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busa VW2.615--1st----------1st-3.801.93---2nd----------2nd-2.061.285-4th-----------3rd-1.261.043-6th-----------4th-0.82 A busa @10.5K after the 1.596 is 6579 RPM at the countershaft. Same type of rpm the VW runs at redline. Also similar rpms under all drive conditions as the VW. The VW seems like it has a nicer spread of ratios also. Actually lower by a lot that I think would improve all around drivability.So the question I REALLY need an answer to is this-What is the real world torque at the busa countershaft if the dyno shows REAR WHEEL TORQUE of say 200 lb Ft.? Is it an actual 200 at the countershaft? I'm a bit confused on that point.
http://www.europeancarweb.com/projectcars/0310ec_1986_porsche_944_turbo_specifcations/index.htmlThese trannys already have the nosecone built for you. Just flip the Hayabusa sideways and get a driveshaft adaptor. Get a lil driveshaft made up. It would be a tad longer though. You can see all the specs above at the link but the car weighs 3040 pounds and the motor stock makes: Power (SAE net): 217 bhp @ 5800 rpm Torque (SAE net): 244 lb-ft @ 3500 rpm Plus HUGE tires on pavement. Just some food for thought. You be your own judge on it but share opinions with us!
Hold on fabr, I am not following your math, and where are you getting the 1.596?Just for reference the primary reduction on the busa is 2.352, and the gear ratios are as follows: 1 - 2.615 total reduction (2.352 X 2.615) = 6.15 2 - 1.937 total reduction = 4.56 3 - 1.526 TR = 3.59 4 - 1.285 TR = 3.02 5 - 1.136 TR = 2.67 6 - 1.043 TR = 2.45So with the Busa at 10,500 RPM the output shaft speed would be: 1 - 10,500/6.15 = 1,707 RPM 2 - 2,302 RPM 3 - 2,925 RPM 4 - 3,477 RPM 5 - 3,933 RPM 6 - 4,286 RPMLets just say your Turbo busa makes 300Hp @ 10,500, and it also peaks torque there. Its torque will be (torque = (horsepower x 5252)/engine speed) 150 ft/lbs at the crank. If we look at it in 6th gear at the countershaft it will be 150ft/lbs x 2.45 = 367.5 ft/lbs. That is why busas tear the crap out of things.....If we look at a stocker 178Hp = 89ft/lbs at the countershaft = 218 ft/lbs, at 4,286 RPM.If looks like if you buy aftermarket gears for the 091 you can get anything but lets run the numbers so see what we will have in 4th with your ratio of .82, and a 4.57 ring and pinion.4,286 RPM / (.82 x 4.57) = 1144 RPM at the CV flangeAdd a 31" tall 1300 plus.....31in x 3.141519 = 97" rollout x 1144= 110968inches/minute divide by 12 for feet, divide by 5280 for miles, multiply x 60 for hours instead of minutes = 105 miles per hour.Looks about right. When will it be done? I want to see how it works.
Why would they quote the RPM at the crank, and the torque at the countershaft?I could be wrong about the primary reduction. Where did you find your numbers? If you are correct then is the 1.043 6th gear, the total reduction from the crankshaft? That would mean that it is overdriven in the tranny to almost eliminate the primary reduction?