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I have a lot more photos on my computer at home. Right now I and at my aunts home with my wife visiting and my computer is back in our home in California. There are some photos on this computer.
Originally Posted by mustanghammer;11933780Here are some shots of the car as it sits now:
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Those shots are pure money!
Congrats on getting it out and rocking as well, should be a blast for the rest of the summer!
Cool stuff! Love the art work! Was the rear engine chevy a super modified?
You should start a build thread and share your work. Would love to see it.
Yes it is a modified the winged modified with all the guys in front I am the good looking one (LOL) just under the number 15. I built the chassis and was the crew chief and set the car up at the races. I started racing back in the 60s when I was still in high school I was a crew member and then became the crew chief on a SCCA F modified (later B sportsracing) we were San Francisco SCCA champions. In the 80s I was the jackman on a NASCAR Winston West stockcar. Pat Minty would call me when he was racing at Sears Point. Anyway I sure do like what your doing on your car. I have two RX7 the 15 car that I race and another gen1 that I bought that got hit in the right front and I plan on building a full on tube front and may even got Mustang 2 on it. So keep up the great work.
Last Friday I took the car to Raceway Park of the Midlands in Pacific Junction, IA for some track testing. The results were promising!
This is a good track to test on for me as I have driven the track numerous times in the past when the car was set up for ITA/IT7. Also the weather was perfect for testing the car's cooling system with temps in the low 90s with 60% humidity.
My first impressions were that this car is fast OR the straight a ways are allot shorter than they used to be! I have no numbers to back this up because the timing system was not turned on but there is some real speed here. Things that used to take foreeeeeeevvvvvverrrrr when I was running the stock port 12A now seem to flash by. Didn't even have time to look at the gauges that much!
The brakes kick ***. Super predictable with no weird lockup issues at the limit. Pedal feel is super firm and that concerned me a little in the shop but on the track with the bias adjusted correctly there were no issues. Love the Hawk HT10 pads.
The cooling system worked well also. Despite the heat, oil temps never got over 205 and water was 195-200 no matter how hard I pushed the car. I was a little worried about how it would cool because the radiator I am using is allot smaller than what allot of other KC area racers are using.
I am also happy with the transmission. It is a Miata gear set in an RX7 case and it gives me a second gear that can be used in several critical areas on the track. Would have killed for it when I was running the car in IT......but that would have been cheating
And the best part......it stills drives like an RX7. Super balanced and toss-able. The fun car I always loved to drive only better in every way.
Now for the issue.......
Later in the day, I started to experience high RPM break up. This would show up after the car had run a few hard laps in a session. Prior to acting up the car ran fantastic. But once the issues started there was no correcting it.
All of the fuel system components are new, fuel pressure never changed and pyrometer temps were good at 1450 degrees. Also, as mentioned earlier, engine temps were very good so it was getting too hot.
So, at this point I suspect an ignition problem and I am leaning towards a failing MSD 6A box. Some things that lead me to this conclusion is that the both tachs were reading inaccurately (they worked perfectly at the autox) and they use the same signal from the MSD. Also the digital tach that fires the shift light was making the light come on at odd times - it is supposed to come on at 8K. Finally, the MSD is 15yrs old.
Before I buy parts I will inspect the ignition wires for signs of arching - had that happen before. Plus I will test the coils.
I wish I had something intelligent to say here, but I don't other than I'm glad to see you have built the monster I think we knew you would! Glad to see that this is one badass toy that's performing great! Hope you have an easy (and cheap) fix to your issue.
Impressive. How often do that many things work right the first time out? The ignition woes should be almost reassuring, because something just had to go wrong and it's a relatively easy fix.
Thanks guys! Yes, all things considered I am very pleased with the car.
I spoke with the local RX7 racing guru and he doesn't think the issue is ignition related based on the symptoms. Instead he thinks it could be a sort of vapor lock issues that allot of the racers have experienced with street port/weber IDA engines. Their fix is to duct cool air to the outside of the carb. He also wants me to install shielded wire from the pickup to the MSD and from the MSD to the coil. So I will give this approach a shot.
I will also connect my dash tach to the trailing coil and leave my shift light switch connected to the MSD.
Vapor lock is indeed a problem with the Webers. I cannot restart after a red flag due to fuel boilover into the intake. It is unfortunate but it does not get me very often. I always pop the hood as soon as possible to release heat. It starts fine after 15 or 20 minutes of drying out.
Vapor lock is indeed a problem with the Webers. I cannot restart after a red flag due to fuel boilover into the intake. It is unfortunate but it does not get me very often. I always pop the hood as soon as possible to release heat. It starts fine after 15 or 20 minutes of drying out.
Yeah I kind had the same experience when I was testing. I got black flagged and had to come in for a consultation and when I got going after the car ran like crap. Felt like an over-heating issue but all temps were good.
I will be ducting in air from the left front turn signal and installing an inline blower so I can move air when the car is stopped.
