Dyno Thoughts

[DamonSlowpokeBaumann]

Being that a Mustang dyno imitates real world load better then a Dyno jet Dyno.....Why is it that I see most of the members here using a Dyno Jet to tune their cars?(Besides Dynojets numbers being higher)

I know quite a few tuners that refuse to tune any kind of unaturally aspirated cars on a Dynojet due to the increase load in real life causes bad things to happen...

So what are your thoughts on this subject?

[David Neibert]

Damon,

I think dynos are good for tuning, testing mods and bench racing. There are too many varibles and ways to tweak the numbers for them to really mean much. IMO the SAE correction factor is also skewed towards naturally aspriated cars. So if you dyno an SC at high altitude it's going to give you a little more credit than it should.

The only way to get an accurate comparison is to test all the cars on the same dyno on the same day, and that's just not pratical unless your at a meet.

David

[fastsc92]

also, from my understanding.....a dynopack dyno will read higher than any chassis dyno. This is because the machine is bolted dirrectly to the hubs of the rear wheels, and there are no tires and rims, thus reducing the amount of rotating mass.

[XR7 Dave]

I would say because most of us have no idea what we are doing anyway. :rolleyes: Plus very often you don't get the chance to choose one or the other anyway.

I know that most shops like the dynojet because they make more money. Faster on, faster off. My car always runs good on the dyno and then rattles on the street. I think if a tuner knows what he is doing he can compensate for that.

I think also that a lot of people make the mistake of tuning for a HP # rather than for the real world. Sometimes it's just the tuner giving the people what they want. People who race and put their motors through the paces know better than to tune for a max HP number.

Just ask that guy who was trying to road race his CMRESII motor with a 12.5:1 AF ratio. :cool:

[DamonSlowpokeBaumann]

Thsi si why I mentuioned it..With a Mustang Dyno teh tune is generally almost dead on...When tuning on a Dynojet you almost alway shave problems..I learned this first with my motorcycles and later on with cars

The Mustang Dyno imposes a more realistic load..Its not even about Dynio numbers,.,,Its about a tune that will work in the real world..

I hear of many people complaining about their custom burnt chips and figured if they were done on a dyno jet that could be a potential problem..

If interested I can state the differences between dynos

[fastsc92]

Ya most people go to the dyno just to get impressive numbers. However the reason for any dyno was to have a tuning aid, and have it be consistant rather than heading to the track all the time. The hp number are usefull for figuring out shift points and such, and to see any problems with mods not living up to their potential.

But yes you are right, i;ve heard that the mustang dyno and dynojet put a more realistic road like load to the car. If you tune on a dyno such as that...you'll prob. have the most streetable car.

On a side note....whats the proper air/fuel ratio we should be shooting with on the sc.......with and without nitrous.

[John Shelton]

Damon, this is interesting. What are the differences?

When I go to the dyno, I'm looking for data for tuning - to optimize and protect my engine...and have gotten mixed results. I've used Dynojet, not realizing Mustang gives more realistic numbers.

[DamonSlowpokeBaumann]

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[FastSC]

cars blow up after dyno tuning usually because the tuner is inexperienced, or because of hardware limitations (I.E. maxed injetors/pump/MAF, or configuration problems). A good tuner can use either a mustang dyno or a dynojet to tune a car. With proper data logging you don't usually have to see real world load to tune a car on the dyno. Sure it's better to have real load, but as long as you tune it the right way the EEC can correctly make load calculations based on engine airflow.

That being said, I use a Mustang Dyno. But for the last two years I used a Dynojet 248, and I am happy with the results I had tuning on that


Brian

[DamonSlowpokeBaumann]

WHat you get with your datalogging equipment when tuning on a dynojet is misinformed data being the loads imposed upon the car are not real...

For instance..WHat may be showing up as a slightly rich condition on a dynojet can easily be lean when imposed upon real world load

Being the Mustang type dyno imposes a truer real world load you can therefore tune more acurately..Some of the top tuners that I know dont even use a dyno to tune because of these reasons,,And they blow cars up too:O)

[FastSC]

well not exactly :)

WHat you get with your datalogging equipment when tuning on a dynojet is misinformed data being the loads imposed upon the car are not real...

