While talking to my wife (who took the above pictures), she said it was very obvious when I was coming around and was by far the loudest car at the track Tuesday. What the RX-7 lacks in horsepower it makes up for decibels!
I suspect it's the two stroke style exhaust port opening. No silly valves to baby, port opens faster.
I'm definitely looking forward to that! It took about 2 laps before the Porsche let me past and I was looking for ways around him... which wouldn't have been too hard if the rules had allowed it. Oh, and looking through the gallery, I realized there were a couple other cars I passed that I'd forgotten about. I think the total number for the night was 6-8. I don't remember how many cars I pointed by me. One influencing part of that is where you are in the pack. With 20 minutes of track time and the way they space everyone out, you're in a section of the pack that you're pretty much going to be in. You line yourself up in 3 rows. First and third I set myself up in the front of row 3. Second heat because of timing, I ended up at the very back or row 3. That one I think was actually the only one I got passed on, because the people in the front of row 1 (who were the faster cars mostly) were coming back around by the time I got on track. Another thing that has me happy with the car is that a lot, lot of cars were pulling off before the end of their track times due to overheating. Me? Nope. If she was able to run all out on that day, she's good for about anything temp wise. I'll see if I can find those, or borrow some scales somewhere at some point to see. It would be interesting data. As it is, I imagine there are some differences just from switching shocks from your Tokicos to the junky KYBs. That area needs improvement, of course, and I know my lap times would get better with better shocks. I don't want to make any significant suspension changes at this point. Adding a rear sway bar (and upgrading the front one to match) would help handling, but until I know what I'm doing race wise (as opposed to just track night where there are no rules as far as the modifications to the equipment). And like you said, then go through and rebalance everything else. I'm sure when you were racing it it was set up better with my current rebuild, and specifically the shocks. But this all makes sense. I was shooting for late apexes. There are a few slower, tighter turns where I was seeing the pushing, and a few of the faster turns where I was just flat out the whole way through. I was definitely harder on the brakes Tuesday, but I am normally pretty easy on brakes by nature and noticed zero brake fade, even with those temps. Definitely did what you suggested once the checkered flag was out and just coasting to let the brakes cool down. None of these straights are that long, which is good for me in this car. On the main front straight I'm getting to where I can get into 5th for the last bit (I'm generally shifting at 7-8k RPM, I know it can go higher but that works for the moment) if I get my exit of the turn right and pick my line. Definitely not worth changing anything for track nights at this point. I'm debating whether to do novice or intermediate next time around. I'll think about it.
Tonight was the third track night I've attended with the RX-7, and the last one being held this year. I was really happy with the performance of the car, and I feel like I have it fairly well sorted and dialed in now. After the last session (which was about 100F out and the first session I completed), the primary note I had was that the right front wheel seemed to be rubbing in hard left turn. Upon inspection, I found that its spring perch was significantly lower than the one on the left front wheel, and that corner of the car was observably lower than the other three. I raised it to match. In the past month, I've also read a couple of books on racing - both involving driving techniques and also tuning techniques. And from that, I decided that I should try to push the caster of the front wheels further forward and also try some more toe out in the alignment. There's not a ton of adjustment that you can do with caster, but I made what adjustment I could. Lastly, I wanted to run with more fuel in the tank to try to have more weight over the rear wheels. I may have ended up with a little more fuel than I had on the last session, but not very much more. It was also a very different day - mid 60s and strong winds vs. upper 90s. That impacts everything - horsepower, tire grip, and then what drag or extra forces the car must either overcome or be helped by. I was also running in the intermediate class instead of the novice class, which had me as the lowest horsepower car by a significant margin, and in theory the drivers should be better. Unlike the two times in the novice class I ran, I didn't pass anyone today, except for that one Viper that spun out. With all that said, the car performed very well, and I think that the changes that I made helped. There was no more tire rubbing on left turns, and the extra caster seemed to help the car's cornering as it should (granted at the price of some higher steering effort and more wheel turn required). I got a better hang of when I should be downshifting (it was too early) and got to the point of taking more corners flat out (which the car can do). I'm sure that these tires are now starting to lose their maximum grip potential, which negatively offset the other factors somewhat. However, I spent a lot more time in 4th gear this time around than 3rd, and had two straights that I got into 5th on (only the main front straight would sometimes see 5th before). Some of that may have been due to more horsepower from the lower temps, but I think that more of it was just being able to carry more speed through the corners. Admittedly, the worst component today was the driver. There's been a lot going on this month and I've had a lot on my mind. My head wasn't fully in the game today, especially on the first run. I have no data acquisition, so I haven't been able to track my lap times, but my wife was watching for at least the first run. She said that she could see me closing the gap and gaining on cars in the corners, but then the gaps grew on the straights. End result, though, is I think the car itself is doing very well. Now starts the time period of being able to plan for next year and make changes/upgrades over the winter. I believe that the power brake booster has a vacuum leak and is bad. When I step on it, there's a noticeable change in idle, and at least it seems to have a bad check valve as any vacuum goes away immediately when the engine turns off. I didn't replace the vacuum hoses going to the booster, but I need to do some more inspection and look into that. Potentially related is that when the carb is running on the primaries only, it seems to get lean and start sputtering, especially towards the top of the primaries throttle travel. Maybe it's a vacuum issue related to the brake booster. Fresh fluids are an obvious one. I also want to replace the driveshaft U-joints, more than anything because they appear to be original (making them 40ish years old). I haven't yet checked the ignition timing, and that's something that I need to do on the car, although I suspect it's fine. From there, it's just a general inspection and decide what the plans are for it for 2023!
