by Warren Leveque
ARTICLES ON THIS PAGE. [click on subject to Jump to the article]
Turbo Weber Setup
Front Wheel Drive
Turbo QuadraJet Setup
Rent - a - Racer
The Road to Mid - Ohio
Requiem for the Lightweights.
H / Stock
Have you ever wondered about the attraction of the Grocery Getter or Shopping Cart class? that certainly isnt the perception of the drivers in that class, however they do seem to disguise their cars with at least 20 magnetic decals. Instead of discussing this subject to death, it was decided to interview the H/S competitors at the largest event in our area.
The answers to Why H/S ? were as varied as the cars themselves. the most common response, if you can totally believe it was: This old thing? I was just something that I had lying around. This is may be somewhat believable from novices, but hard to swallow from 20 year veterans, but it still makes a lot of sense. If you dont want to or cant afford to dedicate a car total to autocrossing maybe five or six times a year and endure a penalty box the rest of the times, then Hatchbacks, big trunks, head room, four doors, good ride, economy, and reliability make smart choices.
Another sensible response was This car also comes with a larger, heavier, more powerful engine, so with the smaller, lighter, engine, it should be better balanced and more reliable. A lot of drivers started autocrossing in H/S because of the first reason; H/S is a natural starter class. they feel comfortable with the cars and the friends that they have made. The lower performance level of the car lends itself to driver training. There is more time to think about the lessons while driving. They also realize that the H/S trophy is the same size as the trophies for the prepared and modified classes. You also get to run more without all of the breakages, costs, and headaches.
Still, most every interviewee felt assured that they had made the correct choice and had The Car for the class. The eternal hope is for a Ringer. H/S does have the most new cars available every year and therefore the most choices. Unlike most classes, the governing body seems unwilling to let a particular car dominate H/S, so your Ringer may be in E/S next year. The down side therefore is that you may have to constantly trade cars to stay competitive. This could be seen as a $20,000 performance improvement.
The champions are always updating to the best car.
Several respondents were eager to tell about their wins, championships, and close competition. NO one mentioned a particular fondness for their car, their was no marque worship here! Also, no one mentioned the thrill of acceleration or cornering power, or the excitement of driving their cars. Apparently, its an efficient tool to meet their goals and to be replaced when a better tool comes along.
SCCA has recently introduced a new class to encourage entry level drivers to compete. It is acknowledged to encourage newer front wheel drive pocket rockets but does not eliminate older rear wheel drive cars . All cars must have rear seating ( no 2 seat Stingers) . Rear drive cars cannot have limited slip (obviously to handicap rear drivers- but not Corvairs). Front drivers can only have limited slip- non torque sensing differentials. Engines are limited to 3.1 liters.
This has come about , in my opinion, because of the failure to foresee the technical expansion of Stock and Street Prepared classes. Stock isnt stock because of front anti-roll bars , adjustable shocks, and most importantly short, wide tires that are as sticky as slicks. They regear and lower stock cars and often put them on their tops. Street prepared cars are the most expensive of all to prepare, the sky is the limit other than inner engine modifications.
You cant recruit new people by telling them that they need $1000 worth of tires and wheels, and trailers to run stock. Conversely, you cant tell them to take off their dress -up spoilers, air dam, wings, scoops, wheels, and fancy interiors or run prepared or modified. They have addressed this by providing Street Touring S, Street Touring R, and Street Modified.
Basically in Street Touring S, you can do everything as in stock except for the street race tires. Tires must have a tread wear rating of 140 or above and they may be no larger than 225 mm cross section. Wheels can be of any diameter up to 7.5 inches wide.
Engines must be stock except for cold air intake, filters, computers, and 50 state legal free flowing exhaust systems. Up dates and back dates are allowed. Under drive pulleys are allowed. Popular bolt -on suspension kits such as slip on coil over struts, strut braces, camber plates, cross drilled rotors, springs and anti-roll bars are allowed.
Body and interior dress up items are allowed. Spoilers, air dams, and body kits are okay. Quick shifters are allowed. Batteries may be relocated.
Street Touring R is the same except for allowing the R DOT approved racing tires.
These classes are fairly compatible with CORSAs Improved stock three and the Street Mod class, if you have too many points.
New for 2000 is the Street Modified class. As in the above classes all cars must be legally registered for the street-no dealer, temporary or transporter tags are allowed. In addition to the above:
Engine transplants are allowed if from the same manufacturer. The limit is 3.1
for forced induction, overhead cams, 4.0 liters for pushrod forced induction, 6.0 for naturally aspirated engines, and 1.5 liters for rotaries.
Suspension changes are free provided that the factory attachment points are used. Frame and chassis stiffeners are allowed. R compound DOT tires may be used.