What data logging shows is actual engine load, and it's not wrong.

For instance..WHat may be showing up as a slightly rich condition on a dynojet can easily be lean when imposed upon real world load

Being the Mustang type dyno imposes a truer real world load you can therefore tune more acurately..Some of the top tuners that I know dont even use a dyno to tune because of these reasons,,And they blow cars up too:O)

There two ways to tune. One is where you change either the WOT fuel multiplier or the base fuel table to achieve the desired air/fuel ratio. It's rather easy, and when you spin the car on the dyno you have corrected fuel for just that load and RPM range, so it seems all good.

Now that I explained the wrong way to tune, I'll explain the right way. What you do is run the car on the dyno (any dyno) or street, and record the air/fuel ratio, RPM, and MAF voltage. Then what you do is correct the air meter transfer function so where the MAF voltage crosses the RPM point you achieve the desired air fuel ratio. This usually means correcting certain points on the MAF transfer function.

What you do by tuning it the right way is essentially calibrate the air meter transfer function to the real world. Once you have done that, you have given control back to the EEC to determine the right fuel requirments based on engine airflow and load. Once done correctly, load can go to whatever you want, and as long as your MAF transfer function matches up to what is really happening with the meter it will be all good.

There are a few exceptions. One is a car that is pegging the MAF sensor. It's stupid do even run a MAF that is our of range, but some people do it. Under that circumstance you have to test real world load to get air/fuel readings. The reason is because load WILL be higher off a dynojet, and since the air meter pegs you are doing nothing more than a WOT fuel multiplier. No matter what you do in this circumstance the air/fuel will always change with weather conditions and load conditions in the area where the meter is out of range. Because if this, I don't recommend it.

The next exception is fuel system. If you are on the edge of your fuel system on a dynojet, you are probably past the edge in the real world. This is pretty easy to deal with on any dyno though, you just monitor the fuel system. If it gets near the edge you upgrade your fuel system before you finish tuning.


That's the very raw basics of air/fuel tuning. If you do it the right way and have everything in control, air/fuel does not change with load, period.


Working with timing is different, and it is load dependant. But if you are tuning a good car (i.e. 600RWHP) you are going to reach a load of 1.9 whether you are on the dyno or not. If there's intrest, I can go over the basics of how to develop spark tables on the dyno.

Brian

[DamonSlowpokeBaumann]

Detonation besides A/F seems to be a problem when tuning on a dyno when trying to optimize a combination due to the load imposed. At least from what I seen and experienced..Mind you I have never played with an SC or any distributerless ignition type car on a dyno. All My experience has been with DFI(my turbo v8 car is running the old batcg fire DFI) or the good old standard 5.0 EEC system in which we are just playing with Timing and fuel pressure without the means on any type of EEC tuner..

In both cases when tuned on a Dynojet the tunes were off..I'd get to the track fiddle around and always produce better times that way..When tuning with a mustang dyno the fiddling decreased at the track and gains were minimal.

So in both my cases playing with MAF tranfer function curves was not an option however the load imposed by the dynoes made a difference when tuning....And in both cases tuning at the track was optimum..

Of course I dont do any of this stuff anymore and generally pay someone due to having no time:(...

However being My SC will be in need of fiddling Im all ears on that one

[Grims95SC]

I've gone through a bunch of different threads looking at what all of you have to say about tuning. It seems to be pretty much a must to get the max out of your setup regardless if its mild or wild. You'd obviously get more out of it if it was a wild setup.
My question is what is the difference? Throttle responce, high end/low end, smoothness. Also around what kind of power increase do you get? Or is it that the powerbands are rising quicker with not as much of an increase in max output?
Thanks in advance guys! :)

[DamonSlowpokeBaumann]

The Sc being supercharged seems to gain overall power with a tune. Now if you have a 94-95 sc you can also firm up youre shifts and change shiftpoints.

I noticed a huge difference with my 94 overall

[tim]

I know by speing time I will need a new dyno tune since I have made and plan to make some more mods to my caar. I trust my tuner but really dont know much about the differances in the types of dynos. I have a two stage chip. I want to get the car tuned for street griving and for racing. I think right now its a little rich.