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Post by Simon on Sept 5, 2015 14:07:00 GMT -5
Having decided my slowness is pretty much caused by the driver rather than set up, I downloaded a lap from Davis last week from the MyChron and graphed it in Race Studio, Here's my quickest lap from the main. I have annotated it with my thoughts (hopefully you can read it!) but an interested if anyone else has any other comments. (note that once the rev limiter kicks in the RPM trace goes all over the place due to missing sparks) I would dearly love to compare this with one of Rich's laps !  If you can't read this, download the image from here .... i518.photobucket.com/albums/u349/wormoid/DavisLap_zpsblyuvzuo.jpgOh, and that was NOT a 20 lap main ! |
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Post by norcalacr on Sept 5, 2015 20:06:46 GMT -5
Gearing looks about right. You spend 1 sec at the clutch stall speed in the hair pin but otherwise it's fully engaged. While you don't Rich's trace you could compare lap 17 to one of your slower laps to see what you did differently.
Brake and throttle position would be good to have. Even binary signal would be valuable.
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Post by Simon on Sept 6, 2015 11:56:20 GMT -5
You think that flat bottom on the curve just after second 34 is the clutch disengaging ? That may well be the case. I'll overlay some other laps of mine to compare. The mychron pedal position sensors are stupid expensive, but it looks like you can do a DIY version, this might be an interesting little project to get brake and throttle position data. mychron4.webnode.com/sensores/building-custom-sensors/ |
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Post by Dan Pell on Sept 7, 2015 18:25:35 GMT -5
Good stuff, Simon! The best way to understand one's challenges, is to review data. I'd be interested in comparing this to earlier data that day, with different gearing, a chassis adjustment, or cooler asphalt. can you post that?
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Post by Dan Pell on Sept 7, 2015 18:35:24 GMT -5
BTW, turns 1 & 2 are interesting, turn 3 looks normal. The time @ 6600 rpm is strange, (either brake or WFO, pick one???) they why 2 seconds of limited rpm gain? At the .36 second point, to start to gain rpm, then lose some might be a tight chassis?
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Post by brad42 on Sept 7, 2015 23:09:58 GMT -5
Do you have the associated video? I do not recall where the HP and Torque peaks are on a WF which needs to be part of the analysis as well.
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Post by Simon on Sept 8, 2015 12:49:55 GMT -5
Do you have the associated video? I do not recall where the HP and Torque peaks are on a WF which needs to be part of the analysis as well. Unfortunately I don't have any video Brad, agreed that would have good to have side by side. |
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Post by Simon on Sept 8, 2015 13:00:02 GMT -5
BTW, turns 1 & 2 are interesting, turn 3 looks normal. The time @ 6600 rpm is strange, (either brake or WFO, pick one???) they why 2 seconds of limited rpm gain? At the .36 second point, to start to gain rpm, then lose some might be a tight chassis? The time at 6600 PRM is most certainly the mega bumps coming down the hill, I just never felt confident / comfortable enough to keep it wide open down the hill so I'm sure it's just partial throttle and hang on. I need to fix that, or find a less bumpy line down the hill (not sure there is one). The drop off at .36 is almost certainly the left turn of the esses coming onto the back straight. Like you say, the kart is probably tight there at low speed, it did sound like it was bogging down. Any ideas on how to free it up at low speed withut making the back end way loose in the faster corners ? The only other laps I have were from earlier in the day when I was running 2 less teeth on the back. I'll grab a fast lap from that session later and compare. |
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Post by ron90 on Sept 8, 2015 14:40:29 GMT -5
I am having a hard time seeing the picture, but here is my best shot because I do understand Davis.
Turn 1 should not drop that much. Lower the rpms to mid-range but stay on the throttle to keep the kart loaded up. If you drop really low in the middle of Turn 2 the kart will unload and you slide. Then Turn 2 should be a slight lowering but get ready to get on throttle hard to rotate out and up the hill. Remember after slowing for turn 1 a little you are not up to speed for Turn 2 so you don't really have to get off too much. Mostly full throttle from mid-Turn 2 to get ready for the uphill after Turn 2.
Turn 3 is supposed to be full throttle and rotate kart. I had to work on that a lot years ago to trust the turn and kart setup. Those that lift at Turn 3 struggle to get back up to speed in the sweeper. You should be full throttle from mid turn 2 until you lift at the bottom of the sweeper. You never get to full throttle before the bottom of the sweeper. Losing a lot of time.
If you are hardly getting to your limiter, maybe add 1-2 teeth to keep you higher in the rpms until you get quicker and then drop teeth. More teeth around the track, with a little more time on the limiter on front and back should be quicker, and give you more confidence coming out of the corners.
I cannot run the low teeth like Rich, but I am always about 1 tooth away. Sometimes we match but my problem is kart setup with my screwed up front end.
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