yellowss7 Posted May 30, 2016 Share Posted May 30, 2016 Are there better tires for autocross, or do people use a narrower tire to build heat? Nice Run! I use to run the R25B compound on 10 inch hoosiers front and back. Tire pressures would be around 14 or so, even went down to 12 occasionally. As for building heat, Pretty hard to do on a 60 second or less run. Narrower tires would help a bit. Best way to get heat in them is to come out to NJMP with us in July and run for 25 minute sessions. :jester: Good luck with the car. Tom Link to comment Share on other sites More sharing options...
super7guy Posted May 31, 2016 Share Posted May 31, 2016 If you want softer tires, try Avon A15 (soft) or A92 (super soft). The A15 is available in the most sizes compared to the A92. Wayne Link to comment Share on other sites More sharing options...
xcarguy Posted May 31, 2016 Share Posted May 31, 2016 So I had my first shakedown yesterday . . . I had fuel starvation on my second run, which I need to spend some time figuring out. Will, visit this thread if you haven't already...may be helpful: http://www.usa7s.net/vb/showthread.php?11160-Surge-tank-suggestions Link to comment Share on other sites More sharing options...
Silk Posted May 31, 2016 Share Posted May 31, 2016 Are there better tires for autocross, or do people use a narrower tire to build heat? Will, I used to run A6s with R25B compound, and with a light car had trouble getting heat in them on a cold autocross day. Switched to Hoosier bias slicks - also R25B - lighter, good grip, much easier to heat up on a cold day. They cycle out more quickly than the DOT slicks, but much better for autocross in my opinion. Link to comment Share on other sites More sharing options...
MichaelD Posted June 1, 2016 Share Posted June 1, 2016 Will, I think that most D MOD cars at the National level run Hoosiers and a few on Avons or Goodyears [TABLE] [TR] [TD=width: 18%][/TD] [TD][/TD] [TD][/TD] [TD][/TD] [TD][/TD] [TD][/TD] [TD][/TD] [/TR] [/TABLE] [TABLE] [TR=bgcolor: #f0d3f1] [TD=align: center]43186[/TD] [TD=align: left]20.0 x 9.0-13 A2500[/TD] [TD=align: center]FA, SR [/TD] [TD=align: center]9.75"[/TD] [TD=align: center]20.6"[/TD] [TD=align: center]64.7"[/TD] [TD=align: center]8-10"[/TD] [TD=align: center]10"[/TD] [TD=align: center]11.0"[/TD] [TD=align: left]R25B [/TD] [/TR] [/TABLE] Link to comment Share on other sites More sharing options...
teamking Posted June 6, 2016 Author Share Posted June 6, 2016 Thanks for the help with the tires and starvation issues. I'm getting ready for the track so I thought I'd post some pictures of me in the car. Everything is set from a safety standpoint, except I forgot to put the gloves and the arm restraints on prior to the pictures. Anyway, I'd love to get some feedback on any safety issues you see. Link to comment Share on other sites More sharing options...
teamking Posted June 6, 2016 Author Share Posted June 6, 2016 Oh, and another (dumb) question: how do I obtain the "shroud" that goes over the peddle box assembly? (My car didn't come with one and I'm thinking it would be helpful in the event of an engine fire to keep my feet protected) Thanks!!! Link to comment Share on other sites More sharing options...
Kitcat Posted June 7, 2016 Share Posted June 7, 2016 Check with Dick Brink, at Texas Motor Works. He used to be the Bikin dealer in the USA. He has a bunch of left over Birkin parts he is selling and he might have the shroud. Or try Tom Carlin, the new USA Birkin dealer. Fire concerns aside, that shroud keeps the majority of engine heat out of your foot well and it makes driving in warm/hot weather much more tolerable. But not cool. When I have measured the heat there it is typically 110-120 degrees, with the shroud.... Link to comment Share on other sites More sharing options...
