Trip to the Dyno - LOTS OF DATA!

[CraigO]

Went to the local Dynojet 248C....out-pulled 5 other Porsche 911s [8D]. The '03 Dream Cruiser with *auto*, BTG exhaust, and Hallman boost controller did 189.1 AT THE WHEELS - with torque at 221.8.
Chrysler drivetrain losses are 18% to 20% -- this is approx
240HP and 280 lb ft of torque at the flywheel! [}]

Some interesting items:
*Max power is produced at 86 mph in 3rd gear
*Power tapers off by *20 hp* after shifting into 4th at 100 mph
*Air/fuel ratio is very rich - these suckers can take 15 psi boost
with no problem, BUT
*Right after a shift, engine goes a bit LEAN for 3 mph; the air/fuel ratio goes from a rich 10:1 to a leaner 12:1.

[MX-5]

I've dynoed many PTs on the Dynojet and the drivetrain loss is close to 27-28% with the auto trans.
The same dyno is used for my NHRA and IHRA customers who have had the engines dynoed at the crank. We know exactly what kind of loss the drivetran eats up.
BTW, I'm at 190.3hp at the front wheels.

[CraigO]

I'm interested to know *how* you know what the drivetrain loss is - how did you arrive at that number?
I got my 18%-%20 from the owner who has seen many engines which were run both on the rollers
and on an engine stand dyno.

[MX-5]

Seven PTs with engine horsepower rated at 150hp at the crank all pulled between 103 and 109hp at the wheels. Break-in mileage made most of the difference.
I ran an NHRA super gas drag car with exactly 674 at the crank through a 2-speed powerglide and got 536 at the wheels. That's the best ratio I've seen with 21% loss.

I'm partners in the business with the dyno shop. I own a performance shop down the street. I supply the 100/110 octane fuel and am the only nitrous refilling station in town. I build the cars, they test 'em & I tune 'em.

[sakigt]

PTs vs GT trannys.....

[TripleJackInGA]

In my past life with Dakota R/Ts, the truck was rated at 250HP, and when dynoed, RWHP would vary from 190-205HP. It really varies and after about 30K miles, they would really wake up and give a noticeable difference.