I entered an SCCA club race to put my newly minted Full Competition license to use. My return to the track was short lived, however, as I broke 3rd gear after about 6 laps in qualifying. Likely started the failure during some sloppy test day downshifts and then killed it on an upshift trying to set a good time.
Up to that point I was happy with how the car was working. The shielded wiring eliminated the weird reactions I was getting from the shift light and tachometer. The carb blower seemed to do the trick regarding the vapor lock issues I had seen in testing.
While I am disappointed about what happened I am excited about how well this car works. It is fast out of the box and I have not yet begun to tap its full potential. I also got a chance to experience a Saturday evening bench racing session with good friends at the track. One of the best things about this sport.
So this winter will be about a transmission swap of some kind. I am learning all I can about Jerico transmissions, Quaife gears sets and OS Giken gear sets.
Car is looking great, sorry to hear about the transmission though. Do the Turbo 2 trans's not suit your needs gearing wise? They are typically very stout, that's why I ask - would be an easy swap
Yeah the OE gear ratios in the Turbo 2 transmission are not very good and are pretty similar to what is in an NA RX7 transmission. Of all the factory transmissions, the Miata ratios are the best.
Here is a comparison between the Miata ratios (on top) and the Turbo 2. With the Miata, 2nd gear can be used in slow corners however the gap to 3rd is still pretty big.
3.13 * 1.833 * 1.303 * 1.00 * .814
3.483 * 2.015 * 1.391 * 1.00 * .762
A Jerico 4spd set up for a Rotary would have ratios like the ones listed below. Getting around in the pits is a little tough and it couldn't be used for an autox but on the track you would have 4 good gears.
1.8 * 1.5 * 1.2 * 1.00
Last edited by mustanghammer; 09-02-15 at 09:42 PM.
Sad to hear about the Miata gears breaking for you. I need to find something that can live in my car, we have broken 3 transmissions in the last 5 races. One was a strange failure where the shift rots galled up in the housing and wouldn’t slide back and forth to select gears, but the other 2 were simply shearing teeth off of the gears. At AMP we lost 3rd gear which was tough since it was the gear we were using 80% of the lap and shifting from 2nd straight to 4th is a great way to lose all of your momentum with a rotary, but it hung in and we were able to finish the race. At the VIR 24hr we lost 5th gear which was bad since we were using it a lot on the long straights, we thought we could work around it just revving the engine a little higher, but soon the driver called in that he had lost the other gears and smelled gear oil, the teeth managed to do a serious number on that one even cracking the case. We left that transmission in a trash can at VIR…
I would love to find something that can pass for stock but be more reliable, I may still build a Miata geared transmission, our next race is back at AMP and it is one of the most difficult for gearing, with 2 really slow corners. If I am going to pay the points for a transmission swap I could look into pretty much anything that would fit, since I have access to the equipment to make adapters. Is there something out there that would be even more reliable than a turbo transmission that I could get to fit?
I agree, j9fd3s, there have been several fast EP RX7s that use Miata transmissions like Bob Neal who had Mazdatrix power in his car. So yeah the Miata conversion has worked for others in the past and it is the reason why I went with one in my car. Fixing what I have isn't off the table and if I do I will buy a new 3rd gear from Mazda.
650...Eewwww that is ugly!
From what I have read it appears that a Turbo II transmission would be the best choice for a "stock" alternative that is stronger than an NA or Miata conversion. The ratios just suck for racing. However, if you are getting by with a stock NA box then the turbo II ratios would not be any worse.
I am not sure what you are allowed to do in Chump/Lemons/WRL but a lighter flywheel with a good sprung hub clutch would help with longevity. Before I started my build I ran my car with a 215mm light weight steel flywheel with a Center Force dual friction clutch; downshifts were like butter! Way smoother than with the stock boat anchor flywheel with the same clutch or the 7.25" dual disk clutch I have now.
The other thing we started doing to help the stock transmission live longer was run 75/140w Amsoil or Royal Purple gear oil. The higher viscosity helped the transmission shift smooth when it was hot. The 75/90w Mobile One just didn't cut it at the end of a race.
Can you run a trans cooler?
We've had a couple EP RX7s running one of these - NASCAR Jerico with qualifying gears out of KC. Pretty much a bullet proof solution. It is not a bolt in as the install requires allot of transmission tunnel surgery. Also a custom drive shaft is required and the slip yoke has to have a hardened shaft because a Jerico has roller bearings in the tail shaft.
This car in the photo and that transmission won the runoffs in 2011. It had an adapter for a REPU bell housing so that a NA flywheel could be used. The input shaft was out of 426 Hemi. I believe that Jerico has an adapter/input shaft combination that is specific for a rotary.
Lakewood/Quick Time now makes scatter shields that adapt a number of V8 transmission including a Jerico, Super T10, Muncie, etc to a 13B with a turbo flywheel.
Back when this transmission was installed, used Jericos were selling for around $2k because NASCAR had outlawed qualifying transmissions. Then the Car Of Tomorrow obsoleted transmissions with shift rods on the left side of the transmission. So there was a glut of good transmission available but this bargain seems to have dried up now...
07-03-15, 01:23 PM
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