teamking Posted June 8, 2016 Author Share Posted June 8, 2016 Check with Dick Brink, at Texas Motor Works. He used to be the Bikin dealer in the USA. He has a bunch of left over Birkin parts he is selling and he might have the shroud. Or try Tom Carlin, the new USA Birkin dealer. Fire concerns aside, that shroud keeps the majority of engine heat out of your foot well and it makes driving in warm/hot weather much more tolerable. But not cool. When I have measured the heat there it is typically 110-120 degrees, with the shroud.... Wow, I wouldn't have expected it to get that hot! I am used to it-- my previous track car was a 944 turbo that I had removed all the HVAC and insulation. With only two windows, it used to get baking hot in there. My data acquisition would run at 118* (although it produces some heat of its own so I don't know how accurate that is for the actual temp in the car). I was debating whether or not to install the cooler for the cool suit-- finding space for the cooler means removing a cross brace that is running from the center of the rear bulkhead across to where a passenger's right knee would be. You just helped me make the decision! And anyway, that brace wouldn't be there if I had a passenger. Link to comment Share on other sites More sharing options...
yellowss7 Posted June 8, 2016 Share Posted June 8, 2016 I got the six pack soft cooler that I just buckle in in the passenger seat. You could always strap it in in the boot as they say in UK as well. The six pack keeps me cool for the 25 minute sessions on track that we do. They do sell a 12 pack if you needed more time. Tom http://www.ebay.com/itm/271911605337?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT Link to comment Share on other sites More sharing options...
teamking Posted June 24, 2016 Author Share Posted June 24, 2016 Hi all, Wanted to give an update. I took the car to VIR Wednesday/Thursday and had a real challenging time. I struggled with fuel starvation the whole time. I had chalked up my fuel starvation in the autocross to the fact that the tank only had 1.3 gallons in it. So I filled the tank for VIR and went out. After about 3 laps, it started to starve in turns 4 and 5. 4 is a 90* left, whereas 4b and 5a are a nearly 180* right. Note that Oak Tree is a 180 degree right and that Hogpen is a left followed by a long right (but with significant compression), but it was 4/5 that was giving me the problem. My starvation at the autocross had only happened on the run where I got a little offline and took a jink to the left before my 180* right. Hmmm. Anyway, it gets worse on the successive laps and I decided to go in after 5 laps. Also, my mirrors were not adjust properly (and I couldn't reach them with my arm restraints), and twice my AIM solo had come off it's magnetic mount (and I actually caught it in midair both times-- wish I had video of that!). So, I figured I'd bring it in, get the mirrors right, put some zip ties around the solo, and out I'd go. Except that it wouldn't fire up. Crank crank crank, but no catching. Got some advice from the Wisko guys (they build/maintain hayabusa-powered Radicals out of their shop at VIR and seem to be really sharp) and put the car up in the air and took out the sponge from the tank that was 8 years old since it was probably deterioriated, and removed the fuel filter. The sponge was deteriorating just a little, but they cut open the fuel filter and it was fine. But now I needed a new filter so went into town and got a new filter at Advance (20 minutes each way). Since the next step after reinstalling the filter was to test the pump, I thought about getting one while in town but decided that that would just be throwing parts at it and headed back to the paddock. Sure enough, although it clicked and I could feel pulses in the hoses, there was absolutely zero flow. So I went back to Advance and got a replacement pump. Hooked it up and it was flowing. I'd thrown away the sponge but figured if I kept the tank full, I should be OK. Got everything put back together by 8:15 pm and took a shower (rinsing out the gasoline from my hair and at this point I will mention that gasoline doesn't taste good, stings the eyes, and is a significant irritant on little cuts and scrapes on your hands...). Dinner and a beer at a crowded Oak Tree Tavern and back to the room by 10:15, exhausted an hoping for better things in the morning. Woke up and got out on track by 9:00. Five laps and starvation in turns 4/5. Came in and filled the tank (with two gallons). Five laps and fuel starvation in 4/5. Went out again and started getting starvation after 3 laps. Came in after 4 laps and filled up and went out and started getting starvation after two laps, and was starting to get it in the climbing esses (not a great place to lose control of the throttle!)