X64v

Hey guys, I'm getting close to my very first track day (Jan 26th/27th), car's just about ready, but I really feel that I need to know more about track etiquette. Obviously I'm gonna make some beginner mistakes, but I don't want to establish myself as that 'stupid noob' that gets on everyone's nerves or potentially causes a dangerous situation out on the track. I've read up all I could find in a google search on the subject (which surprisingly wasn't all that much), but I'd like to hear from everyone some tips to good track etiquette, especially things that lots of beginners tend to do, or things that may not be obvious to do/not to do. Also, I'm probably going to buy a book on the subject (not high performance driving, but more track day tips/etiquette), any suggestions as to good/bad books out there? Sean

Everything's connected to a single good ground. I do not have a spare set of wires to check with. Cap and rotor are fairly new, and it's done this since they were brand new. Come to think of it, it's only done this since I started using spark control with megasquirt. When I had megasquirt running fuel only, with a pertronix ignitor in the stock L24 dizzy for spark, I never had this problem.

Hmm, battery voltage stability is definitely tied to rpm in my logs. Perfectly steady at idle, increasingly noisy as revs climb. Could this be an alternator problem, or just a wiring thing? My datalogs of the problem don't appear to contain any resets (everything is continuous and consistent).

I think you may be on to something. Looking at that graph, along with all my other datalogs, with battery voltage plotted in the lower graph in megalogviewer, my battery voltage goes crazy as the revs increase. Is that normal, or is that a problem for me? Something else to think about: That 2nd gear pull didn't have any misses. These battery voltage spikes are always present as the revs increase, but I only get a miss after at least an hour or so on the freeway.

The miss 'feels' like just a single spark event being dropped, perhaps once or twice per second. For a little more info, I'm running spark control as well, firing the coil via the vb921, and triggering via an '82zx VR dizzy (from a N/A zx, not a turbo). It doesn't always miss at high rpm's, only on the freeway after perhaps an hour or two of driving. Attached is a datalog of a second gear pull. After 5k, is that rpm graph normal, or too rough? tune 4-c.zip

Just snapped a few on my road trip through the mountains today. Nothing too special, as I was freezing and eager to get back into the warm car (okay, so I was playing in the snow...). And excuse the z, it's filthy from hours of roadtrippin.

Can I get someone to post a datalog up here that goes up to 6k or 7k rpm? I've been chasing down a slight high rpm miss for quite some time now, and I think it might be due to an inaccurate rpm signal above ~5k rpm, but I haven't been able to find any datalogs to compare my signal to. Thanks.

Yes.

It flatlines, I've seen it on my own datalog of some unexpected boost creep. It will use the highest VE value in the current rpm column. I'm not saying that Phil should put it right at 310kpa if he expects to see 308kpa manifold pressures, but simply that his highest number does not have to be 408kpa. For example, when I expected to see a max of 150kpa, I'd write my fuel map up to 170kpa, and set my overboost cut right there at 170kpa. I could, but it's a matter of time vs. results. Since Megasquirt extrapolates between values, and I already have six kpa values between cruise and W.O.T. (50-100kpa), I've already got all the control I need over the map. Going between 20-100kpa in 7kpa steps would give me eight kpa values between cruse and W.O.T. instead of six - not enough to make a difference in driveability in my opinion, especially since Megasquirt would have extrapolated my numbers to those anyways. Those two extra values, however, would give me 24 more entries to edit when I change the curve of the fuel map any more than just some fine tuning. In short, if I can get the AFRs I want everywhere with six even kpa values, why use eight oddly spaced ones?

The highest KPA entry in your fuel map doesn't have to be the max that the MAP sensor will read. The highest entry I have in my N/A fuel map is 100kpa, though the sensor goes much much higher. Right now I have one that reads: 100 90 80 70 60 50 40 30 20 10 0 0 (The 0s are at the bottom because I really don't need any more than 10 pressure entries in my 12x12 table, though the 12 rpm tables help a lot)

Bryan - I see you said you got those 'cheap new turbos' for $400 for both. Are those the eBay turbos that everyone talks about, or did you just get a good deal on name brand ones somewhere? If they're the eBay specials, please keep us updated on their performance/quality. It's always interesting to see how good/bad they are.

I've been daily driving my 240 for almost three years. It's not totally trouble free, but as long as you're ready to replace normal wear parts on short notice, it'll be fine.

To quote a local radio dj from earlier today, "Merry Christmas or Happy Hanukkah or Kwanzaa or whatever... or if you're an atheist, just have a nice day." I personally enjoyed Christmas shopping with the windows down in the car on this 70° Christmas Eve in Phoenix...

I, too, have run original E88 'leaded only' seats for 25,000mi (5,000 of them under boost) on unleaded gas with no problems. That's all it's run in my lifetime, but it's got tens of thousands of miles more on it running on unleaded since the 80's.

