Tach: There are two obvious solutions. First, just take the tach off a Hayabusa. Second, take a standard aftermarket tach and tell it the signal is coming from a V8. Instead of two sparks per revolution, the tach will expect four, so it will read half of actual engine speed. You can then do the math in your head (6000 on the tach = 12,000 under the hood) or you can pencil in the real numbers.
Festiva Coil-Overs: Tein makes coil-overs for the Mazda 121, which happens to be mostly the same as a Festiva.
Back to the Adaptor Plate: Umm... the Hayabusa already has a transmission and like most motorcycles, it's built right into the crankcase. There is no bellhousing, and therefore no bellhousing adaptor is possible, especially in Minnesota. Power isn't taken off the end of the crank like a car engine, but off a gear in the middle. The clutch is somewhere downstream after that gear, but the exact location doesn't matter, since you can't separate the engine and transmission. Using the bike tranny causes a new problem, though, since it doesn't have a differential or an internal final drive.
Putting a motorcycle engine in a rear-drive car is relatively easy. You simply take off the chain sprocket that serves as the transmission output and replace it with a flange that can mate up to a driveshaft. In a front driver, you need some way to get the output through a final drive gear ratio and through a differential, and I have no clever solutions for that.
Now Accepting DonationsI have the answer to a modern mid-engine, AWD Group B car. It involves an MR2, an STi and 500 readers each sending me $100 a piece. I promise it'll be done in 6 months!David WilliamsSt. Louis, MO
Injector SizingI'm currently developing a new intake manifold for my Sentra SE-R, and I had some questions about fuel injectors. How do you determine the proper size of injectors? I don't want to buy a pack of injectors, then find out they don't flow enough, or worse yet, that they flow too much.David MayernickOptimism, PA
First off, you need to be sure the ECU knows what size injectors you have. The ECU just tells the injectors to open for a certain amount of time and assumes the injectors will flow the same amount during that time that they did back when the ECU was programmed. If you change from 260 cc/min injectors to 550 cc/min injectors, the ECU will have to send a shorter pulse to deliver the same fuel.
Once you've handled that task (On an SE-R that means a simple call to Jim Wolf Technology and a little exercise of the checkbook), you need to make sure the injector is big enough for your power goals. This is simple. Just plug your pipe dreams into this formula:
BSFC just means brake specific fuel consumption, or how much fuel your engine takes to make power. Most naturally-aspirated engines will consume about 0.5 pounds of fuel per horsepower, per hour, so use 0.5 lb/hp-hr in this formula. If you're turbocharged, try 0.6 or even 0.65. BSFC might be lower if you're running on the ragged edge of too lean, or if you have really high-octane fuel that lets you advance timing and make more power from the same fuel. None of that matters here, though, since you want a conservative number that will ensure your injectors aren't too small.
For duty cycle, you want to use 0.80. This means the injectors are open 80 percent of the time. Not only is this about the highest duty cycle you can run and still have the injectors follow the ECU's commands accurately, but it's the duty cycle at which injectors are flow rated. You have to use 0.80 if you want the number from this formula to mean anything when you go to the injector store.