SLP

Dennis, have you had any posititive experience with any of the desk top dyno programs. I had my SBC freshened up last winter but did not dyno it based on the advise from the builder. He said that engine mods to the SBC are very predicable due to the overall age of the SBC. Based on our plans and predictions
the intended HP level would be in the 300-325 range. After ploting out the data on the Desk Top Dyno it showed the following. @ 5000 rpm the motor should be creating 320 hp with 380 lbs of peak torque @ 4000 rpm. These numbers fall in line with the original plan but I can't be sure if they are accurate. Any thoughts on this matter would be appreciated

Thanks
Sam

FindMe

The last 2 motors I did (matched pair) of 468 CI BBC's were carefully blueprinted and every detail, including valve seat angle and width, valve height (tips) cylinder and head CC's, head flow numbers, and many more things that allow a motor to be punished regularly were recorded, and the input data needed for Desktop Dyno was also carefully calculated and recorded. We then ran desktop dyno for the hell of it, and came out with 555 hp @ 5700 rpm, and 585 ft lbs of torque @ 5100 rpm... naturally data used for both motors... we were optimistic until we did the actual breakin and pulls on a Superflow SF-901 Engine Dynamometer with full computer controlled Data Acquisition... I dyno'ed the motors on different days (wed & thurs), under a controlled environment in a sealed dyno room including the ambient temp,density of the air, dew point, and engine testing temps, and to our amazement (and still to this day), the 1st motor dyno'ed at 552.3 hp @ 5750 rpm & 578 lbs of torque @ 5300 rpm. The 2nd motor the next day, set up identically including breakin time and conditions scored a 553.1 hp @ 5750 and 577.6 lbs of torque @ 5300. We then added phoenellic 4 hole 1" carb spacers on the open plenum Dart manifolds and dropped the rpm figures across the board by 175 rpm, recording numbers within .2 of each other! Needless to say, I have never been so surprised or impressed by a "seat of the pants" desktop anything that was as close as it was. We did 6 full pulls on each motor to ensure accuracy, and was never off more than 3 hp, or 5 ft lbs of torque on all 12 pulls... I still can't freeking believe it, and if I hadn't had the chance to do the testing myself, never would have believed it. Its no substitute for the real thing for obvious reasons... but it will DAMN SURE get you as close as anything possible without starting the motors, or turning a screw, and IMHO is invalueable for cam selection, head choices, or anything else you may ponder on buying cause it's a good deal. Now the biggeeee... we picked up almost another 45 hp making the pair a taste under 600hp & 600 lbs of torque by changing between the Stock 360 hp Mercruiser spark arresters, and a custom set with 60% more flow capability. DO NOT let anyone tell you the area of a spark arrester isn't important, or the amount of fresh air you are able to get into, and out of your motor compartment... I have gained 5-8 mph by just doing some simple math for air intake, and always remember... if you allow it in, you best let it out, or it's all for not! So, I say it is a very cheap, simple, fast and easy way to avoid mismatching components... the #1 cause of major engine failure, and sometimes spending 20 to 50 grand on a pair of motors, only to lose 6 - 10 mph... and thats a hard one to explain to anyone...

SLP

Warlock, thanks for the indepth reply, it gives me a little more confidence in my desktop results. What was the brand name of your program.

THX
Sam

FindMe

Desktop Dyno, marketed under the Mr.Gasket name, by Motion Software. Good luck!

ragtop409

Yes Thank you I think there is many of us on this board that have that program and many of us that ponder its capabilites. My engine man also sweres buy it. Charlie

bobl

I've been using it for several years now, and have compared many actual dyno numbers with it. The accuracy is pretty remarkable if you get good data into it. The biggest variable is cylinder head flow. You can really skew the numbers if you don't have good flow numbers.

tomcat

I agree with bobl about the cylinder head data. Until I started using the data on Chevy High Performance website. Many different stock and aftermarket heads all tested the same way on the same flow bench by the same operator, with and without exhaust pipe.

paradigm shift

Do these programs work for blown applications or just naturally aspirated motors? Thanks

cobra marty

It works for N/A and S/C. I can't get mine to load onto Windows XP. Anyone else have this problem?

Ric232

Tomcat,

What is the Chevy High Performance web site you are referring to?