Found a few more looking around Pictures of handwritten math speak to me. This one, perhaps something about focusing on your mistakes, and missing the bigger picture?

A few that I had fun with. This last one isn't mine, but the girl is a good friend of mine, and I thought it was nice enough to share.

If I would have grabbed 5th, I would have been stuck right about there I think. However, with my gearing, 5th is very deep (2500rpm at 70mph). I made my own drag calculation based on the aero test. That test for my model showed it took 108hp to push that car 120mph. Obviously it takes 0hp to push the car 0mph, and drag goes up with the square of speed, so with some simple calculation, the equation for my car is found to be: Req. Hp. = .0075(mph)^2 Throw 141 in there, and you get 149.xxx hp. Now remember, this 141 was at 6600rpm, probably not at my horsepower peak with a stock head and cam with a T3 turbo. Drop into 5th, and then I'm just under 5000rpm, probably not my peak horsepower either (I was thinking around 5500rpm or so). I could have perhaps made it to 145mph as I was, and proper gearing may have given me maybe 150mph as an absolute top. It takes ~170hp to push my car 150mph.

81-83zx 5 speed, 3.364 R180, 215/60/R14's. I hit 6600 in 4th, according to the tach in Megatune. Aerodynamically, my car best resembles the #6 windtunnel test. I don't have one offhand, but I'm pretty sure I saw that 1 fast z has some baseline flow numbers somewhere, and I'm willing to bet if you were extra nice to Braap, he might just tell you as well (I don't know for a fact that he has any, but I'd be mighty surprised if he didn't). Edit: Found one. Not sure exactly what head this is, but it's probably either an N42 or a P90. Blue (test 1) is stock. http://forums.hybridz.org/showpost.php?p=745040&postcount=12

For the N/A side, I have an old dyno graph. For the boosted HP, it's a seat of the pants guess. I was able to do 141mph with a bit of throttle left at about 7psi, and comparing my aerodynamics with that of the tests run in the aero forum, I came up with a required 150hp for that. I also used the pressure ratio method, which said 180hp at 7psi. I figured after additional losses it'd be about 165 or so at 7psi, and 180 or so at 10psi, but again, those are just guesses. As to your use of the cfm numbers, I totally understand how you use them in the first part of your calculations, I have no argument with that. What I mean is directed solely at the added HP from the turbo/supercharger. The part where you guess added HP isn't 'based' on cfm, or anything else for that matter.

Honestly, I don't know what the flow charts look like for those two heads, but as far as your original process goes, I don't see where it matters. You only used head CFMs as a method to predict the horsepower of the normally aspirated engine before it was built, and we already know the normally aspirated horsepower levels of these two engines. All I'm getting at is that in your equations you've been using 14.7hp/psi, which is, to say the least, very unqualified. I think you're going to be much closer with the pressure ratio method, though it will be a bit of an overshoot, because it does not take into account the flow restriction the turbo presents on the exhaust side, or the drag the supercharger places on the crankshaft.

For the record, that's exactly how I have mine set up, as well.

Bam, that's my problem with all of your theory, right there. In my opinion, that is a horrible assumption. So if you take one of the original 36hp VW Beetle engines, boost it to 10psi (assuming the motor holds together), you're magically going to add 147hp, for a total of 183hp? Your equation seems only to work on v8's around 400-600hp, because those are engines and power levels where adding 1psi may indeed add 14.7hp, but that is merely a coincidence. Boosting my 120hp L24 to 10psi gave me what I could best guess to be 180hp. It was certainly no 267hp...

I have C30 and C12 installed, as well as D1 and a 22V Zener diode backwards in D2. These are from when I was running fuel only, before I switched to spark control via the VR dizzy. It seems like setting up the jumpers for the VR circuit bypasses these altogether, but if you really want to play it safe, I have mine set up as stated, and the car's been running fine. Also, I don't remember for sure, but IIRC VROUT is correct, VROUTINV is not. EDIT: Looking at the vr wave diagrams at msextra.com, it looks like it doesn't matter whether you use regular or inverted, and it also doesn't matter how you wire up the red and green wires coming out of the dizzy, though it may change your trigger angle quite a bit to change between them. The only time it would matter is if you were using a ford vr sensor to use a 36-1 wheel, where it needs to skip a count where the missing tooth passes.

I bought one of these from MSA about two years ago (they were $13 at the time). Specifically, the 240z walnut one. The metal threaded insert was glued into the knob, and it has not rattled or come off in two years of daily driver use. I dunno if they changed suppliers or what, but mine was (is) excellent.

Jeez Mario, you never have any luck with this motor. I think it's cursed. Sounds like it's getting hot spots in the head, above the combustion chambers, and you've got it tuned close enough to detonation that that's pushing it over the edge. Perhaps try running some water wetter? I don't think your intake temps are to blame. I've hit 210*F MATs before in the summer, and I didn't have any ping problems even when water temps hit 220 (was a bad radiator). I was running water wetter, though, as I always do.