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For those of you involved in serious sanctioned racing of any type, please remember that it is an impossible task to write a website section like this and cover all the bases. The incoming phone calls we receive cover the full range from a person who is just beginning to think of going racing, all the way to full-blown professional fully-sponsored organized teams. The first person needs many elementary questions answered and advice on the direction to go, with corresponding expenditure estimate and time tables. The second already knows it all, has the budget, but needs it done, dynoed, shipped, and delivered yesterday. They are both very valued customers that require and expect the right honest answers.
For liability reasons we must state emphatically that street racing is illegal, and should never be done, PERIOD. It is extremely dangerous and your efforts will be much more rewarding if you investigate the many types of sanctioned racing events run by licensed and insured organizations. Even then we cannot encourage anyone to risk injury by participating in a very dangerous sport.
The term "Racing" appears to have tremendous variance of definition depending completely on any specific person's opinions. Please bear with us while we ask the many pertinent questions that must be answered before we can make the decisions relating to engine, intake, exhaust, chassis, trans, diff and tire combinations for your specific type of "Racing".
Our view is that a winning combination/package is a much better approach than to build only "MAX HORSEPOWER" engines. A less than maximum engine combined with better suspension, tires, gears, and much less weight will usually be faster than a "MAX" engine in a less than optimum "PACKAGE".
The major types of racing that need discussion are: Street, Drag, Oval, Road, and Off-Road. Each one requires a different package that may or may not be applicable to some other type of racing.
There are many "sayings" that float around the racing crowds, but some are particularly applicable to all forms of racing, and the ones that give an overall view of the attitude necessary for "successful" racing are:
1. THE WAY TO MAKE A SMALL FORTUNE IN RACING IS TO START WITH A LARGE FORTUNE.
2. SPEED COSTS MONEY, HOW FAST DO YOU WANT TO GO?
3. IN ORDER TO FINISH FIRST, YOU MUST FIRST FINISH.
4. YOU CAN BE CHEAP, FAST, OR SAFE. PICK TWO.
5. I KNOW THERE'S MONEY IN RACING, I PUT IT THERE.
Although they may seem trite, or have been heard way too often, they are still very true. No matter what type of racing you are in, or would like to be in, there really is no limit to the amount of money that can be spent. The more that is spent (assuming it is spent wisely) the better and faster the package will be. BUT, the car MUST finish, which means reliability must ALWAYS be at the top of the list.
Before the individual types of racing are discussed, the few common denominators that do cross all the lines should be addressed first.
1. MONEY - Most customers don't like to be addressed at this level first, but it must be acknowledged by everyone early in the conversation. We will be doing our reputation no good at all if we know what we are forced to supply will not work very well, won't last, etc, etc. So please be honest with us on what you are planning to do with what we supply, and how much you can afford. We really have had a few serious customers who had budgeted way too much for an engine, and were shocked (and obviously pleased) when we informed them an engine to do everything they needed would not cost anywhere near what they thought they needed to spend. We try very hard to come up with the most economical package to supply your needs, and tailor all of our suggestions and recommendations to your specific budget. But please understand that if we tell you it can't be done for what you have available, that's our honest appraisal of the situation. One of our least favorite things to hear is: "Your were right, I should have had you do it right the first time instead of letting "so and so" do it because he quoted cheaper". This is invariably followed by "now I don't have enough money left to do it right - what can you do that won't cost so much".
2. WEIGHT - There is virtually no type of racing where the lighter of two cars (assuming all else is equal) will not always win. It takes horsepower to accelerate weight, brakes to slow it down, shocks and springs to control it up and down, and chassis to support it all. If weight can be removed without detrimental effects on other systems, it should always be done. That's why they have minimum weights on racing classes, and all race cars should be built to be right on that minimum. The example we use for a serious "street" drag racing car would be stripped to bare metal, acid dipped, single paint layer, major chunks of body interior panels removed, no carpet, lexan windows, single sheet doors, fiberglass bumpers, skinny front tires, big slicks in back, virtually no electrical wiring, one seat only,one gauge only (tach obviously), no bracing on the hood, etc, etc. The car would obviously be not street legal, but would look like an ordinary car on the outside. Then, start deciding on engine/trans/gears etc.
