I said there was something wrong with the dynos posted because they don't cross at 5252. You disagreed saying it should cross at 7119 even though one crosses at 3700 and the other at 5600. It's gone back and forth a couple times. So how am I diverting this thread? Btw, 5252 is a constant.

 

Tq & hp cross at 5252 only if the graph is scaled so...ie. power & torque have equal values in Y-axis. Mostly done only with imperial units.
If you look Karol's dyno graphs you'll notice that the scaling varies between hp & tq AND units are according to SI.

 

TT Dude,

I think to sum it up, as Pete95 above said, if the scales are different, the numbers will cross differently.. The best way to look at this is by doing the conversion yourself.

Take the first dyno graph and calculate the conversion from Torque to HP at a certain RPM, they should match..

In the first graph for example the lines cross at about 5600RPM and 875 NM. Calculate the HP at that point: HP = (875NMx5600)/ (5252 x1.356)= 688 HP, which looks right on the graph. On the second graph, the same calculation at any point across the RPM range will also give you the right HP number.

So readinng a graph in lbs.ft or NM is not the same.

As to the 5252, it is only a constant in lbs/.ft, not when you measure N.M.
1 HP= 550 ft.lbs per second = 33,000 lbs.ft per minute
33,000 lbs.ft min/ 6.2832 lbs.foot = 5252 (6.2832 is PI x a two foot diameter circle).
In N.M. you need to apply the conversion of 1.356 to the above..

 

this may help



First thing we learned about using the MaHa lps 3000
Is… forgetting everything you learned about all other wheel power calculating dynos. This is what we had to do, Joe and I have been using other dynos for years to tune and test cars and we put up some resistance at first until we unlearned what we had gotten so used to.

Other dynos can only give you wheel power #s. and this is ok if all your going to do Is look for the gain from a modification compared to stock, and you don’t need or care to know what the real power is. The wheel numbers are completely arbitrary.

One of the most common miscalculations in determining horse power was guessing the drive train loss.
Most people think that there car has a certain percentage of drive train loss, in fact drive train loss is not one set percentage its multiplication, the most common example is a person that has had there car dynoed at a shop with a DynoDynamics or a Dynojet or other simalar, will say something like… my car dynoed at 280 whp and the dyno operator told me my car is approximately 25% drive train loss, so my car must have 350hp at the crank.
First question we usually ask is At what RPM. if your peak HP is at 5000 RPM then you drive train loss is much less than it is at 7000RPM so for example lets say your drive train loss is 65 hp at 5000 rpm and it is 80 at 7000RPM then you have to know what the loss is at the exact RPM that you are making your max HP, or your #s are again completely arbitrary. And with all the different wheels brakes, light weight drive lines, even tires,,.. with out the ability to dyno you driveling you have no way of knowing what your real Hp # is.
This is why we have no question about high or low reading dyno we can always throw a stock car on and compare it to the factory SAE #s
A stock e46 M3 will put between 332 and 334 crank horse power on the MaHa dyno all day, factory #s 333.0 Hp, YES its that accurate.

So we have a sheet to use for example
And I must say for anyone that was wandering if APRs # s are true we can say for certain YES.
This is a 2.0 with APRs software installed


and from what i've read i also think that pete95 is 100% right
see below ..

Maha dyno vs Dynojet results!
I just want to share my results with everyone here. Alright guys before I start, I just want to say...take this for what it is and that this is NOT a direct comparison between the two dynos, by ANY means! WAY TOO MANY different variables!!!! For starters, these runs were done at COMPLETELY different days, COMPLETELY different locations, different altitudes, different temps, etc....heck I dont even think they were done on the same gear!!! Anyways here is the DL.....I always got a lot of crap from a lot of members on here for the dyno results I ended up with for my setup (everyone was saying that they were too low). I never understood where people were getting all of these "higher" NUMBERS! I always heard that dynojets read the highest out of any other dyno. So for *****s and giggles I drove 2 and a half hours to get dynoed on the only AWD dyno in the State of New Mexico, which just happens to be a dynojet!



Dynojet.jpg?t=1239238485


Several additional notes.........these dyno charts are for 91oct. at 19psi. The Maha dyno(which is the only one in North America, I believe) is that of GoodSpeeds located in Tempe, AZ roughly 1200ft elevation. At the time that I was dynoed (July 25, 2008), GoodSpeed had not yet received certain software in order for it to read WHEEL torque. The dynojet run was made this past weekend (April 4, 2009) roughly 5300ft elevation. I believe this run was done on 3rd gear. In the end....dyno numbers are just numbers. But very good tuning tools. Mods were exactly 100% the same on both runs. And finally a mod list that influenced these results......

this has been quoted from

 

Thanks for pointing out the difference in the scales. I did not notice that. They are widely different between the two. One has 450 KM=562 NM, while the other has 450 KM=850 NM. No wonder they don't cross consistently. I guess you can present the data any way you like but equating tq and hp values gives a very visual and easily recognizable method of comparison.

 

Could you please clarify how you check boost pressure,
In durametric logs maximum boost showing is 1.55bar

 

im glad it helped

 

May i ask whats the boost pressure input value in durametric??

 

i think it's showing maximum boost 1.55 , its tuned to reduce the boost pressure in high RPM and rise it in low RPM

 

here is picture of my boost @ middle rpm, it won't show more as dme is sending only 1,55 to the instruments.

if I would have more boost @ middle I believe I would have also more @ the top, but there is still maximum 1,2 bar which I'm reading from original porsche gauge.

there is one more interesting thing about this car, during hard acceleration starting from first gear my throttle body is closing @ 5000rpm for a moment and than on the second gear @ 6000 rpm for a moment.
with those two problems still I'm reaching 0-100km/h in 3,4 sec, but you can feel immediately that TB is shutting as car is under full load.

My ecu guy said it's problem with traction control which is still in position off, but still is working as too many strange things are going on, like rpm's are running too fast. He also asked me to check all 4 wheels speed at acceleration time.
now I'm running without some psm fuse, so no traction control at all.
he will switch traction off permanently in the ecu.

 

Dominik, I have a stock 997GT2 so I do not see 1.5 Bar and not sure whether you can have values above that on the durametric. The parameter I tick is "Pressure Ahead of Throttle plate" and deduct form that the atmospheric pressure given that the sensor measures absolute pressure.

In relation to Almutawa's post, the MAHA measures transmission and RR losses while actually coasting down (deceleration) rather than having a set value % for each car that usually comes programmed on most other dynos, the losses in HP are the green line that is shown on the dyno sheet.

 

here is another dyno, look at the date

it's 48mm vtg's in combination with my cams.
same situation, stopped at 300km/h as this is dyno limit.

 

and why you are running stock gt2 ?

 

My GT2 Boosting 1.6 bar and only shows 1.4 in the gauge really strange

 

your is stock, mine not.