Thread: Dynosim accuracy???

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i was on here a while back, i had problems with cranking compression and missing horsepower, but since then i've been doing a lot of research. i also decided to have fun and purchased dynosim. has anyone had any experience with this program at all??? i know how to use it i just want to know how accurate it really is?

what got me thinking is the TRICK FLOW 490HP top end combo. i entered in all the information and dynosim said approximately 415hp would be had. but then i have read articles in car craft, super chevy and other various resources around town who've had this kit, and they all say that TFS rating are VERY conservitive. and the kit should make 490hp minimum.
BUT, then i plugged in all the stats on my motor and two other friends motors, and it was only about 10hp off (high or low), what our cars dyno'd at.


any help please........thanks

I program another dyno simulator (http://www.virtualenginedyno.com) and ran a dyno for rears at a race engine shop. Hopefully I can give you some insight. First off, a computer will never exactly predict what will happen in real life. The factories spend millions on testing engines and programming simulations, but its not a exact science.

What you need to look for in a simulation is the change and not the peak value. For example, this intake gave me 10 more hp than that intake. This camshaft game more bottem end torque than that one. Thats the benefit of simulating a engine on a computer.

When I ran a real dyno, a back to back run could vary by 10 or more horsepower. You try to run everything exactly the same, but its impossible to be perfect. Ideally, you would want the oil temperature, water temperature, block temperature, cylinder head temperature and everything else be the same on each run. We alway did three pulls and used the average of the three to determine our output.

A day to day weather change (barometer, humidity, temperature) or even a before to after lunch change can make a difference. The dyno computers try to correct for this, but its not exact.

Now imagine running a engine in one part of the country and then testing that same engine a different time of the year in another state, on a different brand dyno and imagine how much the difference could be. We always got a kick out of the magazine articles and headline (500 hp blah blah blah) and knew good and well that combo on its best day would not make that power. This was typically a result of them twisting the numbers and using a 'friendly' dyno calibration.

To sum it up, do not worry about some peak number, be more concerned with the relative changes in hp and tq curves vs what different parts you are considering. Dyno simulation programs will typically be within 5%, but this assumes that you input the engine parameters correctly. The more accurate input, the more realistic your output will be.

Man oh man, did rhamm1320 hit the nail squarely on the head!!!!!! Excellent reply to the question.

I use a DynoSim Version 4.20 with Pro Tools and haven't had so much fun in years. The results obtained with my software against actual dyno pulls have shown to be within 2%, so I'm happy with that. But like rhamm said, it's the DIFFERENCE in hp and torque that you see from changing parts around that makes the DynoSim so much fun to use. You can build 5 different combinations of the same motor within an hour and all it costs is your time. It's not like buying the actual parts and doing an expensive dyno pull with them. Here's a link to four sims I did for a fellow on another forum. Note my disclaimer at the bottom.....
http://www.hotrodders.com/forum/whats-deal-155307.html