Club Cobra - Anyone ever strap their cars down to both a dynojet....

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A friend has a Ford Ranger with military duce & half axels under it and a 460 engine. Mud runner is its only use.

First engine was done by builder "A" and dynoed at ~700 Hp. When it came time to freshen the engine up, builder "B" talked him into letting him do it. Builder "B" said he could improve the porting and the cam was too much for the RPM range he was running. He let him do it. It dynoed almost 100 Hp less than the first build. He was kicking himself and sick over it. I told him to put it in a run it before he got upset because he could not trust Hp numbers from two different builders to mean the same thing. He put it in his truck and said it had way more power.

I believe that numbers do not lie, but lairs use numbers. No two dynoes are going to be exactly the same, but more than a 100 Hp. Something is fishy. Both of these builders are well known and know what they are doing.

I'm sure there are a thousand other similar tails. Difficult for anyone to be an honest advertiser in this market. I wouldn't try to think too hard about it. It will only make your head hurt.

If you want to list engine dyno and chassis dyno numbers then just state the type of dyno used and the conditions it was tested under. Even the dyno operator, if they do not object. Then the "not responsible for the accuracy of these numbers" disclaimer.

Well I just got watching my son Corey dyno a late model Camaro on a dynojet chassis dyno-I will post some pics later after I get them from Camera to Computer------

He said that after many chassis dyno runs compared to engine dyno that the late Camaros are right at 17% loss on the drivetrain--a very interesting thing was that he told me with this particular dyno they could do a run down drag curve from high speed and that they could even do the drag co of different oils that same way!!!!!!!!!

More later

Quote:

Originally Posted by Ace23 (Post 1314066)

Not to argue but I'm sure if a car manufacturer had or does have any in house dyno then all their production of a certain model would generate like conditions wouldn't they? For example if you take multiple factory coyote motors or factory LS3 motors and stick them on the same dyno they are going to make very similar if not almost identical power levels......these levels may fluctuate from dyno to dyno but that is not a component of the motors but more so the actual dynos. I'm a fan of chassis dyno as I feel like your are tuning the motor "IN" the car with load as opposed to just the motor on a stand.......not a deal breaker but a chassis dyno would make me feel better......then again I'm no tuner or builder

That sounds like a reasonable position/explanation until, the regulatory authorities show up with their analytical measuring equipment. As the manufacturer you not only don't want inconsistent dyno numbers, ambiguities etc., you can't afford them. If Detroit can measure repeatably year after year, model after model, engine family after engine family, and engine after engine, the pregnant question quickly becomes that wonderful word — how ?!??...

Ed

Well I can't upload my pics directly to the site and my photobucket account is over full so I can't use it so will have to reformat/downsize the pics to load---this will take some time

I asked how the dyno was calibrated and Corey explained that it had a weighted arm that was a specific length and weight that was the standard--------

Tonight I'm going to be with him at another shop on a Mustang Dyno (big roller) doing something that is direct injected? I think that there is 6 or 7 dynos in the Chicago area that he has done work when someone is past there line??????