooler - either below the existing one or in the tail section.
Oil PRESSURE is more of a concern than CFM.
 
Thanks for the advice,

Unfortunate the thing with auxiliary coolers is it does not make much of a difference. These older bikes require you to be moving to keep the air flowing through the rad. The auxiliary cooler will maybe give me a couple of more minutes of idle time but wont be able to handle traffic duty on a hot summer day.

Lightcycle....

If the bike sits for about 10 min it will start to get really hot. I have tried different oils and doesn't make a difference. Yes , I will be triggering the fans remotely through a switch. Both fans will have a separate relays tied into 1 switch. The thing with temp sensors is most are only up to 195 degrees. These bikes normally run 200 to 215 degrees so quite hot haha.

Mach12.... Sure anytime, love the old bikes.
 
Smart *** comment ... don't let the bike idle for 10mins, especially big air cooled sportbike. 10mins is really loooong time, to design your cooling system to withstand something like that without overheating ... Perhaps you are talking about 401 commute and accident happens ahead of you?

Shut her down for a bit, or lane split, in those circumstances, but keep moving. Eventually buy a different bike for commuting.
 
Engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water’s boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings.

As for ultimate power potential, the general consensus among most racers is that hot oil and cool water make more power in most engines. Cold engine oil causes excessive frictional drag on the bearings and cylinder walls. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees.


A full-synthetic oil will withstand sump temperatures in excess of 300 degrees, and for hard-core professional racing, some race teams are experimenting with ultra-thin, specially formulated, race-only synthetics operating at 350 degrees or even higher.


Also remember that a high-end engine is built as a total combination. Piston-to-wall clearances, piston ring end-gaps, and bearing clearances are specifically tailored to match the engine oil’s characteristics and intended operating temperature.


Maybe you're trying to solve a problem that isn't there ?
 
Stuck in traffic is trouble for plenty of bikes. If you are wanting to put cooling fans on the oil filter to help with that, it's pretty likely that two fans will cover the oil cooler better than one. It's better to have a little bit of airflow over the whole oil cooler than have a lot of airflow over only a piece of it. But ultimately it will be determined by how much you have space for.

Find a way to monitor the oil temperature upstream of the oil cooler (because that will be fairly close to the temperature in the oil pan).

I've seen hot-rodded air-and-oil-cooled gixxers with multiple oil coolers to try to keep the temperature under control.
 
Thanks guys.

Ultimately I'm looking to see how much cfm would equate to the bike moving at a certain speed across the section of the oil cooler.

I understand that it's a little bit different than moving due to the fact that the motorcycle is under more load. I could essentially build the cooling system between 400 CFM and 1000 CFM.

I'm leaning towards dual fans totaling 500 CFM but I'm not sure if that will be enough. Most modern sport bikes are pulling about 700 CFM but that is through a water-cooled radiator.



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You're not pushing the envelope too much with those mods. I'd just put any fan that fits, it might not need to blow directly at the oil cooler either. Think Buell XB. Monitor oil and cylinder head temps, run fan to suit. IMHO, too many variables to pin down a cfm.
 
ANDRASTA said:
Lightcycle....

If the bike sits for about 10 min it will start to get really hot. I have tried different oils and doesn't make a difference. Yes , I will be triggering the fans remotely through a switch. Both fans will have a separate relays tied into 1 switch. The thing with temp sensors is most are only up to 195 degrees. These bikes normally run 200 to 215 degrees so quite hot haha.

Mach12.... Sure anytime, love the old bikes.
Click to expand...

You want to be looking for a switch, not a sender, to turn something on/off at a specified temp. Hot as you like, VDO brand for example.

https://www.vdo-instruments.com/sensors/temperature-sensors-switch.html
 
What is it exactly that you're concerned about - mechanical longevity or rider comfort ?
As has been posted previously, without an oil temp gauge you're wasting your time.
 
inreb said:
You're not pushing the envelope too much with those mods. I'd just put any fan that fits, it might not need to blow directly at the oil cooler either. Think Buell XB. Monitor oil and cylinder head temps, run fan to suit. IMHO, too many variables to pin down a cfm.
Click to expand...

I think your right. Might go with the smaller fans.

Neil_V said:
You want to be looking for a switch, not a sender, to turn something on/off at a specified temp. Hot as you like, VDO brand for example.

https://www.vdo-instruments.com/sensors/temperature-sensors-switch.html
Click to expand...

Thanks for the link!! I might go that route. I was initially considering just mounting a small switch to manually activate.

TK4 said:
What is it exactly that you're concerned about - mechanical longevity or rider comfort ?
As has been posted previously, without an oil temp gauge you're wasting your time.
Click to expand...

Yes, for sure, will be mounting a gauge for temp. Going to most likely run it from either the pan or the crank case.
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