GT750 Powered Race Car (D-Sports Racer)

[sav0r (CL MotoTech)]

It was really nice meeting you! Make sure to come and hang out next year!

It has a Pertonix based ignition. Heat may have been a factor, but who knows? In a month once we feel willing to look at it all again we will assess.

[pidjones]

You might consider reset-able circuit breakers that you can reach in the cockpit. Burning a wire isn't too bad. You don't want it to burn down the while car!

[sav0r (CL MotoTech)]

We had that discussion after the race. Either auto reset breakers or a second ignition circuit with a second ignition switch. The latter being common in stock car racing. We have a while to think about it.

My guess is that we will chase the wires, fix the chaffing or whatever, thereby correcting root cause. Hopefully then we will never have the issue again. As Clem says, there isn't much there to look at.

Typically in race cars you let the wires burn and if there is fire you pop the bottle and hope for the best. This is very common race cars, the only race car that I have ever driven that had fuses is this one. Keep in mind there is literally one of these cars. So my father has been a bit more cautious with it. Of the many professionally built race cars I have driven, where you get many spares should you need them, there isn't a fuse on the thing. But they also have wiring looms designed and braided by professionals.

Anyways, I think after a week or so we will feel a little less deflated. We were truly close this year with most things going our way and yet another gremlin emerged. The game of whack a mole continues.

[Clem710]

Complete 2nd set of ignition system is also common in aviation and it really shouldnt add much weight.  I could put you in touch with a guy in E. Liverpool that builds his own frequently if it will help.  Also, I think its been tested that dual plugs make more power. 

Really shouldnt be necessary though, I'm thinkin you'll find something simple and obvious once you see it.

Good luck, more fun to drive em but good fun working on them as well:)

[sav0r (CL MotoTech)]

We pulled the head yesterday just to do some analysis of the engine condition. That lost needle circlip did just about as much damage as a circlip can do. Certainly not terminal but the head took a nice mashing. The ports look clean on initial inspection. We were planning on a new head anyways, so we aren't gutted about it. The piston seemed to survive without much damage at all. I guess that is one benefit of that soft Suzuki aluminum.

[irk_miller]

I shattered the rings on an SBC in a race once.  It's amazing how metal can imbed itself into things while simultaneously bouncing around like shot peen.

[automan]

I shattered many HEMI pistons.
No foreign debris, just bad iggy timing and/or hot exhaust valves(bad seats)

OTOH, I lost a few parts in the intake and did zero damage.

Funny luck.

[sav0r (CL MotoTech)]

Well boys, the band is back together. And by that I mean, Mom's bout with cancer is over and my divorce is finalized. So my father and I are free to ignore the real world and indulge ourselves with 2 stroke powered race cars.

We have slowly been working on the car in the background, but with life getting in the way, things were slow. Probably the the biggest update was the rear brake.

To save you from digging through the thread, failing brakes on the street course was a common theme for us. We think we narrowed it down to pad knock back on the rear caliper. The single rear rotor had a lot of run out, this knocked the pads back, meaning a long pedal. To prevent the inconsistent pedal I would touch the brake pedal well before the brake zone to return the pads to the rotor and get the pedal feel I desire. This generated excess heat at single rear caliper, boiled the brake fluid, and meant that it was difficult to achieve proper braking pressure at the front due to the balance bar. If you are familiar with how a balance bar works you probably understand.

Beyond that, we made yet another head. I, like a fool, didn't get a picture of it. It has a nice toroidal combustion chamber. We went slightly large on volume, squish came in at .032" with a .035" gasket. It should be a cool runner. I'll check squish again after a heat cycle and retorque.



We have better tires lined up. I am working on licensing. The plan is to get a test in mid June, a month away. Then off to PVGP in mid July.

[RDnuTZ]

very cool Chris  Getting that kind of weight off your shoulders makes life a million times more enjoyable and easier to think about fun in your future 

[sav0r (CL MotoTech)]

Center cylidner a little smokey after CC it with the Marvel. Not too shabby for first real fire up after the slumber.

The van is together and working. Transmission temps are a bit high, we think it has about half the amount of cooler it needs.



Had the PCM up checking those temps on a drive for dinner.



Made a tool to adjust float height. Instead of a standard needle these use a ball, this is intended to handle the mild fuel pressure that the fuel pump supplies. Setting float height was tricky and the old float arms were pretty worked over. We got some new ones, then with this jig were able to get the float arms within like +/- .004". Not sure this will help much of anything, but it's a thing we did.



Oh, and a semi-aero camera mount. It looks better than the old one. That's the biggest improvement.



We are well on track for the test on June 15th.

[Simmons1]

Cool update!

[sav0r (CL MotoTech)]

I finished prep on the car Saturday and it was ready to load. After testing the van while towing the trailer we decided to postpone our test at Nelson's until next week. I was watching the data on the transmission temps and when the torque converter slipped for any period, temps would climb pretty quick. This is with additional cooling we added since my last post. In my last post we noted high temps without the trailer. The additional cooler meant normal temps sans trailer. Then we tested while towing and found high temps again.

We have a lot of hills to climb in our region. Luckily we had penned in this coming Wednesday the 25th as a potential backup date. Hopefully the weather is good. The van should be ready. I am fairly confident the new cooler arrangement will solve the over heating issues. We should have it together today or tomorrow.



Bonus shot of the Mini. It hasn't been outside much. This is a project for August. It hasn't run much since we did the standalone ECU. I am looking forward to it. Maybe my dad will get the new composite hood painted too.

[2steve]

I see the red outer covers on your UNI filters and remember having to switch to bigger main jets when I slid them off of the RD400 filters.

Lost some coarse filtration protection but must have gained some top end.

Apples to oranges, though.

[sav0r (CL MotoTech)]

You are correct. I know many have experienced this in other scenarios too. We tried the car without the red pre filters and sure enough it went lean.

The truth is that we don't see enough track time to chase these types of things. Usually encountering other failures that distract us from really tuning the car and engine. Such is life in grassroots motorsport.

When I was driving professionally and we had mechanics and engineeers etc., the expectations were much different.

[sav0r (CL MotoTech)]

I talked to my dad after that last post, and without any prompting he says that we should pull those red filters and go up a main jet size. I about died. He's waiting on parts for the van so maybe he will do it before the test on Wednesday.