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Allison Legacy 3/4 scale, Mazda powered race car
I can't believe it, this engine has pistons and valves! What am I going to do? After a decade of drag racing and a "taste" of road racing recently driving my Maxton Rollerskate at a local NASA event at Eagles Canyon Raceway, my arm was twisted ever so slightly to get into one of these spec cars and go road racing. Well I purchased this blue car with a Thunderbird body from a colleague at work and then went through it, inspecting it from front to back, left to right and repaired a bunch of things. I added a few additional things such as brake ducts, EGT and AFR because it had a carburetor and I couldn't imagine not knowing the tune. Weighing it at the 1675 lb. (minimum) with driver, it is balanced 50/50 cross with about 40 lbs. of lead in the right side frame rail. I remember thinking this car would scoot with a rotary (13B) instead of this heavy 1991 Mazda B 2200 truck engine. After competing in a couple of races, the body on the car was pretty beat up and so with the help on my friend Jay Carley, I purchased a new body and painted it the Black, white, red and yellow, similar to the then Australian "Super Cheap Auto Parts" V8 Super Car. Our goal was to make it resemble a Mazda 3 as I am part of the Mazda racer program, hence the Mazda logo's.
Below: One of my favorite tracks, Hallett Motor Racing Circuit, Oklahoma
As my seat time increased, my performance level improved and the road racing soon became competitive, just as I had felt drag racing. Probably the most memorable race back then was at Hallet in Oklahoma when Jay and myself raced door to door for several laps until Jay passed to win the race. That was such a blast! It was about this time frame when I felt "lost" without data acquisition, not knowing what the car was doing or what I was doing as a driver. Since I had the hardware and experience with the PCS D200 from my drag racing days, I installed one in this car and once I could "see" what was going on, that's when I felt compelled to make improvements, mostly how I was driving the car from the steering input, braking, accelerator etc. Below: Allison cars doing battle at Texas World Speedway.
Jay and I realized we were always being beaten by the other cars in our run groups so I went about researching performance parts for these engines. There weren't any available. The next step was to make our own and the first improvement came from a stock camshaft that was re-ground. This made a noticeable improvement with a 14 horsepower increase in power and it was with this power we decided to enter and compete in our first NASA National event at Miller Motor Sports Park in Utah. That was a great road trip but we still managed to get our butts kicked on track. Below: Jay Carley and myself at Miller Motor Sports Park.
Soon the car count began to dwindle leaving just two Allison cars at our NASA events, Wyatt Brennan and myself. With the lack of interest in competing at each event in these cars, I was determined to use the opportunity to further increase our power so that Wyatt and I could race with our fellow run group race cars straight up, they being the Miata's, Spec 944's, Ledgens and Thunder Roadsters. I consulted with knowledgeable guys in this arena and my mission was to have higher compression ratio piston manufactured for this engine. The stock 8.7:1 ration was boosted up to 10:1 and suddenly, the car came alive! I would also learn that my carburetor was always changing, some times the tune up would be fine then all of sudden, it would lean out and for months and months, this baffled me until one day I got lucky and found the problem. It was a worn out emulsion tube. That was it, I was not about to waste $300 on a new carburetor so off came the carburetor and on went fuel injection. Wyatt's dad had found some rare EFI manifolds for this cylinder head in California so I purchased one, modified it to fit under the hood and then this car was kicking butt! It was such a good feeling. In one particular race at ECR, we (Allison Cars) started 30 seconds behind the Spec Miata's in a split start and by the time our 45 minute race was over, I had passed every last one of the Miata's and won the race by some 6 seconds. Finally, we had us a racecar which is what laid the groundwork for our new car.
As you can see below, the stages of modifications yielded remarkable results with relatively low cost items. I probably spent about $1,000 on hardware and machine shop work plus my labor. Cheap I'd say!
This car, without a doubt, is a whole lot of fun to drive, very low budget, runs on pump gas and you can race all year on one set of tires. How cool is that? Modifications that I made over time to improve the car folow: I decided I would rather save my time and effort to build the "real thing" after the new chassis was built. Instead, I focused on the front brakes. My current Allison Legacy car with it's modified engine and increased power was great to drive, however, the brakes on the stock Tier 1 car simply could not take the abuse of road racing, especially in the hot Texas heat and the fact that the rear brake rotors are slightly larger than the front rotors with the same brake caliper on all 4 corners. Even with a brake bias adjustment and the single master cylinder, this would not work. Initially, I removed the single brake master cylinder and bias valve and installed a new pedal assembly with dual master cylinders. With a brake pressure sensor on the front and rear brake lines connected to the touch screen data acquisition, I would soon learn just how far off the brake bias was. Using the stock Outlaw 1000 brake calipers, I ended up adjusting the bias bar so that I could brake really hard and not lock up the rear brake with 590# on the front and 370 on the rear. As the brakes heated up and the front brake pads began to heat up, this ratio would be worse. Next was brake fans and that still was not good enough. Without changing the front brake disc (which is custom for this spindle) I focused on the caliper. I ordered a pair of 4 piston calipers, new pads and when I had the on hand, had custom brackets manufactured so that they could be mounted the the stock spindle. This modification literally doubled the surface area of the brake pad, in turn allowing for improved cooling by dissipating the heat out over the larger pad. Unfortunately, the earliest testing of these new brakes was just last week (Dec 22) and all I can say is wow. The difference is like day and night. Now I believe we will have a greatly improved brake package for the new car.
Another piece of research I did was to improve the stock lower front suspension control arm and the front sway bar that was on my car when I purchased it a few years ago. First, the lower control arm was bending and as a consequence, the geometry and ride height would change during an event. The solution, add a gusset plate welded vertically to strengthen the existing tubing. Additionally, the front sway bar which was mounted to the lower front shock absorber would cause the entire front suspension to bind and restrict movement. With some 1/2" aluminum, I lengthened the sway bar control arm so that it would reach the center line of the lower control arm. I fabricated two tabs to mount the hiem joint or rod end to the lower control arm and used the same adjustable rod to couple to the new sway bar arm.
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