Guest bastaad525 Posted July 24, 2003 Share Posted July 24, 2003 Where do you guys shift your cars when racing? I'm thinking the optimal shift points are going to be quite different from my N/A motor. My new motor is just a bone stock '81 ZXT motor, with stock efi, just a blowoff valve and manual boost controller set to 10psi, thru an '82 5 speed and 3.54 gears. Seeing as how turbos usually hit their peak torque so quickly, I'm guessing you dont really rev them very high before shifting? Quote Link to comment Share on other sites More sharing options...
Guest zpeedracer25 Posted July 24, 2003 Share Posted July 24, 2003 If you're gonna be racing your car and want to find the optimal shift points, I recommend getting it dynoed to find out exactly where your power band is. This in turn will help you determine exactly what RPM band to keep it in. Turbo motors usually have awesome torque numbers across the board but shifting too early will keep you from hitting peak horsepower. I think max torque on the stock engine was reached at 2800 RPM and peak horsepower was around 6000 RPM(?). Quote Link to comment Share on other sites More sharing options...
jgkurz Posted July 25, 2003 Share Posted July 25, 2003 Hypothetically if peak torque was at 4500RPM and peak HP was at 6500RPM where should you shift? I've also had difficulty understanding this question when transmission gear ratios are factored in. Typically when drag racing I shift a couple hundred RPM above my peak HP so it drops back into the powerband. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 25, 2003 Share Posted July 25, 2003 factory hp peak was rated at 5600 rpm, and yeah torque was at 2800. forget the numbers for a second though, when you say 'shift to get you back in your power band' where do you want your rpm to be after the shift? at the beginning of the torque's up-curve? right at the torque's peak? I agree that knowing what RPM to shift at is really something that cant be figured without going to the dyno, but lets say after I have my dyno sheet in hand, THEN how do I know where the optimal points would be? Lets say my n/a engine, which peaked torque at 5000rpm, and peaked hp at 5500. The torque curve comes on right at around 3000rpm, where the torque is up at 160ftlbs, then is pretty flat and steady up to peak, which is 170ft lbs, then drops off sharply after 5500rpm. Where would I want the rpm to fall after each shift? Quote Link to comment Share on other sites More sharing options...
Guest zpeedracer25 Posted July 25, 2003 Share Posted July 25, 2003 Another thing not exactly mentioned yet is that you need to know how many RPMs you drop in each gear. My 1980 drops about 1000 RPM per shift. I'd say if you know your power band and know how many RPMs you drop when you shift, try to stay in your optimal horsepower curve. The torque curve is more important when launching rather then keeping you going fast. Quote Link to comment Share on other sites More sharing options...
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