ws6transam

I am a DD2000 skeptic, and will remain so until I get the engine actually built. Motion Software has not responded to any of my messages (three so far, plus a phone call). The software technician on the other end said that all of the technical support people were off-site, and I could not reach them except through the Motion Software dWEeeB site. <(that was a typo, btw.)

He did say that if you know what you are doing, the DD2000 is accurate within 3% of the real world. I countered that they were making many assumptions on many engine details, and that the 3% accuracy figure is probably only true for engines that match their assumtions. How will I know if my engine meets these assumptions as well, if they wont return my feedback?

Anyway, FWIW, here's the predictions that I hope to put to the test next spring. Most of the parts are already here, except the wiring harness, chip programmer, and cylinder heads.
The flow numbers are based on Traxion's ported AFR heads, which I plan to mimic in my own design. It's a TPIS Minirammed 385 smallblock with 10.5:1 compression and a custom roller retrofit cam with Xtreme Energy lobes. (230/236 dur @ .050", .545/.555" lift, 112 LSA, 110 degrees intake centerline)


RPM TQ/HP
2000 447 ft.lb / 170 HP
4000 536 ft.lb / 408 HP
5500 487 ft.lb / 510 HP
6500 393 ft.lb / 486 HP

If I'm within 5%, I'll be awfully lucky, dont you think? We'll see, and I'll be posting the results next April.

Has anyone else created a DD2000 simulation and then dynoed the real thing?

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Daniel Burk
View my third-gen hobbyist performance page!
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branz28

I think i remember some posts from a while ago stating that it exaggerates low end torque and highend horsepower. I could be waay off. In any case i do remember various posts saying that the numbers were high compared to actual flywheel power on the dyno. One instance i recall from last week on a mailing list. A guy had a 850hp engine with Desktop Dyno, come time for the actual dyno it was actually like 721. Might i add i've also heard of people claiming it was only 30 - 50 horses off so i imagine it depends on what features you use.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes

[This message has been edited by branz28 (edited July 13, 2001).]

jcb999

i tend to believe its about 5 percent optimistic in some cases. Most engines are not prepared with the detail that DD assumes (perfect in every way). It does seem to be pretty close on smallblocks that use AFR heads. I also found that it gets real close by droping the compression down by about .5 to .75 point from what the engine actually has.

IROC5.7TPI

Dan,

I have both DD and a program called Engine Analyzer2.0

EA20 is superior in every way. It leaves room for more variables, as well as octane, coolant temp, air temp, humidity, etc.

It also has its own library of heads, intakes, cams, etc.

If you can find it, try it out. I recommend it highly.

We inputted a friends 427 BBC, and on the computer it came up with 575 FWHP and 650 Lbs.TQ

After strapping it on a Dynojet, it made 502RWHP and 575lbs. TQ. This was with a 4-speed manual and 4.10 gears in a 69 Nova.

I was impressed and have never used DD since. I think its way overrated.


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Mike L.
It ain't pretty.......

1987 IROC Z TPI 350 A4 3.27 Borg-Warner.

Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog

http://www.MichaelLasiuta.home.att.net

**BOYCOTT LAPEER DRAGWAY**

[This message has been edited by IROC5.7TPI (edited July 13, 2001).]

Monty

I used Dyno2000 when I was designing my SBC 427, and then had it dynoed on a SuperFlow Engine dyno. Dyno2000 proved to be amazingly accurate across the entire rpm range, in most cases within 1% of the actual Dyno readings:

-----DYNO2000-----SUPERFLOW
RPM---HP---TQ------HP---TQ
2000--164--431------------
2500--229--481------------
3000--286--501-----288--502
3500--354--531-----356--532
4000--420--551-----422--552
4500--488--569-----489--569
5000--547--574-----551--579
5500--597--569-----598--570
6000--625--547-----620--543
6500--643--519-----642--519
7000--646--484-----621--466
7500--647--453-------------

We had the rev limiter set at 7000, so the SpeedPro SEFI was starting to pull out timing and fuel. The motor should be good for up to 8500 rpm, it has a Crower 4340 billet Ultralight crank, Crower 4340 billet rods, JE pistons, and full JESEL Nascar valvetrain, but since it's a street motor, I'll never rev it past 7000.

