Can someone explain to my why an unlocked converter dynos low?
02-26-2005, 07:02 AM
#1
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Can someone explain to my why an unlocked converter dynos low? I'm wondering what is physically going on that makes cars with an unlocked converter dyno low?
Also, is there a known multiplier for converting RWHP to crank horsepower (drivetrain lose factor)?
Thanks
Also, is there a known multiplier for converting RWHP to crank horsepower (drivetrain lose factor)?
Thanks
02-26-2005, 08:19 AM
#2
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Biggest reason is the software in the dynojet is based on a 1 to 1 ratio. Which is what you get with a manual in 4th. A lockup auto will get close. An unlocked auto is trying to fluid lock at higher rpm's but it screws the calcs on the dyno.
02-26-2005, 09:04 AM
#3
Especially with a looser converter, some of your hp is being drawn off just from thrashing the fluid...
The difference on my TCI 3000 was 381 unlocked and 392 locked. So about 10hp was getting sucked out in the fluid churning.
That hp loss shows up as extra heat being built up in the fluid.
The number I see used most often for an automatic is 18% drivetrain loss.
The difference on my TCI 3000 was 381 unlocked and 392 locked. So about 10hp was getting sucked out in the fluid churning.
That hp loss shows up as extra heat being built up in the fluid.
The number I see used most often for an automatic is 18% drivetrain loss.
02-26-2005, 10:34 AM
#5
Originally Posted by onfire
Biggest reason is the software in the dynojet is based on a 1 to 1 ratio. Which is what you get with a manual in 4th. A lockup auto will get close. An unlocked auto is trying to fluid lock at higher rpm's but it screws the calcs on the dyno.
The loss in HP is due to the inefficency of a fluid coupling. Some of the lost HP is directly observable as the increase in tanny fluid temp.
02-26-2005, 11:24 AM
#6
You have to remember the the converter pumps fluid thru it, thats how it works and the pump of the converter is bolted to the engine and the turbine is on the transmission ,so the pump Must turn faster that the turbine to pump oil and push the transmission and you will never have less than 3% slip in a true torque converter thats 97% eff. and as heat go up from this slip it makes the eff. goes down!
BEST case will be m-6 verses a-4 = 3% converter loss plus transmission friction loss
and most 4l60-e transmissions have diff. HP loses, to how they are built from 8 to 26 HP have been tested
BEST case will be m-6 verses a-4 = 3% converter loss plus transmission friction loss
and most 4l60-e transmissions have diff. HP loses, to how they are built from 8 to 26 HP have been tested
