Re: Torque converter efficiency?
[Re: dmerc]
#822311
10/05/10 12:47 PM
10/05/10 12:47 PM
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Joined: Jul 2006
Posts: 4,319
Puyallup, WA
StealthWedge67
master
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master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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That's like asking "how much water is in an unknown amount of water". Each converter is going to be different, and this is not something that is exclusively related to stall speed. Essentially, this is exactly why racers pay big money for good converters.... Essentially, a good converter is efficient. An innefficient converter isn't good.
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: Torque converter efficiency?
[Re: dOrk !]
#822312
10/05/10 01:06 PM
10/05/10 01:06 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
LOTS of variables ....
Is this uNder WOT ? ... depends on the AERO of the vehicle if WOT at say 110 mph....etc, ETC.
I guess the question is a bit vague  Maybe I should say How much does a (good) converter slip at wot at 100MPH? Then again how much does a (stock) converter slip at WOT and 100MPH? Just looking for some numbers to play with to determine my final gearing. Car is my Duster Don't know the aero (drag?) for this car
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Re: Torque converter efficiency?
[Re: dmerc]
#822313
10/05/10 01:35 PM
10/05/10 01:35 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
master
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master
Joined: Oct 2004
Posts: 8,165
Left Coast
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Quote:
Quote:
LOTS of variables ....
Is this uNder WOT ? ... depends on the AERO of the vehicle if WOT at say 110 mph....etc, ETC.
I guess the question is a bit vague Maybe I should say How much does a (good) converter slip at wot at 100MPH? Then again how much does a (stock) converter slip at WOT and 100MPH? Just looking for some numbers to play with to determine my final gearing. Car is my Duster Don't know the aero (drag?) for this car
Torque converter slippage has a lot of variables like was stated. Weight of car, torque output, rear gear ratio and even trans fluid tep/viscosity all have a pronounced effect on slippage. For instance, our car weighs 2950 and has right around 2500 HP. If we run a 4.10 gear our converter slips about 12%. If we switch to a 4.22 and do nothing else it slips at 9-10%.
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Re: Torque converter efficiency?
[Re: dmerc]
#822314
10/05/10 02:10 PM
10/05/10 02:10 PM
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Joined: Aug 2003
Posts: 43,157
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,157
Bend,OR USA
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A good 8 inch race converter will slip 3 to 5%, anything more is consider not good  As already said many things contribute to the effeincy of the converters, mainly the size, maker and the application information furnished to the maker on the initial build  I use a rule of thumb on converter slippage on counting on 8 to 10%, again depending on many things, a radial tire will change the converter slippage numbers due to no relative tire growth  Maybe you should post the car weights, motor size and type,BB or SB, trans and converter size and brand, tire size in circumference and the intend RPM crossing the finish line and we can back into the gear ratio for you, also where your going to run the car , altitude and typical weather conditions like humdty, actual altitude, temperature and actual or corrected(specify which) barometric pressures.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Torque converter efficiency?
[Re: Cab_Burge]
#822315
10/05/10 02:54 PM
10/05/10 02:54 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
A good 8 inch race converter will slip 3 to 5%, anything more is consider not good As already said many things contribute to the effeincy of the converters, mainly the size, maker and the application information furnished to the maker on the initial build I use a rule of thumb on converter slippage on counting on 8 to 10%, again depending on many things, a radial tire will change the converter slippage numbers due to no relative tire growth Maybe you should post the car weights, motor size and type,BB or SB, trans and converter size and brand, tire size in circumference and the intend RPM crossing the finish line and we can back into the gear ratio for you, also where your going to run the car , altitude and typical weather conditions like humdty, actual altitude, temperature and actual or corrected(specify which) barometric pressures.
Here is the info. This is a street car.
Car 71 Duster 408 SB engine 375 HP@5000 RPM (Probably less at this altitude) 500 ftlb at 4000 RPM
Weight 3100
Altitude 5000 ft
12 inch Hughes 2200 rpm stall converter
Tire size 275/60-15 TA radials
Goal is to cross the stripe at 100+ MPH and 13.5 or better times at a mile high elevation. Possible? Car currently has 3.23 gears
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Re: Torque converter efficiency?
[Re: dmerc]
#822316
10/05/10 05:24 PM
10/05/10 05:24 PM
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Joined: Aug 2005
Posts: 760
Southington Ct.
turbobitt
super stock
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super stock
Joined: Aug 2005
Posts: 760
Southington Ct.
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Torque converter slipage will depend on the amount of power input at the time its measured. For example, if your car reaches max RPM before the end of the 1/4, your slippage will obvioulsly degrease significantly over pulling through the gears at max torque. In this example, the converter may look more efficient then it actually is.
To get a true picture of converter efficientcy, you need to compare slippage in an A/B comparison on the same combo.
Allan G.
1970 Challenger w/572 Hemi street car and my pride and joy.
1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno.
1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
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