Logs pulled were from the exact dyno pull pictured......somethings outta whack....

Dynojet



VDR

 

I'm not an expert on dynos by any means, but for a dynojet, wouldn't you have to input the weight of the rollers instead of the car and occupants. What is in the car or the car weight isn't going to matter. You're not accelerating the car, you are accelerating the rollers.

Do you know what exact model of dynojet that was on and what the drum/roller weights were? Try editing the weight until your torque curve looks similar to the dyno. You may to mess with the trim value since the spreadsheet tends to keep the torque/hp too high right at the end of the run. Also, only use enough smoothing to get a nice curve, not too much.

 

The dyno model is a Dynojet 424X

Edit: I am seeing some preliminary info leading to the rollers weight 1800lb a piece....

2nd Edit: Another thing I am seeing is the Evo Scan logs are not showing any RPM over 7900......its obvious we turned the engine to 8300-8400 on the dyno......yet, the logs do not show anything in the 8x range

 

The DJ doesn't load the car like driving on the road. Go do a road pull and compare the results.

 

Try lowering the smoothing factor on the VDR to like 2 or 3. That should help some but it'll probably still be off a bit.

 

Doing a quick search someone said the rollers were 1800lbs each. Try using 3600 lbs as the car weight and lower the smoothing some...only enough to first get a somewhat smooth curve.

Edit: Another link listed roller weight at 2500lbs each. So, try 5000 lbs too.

 

My older brother used to own a 224x, which a 424x is two stacked 224s and he said one roller was around 2200lbs

I fidged with the numbers and with a smoothing correction of 3, it actually shows a dyno curve instead of that straight up line you see in mine. I ended up with 4150 which put me within 1hp at peak HP, and 10tq at peak tq. The peak numbers were in the same spots as well (6800rpm for HP, and 5600ish for TQ)

 

this is intresting ... so this is still the dyno log? just added weight to get something close to the read out?
or was it a road pull log? never did this before my self but what you should try to get a nice comparison is find the correct "correction" of the dyno and then input that in vdr and do a road pull on a flat road and see how it compares..

 

Here's my dynojet vs VDR (log from pull that made 515whp)

 

There seems to be a setting for the max RPM for the graph. It's set at 7850.

 

You have the max rpm trim on the VDR set at 7850 so thats all it's going to show. Also agree that you really can't use the log from the Dyno pull for the VDR program. The VDR program takes into account vehicle weight, passenger weight, frontal area, etc. which are nullified on the dyno. Do a road pull and then run it through the VDR to compare.

Dan (drb)

 

Sorry I missed this til now. You can't compare the datalog from the Dynojet with the actual Dynojet values. There a few reasons why. VDR adds compensation for the wind resistance of the vehicle but the log from the DJ doesn't have the same resistance curve that you would on the road. DJ's don't use vehicle weight because all it measures are the rollers RPM and calculates power by the inertia of the roller weight. The DJ software also compensates for the inertial resistance curve that is always a factor since it will be hard to initially get the roller started but will kind of smooth out once its in motion. There is no way for me to match this curve without knowing a LOT of details from each model of DJ and how DJ does the math....totally no point though since you dont need VDR if you are able to just buy dyno time lol.

VDR takes real world STREET conditions and then tries its best to mimic the 'results' of a DJ.


Mustang dynos will be MUCH closer when comparing the dyno results vs the actual datalog from that pull. This is because the dyno has an Eddy Current braking system which closely matches the resistance the vehicle would experience on the street. The dyno applies resistance and then applies compensation for the resistance in the dyno results just like VDR does with Drag Coefficient and frontal area. The one thing that usually is required is that you enter the vehicle weight used on the MD. Default vehicle weight is 3625lbs for Evo 8's and probably for Evo 9's too (cant recall). Don't ask where they came up with that ridiculous value for vehicle weight, I haven't a clue. Its close to the vehicles Curb Weight plus 2 occupants so maybe thats how they calculate it.

In short (lol), just do a street pull and do a comparison and see if things are closer. Also, the DJ was adding STD weather correction to the values so its best to compare the uncorrected values vs. VDR's uncorrected values. If you have a printout, it should show the STD correction value somewhere, like 1.03 or 1.05 or something. Let me know if you find it on there.

I plan to focus more on getting 2 settings for comparing actual datalogs while strapped to MD's and DJ's in the future but I have to finish up my other project before I start adding any more stuff.

 

You CAN'T datalog on the dyno and then use this data in VDR or in any other "road dyno calculator".
You must log on the road.

 

Ok, so I ran your log thru VDR 6.00's excel beta real quick and first thing is....

Jesus, what are you logging with!?!?!?!? It was 25 rows of data from 3400-7900RPM!! Thats not enough to log anything well! Yikes, we'll have to help you with that. So I set the Drag Coefficient to zero and just messed with the correction factor so the numbers matched your dyno pull JUST to see how well the power curves seem to match up. I'd say they match pretty well considering how small your data was and there is no way to compensate for the roller resistance curve which will affect the shape of the curve a bit. There was no MAX RPM TRIM adjustment in this log since VDR v6.00 does this automatically now

I'd love to see a street pull while ONLY logging TPS and RPM for the greatest resolution. THats the only way to really do a fair power curve comparison unfortunately.

 

Oh yeah Andy, 1-Byte RPM does limit you to 7968 RPM but 2-byte RPM is limited to like 250,000+ RPM lol. Problem with 2-byte is its tendency to have random HUGE spikes once in a while which can wreak havoc on all Dyno simulators out there.