OUSTANDING!! Glad you and the car are doing so well! It's an honest, solid car, and it'll do its part of the driver is doing his. Quite a blast to be on a track in a real race car, isn't it? Which books? If you don't already have Carrol Smith's "XXX To Win" series, get it. It's a bit outdated, but the fundamentals and principles are sound. I thought "Engineer To Win" and "Prepare To Win" were very good. https://www.amazon.com/Engineer-Win...&sprefix=carroll+smith+enginee,aps,216&sr=8-1 https://www.amazon.com/Prepare-Win-...&sprefix=carroll+smith+enginee,aps,216&sr=8-5 https://www.amazon.com/Drive-Win-Es...&sprefix=carroll+smith+enginee,aps,216&sr=8-7 Also, some good winter reading for you would be "The Unfair Advantage" by Mark Donohue. It's a classic. https://www.amazon.com/Unfair-Advan...mzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0 I presume you did a little friendly rubbin'? Almost certainly. It's a low HP car, so significant improvements usually come from setup or driving technique. It sounds to me like you're gaining more confidence in the car and becoming more willing to push it harder. My data acquistion was usually @2-Bit Speed holding a stopwatch and a clipboard. What do you have kids for, if you're not going to make a pit crew out of them? Please, please, please attend to the safety stuff over the winter. The harness really needs to be re-webbed; it's probably 20 years old. Same for the window net. You need a new fire extinguisher, too. I'd be messed up for life if you got seriously hurt in my old car. That doesn't sound right. That carb should almost never be on primaries only. We had it set up so a very slight application of throttle opened the secondaries and it was jetted appropriately. BTW, on a related note, pay attention to fuel pressure. It's pretty easy to have too much pressure and overpower the floats, causing flooding. It seemed to happen mostly in hard left corners, like the Sebring carousel. Before we caught on, we misdiagnosed it as fuel starvation when it was actually the exact opposite. That's why there's a pressure regulator in the fuel line, but after all these years I wouldn't trust it to be doing its job. So when is your wife going to get a chance behind the wheel? Better start developing your co-driver for enduros! I'm delighted your having such a great time with the car. Keep us posted on your progress!
Congratulations are in order here, you brought that car back from the dead and had a very successful first season. Hmm, sound like you should be Team Ted's safety equipment sponsor.
It definitely is a blast, and it is an honest, solid car like you said. I've added the last one to my list, and Carrol Smith's are on my list already, but haven't read them yet. We have a Kindle Unlimited subscription, so I'd started with a few books that I found for free on there, one of which gave me a huge list of books to read and led me to another one (which was far more technical in nature). Off the top of my head I forget the names, and I don't have my Kindle handy. But, the second book gave some good driving tips, and then also pointed me in the direction of adjusting the alignment to have more positive caster, which definitely seemed to help on this last session vs. how I had it before. That would've been highly unappreciated. And I don't think I could've gotten close enough for that other than when he passed me! Absolutely! Gaining more confidence in the car, and also learning what it can do. Getting it setup noticeably better each time has also been huge. Thus far, the kids haven't had much endurance for the track time, but maybe that will come more later. I definitely do plan on doing some of that, if nothing else because one of the goals was to have the car set up to be able to take a passenger. Remember that when I rebuilt the carb, I converted it to mechanical secondaries. On the forums, people have done this successfully. However if it's jetted to not run like that, then maybe that's some of my issue. However, it also seems as though the brake booster has a vacuum leak in it, and I'm wondering if I don't also just have a good old fashioned vacuum leak contributing to some running problems. I plan on converting the car to manual brakes over the winter, removing the booster (and saving the weight) and plugging that vacuum port on the intake. After that, I'll also do some more checks for general vacuum leaks and see if there isn't something there. And then I'll dig into the carb further if I can't solve it. Also a good point on the fuel pressure regulator, and I could be misreading what's happening. But it does act a lot like a vacuum leak. Hopefully I can get my wife on the track with it next year. I definitely want to get it in top shape before her doing so. It has no funny behaviors handling or braking wise, and engine wise it's only that one issue noted above. And so with that, here is the JIRA ticket list: - Convert to manual brakes - Investigate for vacuum leaks - Safety equipment (see what I did there? ) - Fix the running issue noted above - Replace the driveshaft U-joints - Change all fluids - General once over and fix anything noted during that (haven't done that yet) Not this winter, but this thing would be really fun with a 13B Genesis out of an RX8. Maybe if I wear out the 12A... And, of course, figuring out the plan for what to do with it next year besides the track nights.
