How to build 700-1000 hp 30 psi boost 13b?
#26
the way i see it, you need a peripheral port, a turbo compressor the size of a jet engine, and a steady supply of Depends
A race driveline will have lower driveline losses than a normal driveline... straight cut gear trannies have less loss because they only load the bearings in one direction (radially) instead of two directions (radially and axially) think about that... if you have 500lb-ft of torque, and say a 6" diameter input shaft gear (making numbers easy) the gear is trying to force the countershaft out the side of the transmission with 2000 pounds of push - the bearings absorb that. the harder you push, the more they have to absorb. this is true for all of the gears under load in the transmission, and the rearend as well. with bevelled gears in the transmission, let's say a 30 degree bevel again to make the numbers pretty, that would be a 1000lb axial load - trying to shove the shaft forwards or backwards through the case depending on the direction of the bevel. again that's something the bearings have to absorb. eliminating the side load by using straight cut gears means less stress on the transmission, as well as having a lot less sliding friction as the gears wipe across each other (again, that friction increases as you increase the load).
now, one thing to think about, is what GEAR is used on the dyno. You get pretty numbers if you use 4th gear (stock 5-speeds) because 4th gear bypasses all of the gears in the transmission and just locks the input shaft to the output shaft - this eliminates parasitic losses. If you measure driveline losses in 3rd or 5th gear, and then make passes in 4th gear, you'll get some very pretty numbers indeed! (not very realistic though!) Also, I think he's running a solid rear axle, meaning no CV joint losses.
Any way you cut it, 651 at the wheels is extremely impressive (probably 750ish at the crank), but it's still a far sight away from 1000 at the crank!
A race driveline will have lower driveline losses than a normal driveline... straight cut gear trannies have less loss because they only load the bearings in one direction (radially) instead of two directions (radially and axially) think about that... if you have 500lb-ft of torque, and say a 6" diameter input shaft gear (making numbers easy) the gear is trying to force the countershaft out the side of the transmission with 2000 pounds of push - the bearings absorb that. the harder you push, the more they have to absorb. this is true for all of the gears under load in the transmission, and the rearend as well. with bevelled gears in the transmission, let's say a 30 degree bevel again to make the numbers pretty, that would be a 1000lb axial load - trying to shove the shaft forwards or backwards through the case depending on the direction of the bevel. again that's something the bearings have to absorb. eliminating the side load by using straight cut gears means less stress on the transmission, as well as having a lot less sliding friction as the gears wipe across each other (again, that friction increases as you increase the load).
now, one thing to think about, is what GEAR is used on the dyno. You get pretty numbers if you use 4th gear (stock 5-speeds) because 4th gear bypasses all of the gears in the transmission and just locks the input shaft to the output shaft - this eliminates parasitic losses. If you measure driveline losses in 3rd or 5th gear, and then make passes in 4th gear, you'll get some very pretty numbers indeed! (not very realistic though!) Also, I think he's running a solid rear axle, meaning no CV joint losses.
Any way you cut it, 651 at the wheels is extremely impressive (probably 750ish at the crank), but it's still a far sight away from 1000 at the crank!
Last edited by peejay; 02-20-02 at 04:43 AM.
#32
Originally posted by peejay
You get pretty numbers if you use 4th gear (stock 5-speeds) because 4th gear bypasses all of the gears in the transmission and just locks the input shaft to the output shaft - this eliminates parasitic losses. If you measure driveline losses in 3rd or 5th gear, and then make passes in 4th gear, you'll get some very pretty numbers indeed!
You get pretty numbers if you use 4th gear (stock 5-speeds) because 4th gear bypasses all of the gears in the transmission and just locks the input shaft to the output shaft - this eliminates parasitic losses. If you measure driveline losses in 3rd or 5th gear, and then make passes in 4th gear, you'll get some very pretty numbers indeed!
4th is just a pair of gears just like the others. They just have the same number of teeth for a 1:1 ratio. Remember with spur gears the output shaft turns in the opposite direction to the input shaft so locking them together would be just like putting it in reverse!
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