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1982 Corvette
Tremec TKO
<A HREF="http://www.geocities.com/monty_williams" TARGET=_blank>SBC 427 650hp/580tq
</A>

[This message has been edited by Monty (edited July 13, 2001).]

jcb999

it's Mr Big Small Block, monty

funny i guess the version of EA i got was 1.nothing. It only had chevy small block engine paramaters and not very many of them. I never updated to anything new.

[This message has been edited by jcb999 (edited July 13, 2001).]

Brent

iTrader: (1)

Some interesting articles for ya:

http://www.motortecmag.com/archives/...MAR010501.html

http://www.motortecmag.com/archives/...FEB010301.html

AlkyIROC

I have no commercial dyno software but from what I've heard, the most accurate is Quarter Jr.

------------------
Follow my racing progress on Stephen's racing page
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461 naturally aspirated Big Block

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Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

Apeiron

Whether its accurate or not, one of the most interesting things to do with it is just to model your current engine, and then make changes and see what it does to the shape of the power and torque curves. If you don't trust the numbers it gives out, just ignore them.

[This message has been edited by Apeiron (edited July 13, 2001).]

Monty

Apeiron,

I agree completely. It's not necessarily the absolute values that matter, but more the relative values. I admit that my results are probably best case, and I did tweak the Dyno2000 inputs to get the predictions closer to the actual results. For instance, even though I used stepped headers, the results were much more accurate using the large tube, open exhaust option. I've seen other instances where the results were more accuate using hydraulic or solid lifters as the input, even though it was actually a roller cam.

I also have a copy of Engine Analyzer Plus. It retails for about 10x what Dyno2000 does. If you build alot of engines, EA Plus is probably worth the investment, but if you're like most of hobbyists, Dyno2000 is a useful tool.

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1982 Corvette Tremec TKO
<A HREF="http://www.geocities.com/monty_williams/434specifications.html" TARGET=_blank>SBC 427 650hp/580tq
</A>

[This message has been edited by Monty (edited July 15, 2001).]

ws6transam

Ah, there is the crux.

In order to get accurate predictions you must tweak the model to fit the existing engine.

If you have to wait for an accurate DD2000 prediction until AFTER the engine is built, is it really a prediction? As they say, hindsight is 20/20...

Apeiron

It depends on what kind of accuracy you want. If you expect the model to exactly duplicate your dyno results, you're probably going to be disappointed. I do find its results to be quite optimistic. If instead you want to do something like get some kind of idea what effect a new cam is going to have on your curves, it's a bit more useful.

Monty

ws6transam,

If you look at the actuals vs, predicted numbers I posted above, you'll see that they are within less than 1% almost all the way across the rpm range. Before I tweaked the Dyno2000 inputs as I mentioned above, they were still within 3% or less.

Not everyone is willing to spend $400 for Engine Analyzer Pro, or even $100 fro the standard EA. $40 is not bad for an application that will produce predicted results within 3% of actuals, in my opinion.


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1982 Corvette Tremec TKO
<A HREF="http://www.geocities.com/monty_williams/434specifications.html" TARGET=_blank>SBC 427 650hp/580tq
</A>

ws6transam

Thanks for the posting Monty!

I really do hope that DD2000 is somewhat close to the real world. I just received my balanced reciprocating assembly today for the MR385 project. The numbers that are predicted by DD2000, even if off by 3% would make for phenomenal performance. (Who wouldnt want a 536 ft.lb/510HP street engine???)

I was just surprised to see numbers like that when I was expecting to see something on the order of peak 480 ft.lb and 460 HP.

I did use DD2000 in order to select my cam and intake centerline. Hopefully I can get the engine in the car within the next 12 months for testing. Then I'll be able to report on DD2000 accuracy. If it gets within 5%, believe me, I'll probably become a big advocate of the software.