dynocar

I have a dream, wouldn't it be nice if we could accurately compare chassis dyno numbers. This is very reminiscent of the auto manufacturer's HP ratings of the 60's muscle car era, we could not compare their advertised numbers either. Then came 1971 and 1972 when finally all U.S. manufacturers agreed on an SAE "standard" for testing proceedures and corrections. This probably cannot be accomplished until all chassis dynos become measurable load bearing and then establish a standard engine rate of excelleration. Here again, the manufacturers of chassis dynos would need to agree on this. Some may say that this standard should just be a given enertia rating but this is not enough because different gearing, tire diameter etc has such an varying effect on their numbers. The only vehicles this leaves out is the high stall autos, I can't think of a chassis dyno solution for these. Now that Dynojet is or is getting ready to go the load bearing route, this dream could eventually become a reality. My questions are, how do we get this to happen? What kind of pressure was put on the auto manufacturers back then? Was it public, SAE or ,God forbid, the government? Am I the only one interested in this? If not, where do WE go from here? Could it start here?

EJ

DynoDR

iTrader: (1)

Sounds good to me. I think we have touched on this before about using a standard accel rate, etc. I also think there will always be people that "race" dyno numbers and feel like Hp/Tq is a concrete measurement of what the vehicle makes and nothing else will change this number. Hell, everyone knows "std or sae", but most could care less about the other varibles.

You are not the only one interested in this dynocar! It's good to dream, but I don't believe we will ever see it.

dynocar

Well, at least there are two of us interested in dyno number credibility. I agree, the public just wants to "race" dyno numbers even if they vary dramatically from place to place, combo to combo with equal engines. Sad, but if someone designed another type of dyno that read higher and varied more dramatically with different combos, they would probably get the most business from the public. Again, like back in the '60s' muscle car HP rating era, twenty years from now people will look back and laugh at the numbers the "racers" were baseing purchaseing decisions and "race" winners. Back to trying to explain why numbers vary so much every day. EJ

P Mack

iTrader: (6)

Neat idea, but the hard part about it is calibration. An inertia dyno's advantage is in its simplicity because the drum's moment of inertia is known and the rate it's accelerated can be measured very accurately. With a load dyno, you're throwing in the error of the load cell into the mix. You'd have to make sure it was calibrated regularly with precision weights with no hysteresis. I have a feeling you'd get results that vary just as much with the load dynos and a set acceleration rate.

Another thing, instead of a set acceleration rate, you'd want 0 acceleration or very close to ensure the inertia of the drivetrain isn't a factor.

Christos

Interesting, and yes, this would be a great idea.

I heard from some people that the 69 z/28's 302 was underrated, and put out closer to 400 hp according to them. I highly doubt it myself though. What did GM rate the engine at?

Blue Hawk

290hp

dynocar

Today's load bearing dynos seem to stay in calibration very well due to the high tech strain guages utilized, etc compared to the older rheostat type measuring devices. With that I believe that due to the enertia dyno's greater disadvantage of varying acceleration rates, we would acheive much closer comparisons.

Yes, a 0 acceleration rate would be best, such as the step method used on engine dynos which is possible, but a standard acceleration rate, such as 300 rpm/sec, would negate much of this enertia factor. I'm not suggesting a perfect world here, just something much closer then what we have now. Currently I am at the PRI show in Indianapolis where there are several chassis dyno companies represented. I want to get their reactions to this, but the guy in the booth is seldom the person to approach with such hair-brain ideas.

EJ

dynocar

Keep in mind that when GM released the '92' LT1 Corvette engine rated at 300 SAE net brake HP, they claimed that this was the most powerful small block Chevrolet ever produced for the public (they do not consider the LT5 ZR1 engines one of their small blocks). As most dyno operators agree, one of their most dreaded jobs is handing a customer with a car from the muscle car era a HP/TQ sheet.

EJ

ataylors

iTrader: (2)

this would be a great idea. I was very impressed at back to back test on my Mustang Dyno with two differant drivers. I do feel that I can compare with anyone else with a MD also given the same loading factors.