! Came in and parked the car in front of the trailer and tried to decide what to do. Hmmm. Decided enough was enough and I'd just call it a day (it was 2:30 by then). Went to start the car to put it on the trailer and crank crank crank, no catching! Just like yesterday. Fortunately, I have a winch on the trailer and the car was already in position, so up it went. I'm 99% confident that I burned up another fuel pump. I guess my thinking is that a fuel pump has a lifespan of about 15 seconds, in total, or pumping air before it's dead. And that fuel starvation at the engine is both a cause and an effect. Sloshing in the tank is causing starvation *to* the pump, which causes it to start to overheat, which causes it to overheat, which causes starvation *from* the pump as it pumps less and less fuel. Until you get starvation with a nearly full tank and then it won't start at all. So, what is causing the starvation in the first place? Clearly running without the sponges isn't helping. But let me describe my fuel system because I think there are some issues there that should be addressed. The tank is a 5 gallon cube, maybe 15" in each dimension. There is section cut out at the bottom left to act as an additional accumulator, and this is where the hose to the fuel pump is attached. Rear View: _____________ | | | | | | | __________| |_/ The hose to the fuel pump flows down and and toward the front of the vehicle, and then bends to be on a transverse and horizontal path toward the fuel filter. The filter is a cylinder with an inlet on one end and an outlet on the other, and is mounted horizontally such that the inlet and outlet are at the same height off the road. This is the first issue. My belief is that air is accumulating inside the filter (how would it escape) when it is mounted in this configuration. It should be mounted vertically with the outlet directly below the inlet to prevent air accumulation. The fuel pump looks similar to the fuel filter and it is mounted next to the filter and at the same height such that the hose from the filter outlet to the pump inlet makes a 360* decreasing radius bend at the same height off the ground to get from the filter to the pump. In other words, the hose from filter to pump is a big circle sitting parallel to the ground. My belief is that a left hand turn is causing fuel to slosh in the tank and air gets to the outlet of the tank. As fuel is pumped, the air makes it's way into the filter where it stay in a little bubble in the top of the filter. Now we immediately transition to a right turn. Now the air in the filter moves to the outlet side of the filter and as the pump continues to work against fuel it is drawing air into the hose and eventually it runs out of fuel and into air. Now it starts spinning wildly and begins to burn itself up. Now it pumps less efficiently and the problem gets worse and worse. Eventually, it won't start the car. So, my thinking: 1. Get new sponges for the tank. 2. Mount the filter vertically so it can't hold air. 3. Move the pump so that the loop of hose is removed and there is a continuous downward path from the filter. Not sure if the above is possible without moving the tank higher. Another thought is to find a filter that has it's inlet and outlet at the top. I am going to re-read the thread mentioned above on fuel starvation. Any thoughts appreciated. ******************* As to driving the car: It took an afternoon session with a literal back-to-back session (with only refilling the tank in between) to get the tires heated up. Even so, I was lacking rhythm/confidence. I managed a 2:18.2 (my best in the 944 turbo at VIR was a 2:13). Top speed was 124.4. I could have taken the turns leading onto the straights a little better, but it seems like I'm pretty close to top speed by the end of the straights. 130 may be possible but that would be it. I struggled a little bit with the sequential shifting. I only used second gear in the 944 coming out of Oak Tree and it's up to go from 2nd to 3rd. Guess what I tried to do twice coming out of Oak Tree... up! Which the tranny was kind enough to reject before I floated any valves. Argh. Old dog... new tricks. I just decided to use 3rd for Oak Tree rather than risk blowing up the engine after I realized why I was making that mistake. I'll fix it with visualization before I go back. But otherwise the car was well balanced and a delight to drive. Very visceral. I'd never experienced an open cockpit so the helmet trying to pull off of my head at speed was an experience! I think that a 2:10 is possible with the fuel starvation solved and a chance to build some heat in the tires and get a rhythm going. Here's video: Enjoy! Link to comment Share on other sites More sharing options...
jlumba81 Posted June 25, 2016 Share Posted June 25, 2016 Not sure if anyone mentioned it yet, but a holley hydramat might help you out with the fuel issues. Link to comment Share on other sites More sharing options...
