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Race-ready Golf Part 2: A day at the races

Oct 15, 2004 SHARE
0409_01z+1985_volkswagen_gti_coupe+front_left Photo 1/8   |   Race-ready Golf Part 2: A day at the races

Right from the start, the object of this project was to get on the track as soon as possible. That's why I chose a car that had already been prepared for competition and had a successful race history. The car, a 1985 Volkswagen GTI, had been raced for almost 10 years in the Central Division of the Sports Car Club of America (SCCA) and came with all the required safety equipment, suspension modifications and engine tweaks to be ready to hit the track running. That was the theory. The reality is that no car that you buy, no matter what you might think, hope or believe, is ever really truly race ready.

Very few SCCA Club Racing cars are suitable for driving on the street. In the Improved Touring category, minimal ground clearance, significant negative camber of the front and rear wheels, nearly slick shaved tires and the prospect of encountering potholes and rain showers means the cars are primarily for use only on a racetrack .

0409ec_projgolfpt2_02_z Photo 2/8   |   Race-ready Golf Part 2: A day at the races

So how do you go about checking if everything works when you can't blast up and down your local freeway? The answer is to take your car to a speed shop that has a chassis dynamometer. For a reasonable amount of money, you can run your car up through the gears while it is running on large rollers, measure the horsepower and torque at the wheels, and develop a baseline for further tuning.

I found a shop nearby called Advanced Imports (www.RX7store.net). It builds high-horsepower turbocharged Mazda RX-7s for rich clients in the Midwest. I trailered my VW racecar to the shop to find out how it would run. It cost $100 to make several runs on the dyno, and each time I made adjustments in ignition timing and fuel enrichment to try to find the best setup.

Ultimately, my Golf made 98 hp at 5250 rpm and 105 lb-ft of torque at 4500 rpm with a total ignition advance of 28 degrees. Given a typical 10% or so loss through the transmission, this compared favorably with the 102 bhp at the flywheel that a stock eight-valve GTI should make, but it was pretty pathetic compared to the 500- to 600-bhp engines in the hot-rod turbo RX-7 motors. The numbers didn't matter to me as much as the fact the car ran cleanly throughout its rpm range and everything, including the cooling and oil systems, worked as it was supposed to, without any leaks or other problems. I also discovered an annoying problem--the car wouldn't idle after it was warm, but I could look into that in my home garage.

I quickly found the idle problem--a shop rag had somehow been left in the intake manifold during the engine assembly process. It completely blocked the primary throttle valve, meaning no air could get through to let the car idle. Once I removed the rag, the car settled down to a smooth purr. On the other hand, had I not put the car on the dyno, I might have spent half the day at the track trying to find the problem. My $100 was well spent, even if I wondered how much horsepower the engine had lost breathing through a greasy rag.

With the horsepower and torque versus rpm from the dynamometer runs, and knowing the tire diameter, the final drive ratio and the gear ratios in the GTI's five-speed transmission, I could now calculate the best shift speeds for maximum acceleration in each of the gears. Although some racers simply crank the engine to redline in each gear before shifting and hope for the best, a better way is to shift at a rev count where the engine speed in the next gear will land in the fattest part of the torque curve. This is especially true for a class like Improved Touring, where you're limited to the gear ratios in the standard production transmission. Use this calculation:

0409_03z+1985_volkswagen_gti_coupe+left Photo 3/8   |   Project Golf had broken constant velocity (CV) joint. I didn't have a spare so I called Int'l Parts Store, which did.

MPH = (RPM x tire diameter (in.) x 3.14 x 60)(gear ratio x final drive ratio x 5280 x 12)

My Golf has 205/55R14 tires, so their inflated diameter is (205 x .55 x 2)/25.4 + 14 = 22.9 in. The actual rolling diameter of a tire is about 5% less than its inflated diameter, so we'll use 21.8 in. The final drive of my Golf is 4.3:1, and knowing the gear ratios, I can calculate the speed in each gear for various engine rpm. Why is all of this math important? Armed with this table, and the horsepower and torque curves from the dynamometer runs, I can figure out approximately at which rpm to shift gears to give me the best acceleration. Ignoring first gear (I only need it when leaving the pits), I can see that shifting at 6250 rpm (the stock redline) from second will correspond to 45 mph. When I go into third gear, the car will still be traveling at 45 mph and so the engine speed from the table will be just under 4500 rpm. This is right near the torque peak, and the engine will continue to pull strongly. If I had shifted at 5000 rpm from second to third at 36 mph, the engine speed would have dropped to 3500 rpm in third, significantly below the engine's torque peak, affecting acceleration. Using this logic, I can determine the following approximate optimum shift points:

2nd to 3rd gear 6250 rpm

3rd to 4th gear 6000 rpm

0409_04z+1985_volkswagen_gti_coupe+left Photo 4/8   |   Race-ready Golf Part 2: A day at the races

4th to 5th gear 6000 rpm

If I were to delay my shifts to 6500 rpm from third to fourth, for example, I would shift into fourth above 5000 rpm, above the fattest part of the torque curve where there's less potential for hard acceleration. Does this mean you should always shift at these speeds? No. Sometimes you can save a shift by extending a bit further in a lower gear. What it does tell me is that, even when racing, there is no need to rev my 8V Golf engine much above its stock redline of 6250 rpm.