Thank you! I was hoping to get it driving last season, and then at the beginning of this season, but I am overall happy with how it all worked out. He's already the prime sponsor. After all, his name is on the car!
Yes, the vacuum leak might be part of the issue. You’re doing the right thing to correct that before you start chasing your tail with the carb. I’d forgotten about you converting to manual secondaries. Our rules didn’t let us make that change, but nothing specified how strong the spring needed to be that held them closed. I went with the weakest spring I could find (it might have come out of a ballpoint pen). During impound inspection with the engine off, the secondaries stayed closed when the throttle was actuated since there was no vacuum, but when running just a whisper of vacuum would snap them open. Yes it would! Of course the hp increase would probably eat something downstream, like the transmission...
If I did the swap, I would take the RX-8's 6-speed and throw that in as well. Of course used parts on something like that probably would need some work before reinstallation, and I have enough other projects I want to get done vs. taking down a working car for something like that. So for now, the 12A stays, but if I happen to find an RX-8 drivetrain for a good price, I might stick it in the corner. But really, priorities are working on the minor list of things over the winter on the RX-7, do the engine work I have planned on the BMW, get the Cobra driving, some items on the RV, and hopefully make some more progress towards the diesel swap into the Land Rover.
I've finally got around to doing some more prep work relating to getting the RX-7 ready for this season. This year I do intend to actually race it, but there were some open items to deal with. Previously I plugged up what I believed to be some vacuum leaks and started the work of converting the car to manual brakes. Last night I got some time to start changing some of the fluids on it (engine oil, differential, and drain the transmission). All fluids did show a level of wear, but nothing was concerning. Fuzz on the magnets for the transmission and the differential, both fluids came out fairly clear, certainly not dark. After how long the car sat, I figured that, although the trans and differential probably could've been left alone, I figured it was worth changing them if nothing else to check on general health. I had planned on replacing the U-joints on the driveshaft as they were original. However upon pulling the driveshaft, I have no reason to replace them. They move perfectly freely and there's zero play, plus there was zero driveshaft vibration driving it. So, that goes back in. I do need to spend some time going through safety equipment needs and get some of that coming, as well as finish up the manual brake conversion. One thing I would really like to do (as I think it would improve power based on some dyno tests I saw) is add a K&N style top air filter, like this: It's about $85 to add one of those, which seems like more than it should be, but I may decide that's worth it. I've considered adding some more gauges to the car, but I think I probably am fine with it as-is. The engine doesn't make much power so it doesn't need as much instrumentation, the oil is well-cooled now, the engine is extremely well cooled. Mostly, I need to take care of the brakes, add new safety equipment, and make sure that it all works as expected.
While you're doing the brake conversion, you might consider adding a bias adjuster. The car worked fine for me using Hawk Blues in front and Blacks in the rear, but with an adjuster you could probably run Blues (or similar) on all four and dial it in precisely. With the long races you'll be in, it might also help to deal with changing bias as the brakes wear and fade. BTW - if you do change or add guages, keep the warning lights hooked up. Trust me....
So is the "Hey-dummy-you-split-a-cooling-hose" light, which I did on the first lap of a race and I was in such tight traffic that I didn't notice it until the temp guage was pegged. Fortunately, 12A Wankels cost much less to rebuild than Lycomings, especially when Mazda Motorsports will sell you all the parts at factory cost.
On the Legends cars for oval track I ran two bias valves on one of my cars. Year after I got out they made a rule only allowing one valve. A lot of guys would run it on the left front so they don't lock up that wheel. To me this is just a bad setup that calls for a stiffer right front spring. You could run it on the left front of you had a big caster split. My bullring car I only had one bias valve and had it on the right front to help the car turn under braking. Just backed the rear drums off if it was loose on entry.
