Matt
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Road tune Vs Dyno - 2007/10/29 14:02
Now that I've taken the time to learn how to tune my cars reliably, I think I'll weigh in again on a discussion brough up in this thread.
http://www.paladinrally.com/component/option,com_mamboboard/Itemid,95/func,view/id,724/catid,14/
The discussion talked about wether it was better to tune using a dyno, or road tune. Ive had enough expiereince now to offer a very edjucated opinion, even if my spelling sudgests otherwise.
I've found the best possible outcome happens in a combination of the two. This is a slight cop-out; choosing a+b when asked to choose between them, but I'll explaign.
It is best to start tuninmg with a nice long road tune. It usually takes me 2 days to get the car running beautifully on the road. Road tuning is great because first, it is cheap, and second it allows you to tune for every possible load condition of the car. There are some load circumstances that can be tuned on the road that can not be tuned on the dyno, these are mainly low load, and vacum (I've never tuned a NA car, so I can only speak on turbo cars.)Surprisingly these loads are just as vital to the longgevity of an engine as high load, high boost. And, they are much more important for drivability and response than peak power.
There are also weird curcumstances that a dyno can't simulate safley. For instance, quick on off of the throttle, and the RPM jumps that occure in shifting. A dyno opporator might say they can simulate the street, but over 2 days of driving on the road, your motor will do things you never dreamed it might. Once all these circumstances have been figured out and added to the map, and the car runs beautifully all the time, it's time to go to the dyno.
The dyno gives a nice number that corresponds to power output of the engine. A tuner can try different thing to get more maximum power out of a motor, and get accurate real feedback, not just butt dyno feedback. A lot of the time a powerfull motor is so smooth on power that it feels slower than a weak engine that gets power late, but jerks the driver. So a good couple of hours (3-5) at the dyno can set up your car for the maximum reliable power, which can't be done as accuratly with a road tune.
So there you go, a lot of A and a little B makes for the best tune. If I had to choose between the two, I'd take the road tune. It will give you drivability over the largest range. However, racers are most interested in that peak power range, so the Dyno is necessary as well to put toghter that winning tune.
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