Dynojet and Mustang seem to be the dynos used by most shops, especially LS1 shops. After intense research and training on different types of dynos, I cant understand how and why we use these to tune.
Neither of these dynos can hold a load at a specific rpm, not even the Mustang with the brake. This was, in fact, verified at the Mustang manufacturing facility, so I know this is the case (brake pulses can not hold rpm steady enough), so while tuning is better onthe mustang than the dynojet, it didnt come close to the others in ability.

In tuning properly, we obviously need to find max cylinder pressure and adjust A/F ratio and timing for each "cell".
If the dyno cant hold a constant load at a given rpm, under various amounts of load, can we really tune correctly on a dynojet or mustang.
My feeling is...No we can not maximize the potential and give a best case tune.

The two types of dynos that I found to allow us to tune "to maximum effort" are the Dyno Dynamics and the DynoPaks.

Go ahead, defend...or comment please.

 

Have used Dyno Dynamics and they work great.. You are exactly right about the Mustang and Dynojet, although VERY limited tuning can be accomplished with the Mustang / Brake.. - And no tunning on the Dynojet..

 

input fellas!

 

Dynojet now has proportional load control using the brakes on the 248x model. You can do load based on %, 10, 20, 30, etc. Or set the software to keep the car at a certain rpm or mph.

Load isn't required to tune. Cars don't go down the track at the same RPM and load.

 

good info ... keep it coming...

I've always looked at Dynojets as approximate WOT tuning devices... and mustang dynos as part throttle tuning devices...

Load and RPM are required to tune for drivability ...

 

I don't think you will ever find a "perfect" dyno with the "perfect" amount of load placed on your vehicle. Because of external dynamics, ie if your car goes down a hill at WOT there is less load applied than if it goes up hill at WOT. Either way thats what makes fuel injection fun, its infinitly adjustable.

 

Well...going down the hill theres more vacuume do to less resistance...and thats tuneable...so I disagree. I also agree theres no perfect dyno...the new dynojet software above does not appear to work for beans... but thats just my experience. Mustang is working on theirs, but have been for a while.
For driveability, this type of tuning makes a big difference. If your just track tuning for the 1320, than that may be different story.. but not many of us only hit the strip with our cars.

 

Sorry bro, but you are wrong on this one..

 

I fully agree with Jammer as we worked with a Dyno Pack unit today. I have been around the 248 quite a while and can tell you that we are all leaving a lot of power and drivability on the table. Even the load control unit that Dyno Jet offers will not give the "steady state" load control needed to accurately tune the motor. More guys with big motors complain about poor performance below 3500 rpm because most tuners with a 248 start pulls at 2500-3000 rpms. These new dynos (DynaPack and Dyno Dynamics) can keep the motor pinned on one cell for as long as the motor can take it( ie...overheating etc...) This is extremely beneficial with boosted cars as rushing a turbo through it's rpm range never really allows the boost to be loaded as if it would be in a real world situation.

Another big area of tuning, as Jammer started to state, is the ignition side of tuning. An area most people don't talk much about. An engine makes it's best torque at peak cylinder pressure.You want to run a much timing as you can until power drops off. At 2200 rpms at -20 KPA (which would be around 2 psi) how long can a DynoJet hold that rpm while the tuner alters the ignition advance to maximum torque?? Not very long! A good dyno needs to be able to HOLD the rpm and load rock solid. We saw 40+ ft/lbs at that rpm by making a 5 degree timing adjustment. I'm sure anyone who has had there ar pulled on a 248 never saw that rpm get tuned at load!

 

TTT , this should be discussed further.

 

I believe the reasons stated above are why the same cars, with the same setups, can run wildly different times. Some run so strong because they were tuned properly and get the most out of the setup at every point in the rpm band. And others run weak in comparison, since they are tuned for just a WOT high rpm blast.

 

This is a tuner issue, not a dyno issue, nothing prevents you from making pulls off idle on a dynojet.