A little imagination shows that many of our Street Modified (what a coincidental name) are eligible as are many Specialty cars.
Dont forget the CORSA decal
Turbo Weber Set-up
Weber carburetors work basically on a pulsing theory. They are normally installed on a single runner system for each throat and with no balancing plenum. They are very sensitive to signals and are insensitive to flow direction. As soon as these carbs are bolted onto a turbocharger they are forced to become flow sensitive just like Holleys, Q-Jets, etc. Their sensitivity gives very good reaction to the extremely poor signal of a -not on boost- turbo engine. However, since they are designed to operate mainly in a fully open mode and essentially have little or no progressive circuitry ( masked by a HUGE accelerator pump) , they cannot accommodate an engine whose airflow varies suddenly from 300 cfm to 650 cfm. Imagine a 500 cfm two barrel Holley on an 80 hp Corvair or a 250 cfm two barrel Holley an a 350 cubic inch Chevy and you can begin to picture the problem. You essentially have both of these engines in you car. GM put the tiny single barrel side draft carb on to cover the low speed characteristics and said to heck with the high flows, well just use it for a boost control. A 40 DCOE Weber with 26 mm chokes ( venturies) accomplishes the same thing with a much nicer carburetor. At high flow rates, the air flow becomes sonic , goes dead rich (because of that great flow sensitivity), limits the boost to 9 or 10 psi ( gauge) and you must up shift early because it wont rev any higher. This may be just what you are after in some cases. Most would rather have greater engine flexibility and a waste gate. The way to prevent going dead rich is to use larger chokes, which gives the dreaded low end bog.
Obviously, a variable venturi carburetor such as a Rochester Quadrajet, spread bore Holley, SU, or a Predator is needed. LeVair Performance Products has modified 40 DCOE and 45 DCOE Weber carbs to operate in the progressive manner of the above carbs. They have separate primary and secondary bores. The throttle rod only operates the primary side. The secondary side is operated by a signal from the primary venturi booster to a Holley 4 bbl vacuum diaphragm which opens the secondary side only after the primary has adequate air flow.
Normally this carburetor can just be bolted on and driven if jetted according to the Weber manuals i.e. main jet size equals 4 x the choke size, Air corrector equals main for racing, or a/c =main + 60 for economy. If this doesnt work, check to see if the booster venturies are in the small 2 or 3 range. Too large booster venturies give poor signals and require much richer jetting. You never know the history of these cars or their intended usage. Since the idle signal is being strained through a remote, non operating turbo, the idle jet size usually needs increased. This increase may have to be .020 to .030 for racing. this is because the Weber has no real transition circuits and must tip-in on the idle circuits. this is why the secondary idle circuit should be larger and certainly not plugged. The emulsion tubes should have more holes for the street and less holes for racing. The air correction jets can be considered fine tuning.
The secondary vacuum diaphragm is from a Holley 4 bbl. They are shipped with a brown spring which is fine for a hot Corvair which runs like a V8. Some of our customers overestimate the performance of their cars and may need to buy the spring kit. Bog can usually be cured by using the soft yellow spring.
The secondary shooter for the accelerator pump should be plugged to divert all of the fuel to the open primary. This is a lot of fuel and is wonderful for racing. The pump jets are easily changed it less shot is desired.
Almost any combination of chokes will work. We recommend a primary of approximately 33 mm. This gives the same or better response and flow of the stock carb or the two 26mm set-ups. We recommend a secondary of 36 mm to 40 mm for maximum output and to be able to shift at higher rpms without going dead rich. By the way-turbos like load much more than rpms--UPSHIFT. If racing, jet the primaries more rich and the secondaries more lean. For economy jet the primaries border line lean and the secondaries rich. These carbs are very sensitive, make small changes and document everything You WILL get lost.
So far, every complaint of misfiring over 10 psi (gauge) boost if not leanness is poor ignition. Being extremely over rich can cause misfiring also as can too much water injection. Over 10 psi requires more ignition power ( not voltage) than a naturally aspirated car turning 10,000 rpm. Any not experiencing ignition problems are running low boost. After trying several systems; MSD, Allison, Judson, Chrysler, Perlux, etc., we converted to a GM HEI and can run 30 psi with no misfire. A perfect stock system works better than all but the HEI, if using a large coil, mag type plug wires, good bushings, .013 point gap, .022 plug gap and 32 degrees total advance. On hopped up turbo systems, the pressure retard system will be retarded all of the time. A 95 hp 4 speed distributor has the slowest and best advance curve. Use a detonation sensor and dont worry about the advance curve. Develop you system in slow steps, detonation is deadly.
