I was a user of DD2000. I am building a new motor (4.125”x3.5” sbc) and felt DD2000 was way too optimistic on the lower RPM torque values. I liked the ease-of-use of DD2000 so I tried to contact the company to see if their upgraded versions corrected the problem. Several calls to ProRacing Sim got me nowhere. I got the impression that they are merely a front for Motion Software and Motion is not interested in customer questions. So I called Performance Trends, the makers of Engine Analyzer. They were very helpful and I had direct access to someone who was knowledgeable. That sold me and I ordered EA V3.2. (I had also heard good things from other forum members on this product, most notably SWCDuke.)

I’m up and operating with EA. I found the user interface to be relatively straightforward for the average computer user or DD2000 user. In fact, they initially offer so many pop-up help balloons that I found it distracting (you can turn them off). They do require more detailed input than DD2000 but they have good example files that get you through just about all of the popular engine components.

As far as accuracy, I have not plugged in any known “dyno-tested” combinations. The program does seem to have a more realistic low RPM torque profile for my engine combo and the horsepower peaks are in agreement with my models on DD2000. I bought the “plus” version of the program which allows me to tweak combinations while I observe the graphical output. I quickly learned how sensitive power output is to air temperature and barometric pressure. It has some other interesting input options like connecting rod length (a long debated subject), options for accessories, and muffler flow in CFM.

Overall I’m very satisfied with the product and am looking forward to digging further into the program.

 

Hey Cris, how ya been. I've used several simulators over the years. DD is too simple and hard to make specific changes. It did give you a general idea of HP & TQ. I've also used & continue the EA pro version, but i feel it too is optimistic. The pro version does give you lots of variables and has lots of features, but the one i've found to be very accurate is the EA std version which morphed in the basic and plus versions. It bothered me that i couldn't enter complete head flow data in the std version, but i could usually model an engine and estimate an ET within a tenth. I haven't used the pro version as much, but i know my 350 wasn't making anywhere near the 440 hp it predicted., but i think the std version was pretty damn close at 390 tho. What's weird is the same input is in both versions of the software written by the same company and they are different by 50 hp??? Go figure. I like the pro version, but i find i have to make some pesimistic assumptions to get close to reality and it takes quite a while to calcuate the curves (and you can't multitast during the process), while the std version is almost instant. I think you'll like the Perf Trends SW, which ever version you have.

Good luck with it

 

Based on actual tests of engines I've system engineered with EA, top end power is quite accurate. Peak torque is a little high and low end torque prediction is low. Actual torque curves were much flatter than predicted with the LT-1 cam.

The accuracy of predictions is dependent on the accuracy of input data. Getting head flow, valve timing, and exhaust backpressure close to reality is critical to obtaining accurate predictions.

I did one engine using SAE gross and open exhaust since the plan was to test it on a lab dyno. Others I use SAE net correction with accurate models for front end accessories and exhaust flow. Use 500 CFM with streamlined manifolds for a C2 SB with 2.5" manifolds and pipes.

Chassis dyno data ended up very close when factored by 0.85 to to account for driveline and tire loss.

Duke

 

Guys, thanks.

I'm not sure what the "intake vacuum" under the calculated performance means. I'm looking for my manifold vacuum, but the numbers under "intake vacuum" don't seem to make sense for manifold vacuum. Any guidance would be appreciated.

Duke, I am looking at the Dynomax UltraFlo at over 1100CFM per muffler at 20.3" in H2O. Can I make any kind of guess on flow for 1 3/4inch long tube headers followed by 2 1/2" dual exhaust (with X-pipe) and the UltraFlo mufflers? I will be in a world of hurt with only 500CFM.

The other thing I have found is EA tends to overestimate the onset of detonation and it automatically retards the timing. You cannot turn this feature off. My work around is to raise the octane.

 

As flow through the carb increases, manifold vacuum increases. If you have a 600 CFM carb, intake vacuum should be about 1.5" Hg. when flow reaches 600 CFM. Four barrel carbs are rated at 1.5" Hg depression. If manifold depression exceeds 1.5" the carb flow should be increased - i.e. bigger carburetor. For a racing engine max manifold vacuum should be held to no more than 1.0" Hg.

You should be able to model the headers accurately from the header menu. Use "street headers" unless what you have is a true racing design that justifies the higher flow efficiency. The maximum tail pipe allowable is about 60" IIRC and that's what you should use eventhough the actual exhaust system is probably a little longer.

The flow rate of the exhaust system is based on flow at 1.5" Hg. depression, which is 20.3" H2O and includes the entire exhaust system, not just the mufflers. It sounds like your exhaust system is very efficient, so maybe you can used 550-600 CFM. If you can keep actual backpressure to no more than about 3 psi that is good.

Yes, I agree that detonation prediction is overaggressive and as you increase octane to get rid of it, "air-fuel quality mix" degrades, which lowers low end torque. I wish both features could be turned off or modified.

Pay attention to Mach index. Once it gets to about 0.55 you need better head or manifold flow. More cam won't do much except kill the bottom end.

