Is there a difference in horse power between water cooled 107 to air cooled?

 

The water cooled heads will run cooler than the oil cooled brother and maintain a more consistent ideal temperature resulting in a better performing motor.

That said, I think the new oil cooled heads are a brilliant way to help cool an air/oil cooled motor.

 

I would agree with Scottt.

There has been a little evidence on the internet that the "twin Cooled" engines run about 50 degrees cooler than the oil cooled heads. That in theory would provide a minor and more consistent performance increase. However the "twin cooled" engines are also in a bit heavier bike than the base 107. I'd think that would negate any minor performance increase.

Personally I'd be more comfortable starting a serious performance build on any of the twin cooled bikes than on my new StreetGlide.

 

The turnoff for some regarding water cooling is additional unnecessary complexity.

 

At the expense of 30% less torque?

 

From my personal experience, the twin cooled system simply works great. I have been riding Harley's since 1989, my twin cooled 14 Limited is the first ride without any heat concerns. Once broken in, the radiator fans seldom run and I live in a warm climate.

With all this said, I think the new M8 air/oil cooled heads are a great design. Simply not as effective as the water cooled heads. Everything has tradeoffs.

 

If the M8s are similar to the TCs, the advantage in the twin cooled version is the ability to maintain its timing when very warm. In so doing, power is not lost due to retarded timing.

 

The twin cooled engines DO NOT have 30% more torque.

 

You will not find much difference. Yes coolant sheds heat a little faster than oil.

However with Syn oil which has low viscosity is close in heat dissipation. Why to you think engines run cooler with it instead of mineral oil?

So with a much larger oil cooler than in the past and a third larger oil capacity and higher flow oil pump it would be hard to show any difference.

To H-D's credit they run the water pump different than previous wet heads. The coolant temp is no longer controlled by a thermostat but by the ECM. The ECM controls the pump speed when the sensors tell the ECM the head temp the ECM slows or speeds the pump to control the temp within a certain range.

My preference is the oil cooled. Less parts, less maintenance and less weight.

It has worked well for years on my 08 Buell Ulysses and 09 XR1200 which have oil cooled heads.

30% less torque??? How about this example. 2012 CVO 110 spec 122 ft lbs of torque and 9.12:1 compression. Now the 16 CVO twin cooled 115 ft lbs and 9.5:1 compression.

My 12 CVO out runs my 16 CVO any day of the week.

By the way spec's on 17 M8 whether oil or coolant are IDENTICAL.The ECM in twin cams only reduced timing when KNOCK was detected not by temp.

 

I am not going to argue your torque numbers but your math is just wrong. 115 is just 6% lower than 122 not 30%. Just sayin