Front Wheel Drive
Somehow, front wheel drive competitors are either very smart or very lucky. The current generation of fwd cars are uniquely adapted to our sport of slow speed racing or our sport is adapting to front wheel drive. Discounting the Nationals, our events are being run on smaller and slicker courses more and more. As almost all new sporty cars are fwd, consciously or unconsciously fwd -owning course designers favor designs which will aid their own cars. Examples being tight turn ingress turns, no sweepers, no emphasis on acceleration, and tunnel courses with no line selection.
Any inequities resulting will most likely, eventually, be adjusted in the governing bodys performance review process. Its inevitable that resulting reclassifications will lean toward the most popular, newest, and most produced and represented cars--fwd. In the meantime, its the rear wheel drivers faults if they dont volunteer to put on events and design courses.
For low speed, low horse power, racing, fwd cars have the correct weight bias over the drivetrain and toward the front--remember F(c)=mvv/r. Also by nature they are very light which helps in all aspects of performance. Generally, since they are small and light, they have small engines with low internal inertia (flywheel effect) and also have small light wheels and brakes for low rotational inertia.
Initially the performance balance was skewed away from fwd because high horse power to weight ratio was not rewarded due to traction loss by weight transfer off of the front driving wheels. Now, Automatic Traction Control, Limited Slip, and especially torque sensing differentials such as Quaffe and Torsen have dramatically shifted the performance balance toward fwd.
If you accept the premise that tight, slippery, tunnel type, ingress courses (emphasis on turn entry rather than exit) are best challenged by cars that turn the tightest radius (oversteer) then fwds can be the tight radius or oversteer champs. Accepting that oversteer is accomplished by reducing rear traction while increasing front traction, then cornering on one rear wheel is the ultimate in oversteer. Any rear wheel drive vehicle that is cornering on one rear wheel has lost all or nearly all driving force. Even if the rwd has limited slip or a locked rear axle, nearly all of the forward traction is lost due to one-wheel cornering using up all of the rubber.
Imagine a fwd car cornering on one rear wheel, having the most oversteer possible and also having all of the forward traction available with a torque sensing differential and no front roll resistance. Even with an open differential, most of the forward drive is available for utilizing power -on braking principles discovered by performance rallyists driving Saabs in the fifties. This principle of applying brakes to improve differential action has been use for 100 years on farm tractors. It doesnt affect the rear brakes much because they are tiny and unloaded.
Another important effect of fwd which I have not seen discussed is the torque thrust of the driven wheels. Even if the acceleration has used up all of the friction available for cornering, at least the acceleration force is in the desired turning direction and is not contributing to understeer as in the rwd. There is not usually enough room for a rwd car to put the rear of the car out enough to point the driving wheels in the cornering arc. This is similar to a Sprint car accelerating toward the corner apex an dirt. Youve felt both effects while driving in snow or sand.
The maximum output of the Corvair cooling fan is 1460 cfm at 4000 rpm. The output goes down at higher speeds but the horsepower used goes up at the cube of the speed. The engines has to provide 8 horsepower at 4000 rpm, 15.6 at 5000 rpm, and 27 hp at 6000 rpm etc. The centrifugal fan and its housing operates much like the compressor and scroll of a turbocharger by flinging the air off of the tips and compressing it in the housing. It actually is much more efficient than pressure head types or squirrel cage types. The air is flung to the extremities where the cyl. head fins actually are. The Cylinder fins actually do very little cooling. Some racing Porsches leave the cylinder fins off and depend on the oil cooling. When using pressure head type fans (vertical type) baffles are placed between the cylinders to assure air going to the heads. Like a turbo going off of the compressor map , the centrifugal fan surges and reduces pumping at higher speeds. We need to get some of this horse power and efficiency back.
Starting with stock set-ups. Much can be gained with cooling fin clean-up, especially between the combustion chambers The importance of this is obvious after viewing with a light under the heads. A temporary hp gain can be had by adjusting the damper doors to just be opening at the finish of a run. Hold a piece of cardboard either in front of back of a window fan and watch it speed up; same principle and the current draw or electrical hp requirement goes down. Horse power used to accelerate the fan can be reduced by allowing a silicone coated loose belt to slip. Wrapped belts slip better. A ragged belt can be allowed to come off at the 1st to second shift. Runs are usually less than a minute; coast in with the heater running.
As much as 10 hp can be gained by restricting the fan inlet area (stock on a 60 model) with a disc under the pulley. With approx. an inch opening normal flow is provided at idle and staging and shut way down at higher speeds. This is not a road racing item. A cut down fan saves the same horsepower , prevents cavitation, and reduces the flywheel effect ( not much compared to the alternator), but has very poor cooling at lower speeds. In both cases the belt horse power loss is still there.
