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> Help me win at autocross, I wanna be a top 10 car and driver!
crash914
post Jul 1 2014, 06:49 PM
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ok, I need help. currently I am about 3 to 5 seconds off the pace in my local club events. I know most of the time is due to the driver. I think that there is some time in the car also as it is mostly set up for the long track.

Here is what I know so far, if more info is needed..ask...

73 914, blue. bolt in cage, just the 4 plates plus the seat belt for tie in points.

stiffly sprung, Koni yellows, I think 250 lbs in the rear and 21 or 23mm torsion bars in the front.

Delrin bushings everywhere, I have needle bearings, just not installed.

lowered, see pictures for height. 4 inches in the rear to the bottom of the engine mount bar, 4 inches in front to the bottom of the front floor pan.

205 50 15 tires, not sure of the wheel width, 4 lug.

my tires are about 8 year old khumo v710's that have been in the garage and have 4 autocross days on them now.

air pressure I have been running, 22lbs front, 20 rear. see pictures for chalk. looks like I am using all the tread.

Camber is close to -2.4 degrees front and rear. Front toe is 0, not sure about the rear, perhaps 1/4 inch toe in.

Motor is 103 by 80, nickies, split cam, le200 heads, tangerine header, 6800 rpm redline, 11:1 compression, so plenty of grunt.

Megasquirt with twin throttle bodies.

Transmission is open diff, with a flipped 5th gear for 3rd and standard 5th.

no camber plates,

See pictures in the following posts..
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crash914
post Jul 10 2014, 03:03 AM
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Thanks Dave! you are welcome to drive anytime...I know I won't be as fast as Bill or John, (we are in the same class!) so I just want to be top 10. I am running both chesapeake and potomac events as they are pretty close to me..Not ready for the others yet until I get new rubber..next year!
Swing by and say hi!
herb
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crash914
post Jul 21 2014, 09:02 AM
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Latest runs, crappy cell phone video.

Ok, looks like I still spend too much time coasting and am braking late and on the throttle too early...



https://www.youtube.com/watch?v=U9E5_3dCO28


tire pressures were 30/32 I did drop to 29/31 but went slower. I guess I will start higher next time.

Front ride height was bumped up so my control arms are horizontal.
Rear sway bar removed.

Overall, the car felt very good, still a little loose in the rear. The front stuck like glue.
Mostly loose on throttle.

thanks for watching....
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koozy
post Jul 21 2014, 02:05 PM
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Looks much better. There are places you will NEED to coast a bit. Don't let that bother you. In some places it is the faster way around. When you learn better throttle control you will be on throttle in the coasting spots but slowly, and controlled. I would say the loose rear is too high of tire pressure. I suggest going lower before going back to the higher pressures. In my opinion, your pressures are 5 pounds too high.

Do you have the ability to lower the rear ride height?
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koozy
post Jul 21 2014, 04:22 PM
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Coasting is ok, sometimes. This is my run from Saturday. Though, mostly it is a feathering of the throttle when ya need to.


https://www.youtube.com/watch?v=zBBhj3Cybjw
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koozy
post Jul 21 2014, 04:26 PM
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I looked at your video again. You need to get used to the brakes. Get where you are going, in a hurry, and stomp on those brakes. Find where they lock up and learn the threshold just before lockup. This way you will have more confidence to charge into corners.
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crash914
post Jul 21 2014, 05:17 PM
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Thanks Mike,
I think you are right. Looking at my g data, I am pulling much more in turns then on decell. I am still used to the street tires that lock up too easy. I never locked up the fronts and I think I can still keep more speed through the corners. Throttle, I am just about maxed out. I did go to 3rd again as I was on the rev limiter halfway through the straight. It seems to help me to brake and downshift. I just seem to be able to put it together better.

I do have coil overs in the rear. you think I should go lower? I can also stiffen up the front bar. I am about 3/4 soft now.