From my experience with Fords alot of the part throttle driveability issues are from cars just not being tuned the right way (IE using the wrong tables to accomplish something), not because the dyno couldn't load the car.

While a dyno that will provide enough load to hold the engine in one cell may be good for OEM developement purposes, it still doesn't simulate the real world that we all live in.

Even modern OEM quality level engine control systems can't compensate for heat buildup in the chamber, I'm talking heatsoak in the head that will make a car more likely to detonate, not coolant temps or air temps which can be accounted for in modern control systems. But that doesn't stop OEMs or the aftermarket from putting out very well tuned vehicles.

 

While I agree with it being difficult to compensate for heat, I disagree that you can tune well on a dyno-jet in comparison to some of the other options out there. Can a good job be done..thats a matter of opinion, overall, perhaps there isnt alot of gain in all cases, but I think theres alot of potential power under the curve left on the table.. I just dont think the guesswork made in the timing cells can be that accurate. Its become quite obvious that A/F doesnt mean much... At least we were able to say, for example, hold the engine at 4k rpm and any particular load..and adjust the fuel/air mixture fromlean to rich, to the point of stalling on each side, and the tq numbers barely, and I mean barely, moved. So A/F made little difference when compared to the power found with proper timing (of course you still need to adjust the A/F properly).

Again, heats always an issue, are all atmospheric conditions which may change after the "tune"., but an off idle tune just seems , well, adequate, but not professional quality.

I bring this up here for the purpose of input and discussion, so keep it coming and lets make this a back and fourth conversation. Im actually surprised some tuners/sponsers arent attacking my theory. I guess thats an invitation... but meant to be friendly and educational for us all.

 

Maybe I am missing some thing. I have a mustang dyno and we tune all
the time with manual loading and set cell by cell. We spend most of the tuning
in vacume for driveability. I even load under boost with turbo applications
tuning afr etc in conjunction with a good boost controller to get certain cell areas. What do you mean that it cant control steady state being pulsed good enough? We do mostly imports turbod up to 1200rwhp not v8s, maybe torque
on v8s makes a big difference in pau control on the mustang, that I dont know. By the way all our tuning is real time with Fast, Motec etc, I havent tuned with my Hp tuners yet. Thx Ralph

 

I cant explain the difference either, what I cAN tell you is that it was a MOTEC employee and trainer that pointed this out, and it was his crew that traveled to the Mustang facility to prove what they were saying was true (by invitation). Once it was demonstrated to Mustang, the engineers worked on it overnight, but no substantial progress was made by the next days visit. That was this past year, so perhaps some changes were made, but thats not what weve been shown. It will be evident next week as we will use a brand new Mustang (as in,,,installed this week) to see if it holds. I dont want to spread inaccuracies, or half-truths so if its working for you, then Im not sure what to say, other than..Good!
Let me ask this more specificly..
Can your dyno hold, say 4000 rpm perfectly, no matter what your manipulating?
Either way, I think what we know.. is a dyno-jet is not the best way to tune, though it sure can be good for the ego.

 

I for one get sick of the DynoJet talk. I have too many customers that come by with these cams that are so radicly big, bigger than they need and the first thing they tell me is they picked it because it made 410rwhp without heads. But then I put the same cams on the mustang dyno that I tune with and you realy see what they are worth. Granted that some may still think the mustang dyno may not be good compared to the dynapack and the dyno dynamics, but its still a hell of alot better than a 248x anyday. I always see a huge difference in tuning with the mustang dyno. I can load the 4th gear run so much longer than the 248x. You fly through a run with a dyno jet as to a nice long run with the mustang dyno. This way you can see the changes you made and if they even helped or not.

The point being here is that numbers are being talked about way to much on the internet and the wrong cams are being sold all day long. Being on a Good dyno proves this. I always wanted to try the dynopack myself due to the left over room I have in the shop for a dyno. So for now I use my buddies Mustang dyno. I do like how I can do a full road simulation on it. But I will be putting it to the test when I tune in SD on a few turbo cars comming up. So if it lets me hold load, then we know its still good for something.

