496 Mag Dyno testing and myth busting!

[Marty Gras]

"You can please some of the people all of the time, and you can please all of the people, some of the time, but you will never please any of the people on Hot Boat anytime!" HA HA HA! "I like rubbing elbows with all the experts in here!"

[brad22]

I can certainly give you the non corrected data.
Do you still have it?

[Raylar]

Brad22:
Really appreciate you questions and comments about the dyno runs being done by Bob. With 3000 dyno hours under your belt, you have far more dyno expierence than most of us marine engine builders combined. I am curious what type of dyno you have and what type and size of marine motors you've been dynoing. I can supply 496's in various stages of build and I know I can get headers from several manufacturers so we do more legitimate testing. I know Bob makes great efforts to test in real world conditions and though not all of his data aquisition may be state of the art, the before and after results don't seem skewed to me based on my only less than a hundred hours of dyno expierence. I really appreciate anybody in the industry who steps up like Bob or yourself to put the actual accurate dyno comparison numbers on marine engines and equipment changes to those motors for the benefit of honest testing and results for the high performance boating community. I think the whole industry benefits when "real results" are available to our boating community. Hope you can help in this endevor!
Best Regards,
Ray @ Raylar

[brad22]

Brad22:
Really appreciate you questions and comments about the dyno runs being done by Bob. With 3000 dyno hours under your belt, you have far more dyno experience than most of us marine engine builders combined. I am curious what type of dyno you have and what type and size of marine motors you've been dynoing. I can supply 496's in various stages of build and I know I can get headers from several manufacturers so we do more legitimate testing. I know Bob makes great efforts to test in real world conditions and though not all of his data acquisition may be state of the art, the before and after results don't seem skewed to me based on my only less than a hundred hours of dyno experience. I really appreciate anybody in the industry who steps up like Bob or yourself to put the actual accurate dyno comparison numbers on marine engines and equipment changes to those motors for the benefit of honest testing and results for the high performance boating community. I think the whole industry benefits when "real results" are available to our boating community. Hope you can help in this endeavor!
Best Regards,
Ray @ Raylar
Hi Ray,
Our dyno experience started with a Go Power dyno with very little instrumentation. The dyno brake itself was OK but a little small for engines we were testing. We sold that unit and bought a Stuska dual rotor brake with Depac acquisition. We constantly upgraded the instrumentation, which is never ending with any lab equipment. This acquisition equipment is brilliant.
We had a DTS dyno brake and acquisition, two Midwest eddy current dynos, both with IOTech daisylab acquisition. The DTS dyno was a copy of the Go Power we had before. The data acquisition from DTS was horrible. Like something off an old Commodore computer. The servos to run the water brake on both steady state and sweep modes were not capable of holding an RPM or accelerating at a steady rate. Not very good equipment.
The Midwest eddy current dynos are top shelf, heavy duty units and will run 24/7 with no complaints. We can run 800 to 1000 ft.lbs continually with no problems on extended testing. The daisylab acquisition on these dynos is very similar to Labview, and has several hundred channels of data acquisition. The fuel flow meters are made by micro motion, read in grams per second, and are for gaseous fuel as we were blending 70% CNG with 30%Hydrogen. The air flow units are Merriam laminar flow elements and report via an inclined manometer to the data acq. We also run the exhaust thru a five gas analyzer to verify exhaust emissions.
The dynos we use for our land speed record testing are as follows. For sweep testing we use a Stuska single rotor 800hp water brake and for steady state testing we have a Froude AG150 eddy current dyno. These dynos share a Froude Texcel V4 and Texcel V6 control and data acquisition. With over 70 channels we have plenty of data to sort out. We also use a Motec engine controller to make rapid changes in engine tuning. Although most all of are work is done in closed loop, there is no end to trying to optimize combinations.
The problem I have with the information I have seen is there seems to be a malfunction with the fuel flow meter (as reported by the author of the paper). This is more important to me than the 02 sensor for BSFC. Also the fact that you cannot tune the engine due to the locked out engine controller. The GPS I am sure is correct. If the changed parts produced less power on the dyno, the boat will be slower. This is why we have the dyno, to tune each combination to its peak. The dyno cell is a laboratory and can be configured to provide repeatable results. The lake is not a laboratory and has too many variables. Thru trial and error you can probably achieve similar results away from the controlled environment of the dyno cell; however the dyno cell is supposed to take away the variables so we can achieve our result sooner and with documentation. Putting on an exhaust that flows different will always change how the engine runs. Sometimes just more power on the bottom, sometimes on top, sometimes over the entire curve, but never optimum without re-tuning.
We have a Superflow 902 with a lot of data acquisition, and are able to test any marine inboard engines. Just a not enough time and money as any of this work takes plenty of each as you know. It sounds like you are willing to supply a engine for testing of these exhaust systems? We should get all of the exhaust manufactures to put up some cash and each individually test these applications in a true duplicable application. Then and only then can we confirm what the customer is getting. For as much money as these exhaust systems cost that should be no problem for any exhaust manufacture to invest in the facts you would think.
For fun I tried to attach a dyno sheet from an 11L engine running on HCNG fuel. But I cannot upload an Excel file . Shoot me your email and I will send you a copy. The spread sheet is from the IOTech Daisylab data acquisition. This sheet deals mainly with air and fuel flow, however we trap many other channels of data depending on what we are searching for.
Fun stuff, good luck!!
Brad