If the fan pulley diameter is increased and the crank pulley diameter is reduced, the STOCK belt speed is cut in half along with the power required. This requires much pulley realignment. The acceleration rate of the fan and alternator is halved and its maximum cfm at 4000 rpm is achieved at an engine speed of 7000 rpm. It also continues to fling the air off of the tips toward the heads. The reduced flow at lower speeds can partially be compensated for by lower shroud removal . Side sheet metal removal is not recommended for prolonged idling. The hot air rises right back into the fan inlet and onto the carburetors. The fan inlet air can be ducted from the engine cover openings to prevent recirculation. The Porsche style fans are used primarily for belt retention, and are not very efficient at lower speeds.
A good wrapped silicone soaked, loose belt will stay on a 7500 rpm if every thing is perfect. Spring loaded, damped, idlers work if they are robust at the pivot and do not wobble .
For high speed racing only, 8 inch ducts can be run from the headlight openings to plenums over the cylinder heads. Two inches of water pressure is available at 60 mph. This releases all of the fan hp and can really be felt. You CANNOT idle or run slow. A crankshaft mounted fan was tired with about the same results. Since it rotated slowly at engine rpm and had complicated plumbing, you could not go slow. There is much talk of bevel gear driven fans. This would only last if there was some slippage designed to spare the gears the shock of torque reversal. Paxton superchargers have such a device in place.
In our lightweight, powerful, modified autocrossers, belts would not stay on regardless of the method used due to the violent acceleration in the lower gears. Everything was tried, including fendered pulleys and electric fans. Of course the electric fans didnt work Youre replacing at least a 15 hp system. Have you ever seen a 15 hp electric motor? Electric fans can be used to cool down between runs, time allowing. Several manometer tests were made at 60 mph. A mid engined car produces more pressurized upward flow through the engine that a full size full speed fan could not overcome it. An air dam just in front of the engine would help some. Since this was a 60 second autocross car, the solution was to remove all of the sheet metal and let the upward flow of air cool the engine like an inefficient motorcycle. You cannot idle. This worked very well by staging at 220 degrees and finishing at 400 degree. At first I cooled the engine by spraying very carefully with water between runs. This was determined to be too messy and a 10 fan was installed over each head--not used during the run.
The Turbo Stinger is cooled by rich mixtures, water injection, and a mist of water into the inlet of the full size full speed fan. This is injected at a preset amount of boost. It also has a huge front mounted oil cooler. The only decent source of air pressure is at the license plate and windshield base areas.
At autocross speeds a front mounted oil cooler my need an electric fan installed. My Stinger maintains cylinder head temperatures of 350 deg. and oil temperatures of 200 degrees.
The stock side draft carburetor on the turbo Corvair is THE boost control. It was already available for the 6 cylinder Corvette and before that on farm combine engines. This along with the lazy, too large turbo unit avoided all expensive boost controls . The very small carburetor did give good low end performace when the accelerator pump actually worked. When the boost got up around 7 or 8 psi gauge, the venturi became a sonic orfice, blocked more flow, became dead rich and prevented more rpm. This actually suited most of the people just fine. They were more concerned about the gas leaks and the poor heat soak starting.
I had one of these carbs on an engine with an E flow compressor, and a Crown exhaust housing and still could only get 10 psi and had to shift at 5000 rpm. I talked to several people using Weber side draft carbs about their success. With very small venturies for good response they also got about 10 psi. With large venturies and lots of bog they easily got 15 psi or more. Obviously a fixed venturi carburetor could not accommodate the great cfm change of a turbocharged engine- from 300 cfm to 650 cfm. Imagine a 650 cfm Holley on a 95 hp Corvair or a 250 cfm single barrel on a 350 cubic in Chevy. You essentially have both of these engines depending on the state of boost. A variable venturi on demand carb was needed. Examples would be a Large SU, a Predator, or a progressive 4 barrel. I later learned how to make a Weber work by making it progressive but thats another story.
Most 4 barrels that can handle the maximum cfm of the Full-out boosted Corvair engine have primaries too large for good response. The 390 Holley has 1 primary and secondary venturis and would work but would ultimately restrict the boost, which might be fine for some cases. It also is not progressive in its jetting. Its a 2 step carb.
After reading about and experimenting with the Rochester Quadrajet four barrel carb, I determined that it might be ideal. If you use one from a GM small block engine ( up to 350 cid), the primaries are 1 inch in size-- the same as a 110 hp set-up. The primary has fuel enrichment circuit consisting of tapered needed which rise out of the jets at decreasing vacuum signal (increased load --or increased boost!), progressively enriching the mixture. The secondary throttle plates are opened by the linkage but the air vane above them is opened progressively by the increased air flow. This is how all mechanical and some electronic injections work. As the air vanes pivot open they also pull up tapered needles to enrichen the mixture in the correct proportion to the air flow. They start in not weather and dont leak. It cant bog, no air flow, no opening. It also never goes dead rich. With this set up a hotted-up turbo( taking advantage of that oversized turbo) will make 30 psi and a nearly stock one about 18 psi. The opening of the air vane can be controlled by installing a limit screw and therefore controlling boost. Jetting can be changed if needed by changing needles.