Even a car like my Race Ready Golf, one that was on the track just last year, has plenty of small projects that need attention. There is nothing worse than sitting on the grid with a dead battery. Batteries take abuse during a racing season as heat and vibration degrade their performance and life expectancy. It is also an easy item to change and provided an opportunity to improve the mounting bracket to make sure the battery stays firmly in place. In the process of playing around with the battery, I also found that the alternator had been incorrectly wired and wasn't providing a charge. This would have been another annoying thing to find at the track.

Most racing organizations prohibit the use of anti-freeze in track cars--it's very slippery and takes a long time to dry. I emptied the radiator and refilled it with filtered tap water, throwing a bottle of water-wetting agent and corrosion inhibitor into the cooling system to keep things cooler and help prevent corrosion of the VW's aluminum head. I also discovered a minor leak in one of the heater hoses and replaced it with a new one.

0409_05z+1985_volkswagen_gti_coupe+left Photo 5/8   |   Coming out of turn one at Mid-Ohio racetrack.

My Golf came with Toyo Proxes RA1 shaved tires and a mounted set of the same in full tread for rain, so for the short term the car was just about set to go racing.One of my objectives in Project Race Ready Golf is to sample racing alternatives to the usual SCCA club racing programs. One such alternative is the National Auto Sport Association (www.nasaproracing.com) or NASA, a group of racing enthusiasts formed in 1991 on the West Coast. It's been quite successful, growing to 15 regional chapters and more than 10,000 members. NASA has a very extensive High Performance Driver Education (HPDE) track time-trial program as well as several series for wheel-to-wheel racing.

Among these is the Pro Sedan class, which is structured in a very similar way to the SCCA Improved Touring classes. With a 3-day race event set for early April at Mid-Ohio Racetrack, I signed up for one day of sprint races ($175 entry fee) and for the 1-hour endurance race ($125 entry fee) in the Pro Sedan 3 category.

0409_06z+1985_volkswagen_gti_coupe+front_right Photo 6/8   |   Entering "madness" during Sunday's 1-hour enduro.

I had never raced at Mid-Ohio before, so in addition to learning a new car and racing with a new organization, I was also having to learn a new track. I studied the track map, read all that I could from various Web racing sites, and watched a few streaming videos from the Internet to get a sense of it in action. NASA's procedure was relatively painless, providing on-line race registration and good information before the event on its Web site and by e-mail from event coordinator Lawrence Mansier. Once at the track, the car easily passed its technical inspection, and I was issued a NASA logbook. There was a casual atmosphere around the place. Everyone seemed to be there to have a good time, yet everything ran efficiently and on time. The weather was cold but sunny, and I was looking forward to a nice weekend racing my new car for the first time.

My first session was in mid morning, and the temperature was in the low 40s. As I left the pits and accelerated onto the track, I was grateful for the time I 'd spent on the dyno, confident the car would at least make it around the track under its own power. I was also happy to have studied videos of the track; now it seemed pretty familiar--that is until I turned in just a bit too early coming out of Thunder Valley on my second lap. The rear tires caught the edge of the curbing, and before I knew it I was in a big spin across the grass at 70+ mph. When everything stopped spinning, I realized that I was pointed the right way down the track, so I put the car into second gear and continued on. By the end of the session, I had caught Sam Mandich in his Neon, the only other car in the Pro Sedan 3 category. I was content to follow him around the track for several laps until the end of the session.

I had started out with the front tires inflated to 33 psi and the rears at 30.5 psi when they were cold. After coming off the track, I measured front 38.5 psi and rear 36 psi, which seemed pretty good for the Toyos. I was curious about the car's weight and went to the scales, finding that the combination of car and driver, with a nearly full tank of gas, was 2,350 lb. The rules mandated a minimum weight of 2,280 lb, so I reasoned that when the tank was about one-quarter full, I would be at or near the legal weight. The scales also told me the weight at each wheel position, and I noted that the right front was much heavier than the left front and that the left rear was carrying almost all of the rear weight of the car. Because our Project Race Ready Golf has adjustable springs, I spent the next hour or so making adjustments and running back to the scales to try and get the weights even. This is done by jacking up the car and then raising or lowering the spring perches on each corner. I finally settled for even weights on the rear tires and the fronts within 100 lb of each other. Besides, it was time for my qualifying run.

On my second lap of qualifying, downshifting from fifth to fourth to third, I suddenly had no drive to the wheels. I coasted halfway around the track and finally rolled to a stop in the grass in front of a flagging station, well off the racing line. The engine was running fine, and the clutch would engage and disengage; there was no drive to the front wheels. I waited until the end of my qualifying session and through the next until a tow truck came and pulled me back to the paddock. Several other racers crowded around and watched the transmission as I started the engine and put the car into gear.