But those who argue that load is bad for the car...why not load the car? I would rather load the car and make it work for power and know when I get off the dyno that it will do the same or even better on the street. I been the whole dynojet route with people telling me you can tune fine on it. I had a turbo car that ran fine on the 248x and when I drove it back to the shop, It knocked all over the place. Like other have already said...its an ego tool. And with the more power you make, the higher the numbers start to read and nothing becomes real anymore.

Rick

 

In reference to the talk of MDs holding a certain rpm, if you look at MD's website www.mustangdyne.com you'll see the dynos are rated for a peak absorbtion # and then a higher peak measurement #. You'll also see they have large weighted discs to increase inertia. On a higher HP car, depending on the particular dyno, you are going to be working in a quasi eddy current and inertia mode.

I have seen several MDs that show higher HP #s than dynojets, sometimes significantly. The exact reason for this I am not sure, possibly calibration error or it was purposely done.

My car made 399rwhp on a dynojet and then made 424rwhp on a mustang dyno...the MD run actually had a few degrees less timing in the tune. The whole drivetrain was warm and had 40k+ mi on it, so there was no break-in occuring.

For purposes of comparing #s the Dynojets are the industry standard, OEMs use them along with a large % of the aftermarket. You can't screw with a Dynojet to make it read significantly higher or lower. You can play with STD and SAE corrections but thats right there on the dyno sheet so you know what you are getting.

Mustang Dynos can be calibrated to make them do what you want, and even when properly calibrated there are so many different models of MD that they still may read slightly differently. Dynojet is currently producing only 2 models of dyno's, the 224x and 248x.

 

well to me , its like this. if you were a poor man and didnt tune on anything but the street and blind with out your a/f then, wouldnt the next best thing be a dyno that best simulates the real world and its conditions right? while the dynapack are sweet, the mustang dyno is the by far closer to the "real world" that we all drive everyday and before we used dynos to tune with and we all have done it. mustang blows away the 248 by far and even the new 224lxc that can not tell you how much load you appling to your test vehical. which can lead to not enough and then again too much load. if i can find the artical ill put it up here, but a gm magazine best broke it down and on the road test , say 2nd and 3rd gear pulls timmed on the mustang v/s the road were with in .5% of each other, and the dj numbers on the time it took to accelorate were way off from the real world which is where we will drive , part throttle and wot and cruise on. so long story short from my pov is the MD dose the best to tune the car for where the car is going to be used and thats the street or track, being that the MD can also perform dead stop runs. another thing is say you have a 2000hp outlaw car and need to tune it, you going to put it on the dyno to fine tune or are you going to use the FAST or your on car tuning softwear with wide band to fine tune it at the track? your more than likely going to baseline it on the dyno to check it all, but then fine tune it at the track. only because 2000hp will be hard to dyno effectively but a street car around say the 1200hp range or lower can be done due to its simularities to the street power the MD can replicate. and where i am from street cars are the norm here.

sorry if i dont make any sense its been a long day.

 

most aftermarkets use a MD or a superflow from the many i have seen, most aftermarket shops use the DJ because that was the only thing out then, at some times. besides being close to half the price of a superflow, also if i was looking to get a cheap dyno then i would by a DJ hell its only 25K to 30 for a 248 unlike the new 224xlc that most shops will not house. its like mid 40's to 50

 

98tata

You brought up another good point or dyno for that matter. Nobody seems to be talking about the Superflow chassis dynos. Mind you these are eddycurrent dynos, basically use generators to load up the chassis.

The are a lot more expensive than the Mustang dynos but seem to have a lot more bells and whistles and versatility.

With all these posts on SD tuning I would hope people would better understand why eddycurrent dynos > inertia dynos. There is a lot more to tuning a car than just WOT

In all honesty, I could give two ***** about dyno numbers. I just want to be able to load up the engine any way I like