3. TRACTION - Different racing types have very different suspension needs. If your type of racing has turns, then you had better be able to corner with the best of them. If you're racing in the dirt you need traction all the time your tires are touching the ground, and you need to keep them there as much as possible. If you are turning left all the time, then maximum corning power must be maintained and its got to get off the corners with all available horsepower. In drag racing the clouds of smoke at the line are impressive, but the car is not going anywhere.
4. AERODYNAMICS - The faster you go the more it becomes important. It takes horsepower to push a hole in the air. The bigger the hole and the more junk hanging out, the more horsepower is wasted. Many in-depth volumes have been written on the subject, but anyone can make significant improvement on their car by using common sense first. Just stare at the front of the car, that's how big a hole you are punching. Anything you can do to make it smaller will help. Lower it, move the mirrors in closer, get the tires back inside the fenders, etc. The next step is to fix things sticking out - get rid of the antenna, fix that headlight bucket that does not close all the way, etc. Then work on the whole exterior. Air flows best over smooth surfaces (amazing?). Body seams need to be as small as possible, all leading edges must be as smooth as possible. Radical drop-off trailing edges are no good. The rear edge of fender wells with a tire in too far are nothing but a large air brake. If the front of the car is too blunt it will have what is commonly referred to as "the aerodynamics of a brick". However, front air dams that go as close to the ground as possible accomplish numerous things: 1) They decrease the air going under the car which will always become turbulent. 2) A low pressure area is created under the front which pulls the front down. 3) They also direct the air up, over, and around the front. In other words, always run at least a front dam.
One of the most functional ones possible is straight down from the forward most piece of the car, with a small lip on the bottom, and the dam wrapping all the way around the front to close to the outer edge of the front tires.
Rear end aerodynamics are most related to high speed rear traction and chassis balance. Adjustable rear wings are very helpful because it allows you to find the fastest lap/run time in trading off drag versus traction. In simple starting terms it is lay it down for very high speed tracks, stand it up for tight twisty ones, and somewhere in between for everything else.
5) HORSEPOWER - This is left until last because it is what everybody wants to talk about first.
MAZDATRIX LAW - IT IS NOT THE MAXIMUM HORSEPOWER THAT MATTERS, IT IS THE NET HORSEPOWER THROUGH THE RPM RANGE NEEDED THAT IS IMPORTANT.
A "peaky" engine that only makes horsepower from 8500rpm to 9500rpm and is on its' face below 8000, is useless in a car that has to come off the corners at 5500, or has to leave the line at 3500 when the tires hook-up. We have this discussion with customers frequently. It translates to street driven cars perfectly - what good is an extra 40 HP at 9000rpm when you are are down 30-50 HP at 5, 6, 7, and 8,000rpm, and 99.9% of your driving time the engine is run between 3000 and 6500 anyway?
Now we can begin the discussion of individual racing types and their specific packages.
(It is not legal and it is dangerous - DON'T DO IT.)
FAST is illegal, FASTER is uncomfortable and noisy, EVEN FASTER is definitely uncomfortable, very loud and not very functional for transportation, and FASTEST is totally not usable to get to work, can't be driven much faster than about 80 mph, has no stereo, heater, or insulation, and will get you arrested. How fast do you want to go?
All the weight possible must be removed. Anything that can be moved to the back must be moved. The front shocks must let the front go up to transfer weight to the back, but not bounce when it comes back down. Rear-end must be locked and geared to hit the best HP RPM somewhat before the end of the run. Rear suspension geometry must be set to accept the weight transfer and control the squat. Aerodynamics are important to not waste horsepower. Transmission must be geared to get the car out of the hole and then keep the engine in the optimum RPM Range. Flywheel should be sufficiently heavy to get the car launched the best possible, but light enough to not rob horsepower. Whenever possible the engine/trans/driver should be moved as far back as possible. Front tires/wheels light, slicks in the back. Anything that is not necessary should not be there. Entire car should be as low as possible (with corresponding suspension geometry changes). For sanctioned events with licensed drivers and correct safety equipment only.
The chassis set-up for turning left only is all by itself. Build the car to the limit of the rules. If you can move the motor/trans/driver, etc to the left and toward the rear it must be done. When the "left front brake only" system is dialed in correct, and the optimum stagger is found, the corner entry is a bunch easier. Understeer anywhere is a killer of lap times, but too much oversteer can put you out of the race. The tracks are all different and need different combinations. As with most racing, the two key elements are to get the power down as absolutely early as possible, and to be able to go as deep as possible into the turns. On real short tracks with tight turns, the middle of the turn is so short you really don't need to worry much. However, the longer the turns, the more important corning speed becomes. The rotary engine actually works too well in this type of racing. With a good porting (torque band)/gearing combination the fact they can be revved so high is a real plus. Most of the localized organizations we have talked to have just flat out-lawed rotaries. So if you are lucky enough to be able to still race one, please help us all by only winning by the minimum amount. The pay is the same, and the trophy is the same size whether you win by two feet or by two laps. If you have got a really good car and you consistently run away and hide, they are either going to weigh you down or just throw you out.
