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Thanks. It's been a long process really. I think it's coming down to the finish line in terms of wrapping up the CVT, seems like I keep finding stuff to fix/improve....lol.
CVT cooling:
As far as CVT cooling goes, there has been quite a bit done by Juke members and I'll add my thoughts.
My Juke will be running the Setrab 9 series x 20 row (14"x6"x 4.35") with (2) Spal 654 cfm fanpacks mounted in the front of the vehicle. This was to fit in the vertical position left by the stock FMIC location running the 2J FMIC. I'll be running an external oil thermostat set at 180-190*F, and an external large capacity oil filter. With the +330 hp I plan on running, the CVT cooling will have to keep up with the engine output. In case anyone was wondering, a typical CVT uses: 12% power on the CVT oil pump, 4.7% power on the Torque converter, 13.5% power on the Variator/Pulley assembly, & 3.2% power on the Output,Transfer, Differential,bearings, etc. At full TCC lockup (i.e. > 18 mph), the torque converter isn't losing any power, so the 4.7 % can be eliminated. That leaves about 71.3% available to road power and 28.7% wasted in the transmission. At part throttle, the losses are far less, typically better than an automatic transmission, thus the mpg improvement. When I dynoed at P&L, I put down 183 w.h.p., but I know the engine was making near 260 h.p. based on the mass airflow on the datalogger the day before the dyno run on the same tune. That's close to 28% loss.
So if the engine is putting out 330 h.p. (223 kW), then 28.7% or 94.7 h.p. (70.6 kW) is lost as waste heat thru the CVT at full power. The CVT cooler would need to dissipate about 240,747 Btu/hr to maintain a set temperature. Some of the heat is lost thru the transmission case, but for now I'll ignore it. The CVT oil pump also cavitates at 7000 rpms, so this is the practical upper rpm limit of a CVT vehicle.......oh darn.
At 6000 rpms the oil pump is putting out 16.32 gpm or 10.3 cm3/rev flowrate, assuming no oil bypass flow at full engine power. However, the oil pump is only feeding a fraction of the oil supply to the oil heat exchanger, the remainder is doing work. To make it clear, the oil pump is cooling in parallel to the hydraulic circuit (oil lubrication, pulley, valvebody control, etc.). Actually, only 12.8% oil is bypassed to cooler/lube circuit based on my research. That's 16.32 gpm x 12.8% = 2.1 gpm thru the oil cooler for example. The formula for power is: Btu/hr = Pump flow rate (gpm) x 60 min x (Delta T, F) x 3.91. So, solving for the Delta T, using 240,747 Btu/hr and 2.1 gpm pump flow, I get a Delta T of 488*F, or about 559*F oil temp. That isn't workable, since I really only want a final oil temperature of 185*F (i.e. 115*F over ambient). I'd need to ramp the oil pump flowrate to something like 8.9 gpm, even at 100% heat exchange efficiency, which the formula is assuming. Also very difficult to do with (1) primary pump.
Looking at the Setrab catalog they show BTU/hr ratings for their oil coolers at 0.75 gpm, 1.5 gpm, 5 gpm, and 8 gpm flowrates. The performance drops off with lower flows, so how the pumps and heat exchangers are plumbed makes a difference. Now the strategy that might work best is using the primary oil pump (2.1 gpm) and (2 x 2.0 gpm) Tilton auxilliary electric pumps plumbed in PARALLEL and driving thru (3 x 50,000 BTU/hr @ 5 gpm rating) the oil heat exchangers in SERIES. This produces a combined +150,000 BTU/hr., which should be sufficient. Probably could fit (1) oil heat exchanger w/fan packs in the stock FMIC location, then (1) each without fans could fit in either fender well. The Tilton pump is 2x 3.5 lbs ea, the Fanpack oil cooler is 7.7 lbs, (2) 14.40" x 7.60" oil coolers @ 4.35 lbs each. Total would come in at +23.5 lbs without hose. Now all of this is to maintain a steady state thermal condition for something like a race track, which probably I won't be doing but I routinely do extended highway pulls.