The power valve (enrichment circuit ) must be plumbed out of the carburetor manifold to get a proper signal. Next to the compressor it would always see vacuum. Some of these carbs come with electric chokes. An air cleaner snorkel can be directed to the area under the alternator or winter heated air.
When looking for a carb, find the earliest one possible for less emission changes and ask for a Buick, Olds, or Pontiac. Chevy models are pricey, they may give you the others. The only difference is the fuel inlet angle. Of course we make manifolds and kits for this installation.
The only disadvantage of this set up is that some people perceive them as ugly before they take a ride.
This adventure started because my wife, Sharon wanted an airplane ride over Brown County State Park to see the Autumn leaves. A co-worker and friend, Frank Cox, had expressed an interest in driving a race car on a trial basis. Now the plot thickens; Frank is a pilot and owns his own airplane, a Mooney. I had pretty much dismissed the overture because 99.9% of the people dont really mean it.
We had a car show at the plant and I brought my Formula car in A/M-winged-supercharged trim. When Frank sat in it for an inordinately long time (vroom, vroom) , I realized that maybe he wasnt kidding. Fall at Brown County was nearing and so was a local autocross, so the exchange was made.
In fairness to Frank, I begged him to write a similar article a year ago so his chance at first offense/defense has passed. Frank has a background of flying, drag racing, motorcycling, snow mobiling, boating, body building, and is a skilled tradesman. He had zero experience in a road racer or autocrosser. His first experience in the supercharged A/M was none-the -less, mind boggling-his words.
That must be similar to my feeling at the controls of his airplane. The airborne view of the foliage was equally exciting for Sharon. During the winter, negotiating was done by grunts, hints, and innuendo. Neither of us knew where to start bargaining on rent-a-racers. Finally, a Just what would it take? agreement was reached. I wouldnt get rich, Frank wouldnt get poor, and he would help me fix it (little did he know). It was agreed to remove the supercharger and return to B/M specs for reliability.
The LeVair Velociraptor (fast bird of prey) ( they must look like Canaries) is a completely home built Formula Atlantic clone with a total Corvair drivetrain. Its 1105 pounds with a 2900cc , 225 horse power Corvair engine. Because it was built especially for Solo II, any driver could fit-Frank is a big guy. At best, the car is a middle of the pack runner, but is sturdy and reliable ( both to be tested).
At first we both drove it, in separate heats, to set a baseline and to learn all of the nuances. Frank had to learn everything and just charged in with gusto.
It was a little tough at first to be an observer. Frank appeared to be completely unafraid. I had to observe him charging into corners at over 110% with no change of making it, and spinning my baby down the runway. It was exactly the correct thing for him to do, but is surely hard on the owners nerves. Franks wife Barbara found all of this quite entertaining, so stayed around to become good pit help, and cheer leader.
Its an education for a teacher to watch a first timer. Some of the things that we take for granted arent so obvious to a newcomer and sometimes I couldnt answer except We just do it. Why are some of the turns so tight? Why do stock cars get cheater racing slicks? Why do we use 150 pylons when 50 would do and you tell me only about 15 or 20 really count? I dunno.
I may have paid as much if not more attention to Frank as he did to me because I really wanted to see this sport through a novices eyes. He was mostly excited about the competition and very puzzled about the rules development. From a 25 year vantage point I understand and appreciate how far weve come, but I really appreciate a fresh view. Frank seemed impressed with the friendly social atmosphere; apparently drag racers are serious.
Having a student tests some of your pet theories. Hes going to take them as the only way with no preconceived notions.. When you tell him to slow down to get into better position for the straight, hell look at you questioningly but do it. It had better work. Also when you get into the car you had better do what you told him to do, and faster.
Having a student/partner is having two chances to win every event. I was as excited about each of Franks successes as he was. It also gave me a chance to observe the car work or not. Some things were tried at my partners insistence, some worked, some didnt. Less rear bar and shorter gears worked, larger tires didnt.
It you are working far out on the course and the car doesnt appear or disappears, you die a thousand deaths. On the other hand, it is certainly nice to have someone bring a spare car for you if yours breaks. Frank had no interest in running a fendered trainer car. He did well in the Fiero at a school but he was bored.
The agreement was renewed for a second year with some hesitation on my part; renting a race car is not a money maker. The partner/friendship part caused me to renew. Little did I know how correct this decision would be . In the Winter, I had serious, debilitating surgeries. If it were not for our partner relationship, I could not have raced in the Spring or early Summer. Frank loaded and brought me an the car, unloaded and prepared , and staged it. He helped me get in and out and I sort of raced. My regions officials made sure that I had easy work assignments. It was a humbling and bittersweet experience.
