Pulse and Glide for competition. Added mass?

[sendler]

I'm planning to enter my 2011 Honda CBR250R in the Green Grand Prix at Watkins Glenn Speedway in April. It is a hilly race track and should have some good opportunity for engine off Pulse and Glide. Assuming a competition setting where there are no stop signs, no use of the brakes needed in any way as the final average speed must be between 49 and 54mph, wouldn't the effectiveness of engine off Pulse and Glide, and my final average fuel economy be increased by adding ballast to the bike right up to the point just shy of having trouble pulling up the hills in top gear?

[user removed]

I would focus on climbing the hills at best efficiency then coasting downhill with EOC. A slight decrease on the uphills followed by an increase in speed on the downhills, if they are enough grade to do that with the engine off. Using your stock weight and your tuck you should be able to easily get over 100 MPG and possibly 120 MPG on that course (which I am not very familiar with).

Possibly an aero attachment to your back to get the air flow behind you less turbulent, a boat tail that was attached to your back in your tuck.

regards
Mech

[sendler]

Originally Posted by Old Mechanic

I would focus on climbing the hills at best efficiency then coasting downhill with EOC. A slight decrease on the uphills followed by an increase in speed on the downhills, if they are enough grade to do that with the engine off. Using your stock weight and your tuck you should be able to easily get over 100 MPG and possibly 120 MPG on that course (which I am not very familiar with).

Possibly an aero attachment to your back to get the air flow behind you less turbulent, a boat tail that was attached to your back in your tuck.

regards
Mech

I am designing a simple boat tail trunk as every motorcycle needs some kind of luggage. I may then also play with an aero back pack to get the air from the base of the helmet down to the front of the trunk. I also have a concept of a cloth fairing which you put on over your riding jacket like a vest and the back would be a flexible sock that could be stretched back over the tail of the trunk to create a smooth fabric skin. I would eventually like to do something behind the legs like a land speed bike but might just hold off on that until I can get the CBR125R and make that into my all out competition machine.
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I can bring some kitty litter to add mass in the trunk if I get any practice time on the track, which I doubt. Tuning on the track would be the best way to find out if it is feasible or not. You obviously wouldn't want to add mass if it would then require a downshift or brakes anywhere. But barring those handling and power to weight caveats , more mass would mean more energy storage during the pulse. Better and smoother utilization of high throttle angles and a longer coast to make it all much easier to administer. Lower frequency. I'll have to get on google earth to look at the track to see how tight or hilly it is. If there is a hairpin or chicane that is tighter than 50 mph then you would not want to add any mass.

[sendler]

I am assuming the most efficient engine range would be to pulse up at 80% throttle at rpms around the first torque peak of 6,000rpm. Contrary to hypermiling intuition, this will mean running up and down from 45 to 55mph in 4th gear for two hours rather than cruising along at 4,700 in 6th.

[tortoise]

Originally Posted by sendler

I am assuming the most efficient engine range would be to pulse up at 80% throttle at rpms around the first torque peak of 6,000rpm. Contrary to hypermiling intuition, this will mean running up and down from 45 to 55mph in 4th gear for two hours rather than cruising along at 4,700 in 6th.

On what principle do you assume that peak BSFC is in this RPM range?

As to the added mass, lowering the p&g frequency sounds good, but do you have a guess as to the effect on rolling resistance?

[FXSTi]

Not to be a naysayer, but are you sure want to add the ballast to the back end? I thought the idea was to put the weight up front like an arrow.

Kirk

[user removed]

Originally Posted by sendler

I am assuming the most efficient engine range would be to pulse up at 80% throttle at rpms around the first torque peak of 6,000rpm. Contrary to hypermiling intuition, this will mean running up and down from 45 to 55mph in 4th gear for two hours rather than cruising along at 4,700 in 6th.

I would experiment off the track to see which is better.

regards
Mech

[sendler]

Originally Posted by Old Mechanic

I would experiment off the track to see which is better.

regards
Mech

I guess if I want to get really serious I should hook up an MPGuino for practice.

[sendler]

Originally Posted by tortoise

On what principle do you assume that peak BSFC is in this RPM range?

As to the added mass, lowering the p&g frequency sounds good, but do you have a guess as to the effect on rolling resistance?

BSFC normally approximates an inverted torque curve with additional friction and waste heat advantages as the rpm's get lower.
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I guess it would be easy enough to do coast down measurements to find out how much rolling resistance would increase with added ballast. Judging from the photos I have been seeing from last year it looks as if the track is packed all the way around. With 50 cars on the track, if they were perfectly spaced all the way around, that is only 100 meters apart. And I'm sure that things will get buched up more than that so there is not much room to get your ideal pulse. It might just be better to leave the system as responsive as possible for the best and most flexible maneuvering.

[Diesel_Dave]

I guess I don't see how the extra weight is going to help. It's definitely going to increase the rolling resistance, and I don't see how it'll improve the P&G efficiency. Sure you can glide longer, but it'll take more energy to accelerate the additional mass. More energy out only because of more energy in.

You can still P&G going down a hill, just accelerate faster so the %load stays roughly the same.