Thoughts on an engine simulation

[Whittey]

Ok, I've got this program called Desktop Dyno 2000. Anyway, i'm sure its not the most accurate thing in the world, but its fun to play with and its pretty cheap, so why not.

Now, I put in the stats for a stock 4.9L ford and it was pretty close (

http://bigblocksix.com/stock.png).

A typical buildup is here

http://bigblocksix.com/typical_buildup.png

and my new super-great N/A buildup is here:

http://bigblocksix.com/lots_of_work.png

I'm looking at that last pic and i'm seeing two HP peaks. Why would that be?


-=Whittey=-

P.S. That is a simulation of a 4.9l with the alan johnson head and a schneider off-the-shelf cam.

 

[MaxRaceSoftware]

the 2 HP peaks are probably the result of
"calculated" torque curve thats too wide or
not falling off enough

a torque curve thats not varying enough
to simulate real conditions .

your torque should be more like this or some where between
half way between this and Desk Top Dyno

RPM=3000 Torque=218.5 HP=124.8
RPM=3100 Torque=223.6 HP=132.0
RPM=3200 Torque=228.7 HP=139.4
RPM=3300 Torque=234.0 HP=147.0
RPM=3400 Torque=239.3 HP=154.9
RPM=3500 Torque=244.7 HP=163.1
RPM=3600 Torque=250.3 HP=171.6
RPM=3700 Torque=255.9 HP=180.3
RPM=3800 Torque=261.6 HP=189.3
RPM=3900 Torque=267.4 HP=198.6
RPM=4000 Torque=273.3 HP=208.2
RPM=4100 Torque=279.3 HP=218.0
RPM=4200 Torque=285.3 HP=228.1
RPM=4300 Torque=291.3 HP=238.5
RPM=4400 Torque=297.4 HP=249.2
RPM=4500 Torque=303.6 HP=260.1
RPM=4600 Torque=309.7 HP=271.3
RPM=4700 Torque=315.8 HP=282.6
RPM=4800 Torque=322.0 HP=294.3
RPM=4900 Torque=328.1 HP=306.1
RPM=5000 Torque=334.2 HP=318.1
RPM=5100 Torque=340.2 HP=330.3
RPM=5200 Torque=346.1 HP=342.6
RPM=5300 Torque=351.9 HP=355.1
RPM=5400 Torque=357.6 HP=367.7
RPM=5500 Torque=363.1 HP=380.3
RPM=5600 Torque=368.5 HP=392.9
RPM=5700 Torque=373.7 HP=405.6
RPM=5800 Torque=378.7 HP=418.2
RPM=5900 Torque=383.4 HP=430.8
RPM=6000 Torque=387.9 HP=443.2
RPM=6100 Torque=392.1 HP=455.5
RPM=6200 Torque=396.1 HP=467.5
RPM=6300 Torque=399.6 HP=479.4
RPM=6400 Torque=402.9 HP=491.0
RPM=6500 Torque=405.8 HP=502.2
RPM=6600 Torque=408.3 HP=513.1
RPM=6700 Torque=410.4 HP=523.5
RPM=6800 Torque=412.1 HP=533.6
RPM=6900 Torque=413.4 HP=543.1
RPM=7000 Torque=414.3 HP=552.1
RPM=7100 Torque=414.7 HP=560.6
RPM=7200 Torque=414.7 HP=568.5
RPM=7300 Torque=414.3 HP=575.9
RPM=7400 Torque=413.4 HP=582.5
RPM=7500 Torque=412.2 HP=588.6
RPM=7600 Torque=410.5 HP=594.0
RPM=7700 Torque=408.4 HP=598.7
RPM=7800 Torque=405.9 HP=602.8
RPM=7900 Torque=403.0 HP=606.2
RPM=8000 Torque=399.8 HP=609.0
RPM=8100 Torque=396.2 HP=611.1
RPM=8200 Torque=392.3 HP=612.6
RPM=8300 Torque=388.1 HP=613.4
RPM=8400 Torque=383.7 HP=613.6
RPM=8500 Torque=379.4 HP=614.0
RPM=8600 Torque=374.0 HP=612.3
RPM=8700 Torque=368.8 HP=610.9
RPM=8800 Torque=363.4 HP=608.9
RPM=8900 Torque=357.9 HP=606.4
RPM=9000 Torque=352.2 HP=603.5
RPM=9100 Torque=346.4 HP=600.1
RPM=9200 Torque=340.4 HP=596.4
RPM=9300 Torque=334.4 HP=592.2
RPM=9400 Torque=328.4 HP=587.7
RPM=9500 Torque=322.3 HP=582.9

414.7 Torque @ 600 RPM/SEC accel dyno rate should be
equal to 14.00:1 CR

the 470 peak Torque for 14:1 CR is pretty high
even at steady state dyno test

5500 RPM=470 TQ




Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

Support Israel - Genesis 12:3

 

[Whittey]

Would there ever be a case where a motor would have two hp peaks like that? What about torque peaks?


-=Whittey=-

 

[MaxRaceSoftware]

yes...you can have 2 Torque or HP peaks

mostly occurs because of Intake and Exhaust systems not in phased or in other words, not tuned together for one curve

most of times, it will be the exhaust side responsible
for the higher RPM 2nd Torque or HP peak

but looking at the DeskTop dyno picture , the Torque is too high for CID and CR , and this could cause 2 HP peaks also.
Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads - MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

Support Israel - Genesis 12:3

 

[FireLover]

You can get even more than two peaks. This is due to the tuning of the intake system. pressure waves reflect off of the various transisions and plenums in the intake system (intake manifold, resonators, air cleaner box, etc.)