Dyno Run

March 21, 2003 - Dyno Day

Well the time finally came to fire this beast and find out what it's really all about. I though it best if I break in the motor on an engine dyno and dial in the Weber settings. This will simplify installation and minimize and problems. Let's get to it...

Whitman Engines in Kirkland, Washington has a Powerhouse dyno. Craig Whitman builds a variety of motors including Winston West and Southwest tour motors. This is a 347 stroker with a custom Isky cam, Trickflow heads by Total Engine Airflow and Weber 48 IDA carbs. The motor was mated to the dyno and we proceeded to fill it with fluids and prime the oil system. We had a heck of a time building pressure only to find that the oil pump shaft was not properly seated in the pump! Problem fixed, major sigh of relief. After firing the motor we brought it to temperature and continued to run it for 20 minutes to seat the rings. Curious, as on the initial firing I was holding the timing gun on mark and noticed a blue aura around plug #1. The motor ran fine but the exhaust temperatures in cylinder #1 were low.
The PC readout provides a variety of data including oil pressure/temperature, water temperature, RPM, brake specific consumption, fuel pressure and exhaust temperatures. Thermocouples are installed about two inches away from each exhaust port by drilling 1/8" holes in the headers. These become crucial during the tuning session as they indicate exhaust temperatures which along with other data may be used to determine air/fuel ratio and combustion efficiency. After the initial break-in we synchronized the carbs. When you enter the room with the engine running and the dyno fan on it feels like a tornado! As Craig synchronized the carbs I noticed the exhaust temperatures began to even out, except for cylinder #1. We shut the motor down and I checked the plugs. I immediately noted that the #1 plug was cracked. Time for a replacement. We re-fired and, with a minor linkage adjustment, had all the temperatures even. I did notice that the oil pressure was fairly high at 73lbs at 2k rpm.
Now the fun began. We did a number of baseline pulls ranging from 2000-4000, 3000-5000, and 4000-6000 rpm. The motor pulled evenly but the HP numbers were a bit low. We decided to start with timing adjustments. We had started at 36 degrees total. The lighted advance springs were used. We then went to 38. There was no improvement in the figures and the temps went up. We backed off to 34, 32 and finally 30 degrees. The figures changed dramatically! 30 was determined to be optimum at this time. Next we changed jetting. Baseline runs used 135 jets. The exhaust temperatures were a bit high. We jumped to 165s and the motor immediately bogged down. We stepped down to 145s and the temps came down and brake specifics read well. It appeared this was the best setup for 92 octane fuel. We then made a few full pulls ranging from 3500 to 6500 rpm. Valve float was evident at 6500 as the motor rpm broke down. This is a hydraulic roller cam intended for a maximum rpm of about 6200 so it's not surprising. We finished with back to back pulls ranging from 4000 to 6200 rpm. We did a total of 25 pulls over 4 hours.
The results... These are the exhaust gas temperatures for the optimal setup. Note how closely they match. There is a maximum delta of about 70 degrees from cylinder to cylinder. This is excellent.
This is a graph of the torque and horsepower curves. Now you have a better idea as to what this motor really does. ;-)
The final answer... Peak Torque - 455 ft/lb @ 4500 rpm Peak Horsepower - 456 hp @ 6100 rpm The motor has extremely broad torque curve HP curves. It is definitely stout but still idles well and should be very streetable. A few things came out of the testing: 1) Ford breather grommets leak. Oil was spitting around the breather grommet causing a cool aura-like fog at high rpm. 2) Front-main seal spits. Easier to fix now, I'm glad I found it! 3) Oil pressure is high. I need to pull the pump and either replace the bypass spring or get a standard pump. This is a high volume Melling pump. 4) Dynos are cool!
Click on the image to the right to look at the data generated by Desktop Dyno software. The calculated peaks where 483 TQ and 458 HP. Not bad without any consideration of fuel quality, header configuration, etc...