Franks time became very close to mine and the teaching became more like hints and congratulations. He even went to some major events alone, a real sign of confidence. When he started getting FTDs , I felt like I had won them myself. The car went two years with very little maintenance; tires, rod ends, alignment, etc.
A real test came mid year when I loaned the car to a good friend and he wrapped it around a light pole (testing sturdy). It was a racing thing, every one knew the risks, but it was bent. I surely hated to tell my partner, but he jumped right in and we and my friend were able to fix it in a week. I had just burnt -up the Stinger the week before ( turbo fire ) so it was a very busy time.
Alter not driving the car all Summer, I got back into it for the last race of the year. I was admittedly apprehensive. I was rusty, would my student beat me?
Wouldnt it be sort of good if he did? I had to run first. Just go for it, thats what hed do. As it turned out, I won, but by only about a third of the margin of late last year, so it was a win for both of us.
The Road to Mid-Ohio
Everyone starts their journey from a different place. MY place was zero. It didnt have to be, but it was. My state of the old art D/Production Yenko Stinger
( YS 160) in the 70s was to have become obsolete by the coming GT-3 preparation rules in the 80s. I couldnt afford to up -date so I sold it. Vintage racing didnt exist for a Corvair then. It would have been a perfect 90s Vintage racer if I still owned it. A Vintage racer was what I needed for the Yenko Stinger Reunion at Mid-Ohio. I tried to buy an ITA racer but I was too late. The closest thing that I had was my still streetable Stinger ( YS 015) with a turbo engine.
Preparation time for me is deep winter, what else can you do? Unfortunately, I fell ill about this time so my sons volunteered to install the required roll cage. The turbo engine wasnt a problem. This wasnt SCCA and the vintage rules just required the car to be prepared as they were raced anywhere in the era using that eras technology.
My sons began to bring me news such as: The seats were removed without unbolting them. The floor came up with the carpet. The forward rails which support the front subframe werent connected to anything. This might explain why suspension adjustments had no noticeable effect. We bought the available floor pieces and fabricated the rest.
The simple roll cage turned into a twelve point jungle gym with four tubes going forward. If the car is going to have a self supporting frame, this is a good time to order the wider fiberglass fenders and the light 15 x 8 Revolution wheels. It seemed like a plan.
For autocrossing, I had an eight gallon fuel cell. From racers feedback we decided that this wouldnt be enough to finish a race, so an additional three gal vertical cell was added behind the right headlight.
While my sons worked on the chassis, I started on a fresh engine. I had autocrossed a turbo for years ( no, its definitely not an advantage, I just like them) but had never road raced one. A turbo designed for short acceleration bursts in a 60 sec. run just couldnt last in half hour sessions at wide open throttle.
The autocross set-up was 15 psi at 9:1 compression ratio using a 0.4 A/R ratio exhaust scroll, an E-flow compressor, an HEI ignition, and a 45 DCOE progressive Weber carb. This was mostly done to reduce lag, not just to make power. Lag is much less of a problem in road races; a good argument can be made for a completely stock set-up. Since I had no turbo racing experience, I went ultra conservative. An 8 psi wastegate spring (stock boost?), and a 7.5:1 compression ratio was used. this was achieved by milling .090 from the pistons in the valve pocket area. It was decided that the scroll and compressor werent necessary but were proven pieces and probably wouldnt hurt ( oh, yeah?). A stock full speed fan was used with a roller bearing idler. Air was ducted from the
Stinger flaps to get positive pressure and no recirculation. Water from the injection system was also sprayed in the fan inlet. Heat is the enemy of turbocharging, not mechanical stress. Pressure stress is linear; rpm stress is geometric. A front oil cooler was purchased but not used because an air conditioner evaporator looked more efficient.
We calculated the cage to weigh approximately 120 pounds, so weight reduction was a priority. There was no more possibility of a street car or street testing. According to the Historic Sports Car Racing rules, no modern improvements could be made, such as wild fender flares, air dams, racing slicks, etc. but all modern safety equipment was mandatory. This includes, Nomex, harness, fuel cell, cage, seat support, window net, cut-off switch, tow hooks, latest helmet, etc. Luckily this very vintage driver could just barely fit into the equally vintage suit. You have to have a previous race license or go to a school, and take a medical exam. I cant believe that I passed it.
The fiberglass fenders werent going to arrive, so the current sheet metal had to be repaired and painted and the wide wheels couldnt be used. The back-up plan was to use Jon Brakkes one race old tires on heavy 15 x 7 Camaro wheels. We didnt know what race group wed be in at that time.