The lighter the better, down to whatever limit you can go. The best tires you can afford that have the minimum warm-up time. The car has to be able to respond to steering input instantly. You don't have time for the chassis to roll and take a set, the next corner is already there. Engines need a very broad torque band because you cannot waste much time doing a bunch of shifting. The car needs to be as low as possible but don't screw up the suspension geometry - can't run around on the bump stops. Don't put yourself low in the car - you must be able to see the pylons so they can be cut as close as possible. Intake system must function perfectly - any coughs and/or bobbles will kill the time. Brakes have to work perfectly the first time you hit them, and then not fade for the length of the run (or anytime during the day). Steering/driving position are very important, they need to have plenty of room for rapid arm/hand action. The seat must hold you right there. The tach has to be right where you can see it. Be sure to get the fluids up to operating temperature before the run. Understeer (plowing in the front) will kill the corner entry (as well as the times) and looks really stupid. With practice a somewhat loose rear will be easier to get through the tight turns, but you have to be careful through the fast parts. Fast plus a couple of pylons doesn't win. Watch how low the RPM has to go and try to gear it down with rear-end ratios and/or tire diameter. For those of you contemplating putting a rotary engine in some other chassis - the horsepower-to-weight-to-size of the package is unbelievable until you try one. They fit nicely in essentially anything, and are incredibly more tolerant of abuse and over-revving than anything else.
Here the car must perform to its' maximum in acceleration, braking, left turns, right turns, right/left/right/right etc. switchbacks, and do it all for anywhere from 45 minutes to 24 hours. Everything counts - reliability, power, chassis, weight, aerodynamics etc. All classes of road-racing are very tightly controlled/limited by rules + rules + rules + rules (normally carried far into the absurd range). So read all the rules before you start anything. They don't care how much you spent, how long it took, or what you thought the rule meant. It they don't like it - you're out. One of our all-time favorites (Showroom Stock) was some poor soul who was disqualified because he moved the sun-visor location about 2 inches (onto the roll-bar). The rule book didn't say he could, therefore he couldn't, and therefore it was illegal (simple isn't it?). Anyway, we have had a lot of experience in many types of road-racing, the classes are so varied its a lot easier to just ask you to call for our recommendations for your particular class and budget.
A broad torque band and/or a very expensive automatic transmission together with mandatory rev-limiter make the beginning of the package. Suspension travel and bizarre shock valving coupled with a very rigid and strong chassis get it going. Incredible air filters, cooling capacity, and duplicate systems with additional back-ups keep it going. Rotary engines do not like dirt - it must be kept out of the engine. They are also not tolerant of over-heating either the water or the oil system. Large coolers are mandatory but also useless if they don't get good air in, and let it out correctly. Simple things like air-bleed valves at all high air-pocket locations on both systems make all the difference between finishing or being stuck in the desert somewhere with a dead motor. Driver comfort (survivability?) must also be high on the list. If he (or she) is too beat-up too early, the car/truck/rail/buggy will not be able to be driven anywhere near its' potential. We are not at all sure that the words overkill or redundancy even apply to serious off-road racing.
Those of you who have a full grasp of the operating principles of their 4-STROKE and 2-STROKE engines, and understand intake open, intake close, exhaust open, and exhaust close, the degree locations and rotational timing intervals, and the effects changes in them have on torque band width and location, can skip the next few paragraphs.
For side-port engines the intake opening point is the location of the somewhat vertical side of the intake port closest to the aluminum rotor housing. This is the "line" that is first crossed by the side of the rotor during its' movements. This edge cannot be moved much due to necessary corner seal support metal. Thus the discovery of "Bridge" porting. A "bridge" is left to support the corner seal as it passes, and the initial intake opening location is moved to the other side of the bridge, giving a considerably earlier intake opening.
