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Author Topic: Getting ready for Maxton and Bonneville 2008...  (Read 9884 times)
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Rchop
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« Reply #15 on: March 31, 2008, 07:12:42 PM »

This is a "rider's eye view" of the all the onboard information...



« Last Edit: March 31, 2008, 07:36:26 PM by Rchop » Logged

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#4836 A-PBF 750cc(complete)
#765 A/G 650cc
Rchop
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« Reply #16 on: March 31, 2008, 07:19:31 PM »

cool  ! I am not a bike guy but like any thing that is fast
terry

Thanks Terry, it may not be as fast as a modern bike, but this old 1970 R75 can go!!
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Peter Jack
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« Reply #17 on: March 31, 2008, 08:10:28 PM »

Rchop:

Really nice job.

Is it possible to streamline around the cylinders, then allow a limited amount of air in through a small opening and duct it around the cylinders and heads similar to a small airplane?

Pete
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Rchop
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« Reply #18 on: March 31, 2008, 08:29:39 PM »

I have thought about that Pete. I think streamlining the cylinders would just add more drag than leaving them hanging out there. They are pretty well streamlined in the original state. We are only talking about 50-60 hp and top speed in the 130's if I'm lucky this year. My top speed was 123+ last year without all the changes I'm making this year.
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Sumner
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« Reply #19 on: March 31, 2008, 09:17:40 PM »

Very nice, I'd change one small thing though.  Cut those cylinders/heads off and put them straight up and down inside the fairing  cool.  Honestly though it looks like you thought things out and did a good job.

If you are only using one battery have you tried having the LM-1 sensor warmed up and data logging and then starting the motor??  Ours would drop out with the low cranking voltage.  I put a second small battery just for the data logging to take care of that and it has worked fine.  It is the pits if you are on the line ready to go and the engine dies or something and you have to restart it and wait for the sensor to warm and push the record button while they are wanting you to go.  I put a separate battery on the lakester also just for data logging as a result of all of that.

Good luck with the bike,

Sum
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« Reply #20 on: March 31, 2008, 09:24:27 PM »

Maybe a smooth bell mouth on your intake and a bit farther forward would be better---put tube ahead of body turbulence and sharp edges break up flow,bell mouth would smooth it out.
Maybe some of the others here with more experience and expertise can chime in.
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Bonneville 2001,2002,2003,2004,and NO stinking 2005,DLRA 2006, next?
Well,sure can't complain about 2008--6 records over 200 and 5 hats from Bonneville,Bubs, and El Mirage for the team!
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« Reply #21 on: March 31, 2008, 11:08:20 PM »

The air intake tubes look corrugated, maybe that's an optical illusion because of the stripes, but I'd think that smooth tubes would flow better, but I'm prepared to be wrong.

roy
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Rchop
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« Reply #22 on: April 01, 2008, 07:34:36 AM »

Great idea Sum, I will see if my LM1 drops out on starting. As far as moving those cylinders, I would love have an XR750 motor in this bike...if I could find one grin

I'm not sure about the bell mouth. I have seen quite a few intake tubes at El Mirage and Bonneville on cars and bikes...most without a bell mouth.

The intake tube is corrugated on the outside, but smooth inside. The tubes are way bigger than this engine will ever need, so I won't have to worry about any restriction. I set it up this way to give the carbs intakes undisturbed air and maybe...maybe a slight pressure increase if I can go fast enough!! I am not an expert by any means on high speed airflow (advantages/disadvantages), so any input is appreciated.
« Last Edit: April 01, 2008, 07:46:02 AM by Rchop » Logged

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Larry Forstall
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« Reply #23 on: April 01, 2008, 07:44:43 AM »

Nicely done. Difficult bike to streamline. Love the ram air. I think there is something to be gained by pulling the clipons in and forming blisters around the open fairing sides to enclose the riders upper torso. Yes it will be wider, but I believe less drag. Good Luck.  Larry
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« Reply #24 on: April 01, 2008, 07:51:24 AM »

Nicely done. Difficult bike to streamline. Love the ram air. I think there is something to be gained by pulling the clipons in and forming blisters around the open fairing sides to enclose the riders upper torso. Yes it will be wider, but I believe less drag. Good Luck.  Larry

That is on my list for Bonneville Larry. I tried to just turn in the clip-ons this week and they contacted the fairing. Kent had a set of bars on his side car rig at Bonneville that put your hands in position similar to a boardtrack racer. I'm gonna try to build something like that and then fair in the side openings.
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« Reply #25 on: April 01, 2008, 09:50:19 AM »

Cool! Really like them boxer twins vorsprung durch techique.
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« Reply #26 on: April 01, 2008, 10:08:47 AM »

That is one nice beemer. Good luck in NC and see you at SW.     Fred
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« Reply #27 on: April 01, 2008, 11:01:14 PM »

take a look at http://www.profblairandassociates.com/pdfs/RET_Bellmouth_Sept.pdf

roy
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« Reply #28 on: April 02, 2008, 08:04:59 AM »


Thanks for the comments guys, I look forward seeing all of you at the time trials.



Interesting reading Roy, thanks. The question is...will I get a measureable benefit from a bellmouth? I will try to find one to fit my intake before I go to Bonneville and try it. I have found that every little bit helps in LSR.
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« Reply #29 on: April 02, 2008, 09:38:29 AM »


Thanks for the comments guys, I look forward seeing all of you at the time trials.



Interesting reading Roy, thanks. The question is...will I get a measurable benefit from a bellmouth? I will try to find one to fit my intake before I go to Bonneville and try it. I have found that every little bit helps in LSR.

It was interesting and as you pointed out maybe not worth a lot, but some.  One thing to keep in mind is that the article is concerned with the air that goes into the bell-mouth.  We are also concerned with the air that goes around it and is the reason we try and size the opening as close to right as possible to avoid air stacking up in front of it and reducing the aero in that area.  We have tried to round the opening.....



........... edges so we are more in the middle between the straight and bell mouth.  I think the bell mouth, like they show, without finishing off the sharp outer edges would be bad aero and you might need more HP to overcome that than what you are picking up with the bell mouth.  They also criticized the rectangular opening we have on this car and I do see the point there.  Mine on the lakester will be round like on Rick's red streamliner.



While we are on this, I feel openings like on the car in the picture (and is one that goes with us) is a disaster.  It might have the right amount of square inches of inlet, but it is so narrow top to bottom that I feel a lot of the inlet area is ineffective and not contributing to the air the motor needs. The flat leading edges of the opening probably cause air to pile up there and effect both the air going into the scoop and around it.  Neither good.  Now saying this the car has set records.  I still think it would do better with a more oval shaped opening that could probably be smaller.

c ya,

Sum

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