Quote:
Originally Posted by mjorgensen
Rich,
Any dyno can read ANY number based on the inputs of the operator. This is why I always have a hard time hearing these numbers thrown out there. We have always talked with Dodge about the dyno and the "way" they conduct the test. Our numbers at the wheels are always very close to what they are seeing and we have used the exact computations on every car we have done so the numbers stay consistent.
Now I will not profess to be a Dyno "expert" by any means, I am just regurgitating what I have learned over the years. When the Dynojet came to the market and gained popularity the numbers shown at the wheels were always much higher than other (load bearing) dynos. I feel this and cost are why they have been so widely accepted as fact. Since we have run our cars on both and the crank numbers are the same for the most part (on an Eddy current Dynojet) the only difference is how they calculate the rear wheel hp. We do not care about making a great number for us or our customer, just consistent repeatable ones that translate to the crank hp really measured.
We have done well over 100 S/C cars and can show all the dyno sheets and a variance of less than 35 hp on brand new and used cars with just a cat back added to the S/C. Most of these variations are because of the year the car was or how many miles are on them. Our numbers are "usually between 585-615 at the wheels on our dyno. We have seen 1 car hit 639 but I think he spiked the tank before he dropped it off ;-)
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Thanks Mark --
The results on my 2008 (529 rwhp/505 rwtorque) were also from a Mustang (load bearing) dyno and am just trying to get an estimate of how much flywheel horspower is being generated. Just to add fuel to the fire, I spoke with my Viper tech at my dealership and he recommended multiplying by 1.255 which yields 664 flywheel hp and 633 ft lbs of torque. That seems awfuly high for a stock 2008 Viper.
Regarding the break in procedure, I actually drove the first 1,000 miles using the conservative "progressive" break in approach recommended by Herb Helbig:
BREAK-IN PROCEDURE (0-1,000 MILES)
WARM UP ENGINE FIRST
MAX SPEED 70 MPH (113 KPH)
AVOID EXTENDED ENGINE IDLING
NO FULL THROTTLE STARTS/ACCELERATIONS
VARY ENGINE RPM
CHECK ENGINE OIL EVERY FUEL FILL
FROM 0-200 MILES:
LIGHT THROTTLE RUN-UPS THROUGH GEARS: MAX SHIFT POINT 2,500 RPM
CHANGE ENGINE OIL AT 200 MILES
FROM 201-400 MILES:
LIGHT THROTTLE RUN-UPS THROUGH GEARS: MAX SHIFT POINT 3,500 RPM
FROM 401-600 MILES:
LIGHT THROTTLE RUN-UPS THROUGH GEARS: MAX SHIFT POINT 4,000 RPM
FROM 601-800 MILES:
LIGHT THROTTLE RUN-UPS THROUGH GEARS: MAX SHIFT POINT 4,500 RPM
FROM 801-1,000 MILES:
LIGHT THROTTLE RUN-UPS THROUGH GEARS: MAX SHIFT POINT 5,000 RPM
FROM 1,001-1,500 MILES
DRIVE CAR HARD WITH FULL THROTTLE ACCELERATIONS SHIFTING NEAR OR AT
REDLINE THROUGH ALL GEARS
During this last phase I really drove the car aggressively, taking 100-200 mile trips in fairly isolated road areas where I regularly drove the car to redline and with frequent full throttle acceleration. I basicalyl tried to simulate how the car would be driven on a dyno (drive the car in 1st gear for 7 full seconds going up the rev range, then the same in second, third and, where possible, fourth gear). Then follow with quick and hard bursts of full throttle etc. During these extended runs I would also turn the car on and off at least once to allow the ECU to learn and adapt to the new harder style of driving.
Once this break in process was completed, I did the baseline dyno run.
/Rich