[eddy21x]

so how much do mustang autos lose?

[Blitz34]

Originally Posted by eddy21x so how much do mustang autos lose?

18-20% persay. Depends on the person you speak to, someone told me it was tested to be 18% so thats what I always use.

I some how messed up my math earlier, so the real numbers for an auto will be

213.2rwhp/247.64rwtq.

[Eagle2000GT]

To summarize, autos lose around 18-20% from the crank to the rear wheels. Manual transmissions lose around 13-15%. There is no precise way of measuring it. All cars are different and dynos are affected by tempature, humidity, and altitude. All dyno operators make adjustment to give you the corrected numbers. On different days the same car on the same dyno run by the same operator will give you two different numbers. Most people use 15% parasitic loss for manual transmissions and 20% for autos. But these are rule of thumb percentages and are not meant to be precise measurements.

[Eagle2000GT]

Almost everyone on the forum talks in terms of (rear wheel horse power) rwhp. The parasitic loss percentages come in handly for two purposes. The first is explaining why someone with an automatic didn't get the same rwhp as someone with an manual transmission having exactly the same mods. The second is to work backwards and estimate how much horsepower the motor has at the crank. The general rule of thumb (again not a precise number) is that 400 rwhp is safe for stock motors. That is for cars with manual transmissions. 400 rhwp through a manual transmission is somewhere around 460-470 at the crank. 400 rwhp through an automatic is somewhere arounnd 488-500 at the crank. This is something you need to consider if you are pushing the upper limits of the rods and pistons. The stress on them is at the crank not the wheels.

P.S. Every tuner I've talked to says to limit a daily driver to 370-380 rwhp. That's 425-447 rhwp through a manual transmission.

[Blitz34]

Originally Posted by Eagle2000GT To summarize, autos lose around 18-20% from the crank to the rear wheels. Manual transmissions lose around 13-15%. There is no precise way of measuring it. All cars are different and dynos are affected by tempature, humidity, and altitude. All dyno operators make adjustment to give you the corrected numbers. On different days the same car on the same dyno run by the same operator will give you two different numbers. Most people use 15% parasitic loss for manual transmissions and 20% for autos. But these are rule of thumb percentages and are not meant to be precise measurements.

Agreed.

[Shaun03GT]

Id say like 247/281