0409_07z+1985_volkswagen_gti_coupe+front_right Photo 7/8   |   Surrounded by Spec Miatas during Sunday's enduro.

One of them immediately pointed out that the halfshaft was moving but that the wheel wasn't, a symptom of a broken constant velocity (CV) joint. I didn't have a spare with me, but I called International Parts Store (www.intlpartsstore.com) and found it had a left halfshaft in stock. My wife kindly offered to bring it to the track as I began disassembling the left side of the front axle. The parts arrived just as my race began, but at least I would be able to make the next day's Enduro.

Sunday's weather was much worse than the day before. It was snowing when I arrived at the track, and I did my Enduro practice and qualifying session on full-tread Toyo tires, tiptoeing around the wet and slushy track surface. It didn't look too promising, but by lunch the sun was out and a strong wind had come up, helping to dry the track. In a show of optimism, I switched to shaved dry tires and went to the grid for my race.

Aside from my first practice session the day before, this was really my first chance to drive the dry track, and for the next hour during the race I worked on learning the racing line and figuring out where I could brake less and carry more speed through the corners. I finally caught the Spec Miata of Charles Boehly and for five or six laps worked hard on trying to pass him. His smaller car was faster down the straights, but mine seemed to have the edge in cornering. It was fun, and maybe I would have gotten by him but the hour was up and out came the checkered flag. Even with the minor problems, I still count the weekend a success. There are a few mechanical things I now know need my attention. The windshield wipers work very slowly, so the linkage probably needs to be taken apart and cleaned. Sometimes the car doesn't go into fifth gear on the first try; an adjustment can be made to fix that problem.

0409_08z+1985_volkswagen_gti_coupe+rear Photo 8/8   |   Exiting "Thunder Valley" during Saturday's Small Bore qualifying session behind a Honda Challenge Integra.

Overall, I'm pleased with how the car handled and how well the engine pulled. Even when the CV joint broke, it was comforting to know that I was racing a car that's so common, I could find the pieces I needed in stock at an auto parts store on a Saturday afternoon.

With about a month before Project Race Ready Golf's next race meeting, I should have just enough time to fix the little problems. Next time I hope the car will truly be race ready.

Costs for Mid Ohio

Race gas (100 octane)

10 gal. @ $4.50/gal. $45

Graphics for Pro Sedan

and Enduro class decals (6) $60

Dynamometer testing $100

Race entry ($175 + $125) $300

New battery $60

New halfshaft (racer discount) $85

NASA membership $35

NASA race license $55

Total $740

(Not including hotel, meals and tow vehicle costs)

Vehicle Speed (mph)
Gear1st2nd3rd4th5th
RPM(3.45)(2.12)(1.44)(1.13)(0.89)
30001321314050
35001525374659
{{{4000}}}1728425467
45002032486076
50002236526685
52502337557089
55002439587494
57502541607798
6000264363{{{80}}}102
625027456684106
650028476887110


ENGINE

TYPE

1.8-liter, 8V, sohc, four-cylinder

MATERIAL

Cast-iron block, aluminum head

Fuel System

Bosch CIS fuel injection

INTERNAL MODIFICATIONS

Mild porting and three-angle valve job

EXTERNAL MODIFICATIONS

Bosal header and Turbomax race muffler; K&N air filter; oil cooler; engine stay rod; Autotech Power Module fuel enrichment; disabled knock sensor; deep oil pan with windage tray; new motor mounts

DRIVETRAIN

LAYOUT

Transverse front engine, front-wheel drive

ModificationsNew stock flywheel; four-puck racing clutch; OPM clutch-type limited slip; 4.30:1 final drive ratio; shift linkage rebuilt with Neuspeed weighted shift rod

SUSPENSION

FRONT: Koni single adjustable struts; Carrera camber plates; Eibach 450 lb/in. coil springs; Delrin lower control arm bushings; strut tower brace; no front anti-roll bar

CAMBER3.5 degrees negative

TOE1/8-in. toe out

REAR:

Koni single adjustable shocks; Eibach 475 lb/in. coil springs; Delrin lower control rear bushings; OPM rear anti-roll bar

CAMBER

2.5 degrees negativeTOE0 toe out

BRAKES

Stock front and rear rotors with Porterfield racing brake pads; braided stainless- steel brake lines

WHEELS

Stock VW 6J14 GTI alloy wheels; wheel studs and lug-nuts replacing O.E. bolts

TIRES

205/55VR14 Toyo Proxes RA1 tires--shaved

ADDITIONAL MODIFICATIONS

Eight-point welded-in rollcage; NASCAR-style intrusion bars; G-Force five-point racing harness; window net; fire extinguisher; MOMO pedal pads; lightweight aluminum racing seat; kill switch; fuel sample port

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