Engine Simulators

[lmcchesney]

I presently have the DynoShop engine simulator. Lots of good information in the manual. I would be interested if Dave Darling would comment regarding the use and limitations of the available simulators, since his field, I understand, was simulators for NASA.

L. McChesney

[Dave at Pelican Parts]

I have no comment on it. I've never seen it or worked with it, and my "day job" is on a much broader level. Fluid Dynamics is, as a co-worker once put it, "The most empirical and least intuitive of all engineering disciplines." That means that it doesn't make any "common sense" in many ways, and the formulas are set up the way that they are because those formulas fit what has been observed directly over the years.

I have essentially nothing to do with the details of aerodynamic models. Some of the CFD (computational fluid dynamics) guys are in those details up to here, but the facilities that I work for use a fairly simple set of equations to describe an aircraft's behavior. (For details of these facilities, see http://www.simlabs.arc.nasa.gov .)

The only dyno simulation software that I've ever used at all is "Desktop Dyno", which was exceedingly simple and not easy to correlate with real-world numbers for our engines. I think most of the dyno software packages are set up to deal most effectively with V8 engines, since much/most of the hi-po buildup work for years has been done on those, and they are pretty well understood.

Raby seems to think pretty highly of the software package that he uses. I think it's "Engine Analyzer Pro". Rumor mill says it costs a whole lot, and requires much more detailed info than most of us have about cylinder head flow and so forth.

--DD

[Jake Raby]

Dave is right...I use "Pro" .. I don't live by any of them, just experience and trial and error.

[lmcchesney]

Thanks Dave and Jake,
Engine simulators would require massive data input to provide an accurate assesment. I can't help but wonder that, despite inadaquacy in the prediction of one engine, it can be a valuable tool for the understanding of the inter-relations of the engines compoents, such as changes in induction and cam grinds. I too have the Desktop Dyno program. I realize this program is designed for the largest market, that being V8 muscle care engines. However, are the principles used that different? The program has default settings, but also allows specific input such as valve size, cam grind. Are we wrong in using programs such as Desktop Dyno to compare different engine compoent combinations?
Thanks,
L. McChesney

[Jake Raby]

I have the capability of weighing my parts, and flowing my heads.... For these programs to be accurate this needs to be done!

I mainly use the software to calculate piston/valve clearance and to decide on cam grinds... else its pretty useless.

[Dave at Pelican Parts]

It's the "difficult to correllate with real world results" part that would make me leery of trusting it too much on comparing configurations. I mean, yes, the general principles are the same, but there is a whole lotta devil in them thar details.

--DD