Two Guys Rally

What Should I Use To Make a Mudflap

Since I am a poor college student I can’t afford things like predesigned, cut and tested mud flaps,I have to make my own. I’m curious if you have any insight into what I should use to make mud flaps with. Some current ideas have included: Old T-Shirts, Thick Vinyl (melt some records?), UHMW, Roommate’s toenail clippings with resin, rubber bands, cement, aluminum foil (layered duh) and, of course, cardboard.

Please comment with your ideas.

Suggest Us A Car

Hey, so Mark and I have been looking for cars we can afford (<$1000) to turn into a rally car. We need your suggestions but there are some rules:

1. 2WD - Most rally leagues dont let you start in an AWD
2. Less than 2.5L Displacement please
3. Car must be running
4. Street Legal (or workable into Street Legality)
5. Must be a Car, that means 4 wheels (no 3 wheelers or motorcycles)

Also we would like any suggestions as to the type of car you suggest we rally, even dream rally cars.

Ditch Gasoline?!

So Charles and I were talking about the engines in rally cars the other day, specifically how the horsepower in the WRC is limited to 300hp. If you have read my article on engine power and torque, you’ll realize that this means they have the option to make amazing amounts of torque at lower rpm while staying under that 300hp limit. It is possible to design a gasoline engine to stay close to 300hp for a good part of the rpm band. Just size the turbo right so that there is a lot of boost down low and use a control system to taper off the boost in higher rpm to not exceed the power limits, coupled with a well-configured camshaft profile and such.

This type of power output curve very closely resembles that of an electric motor. The most torque is seen at or very close to 0 rpm, with the power output being pretty constant through the rpm range. This torque makes an electric motor great for starting off the line, or coming out of slow corners with lots of acceleration. There is another aspect of an electric motor that makes it far superior for the responsiveness that rally racing requires: the power response is instantaneous. With an internal combustion engine (abbreviated ICE), the throttle valve opens when you push the pedal down. This allows more air to flow into the engine, the ECU will see this through various monitoring methods and inject for fuel to keep the mixture close to what is required for the conditions (usually around 12:1 to 14:1). Then the exhaust gas flows through the turbine wheel, makes the turbine and compressor spin faster, increasing the pressure in the intake, causing even more air to enter the engine, creating more power. As you can see, there are quite a few steps involved here. The throttle response of a typical ICE is considered to be pretty fast, which is why they are used in cars, but in comparison, the electric motor is much must faster.

Simply press the accelerator pedal (not a throttle anymore!), the power control circuitry will allow more current to flow through the motor, and the motor creates more torque. No waiting for air to accelerate into the engine, no waiting for the ECU to compensate for this extra air with more fuel, no waiting for the exhaust to flow past the turbine to spool it up. It’s nearly instantaneous in comparison.

There are quite a few other advantages to electric motors aside from this. The thermal efficiency is often >80%, while a typical high performance ICE will be lucky to get 15% efficiency out of the gasoline it burns. The overall package size and weight of the engine itself is greatly in favor of the electric motor. Same with reliability: a gasoline engine has a lot of moving parts from the crankshaft up to the valvetrain, while an electric motor just has the core that spins.

The two of us sat there and discussed this topic for quite a while, and realized how amazing it would be. There is just one significant technical hurdle left to overcome: the batteries. Getting the range and power output needed for a rally car will weigh a lot. However, it is definitely something to consider as a possibility for the future of rally racing. What do you think about it? What other unforeseen problems do you think there would be? We would really like to hear what you think.

Subaru Wheel Wells and Snow Accumulation

I had a problem this winter: whenever I would go out and play in the snow with my WRX, snow would be melted by the tires and refreeze on the wheel well. I was wondering if you could give me some insight in how to prevent this. So leave a comment, tell me how to fix my problems.

I was thinking that maybe a wax coating would prevent it from happening.