Read the entire users manual so you understand what all the outputs are and how to use them to improve the configuration.

If you are using an OE mechanical lifter cam I have timing numbers that work. Published specs are not accurate relative to what the program needs.

Duke

 

This is a very timely thread, I dropped into Eng Mods to search
for opinions about Engine Analyzer, Desktop Dyno and other modeling
software only to find this thread right at the top.

I recently licenced EA Pro 3.3.

SWCDuke's remarks about detonation prediction address some thoughts
I've had. I also wonder about the criteria for piston speed being
conservative - the nanny dialogs seem to appear at speeds of 500 FPM
or more below where I would have guessed.

Two comments I have are that I have yet to come across the area
where it is possible to model piston-to-valve clearance in EA Pro and
I hope to find a site with sample files of parameters that extend the
defaults provided with the software by Performance Trends. Either
I didn't pay enough attention and the P-V modeling is in one of the
other versions/levels of EA. I asked about an offically supported
file exchange section and was told that there had been an area
on the site in the past but that this had been phased out of existance
- no solid reason given, but we speculated that there could have
been some aspect of responsiblity and onus for vetting files put up
by contributors.

EDIT: Corrected fps to FPM. Oops.

.

 

In EA Pro, it is possible to create a spark curve with up to four break
points in the curve. When the Knock Index results indicated that
detonation was likely, I changed the spark from 'Best Perf' and
manually tweaked until the KI approached 1.0 at points along the
RPM curve.





Before and After: Spark for best performance vs custom curve.
I make no claim as to the desirability of the custom curve, it
just serves to illustrate the feature.



Is the custom curve feature available in EA Plus or limited to
EA Pro?
.

 

My older version of EA -3.0 - has no provision to alter spark advance, so I have to increase octane then "factor" the low end torque up somewhat to compensate for the low bottom end torque due to "poor air-fuel quality" mix.

A well system engineered SB for road use will make useable power to about 4000 FPM, which is high for "stock" components. On 327s I tell all that better than OE quality connecting rods are required, if you don't want to hole the block at 7200 revs.

Considering that the LT-1 redline of 6500 corresponds to about 3800 FPM with a Tufftrided forged steel crank with suitable journal overlap and the "pink" rods, if you are going to run that high, you better ensure that your cranktrain is at least as good, and keep in mind that cranktrain loading increases with the square of mean piston speed, so ten percent higher speed means 21 percent higher loading.

A Magnaflux qualified 350 cast crank should be okay to 6500, but the standard (non-"pink") rods might be iffy. Higher quality aftermarket rods are good insurance if mean piston speed gets up over 3500 FPM, and a long stroke crank - 3.75" or more - without increasing journals above the standard 350 size to restore lost journal overlap can be a recipe for failure unless it's really well manufactured using all the tricks to ensure durability.

On all projects I've found that final tuning of the spark advance map must be done by road testing, but only after the the carburetor or FI is dialed in to provide the proper fuel mixture at both cruise and WOT.

Duke

 

For my purposes & budget, I have been targeting a redline of 5,500.

So for graphing results, I chart up to 6,000 - which is reported as 3,480 FPM
with a 3.48" stroke. In the 'Notes' EA offers for each set of results,
there are comments to the effect that the 3480 FPM is 'Very High' (their
emphasis).

Trimming back to chart just to 5,000 (reported as 2,900 FPM) results
in comments that 'This is somewhat high. If you intend to rev this
engine this high, it will require better than production reciprocating
parts.'

My impressions about acceptable piston speeds were formed in the 80's
when I had a personal project that led me to look at mfr's redlines for
production auto and motorcycle engines of the 60's-80's. I determined
piston speeds and came to the conclusion that, regardless of displacement,
3500-3700 FPM seemed to be a common range for durable operation
in the eyes of the mfr's.

(If I recall correctly, my LS5 BBC from a 71 Monte Carlo had a factory
redline of 6,000 RPM which resulted in a piston speed of 4,000 FPM with
the pedestrian 3/8" bolt rods, forged crank and 2 bolt block.)

Hence my feeling that Engine Analyzer is overly conservative stating that
2900 FPM is somewhat high and 3,480 is very high.

In no way am I trying to hold forth that my number-crunching &
sampling of data is a substitute for first-hand experience. Just
noting what appears to be a disconnect to me regarding EA's
evaluation of current production parts.

Thanks, SWCDuke.

Ken R.

 

Thank you for the tips.

You might recall an earlier thread wherein I asked about the role
of port volume. I settled on some heads and I am using EA to examine
how efficiency, compression ratio and cam specs work together.

The default timing curve settings indicated that a certain combination
was going to be very hard on the hypereutectic pistons. Being able
to alter the timing curve gave me hope that the combination might
be made to work.

Of course I have yet to determine whether just because I can make it
work, that I should go ahead on this course of action. Unfortunately,
I have not figured out how to have EA help me in that regard.

.

 

Found it.

The following dialog appears from the 'See-Engine' menu pad of
the Calculate Performance results display. You step through
forward or backward or set the display to run continuously.



.