There was time for maybe two autocross test sessions. The first proved that rev limiters dont work well with turbos. That nice rhythmic miss turns into explosive backfires; all of the intake and compressor gaskets were blown out. At the second test , the number five piston was destroyed by detonation, the rest were perfect. A real puzzler. After a lot of sleuthing, it was determined that the piston was overheated by exhaust from the waste gate. With an 8 # spring on a 30 psi capable turbo system, the waste gate is always open. This was fixed with a short exhaust pipe to direct the waste gate gas outward.
It was time to go to Mid-Ohio. since Corvairs raced on 13 inch wheels, I demounted the 13 autocross tires in preparation of receiving the correct tires at the track. At Mid-Ohio, the tires werent available, and the slicks werent noticed at tech inspection. In fact not one of the no modern improvements on the other cars were inforced and most were on slicks.
Jim Schardt proceeded to lead me around an get me re-familiarized with the track. Damn, he leads fast in the rain.
The next practice was dry, so it was a real test. Vintage racer Tom Schrum gave me some helpful advice, such as; use tall gears, and a wide ratio gearbox. It makes sense, that what Porsche does. I planned to use 3.27 gears and 21 tall tires. Now, the non-plan was to use 23 tall tires. MY Straight a way speed was near 130 mph at 6300 rpm. Schardt was doing at least 7500 rpm at the same speed. Since we were side by side, torque and horsepower must give the same results.
I tried second gear at the Carousel, and Keyhole which slowed the car too much. Next, third gear was tried at 3500 rpm. Apparently, a nearly stock cam, small primaried progressive carb. and lots of load induced turbo torque can work.
I seemed to be on completely even terms with the full race naturally aspirated Corvairs at this low boost level. There was a regulator knob to increase boost, but I was reluctant to use it for fairness and reliability reasons.. In order to preserve my energy and the engine while learning the track I used the A.J. Foyt technique of charging hard sections and resting on the straights. When you do this you have watch lots of slow cars pass you. I had the same GM metallic brakes as in the seventies. This seemed like NO brakes. Apparently, the low compression, tall gearing, and the flywheel effect of the Camaro wheels is significant.
So far the weekend was a complete success. An oil dry, smokeless Corvair is a victory. Eight gallons of fuel would have been plenty; mileage was better than expected. The suspension adjustments even worked. My crew of Tom Beech and Harry Jensen were bored. The cylinder head temperatures never exceed 350 deg. and the oil temp. never went over 220 deg.
Logically, we should have been grouped with similar performing cars such as 911 Porsches, Triumph TR6s and 240-280Z Datsuns. Instead we were grouped with 60s and 70s muscle cars; Trans Am Camaros, Corvettes, Cobras, and Jaguars. It was a great photo opportunity. We did better than expected, qualifying near the middle. At grid formation, I couldnt hear my engine run. the V8 thunder was chilling.
The race was what I expected, the muscle cars humbled us down the straights and held us up in the corners. Most when it was obvious, would let us by. Jim Schardt, myself, and Steve Olsen had a good scrap going until passed cars began holding us up. Then Jim used his greater traffic experience to show us his heels. One particular Jaguar was crawling sideways through the corners, but was just fast enough on the straight to get by. Were not allowed to touch each other in vintage races, and I guess that he just couldnt give way to a Corvair.
I recall about the time actually saying to myself Im having a great time. There were only two laps left, the Jaguar was just too much. I reached for the Knob.
The boost went from 8 psi to 20 psi to 0 psi. The suddenly closed waste gate fractured the overheated turbo feed pipe, dumping the boost, and eventually melting the oil return hose and starting an engine fire. It was after the flag, and I didnt lose a position.
Im charged up. Not hooked, but enthused. I know the turbo car can work. I cant wait for an opportunity to try a little more compression, a little more boost, little more gearing, the right wheels and tires, and blowing by that Jaguar on the straight. Next stop, Lime Rock, see you there.
Requiem for the Lightweights.
Due do the same genetic defect that all of we car nuts have Ive developed some strange reading habits. When leafing through any car test magazine ( I surely must take them all) . I go immediately to the section of the test which gives the specifications and look for the curb weight. If the car is not under 2500 pounds I immediately lose interest. Porsches used to weigh 2700, now 3200. Even the Lotus Espirit is over 3000 pounds.
Im not impressed by the things that are added onto the cars but what is taken off in the design stage in the name of performance. Electronics dont really add performance. Air flow adds performance. Electronics just makes it efficient and environmentally friendly. Huge tires, huge wheels, and huge brakes are added because they are necessary to control a grossly overweight car. If the engineer didnt do a good job of designing a light car then the above things are added to compensate. Also the public seems to like it this way. Its very salable.
Light cars do everything better. There is just less mass to deal with. The tactile feeling of response in a light car is great. The huge brakes add more than just their weight. The discs are huge flywheels which have to be stopped and started, which requires more power and tires and more weight.