coffee break Posted June 25, 2016 Share Posted June 25, 2016 Check the thread on "surge tanks" http://www.usa7s.net/vb/showthread.php?11160-Surge-tank-suggestions Link to comment Share on other sites More sharing options...
ottocycle Posted June 26, 2016 Share Posted June 26, 2016 I ran a Hayabusa engined car for a while and loved it. I hope to build another. I adapted the bikes fuel pump and integeral filter to my fuel tank and considered the possibility of fuel starvation in high G turns. As it turned out it was not a problem (I am a slow old fart!), but while adapting the tank I allowed for the possibility of putting a swinging pickup in the tank that would follow the fuel in high G turns. If you look at the fuel tanks of radio controlled aircraft you will see what I mean. I agree with "coffee break" in that surge tanks are definitely worth exploring. I think I know of your car, I bought a spare crankshaft off the previous owner (if I am correct). He was pretty successful at tracks in Texas. You might want to talk to him. Your problem might be more related to an existing problem rather than an inherent design issue. I am a great believer in the KISS principle and the fewer links you have in the chain, the stronger the chain will be. Food for thought. Good luck. Link to comment Share on other sites More sharing options...
teamking Posted June 26, 2016 Author Share Posted June 26, 2016 Not sure if anyone mentioned it yet, but a holley hydramat might help you out with the fuel issues. Yes, I'm intrigued. I'm not sure exactly how I would run the plumbing, though. I need to do some more research and plan on calling a talking with someone at Holley just so I can ask a bunch of dumb questions. Check the thread on "surge tanks" http://www.usa7s.net/vb/showthread.php?11160-Surge-tank-suggestions Yes, that thread was very helpful. I should have pointed out that I do have a surge tank after the pump, although I *think* my problem happens before the surge tank. I ran a Hayabusa engined car for a while and loved it. I hope to build another. I adapted the bikes fuel pump and integeral filter to my fuel tank and considered the possibility of fuel starvation in high G turns. As it turned out it was not a problem (I am a slow old fart!), but while adapting the tank I allowed for the possibility of putting a swinging pickup in the tank that would follow the fuel in high G turns. If you look at the fuel tanks of radio controlled aircraft you will see what I mean. I agree with "coffee break" in that surge tanks are definitely worth exploring. I think I know of your car, I bought a spare crankshaft off the previous owner (if I am correct). He was pretty successful at tracks in Texas. You might want to talk to him. Your problem might be more related to an existing problem rather than an inherent design issue. I am a great believer in the KISS principle and the fewer links you have in the chain, the stronger the chain will be. Food for thought. Good luck. You are thinking of the right car. I bought the car from TMW, and either Dick has not put me in touch with the original owner, or the original owner has not contacted me, after several requests. I will try again through Dick, I feel awkward about just looking the guy up in the phonebook-- like I would be pestering him. Link to comment Share on other sites More sharing options...
teamking Posted July 11, 2016 Author Share Posted July 11, 2016 (edited) Hi all, So, I wanted to give an update. I spent the 4th of July weekend underneath the car replacing and rerouting all the fuel lines (see the diagrams for the original routing and the new simplified routing). I guess I'll make the big event next year-- sorry I missed it. Anyway, I must have done something right. I took it out yesterday to an autocross and got FTD! Fuel system was great-- not a hiccup! Dick did put me in touch with the original owner and he was very helpful in getting me up to speed on the system. Thanks to you both! Edited July 11, 2016 by teamking Link to comment Share on other sites More sharing options...
yellowss7 Posted July 11, 2016 Share Posted July 11, 2016 (edited) Congratulations on the FTD!!! and sorting out the fueling. We hope to see you next year on track. Tom That course was nuts, very tight, and I'm sure the Vettes hated it. You'll like stretching the legs of the 7 on track. Edited July 11, 2016 by yellowss7 Link to comment Share on other sites More sharing options...
teamking Posted July 12, 2016 Author Share Posted July 12, 2016 That course was nuts, very tight, and I'm sure the Vettes hated it. http://www.brr-scca.org/forum/viewtopic.php?f=1&t=16574 Link to comment Share on other sites More sharing options...
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