Engine Analyzer Pro - So I've been playing around with the demo and it's pretty neat

[Back Road Runner]

http://performancetrends.com/download.htm#eapro

It's a $400 program, but they offer a 10 day full feature demo which is cool.

I got to playing with it to see how our NA engines fair and to figure out what's messing up our top end.

I sort of worked through the optimization of the engine design to try and make the thing usable out to 7000 rpm while not completely failing on the low end. I started off with a stock setup, or at least as close to it as I can figure out. There is some guessing but not much.

I played around with the heads, intake, exhaust, and cams trying a vast array of combinations of things.

Interesting things I found out, at least as far as the program shows.

Cobbs and TWE's header designs are spot on. They're essentially the most low rpm geared design you can make that will have minimal detriment by redline. I sort of worked through it before and found it to be basically ideal, but it's neat that the software also shows an ideal gearing as well.

Up to 7000 rpm, the ideal average head port diameters are 1.6" in. and 1.3" exh. The valves don't seem to be a problem at all, not for size or lift really. This should be the choke point, and Mach numbers are low enough as long as the port diameters are these sizes. Bigger is not better either and VE drops off. I don't know what stock is. It's typically a percentage of the valve diameter as a guess.

The top end roll off seems to be majorly an issue with the intake manifold. It's simply that the long runners seem to mess everything up. The 1.5" diameter is basically perfect, but they need to be MUCH shorter, like 3" to 4" kind of short. This showed the biggest influence relatively to anything else I did with the program. Unfortunately, the flat engine layout doesn't allow for such a design. Maybe a dual plenum setup or independent TB setup is a better approach. The independent TB route does yield lower VE numbers unfortunately and a good loss of 20 ft-lb over the peak range. Interestingly, AMS is building a dual plenum design:
http://forums.nasioc.com/forums/show....php?t=1600687
It may be a curious option.

Teal/Red - Stock, full exhaust
Blue/Green - Modified intake manifold, intake runner 3" versus 12"


Cams also play a big roll, but going from stock to say the Delta 2000 grind just doesn't do a ton. A big roll is stepping up to some serious cams, like 220 degree duration. I tried everything from stock to 240 degrees duration and between 100 and 110 degrees separation with straight, advance, and redardation in timing. 240 was great for top end, flat HP between 5000-7000 rpm, but 220 was the best mix with improved midrange without great loss on the top.

Stock vs. Delta 2000 grind


Stock vs. Modified cams 220 degree duration, 105 degree separation, 5 degree advance.


Now just for comparison, this is the sum of what I consider a 7000 rpm capable build, high rpm focus but still with a functional lower end.

Stock vs. Modified intake and cams



It kind of makes you wonder what can really be done with the engine.

Now realize this is simply a simulation program, and of course isn't exactly true to real life. It's results are only as good as the inputs given. As well, I'm ignoring unrealistic factors like me being able to even build an intake manifold with 3" runners, and probably engine parameters that may be unrealistic or problematic. It's just me toying with software, apparently decent enough software but software none the less. It's good to get you to think though.

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[Eyedoc Orlando]

woohoo excel spreadsheet drag racing! Simulations are interesting though and somewhat useful

[sorrowfulkiller]

I have a full copy and crack for it if you are interested just pm me

[Back Road Runner]

Originally Posted by Eyedoc Orlando

woohoo excel spreadsheet drag racing! Simulations are interesting though and somewhat useful

Pretty much. That's both the fun and downside of such simulators. They're only an estimation, and you can only hope they're decently accurate.

There are cues that the program decently represents an engine, but it also does things that aren't exactly realistic. For example, the Delta 2000 grind changes the torque curve differently then I get from the calculator. I also didn't do anything with timing which will have a big effect on the power curve. I should probably go through the curves again, but that wasn't exactly the key point. The program has a knock index which indicates probability of knock. You can advance the timing curve if the index is low so you can gain more power. It's worth about 10 to 15 ft-lbs though. It's probably why the top end response of my graphs are a bit low.