Also in the category of engineering misfits are traction and braking aids which are band-aids or cover-ups. Four wheel drive, traction control, active suspension, and ABS braking are all used because the car wasnt designed according to the laws of Physics. My education background is engineering, math, and physics. therefore I cant help myself from looking at things this way.
If you put the engine/drivetrain somewhere other than over the driven wheels, then you have designed in the need for band-aids. Front wheel drive, while useful in the snow, offers no performance help. Putting all of the weight at one end of the car doesnt help the polar moment either. The weight transfers off of the drive wheels during acceleration. The weight transfers onto the already overloaded front brakes during deceleration. The rear brakes are useless ( for marketing reasons disc brakes are on the rear of cars whose wheels are nearly off of the ground under braking) and are made more so by proportioning valves and rear ABS. Performance cars (?) that start out as front wheel drive add four wheel drive to overcome this problem, and the weight goes up! This requires even larger tires, engine and brakes due to the added weight and the weight goes up even more! How about 4000 pound Mitsubishi 3000 GTs? There used to be economy cars weighing around 1800 pounds. Now its surprising to see a Honda civic under 2400 pounds. The popularity of SCCA H/S used to be based on these light and nimble cars.
I saw a show recently about Japanese built drag racers. They had devised hydraulic wheelie bars to combat wrong weight transfer--unbelievable. People will make anything work. What else do they have to work with?
A big disappointment to me as a former GM employee is the size and weight of Corvettes and Camaros. I know that they are a bargain in the bang for the buck, but they are huge 3500 # 2 passenger cars. Putting a V6 into an already heavy car gains (loses?) very little. It needs to be designed around the smaller engine and components.
If you start out with large components, then the vicious cycle starts and bigness begets bigness. How about starting with S-10 truck components?
The simple F =MA formula shows that it takes less energy to control a light object in fore, aft, and lateral accelerations. Colin Chapman got fantastic performance out of light weight cars with small engines, wheels, brakes, and tires, with no power accessories. Although he did say that he could make a barn go fast if he had enough cubic inches and tires. I think that we have witnessed this concept in C/P autocross class. I know it is hard to have 1500# Lotus Elans today, but we have computer design and exotic light materials to balance the Government mandated safety devices. Isnt the new Lotus Elise around 1800 # before GM gets hold of it and makes it 2500#. Actually the Mazda Miata could be thought of as a modern Elan weighing around 2200# with good balance and small wheels , brakes, tires, and engine. It has great performance.
The Fiero and Toyota MR2s were laid out correctly but somehow got too heavy. At least they transfer weight onto the drive wheels under acceleration and evenly distribute the weight under braking. They also shouldnt need power brakes, powersteering, traction control or four wheel drive. Oh, thats right theyre laid out just like all of the purpose built race cars in the world. Yes, NASCAR is big heavy cars but they only run against themselves so there is no performance comparison. Surely, you dont think that they look nimble on a road course? Theres no reason why a sedan couldnt be laid out exactly the same way as a Fiero with a trunk in the front and back. Arent front and rear trunks deformable energy absorbing structures?
In my own small area of interest is a good example i.e, the Corvair sedan.
This huge 108 inch wheelbase car only weighed 2550 # with a 2700 cc 6 cylinder engine. What does an equivalent car weigh today? Yes I know the 3200 # equivalents have more safety features but also have modern design methods. I think that the laws of physics were ignored for marketing reasons. I cant blame them for producing what sells. The rear overhung engine is correct for weight distribution ( acceleration and braking) but the rear mass is wrong for centrifugal force ( high speed cornering). The Fiero/MR2 layout is better.
Still, when heavy powerful engines are put in the back seat of Corvairs ( theoretically better), the added higher center of gravity weight seems to take the advantage away. When the necessary radiator, stronger drive train, heavier suspension, larger wheels, tires, and brakes are added this 3200# car is subject to the laws of physics and is no faster in any mode than a Corvair prepared in the lightening manner. The Corveight is still a hoot to drive but there is a lesson here. I hope that the allowed new lower weight for the racing Corvairs will allow me to put my money where my mouth is. Of course there is still that little cubic inch discrepancy and the polar moment thing.
Surely youve noticed how certain Marques of cars have slowly gained weight and then disappeared from the market. Light Datsun 240Z, then heavier 280Z, then 300 ZX, then gone. Light Toyota MR2, then heavier, then gone. Light Mazda RX7 , then heavier, then heavier still, then gone.
I guess the thing to do is watch for the introduction of a light weight car, and buy it before the poundage and disappearing starts. Get a light and nimble car before we hear the requiem.
Been to the "Patio" lately?
Back to Brians Autocross Pages