Thanks agin..
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ChrisFoley
post Jul 21 2014, 07:05 PM
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Keep adding front bar until you don't like the understeer.
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koozy
post Jul 21 2014, 07:34 PM
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What size front bar do you have and how old is it?
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crash914
post Jul 22 2014, 02:54 AM
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front bar is 22mm...how old? it came with the car...I would guess early 2000's

somehow I misread Marks post on tire pressure....looks like mid 20's to 30 should be the ticket...next event next sunday...
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koozy
post Jul 22 2014, 11:02 AM
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Yea, I'd start with trying to maintain 24psi front and 26psi rear before doing anything else to the car. Start there and bleed down as the tires warm up and the pressures go up. This will likely tame the wild rear end. Then, when you get used to that, a couple of events worth, you can fine tune with the bar if needed. Start saving for tires for next season. Even if it is a jar with pocket change and a five dollar bill every once in a while. Start now and you won't find yourself without competitive tires next season. We'll get ya in the top ten, eventually. How many seconds off of the tenth driver are you now?
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crash914
post Jul 22 2014, 11:18 AM
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yep, tires are on the agenda...results won't be posted for a couple of weeks????? but I was around 52 and change ftd was a 49 something. a couple of stock boxters were 51ish. FTD was a turbo 911.....
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mskala
post Jul 27 2014, 08:28 AM
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Herb,
See about 20 sec in for how to avoid shuffle steering. I always know
exactly where the front wheels are pointing.


https://www.youtube.com/watch?v=9BQ0Kn97vwg
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crash914
post Jul 27 2014, 04:46 PM
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Looks good Mark, I will have to give that a try, I was having some problems with the over 180 degrees stuff when I tried it...

video to follow, but today I think i am within 1 to less than 2 seconds from FTD.. Got beat by another 914 that came to play..oh well.

getting better and its looking up...thanks guys!
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J P Stein
post Jul 28 2014, 10:31 AM
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Other Porsches are no competition.......unless you bring a 908/3. (IMG:style_emoticons/default/biggrin.gif)
This was true before Brit added 150 hp.
Wanna go fast? Just bring money.
You'll note that smoothness is temporary. Brit has "quick hands" and uses them............that is what it takes from the driver aspect.

http://www.youtube.com/watch?v=oFl0zJtdnQM
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crash914
post Jul 28 2014, 12:39 PM
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Yep, no cubic $$ here....that is why I only want a top 10...
here is a video of my first run...you will see where I missed the gate..it was fast though!


https://www.youtube.com/watch?v=oaEsjb5Mx70


my last run should be up soon, faster, smoother but alas no data stream....oh well, need more fancy stuff...
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crash914
post Jul 28 2014, 02:51 PM
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Ok, here is a video of my fastet run. I just need to go faster! The data logs of my runs show that I was only about .8g's in the turns and i never hit the rev limiter...

I think one datalog showed 1.4 g's though...must be wrong...As you can here, wheel spin on acceleration is a problem also..that is down to needing tires and LSD..again, $$


https://www.youtube.com/watch?v=hq_bW_IQ63Y
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mskala
post Jul 28 2014, 03:49 PM
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QUOTE(crash914 @ Jul 28 2014, 04:51 PM) *

Ok, here is a video of my fastet run. I just need to go faster! The data logs of my runs show that I was only about .8g's in the turns and i never hit the rev limiter...

I think one datalog showed 1.4 g's though...must be wrong...As you can here, wheel spin on acceleration is a problem also..that is down to needing tires and LSD..again, $$


https://www.youtube.com/watch?v=hq_bW_IQ63Y



Looking better. I don't follow these courses as well as the more obvious runways.
Hard to tell from the vid how bad your tires are.
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ChrisFoley
post Jul 28 2014, 06:52 PM
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It looked like you were driving a "safe" line.

You need to lean on the tires a bit more - sideways and accel/decel.
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crash914
post Jul 29 2014, 04:22 AM
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The above event times have been posted..damn...11th. out of 53. 1.3 seconds back..FTD by the M3 bmw that started before me....
Getting better however, Steve Lutz beat me in a stock motor prepped 914....by .75 seconds. (with new hoosiers) so a much better driver....

I think I need an instructor to ride along and talk me through my lines and how much speed I can carry. I am still getting a feel for how much grip these tires really have...it is more than I have found yet...hammmm to run this weekend? I just might!
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koozy
post Jul 29 2014, 07:39 AM
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Tell me about the data overlay. How do you like it and what hardware are you using for it?
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