 

Slalom:

Yep, even the el cheapo version of EA will calculate piston to valve clearance, though there are no provisions for valve reliefs. (It assumes a flat top piston.) Plus you have to know the head deck to valve clearance, which is not something you routinely find in a catalog. The feature is found in EA in the cam/valve train menu.

Duke:

Manuals, we don't need no stinkin manuals......I'm actually wading through the manuals. But I seem to have a disconnect, what number do I use for manifold vacuum at idle? I am expecting numbers like 12" of Hg for manifold vacuum and EA's "intake vacuum" is running something like .1 inches of vacuum at low RPM's. This must be WOT vacuum or something.

This exhaust thing has me concerned. I'm trying to clear 500HP and even 600 CFM is going to really hold me back. I am seriously considering dragging the exhaust system down to the dyno to sort this out. (Whoops that's another 1/2 day at $500.)

Guys, it's nice to have some e-dyno guys on board. The software is only going to get better, and it may not be the absolute number, but it will give you a good relative feel for what works and does not.

 

good read

 

Under "special calcs" on the output table menu, the stated idle vacuum is at 2000 RPM. There is no prediction of vacuum at typical lower idle speed.

The manifold vacuum in the output table is WOT.

600 CFM exhaust system flow is about the minimum you need for 500 SAE net at the crankshaft, which is probably going to require 3" pipes, and you are going to have to keep overlap very modest.

That's why I always use SAE net. You can get big SAE gross numbers, then put the engine into a car with a typical exhaust system and the torque and power curves just get killed.

Duke

 

Thanks Duke, I found the special calculations. EA 3.2 uses 1500 RPM for its calculation of idle vacuum. Under special calculations I also found all the other stuff I was wondering about like DCR. On EA 3.2 you find the special calculations under the "View" menu on the "Calculate Performance" page.

 

One other thing has thrown me off with EA 3.2. When you start the program it opens the last engine combination you were working on. It does not matter if you saved this file or not.

The goofy thing is, at start-up, the program shows a file name on the menu bar. This file name does not necessarily match the file it has opened.

For example, you build a motor and name the file "350 Killer". You save that file as your baseline motor. You now try some tweaks to the motor, decide you don't like what you see, and close EA. When you re-open EA, it opens the version with the tweaks, but it still shows "350 Killer" in the menu bar. If you want to get back to the original "350 Killer" you have to open it under the "File" pull down menu.

 

That's probably a nanny feature for those who forget to name and save configurations.

Whenever I open V3.0 is asks if I want to save changes made to [file name], which was the last one I had open. I can either answer it or just bypass it and open up the file I want to work with.

I have a number of configurations that I work with and sometimes open them just to brainstorm and try something different. The results are usually not that good, so I don't name and save them.

Just be sure that if you do come up with a new configuration that you want to save that you save and name it for future use.

Duke

 

Is there a spot where people post library files that they have assembled?

For instance, if I've modeled a Edelbrock 7501 Performer RPM Airgap,
A Holley Stealth Ram and a few Erson cams - perhaps someone else
would be interested in getting these files rather than creating their own.

It would also be useful if the greybeards in the area vetted the files
- ensuring validity (and surely educational when errors crop up.)

.

 

Good thread. I bought EA 3.2 recently as well. I have used it to model different cams and heads combos for the LSx motors as well as DCR.

I am curious to know how reliable the PTV values as modeled by EA are?

I use EA as well as a spreadsheet for DCR/SCR calcs. The spreadsheet and EA match up on SCR but DCR seems to be different and lower in EA. I beleive the spreadsheet to be correct be cannot be sure.

Also wondered about port diameter and runner volume. If you input diameter, it forces port volume in cc's. In talking to folks at Performance Trends, they recommend using port diameter and not worrying about forced port volume. I chose to use port volume and let program force port diameter. I have flow numbers for the heads and intake and it just seems more logical to use a correct port volume and length and let diameter far where it may.

Thoughts/suggestions? A file library would be nice!

 

There is no consistent definition of DCR. Some formulas use inlet valve closing point at .050" lifter rise plus 15 degrees. Some use .004" or .006" lifter rise or valve lift. The DCR calculation is dependent on how you define inlet valve closing point. It gets more muddled because of different rocker arm ratios on various engines and actual rocker ratio at low lift. It varies throughout the lift cycle starting lower than specified, and might achieve the specfied value at peak lift, but maybe not. The only way to know for sure is to measure them.

DCR is just a guideline and not something that you hang your hat on. It eventually comes down to experience and learning the SCR limit with a particular cam and fuel octane. If your engine has knock sensors, there's little to worry about. Modern engines with knock sensors can run much higher SCR/DCR than engines without knock sensors. The control system will reduce spark advance to eliminate knock at high inlet and/or coolant temperatures where detonation is more prevalent. Without knock sensors you have to limit SCR/DCR to the 90th percentile worst case or whatever.

EA assumes that the port is round, but SB ports are not round. If you have flow numbers and port volume and length, EA computes equivalent round section diameter and then flow efficiency for this equivalent round section port, and it appears to produce reasonable results.

Duke