I had planned on posting a mid season report this year, but unfortunately didn't have much good news to report. We definately struggled this year, perhaps it was the infamous ' Sophomore Jinx'. If that was the case then we are looking forward to next year.
While we were doing the shakedown passes on the new motor, it was pretty obvious that we were going to have to do something to keep the RX-7 stuck to the track. The first eight passes down the quarter mile under power, the car would become loose after the 1/8 mile and spin the tires through the lights. Granted this was only happening on the Wednesday and Friday night 'Street Racing' events, when no VHT traction compound is used downtrack, but it is an obviously dangerous situation. The decision was made to put a spoiler on the car. The design we chose uses a horizontal spill plate with vertical endcaps and a removable wickerbill. Geoff cut the aluminum spill plate and had the end caps welded into place and made a 1/4" stainless steel wickerbill. We trimmed and installed the spill plate using adjustable rod ends and set it to horizontal to the ground. The spoiler works great, the car stays glued to the track even under poor conditions. We have a 3/8 inch wickerbill, which will provide even more downforce, but we haven't even tried it because the 1/4 inch piece works so well.
The new motor we built for this season ran great, but the B&M Holeshot torque converter we were using proved to be just a little too tight for consistant launches. Even though the spec sheet on the Comp Cams XE-284 cam stated a useful power range of 2300 to 6500 rpm, which I assumed would be a good match for our 3000 rpm stall converter, real life proved me wrong. The car bogged on the starting line and our 60 foot ET's were in the range of 1.65 to 1.85 seconds. The 60 foot times were not any better than last season, and were in fact worse, because they were inconsistant. After much thrashing of the carburetor, timing, launch rpm and pretty much everything else I could think of, the problem was clear, we needed a looser torque converter. Always thinking ahead, I decided to go big now and although a 4500 rpm converter would be a little loose for this motor, it should be perfect for the 2005 motor that was still in the planning stages. Man was I wrong! Whether we didn't have enough motor or the converter was defective will never be known by me, but the 60 foot times did not improve, we lost 3 tenths of our ET and 3 mph from our trap speed. What's worse is that we were now going through the lights at 7200 rpm! The good thing is the bog was gone, the bad thing is the motor probably wouldn't last the season taking a beating like that on every pass. It is afterall, a 2 bolt main, cast crank, hydraulic motor that I had never intended to take that high. The converter we were using is made by Art Carr, which had recently purchased Torco Torque Converters. These are economical converters and I had heard nothing but good comments about them. Compared to most of the top names in racing converters, the $400 price tag was an absolute steal. After talking to the tech guys at Art Carr, the decision was made to send the converter back and have it modified for a lower stall, in the 4000 to 4200 rpm range. At this point I must say that the people at Art Carr are very knowledgable and excellent to deal with, and I had a converter at my door within a week of our phone call. But, the converter that I received was not the one I had sent them. Whether it was easier for them to just send a new converter, or indeed my converter had problems that prevented them from modifying it, I guess i'll never know, but the converter I received from them performed vastly better than the one I sent them.
Things were looking up, the 60 foot times were now in the 1.60 second range, the ET's dropped to the 11.0 to 11.2 range and our speed was almost all back at 121 to 123 mph. It's time to go win some races!
Our first points race Geoff won three rounds and the race was called at 2 am. That's OK, the car ran well and Geoff drove well, I think we are going to have some fun this season. Until our next race that is. We ran a Quick 32 race at Orlando Speed World and the car was getting slower each time trial. I traced the problem to our 1 year old Holley Blue fuel pump. As the pump ran and heated up, the pressure dropped. The pump was only putting out 5 psi after the last time trial, instead of 12 psi. So, we were able to borrow a pump from another racer, which we installed and Geoff promptly won the first round. After waiting in the pits over ten minutes for him to return, it was obvious something had happened. I found Geoff stalled along the return road and when we got the car running again, it wouldn't idle below about 3000 rpm. Seems that the pump we had borrowed had been rebuilt and a large amount of silicone sealer had found it's way into our fuel system. Now we had thousands of tiny silicone balls throughout our lines, regulator and carburetor. We got the car back onto the trailer and called it a day.
I'm pretty comfortable with Holley carburetors and figured I would simply disassemble and clean the carburetor and flush the fuel lines and regulator, and everything would be OK. Once again, real life proved me wrong. After two massive cleanings and several flushes of the lines, I was approaching wit's end. This had evolved over several months which included three hurricanes, two cancelled points races and one missed race. I checked and double checked everything over and over again, to no avail. I've heard the definition of insanity is doing the exact same thing over and over expecting a different result. Well, I was close. Instead, I first bought a new Pro-Form carburetor body that made quite an improvement but not 100%. Then I decided to replace the metering blocks, again with Pro-Form parts and reinstall a power valve and stock accelerator pumps. That did it! We were now back to the performance we had several months ago. Instead of running eleven 40's, 50's and 60's, we're back into the eleven teens.
We finally got the car running good again about 2 weeks ago, which wasn't any help for the points races, where we finished 30th, but just in time for our favorite race, the Super Chevy Show in Gainesville, Florida.
We were really looking forward to the Super Chevy Show race because it was so much fun last year. This year it was even better! The car ran awesome all weekend, Geoff went out in the third round on Saturday with a redlight, but made it to the fourth round in the big race on Sunday. He had an uncharacteristicly bad reaction time in that round and you know what they say, you snooze, you lose. It was still a blast and Geoff even got a check for $75 for making it to the quarter finals. In the nine passes that we put on the car in Gainesville, it ran between 11.10 and 11.19, and never had a 60 foot slower than 1.60, so I think we have something to work with for our final race.
We have one more race this year, the Night of Fire at Orlando Speed World, and if the weather is cooperative we hope to have a ten second run. The motor will be retired after the next race, and it would be cool if we could break into the tens with it, after all the adversity this year. Before all of the problems beset us, the car went 11.01 at 124 mph so a ten isn't that far away. All of the parts have been acquired for the four bolt main motor that has been sitting in our workshop for the last two years. The motor is at the machine shop now, for finish honing, align boring, decking and crank refurbishing. After the Night of Fire we will pull the motor out of the car and send the damper and flexplate to the machine shop so the new assembly can be balanced. Then we will build the new motor over the next few weeks and have it ready for next season. This season's motor will become our spare.
This new motor should put us into the mid to low tens next season and will probably be the last one we put in the RX-7. The speeds should be approaching 135 mph and since the RX-7 is only back-halved, I feel that this would be a good point to limit further modifications for safety's sake. A full tube frame car with a funny car type roll cage will be our next step if we decide to go quicker and faster. I know that guys run back-halved cars into the eights and over 170 mph, but I won't do it. Especially with my son doing the driving.
When we finish the new motor and get a few shakedown passes on the car, I will post again, if not sooner. Good luck to everyone doing the little car - big motor conversions, RX-7 or otherwise. I hope our project history has helped in some small way. I am presently shopping for a digital camera (Man, there must be a thousand different models out there), and I will post updated pictures soon.