Side-port intake closing position is determined by the location of the roughly horizontal top line of the intake port. As the rotor moves inside the shape of the rotor housing (correct shape name is PERITROCHOID), the edge of the rotor that closes the intake port is moving essentially vertically (as opposed to horizontally when the intake is opened). There is a fair amount the top edge of the port can be moved up to delay the intake closing location.
Therefore the longer intake duration of side-port "street" port engines is gained by delaying intake closing. The duration gain in "Bridge" port engines is by opening the intake much earlier, and closing it later.
Peripheral Port intake opening location is determined by the location of the bottom edge of the intake port as the apex seal crosses it. The intake closing is similarly determined by the upper edge of the intake port as it is passed by the next apex seal. The lower the lower edge, the earlier the intake opens, the higher the upper edge, the later the intake closes.
Exhaust Port timing works exactly the same as peripheral intake timing.
Tremendously simplifying the complete science of thermodynamics, flow analysis, laminer flow, boundary layers, reversion flow, wave theory etc. etc.,the longer the port timing, the higher the RPM, the bigger the port volume needed. This does not hold true unequivocally, however, as port velocity plays a very large roll.
A very definite rule here is that too large a port volume (total volume from the butterflies to the rotor) can kill the power everywhere because the engine cannot produce enough suction to pull enough air/fuel mixture down the runners (the port never gets "moving"). The much better combination is to keep the port velocity as high as possible (by using "not-big" intake runners) and coordinate the "stall" velocity of the intake with the maximum RPM the application calls for.
To summarize most of the above - bigger is not always better, velocity is more important than volume, and port timing is the most important of all. To also answer (and greatly simplify) the questions that customers then want to know - "Why not move all the open/close location to as far as possible?" the subjects of "overlap" and "combustion pressure loss" must be explained.
The shorter the port timing, the longer the gases can be compressed, the longer the explosion can be contained, and the "cleaner" the chamber will be before the next charge is sucked in. These specs give you your basic "stump-puller" engine: lots of torque at the bottom, nothing at higher revs. The later the exhaust closes and the earlier the intake opens, the more intake charge is sucked out the exhaust pipe, but the earlier it can begin being sucked in. The later the intake closes, the later the engine can begin compressing the air/fuel mixture. The earlier the exhaust opens, the sooner the remaining "explosion" is let out the exhaust pipe. The higher the engine needs to rev, the faster it needs to get the maximum charge (longer/bigger intake), the less time it has to "use" the "explosion", and the faster it needs to get rid of as much spent gases as it can (longer/bigger exhaust timing/volume). This is your basic race engine (ignoring incredible volumes of other things going on that do matter) that makes great power at 9000rpm, but won't run below 4000. Everything is a trade-off with something else. If even this overly-simplified explanation sounds complicated - IT IS! Welcome to the world of high performance engines.
FOR CLASSES NOT ALLOWING ANY PORTING
These engines require careful choosing of housings both for shape and year/application. There are many different combinations of end housings, rotor housings, rotors, flywheels, and counterweights that will work, but usually only one that will give the best of everything and yet still be legal. Since power cannot be gained the easy way (porting), the emphasis must be moved to reliability and attention to detail in tolerances and assembly procedures. These types of engines are listed in our ENGINE SECTION under the IT (Improved Touring) option.
FOR CLASSES WITH SOME PORTING, BUT NOT UP TO BRIDGE
These engines also require careful selection of pieces for assembly. Bigger is not necessarily always better. Bottom and mid-range torque is lost to gain upper RPM power but the intake and/or exhaust systems are also usually regulated in these classes. There is no reason to build a engine with porting that makes its best power at 9000rpm if the carb stalls at 8000. A few organizations allow about unlimited intake and exhaust systems but then restrict the porting to a fixed template port. These get quite interesting because again bigger is not necessarily better in that monstrous carb barrels/venturi don't work without the corresponding intake port timing, volume, and velocity.
If your application is in this (limited port) category please call us for our recommendations, but also have all the rules ready for us.
FOR CLASSES USING BRIDGEPORTING BUT NOT PERIPHERAL
Some very serious horsepower is available when using Bridgeporting. Peripheral port engines are definitely easier to build, and are often less expensive and make more power, but are not always allowed. The largest bridge engines approach (and sometimes pass) the horsepower of peripheral engines, but are more fragile and definitely more demanding to maintain. There are different levels of bridge-porting and as the level/degree of porting goes up, the horsepower goes up, the horsepower peak RPM goes up, the cost goes up, the torque band gets narrower, and the reliability goes down. The decision of what to build is yours not ours. What we do is offer recommendations, and then build the absolute best combination that fits your needs and budget.