Anyhow, this is the math I did to size up the heat exchangers.......when I get to that point.
CVT cooling:
As far as CVT cooling goes, there has been quite a bit done by Juke members and I'll add my thoughts.
My Juke will be running the Setrab 9 series x 20 row (14"x6"x 4.35") with (2) Spal 654 cfm fanpacks mounted in the front of the vehicle. This was to fit in the vertical position left by the stock FMIC location running the 2J FMIC. I'll be running an external oil thermostat set at 180-190*F, and an external large capacity oil filter. With the +330 hp I plan on running, the CVT cooling will have to keep up with the engine output. In case anyone was wondering, a typical CVT uses: 12% power on the CVT oil pump, 4.7% power on the Torque converter, 13.5% power on the Variator/Pulley assembly, & 3.2% power on the Output,Transfer, Differential,bearings, etc. At full TCC lockup (i.e. > 18 mph), the torque converter isn't losing any power, so the 4.7 % can be eliminated. That leaves about 71.3% available to road power and 28.7% wasted in the transmission. At part throttle, the losses are far less, typically better than an automatic transmission, thus the mpg improvement. When I dynoed at P&L, I put down 183 w.h.p., but I know the engine was making near 260 h.p. based on the mass airflow on the datalogger the day before the dyno run on the same tune. That's close to 28% loss.
So if the engine is putting out 330 h.p. (223 kW), then 28.7% or 94.7 h.p. (70.6 kW) is lost as waste heat thru the CVT at full power. The CVT cooler would need to dissipate about 240,747 Btu/hr to maintain a set temperature. Some of the heat is lost thru the transmission case, but for now I'll ignore it. The CVT oil pump also cavitates at 7000 rpms, so this is the practical upper rpm limit of a CVT vehicle.......oh darn.
At 6000 rpms the oil pump is putting out 16.32 gpm or 10.3 cm3/rev flowrate, assuming no oil bypass flow at full engine power. However, the oil pump is only feeding a fraction of the oil supply to the oil heat exchanger, the remainder is doing work. To make it clear, the oil pump is cooling in parallel to the hydraulic circuit (oil lubrication, pulley, valvebody control, etc.). Actually, only 12.8% oil is bypassed to cooler/lube circuit based on my research. That's 16.32 gpm x 12.8% = 2.1 gpm thru the oil cooler for example. The formula for power is: Btu/hr = Pump flow rate (gpm) x 60 min x (Delta T, F) x 3.91. So, solving for the Delta T, using 240,747 Btu/hr and 2.1 gpm pump flow, I get a Delta T of 488*F, or about 559*F oil temp. That isn't workable, since I really only want a final oil temperature of 185*F (i.e. 115*F over ambient). I'd need to ramp the oil pump flowrate to something like 8.9 gpm, even at 100% heat exchange efficiency, which the formula is assuming. Also very difficult to do with (1) primary pump.
Looking at the Setrab catalog they show BTU/hr ratings for their oil coolers at 0.75 gpm, 1.5 gpm, 5 gpm, and 8 gpm flowrates. The performance drops off with lower flows, so how the pumps and heat exchangers are plumbed makes a difference. Now the strategy that might work best is using the primary oil pump (2.1 gpm) and (2 x 2.0 gpm) Tilton auxilliary electric pumps plumbed in PARALLEL and driving thru (3 x 50,000 BTU/hr @ 5 gpm rating) the oil heat exchangers in SERIES. This produces a combined +150,000 BTU/hr., which should be sufficient. Probably could fit (1) oil heat exchanger w/fan packs in the stock FMIC location, then (1) each without fans could fit in either fender well. The Tilton pump is 2x 3.5 lbs ea, the Fanpack oil cooler is 7.7 lbs, (2) 14.40" x 7.60" oil coolers @ 4.35 lbs each. Total would come in at +23.5 lbs without hose. Now all of this is to maintain a steady state thermal condition for something like a race track, which probably I won't be doing but I routinely do extended highway pulls.
Anyhow, this is the math I did to size up the heat exchangers.......when I get to that point.