Dave, a standard Inertial dyno does NOT have a variable load brake. It is near impossible to properly tune a partial throttle vehicle on the likes of a DynoJet Dyno, without one of their custom accessories. DynoJet has recently released a LoadPack, but I have not yet heard any feedback, and do not know any DynoJet owners that are interested in getting one. If I remember correctly, the DynoJet load pack uses air-pressure for its braking, vs. the standard water or electronic type eddy-current standard loading type dynos. I am not sure if you may have or be familiar with this option, (would love to hear feedback if you have used it) but is only available for one of their Dyno models. If you are not familiar, an Inertial DynoJet without accessory does _not_ have a variable load brake, and cannot 'hold' an RPM point for tuning specific cells. Another tuning tool that I have never seen an Inertial dyno possess is a 5 exhaust gas analyzer. I know that both Mustang and Dynapack both have the ability to use a 5 exhaust gas analyzer, which is useful for tuning ignition timing. (Cannot use a 4 wire standard wideband o2 for this).
In my opinion, it doesn't make much sense to convert an Inertial Dyno in this way. The very experienced tuners I know who want a tried and true method of fully loadable tuning are using DynaPack or Mustang dynamometers.
As far as business goes, everyone and their brother know about the 'Dynojet 248c' and customers are generally interested in seeing the most horsepower. This dyno is right up their alley is it will graph 'more' HP than a comparable eddy-current type loading dyno, for example. What might be best for getting a perfect tune, may not be in the best interest for a business who is targetting high use of non-tune dynos. (people wanting to see how much peak HP an intake or exhaust gives at 7K rpm..
) For most of the shops with DynoJet dynos, the best use will be to view HP and tune A/F at WOT. It can't really be used for tuning much else. Hope this helps.
By the way, what dyno did you choose, and assuming it was a DynoJet, did you also go with the Loadpack conversion option?
EDIT: To reference KGP's last post, braking type dyno's in fact do allow pure steady state tuning. For example, dyno brake is applied that will 'keep' the car at 1250 RPM.
On an intertial Dyno, this is impossible. Can you imagine trying to target a fuel cell located at 200mBar @ 1250 RPM? The car passes that cell so quickly even with barely any throttle a standard Dynojet will never be able to reliably give the operator a valid result when taking less than a second to spin up to 1500 RPM. Do it 10 times and you'll likely glimpse 10 different readings. Trying to apply a correction would just be guessing. That is the key of loading type dynos, the dyno itself can hold 1250 RPM until you have nailed down specifically whatever A/F you want to run.
DDozier said:
I do not understand this statement, if you want to tune for partial throttle conditions, then strap the car on the dyno and do not push the throttle wide open, with the use of the variable load brake on the dyno you should be able to tune for almost any load, RPM, and throttle possition. Then fine tune your map on the street. If I am missing something please explain, but I sure hope we made the right choice when picking dyno for the shop.
Dave