PERIPHERAL PORT ENGINES
The choices involved here are actually fewer than most other engine configurations, which makes life a little simpler. Let us know what type of racing you are involved in, typical track configurations, wet-sump or dry sump (and brand), carb (& size) or injected (type), what pieces you already have that are usable etc., and we can work up a quote for you.
MANUAL W/STOCK CASE
The factory stock transmissions have remained relatively unchanged thru the years. There are a few that are stronger than others. Gear selection is limited and not inexpensive. Close-ratio sets are available, please call for price quotes. Driven with care they will handle somewhat above 200HP with very few problems.
MANUAL NON-STOCK CASE
Five speeds are normally better than four, even if first gear is only used for driving around in the pits. The most important benefits of these type transmissions are that they have been engineered to take the abuse of racing, and that individual gears can be changed to allow much better adapting to specific track configurations. The brand of transmission choice is limited, but at least we do have a choice of ones that have been designed to bolt to rotary engines. Prices range from around $2500 to approaching $10,000. Give us a call for our recommendations for your specific applications.
The only ones we know of that definitely worked great were used in the Stadium Off-Road trucks. These were hand-made from pure unobtainium with a price tag that had way too many zeroes. A very high horsepower rotary will have a very narrow power band and a correct automatic should work very well. If the RPM can be put at that peak, the torque converter designed correctly, and a light transmission built to handle the power, it should be very fast.
We are using a Ford C4 automatic transmission in our 3-Rotor Drag Car. It was "built" for drag racing and so far has worked quite well. We have had the torque converter changed twice already in attempts to get the launch rpm UP where we want it.
STOCK CASE/HOUSING original rear-ends will actually take a lot of abuse and work quite well from stock classes up into the middle serious power levels. Refer to the Transmission/Differential section of the site for ratio/application choices. If you are drag racing, by all means lock-up the differential (but don't try driving it on the street). Limited-slips are definitely easer to drive in road racing, but they generate a lot of heat and weigh more. With a slightly different chassis set-up (to minimize the understeer) and a driver who understands what happens during corner-entry, mid-corner, and corner-exit with a locked diff, they are easy to drive, much cheaper, and require virtually no maintenance. If you are using a stock housing road racing (79-85), the ring gear can easily be starved of oil (i.e. destroyed) in long corners. This happens when the majority of the oil runs out into the axle tubes while corning. This can be prevented by welding dams into the inboard ends of the tubes, with holes just big enough to slide the axle thru (and in the right place), and adding a higher fill hole so the rear can be over-filled by approximately one quart. Don't forget to drill drain-back holes in the dams so they don't hold the oil up in the axle tubes. Do the minimum amount of welding on the rear axle housing - they warp/bend fairly easy. Always get it checked/straightened before you put it in the car, and check it periodically.
A MAZDA TRUCK differential/axle set has been adapted by some GTU Teams. The gear choices are very limited and the machine work was considerable. The price was very high and it always seemed there surely must have been an easier way to go.
THE FORD 9" rear is a very versatile rear and many teams use them with very good success. There are many race shops around the country that are very capable of building a rear to your specifications for a reasonable price. The gear choices are numerous.
A MIDGET QUICK-CHANGE has been used successfully in rotary powered race cars. The units are not on the light side, but the gear choices approach infinity when compared with non quick-change rears. The option of changing rear ratios in 10-15 minutes was also very nice. Long distance (12-24 hr. races) reliability may be questionable.
HEWLAND TRANS-AXLES have been adapted to the front-engine, front-transmission cars successfully. If the class allows independent rear suspension, this is an option that should be looked at. By direct driving the Hewland input shaft off the driveshaft and gutting the transaxle of all but the necessary pieces, a relatively quick-change and independent rear is obtained. If you have to ask how much it costs you can't afford it. (I doubt we would even attempt it). Reliability and cost + ease of maintenance are very important here.
VW TRANSAXLES are used by many off-road and oval track cars. There are many transmission ratios, and enough final drive ratios available. The reliability starts getting marginal when the horsepower goes much higher than 230-250. For rear engine applications this is by far one of the most economical and realistic choices. The adaptor is readily available and is supplied with flywheel and a 200mm clutch that allows a bolt-in installation.
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