Lately there have been threads/posts about dynos, dyno outputs, and dynos used by aftermarket companies to prove their product performances. I wanted to place this as a post on the Eventuri thread, but it's getting pretty long in the tooth and kinda all over the place now, so I thought I'd start a thread and maybe stimulate some discussions for those who have either used dynos or received results of their car's performance. I want to say a whole lot more here, but the post will get too long and lose too much meaning.

Commercial dynos will produce different numbers for the same car. One dyno might read 440whp and another 460whp. There are very few dynos that are accurate at correcting to crank however accuracy is defined. And then, worse, you’ll see shops using consumer level fans to cool the car. I’ve seen back to back dyno pulls moving a fan over 1 foot and producing a 30 whp difference. Also, it's important to know that every car (of the same model) will produce different HP/TQ numbers SELDOM hitting the manufacturer's published numbers corrected at the crank. One car, for which I tuned routinely, advertised 430HP and car after stock factory car produced in the 370hp to 400hp range and I never saw one that hit 430hp corrected for the crank. So there's that as a starting point.

Tuner shops are using various consumer dynos from Dynapak hub dynos that produce consistently high wheel numbers, to Dyno Dynamics that produce consistently low wheel numbers to small drum Dynojets to big drum Dynojets to Mustang dynos that read all over the place from machine to machine. The MAHA dyno is the one used by OEM and some governments to give crank power, but you don’t see these in the aftermarket at all.

When I was actively tuning, I started using dynos, then gave it up, preferring tuning with data logs and doing actual street pulls. I could get the tune dialed in much better and in a more realistic environment than just sitting still and spinning on rollers which is not how the car will be used. Dynos also don’t do that well setting up a tune for a specific use. I would set up a tune differently for a track car vs. a straight line car. The stage1 stage 2 tunes sold commercially are like the modern day cure-alls of the old elixir salesmen. They don't do anything particularly well (like a custom tune does) except bump HP/TQ which impresses the average customer.

I always chuckle inside when someone posts dyno sheets. I outright LOL when vendors use dyno sheets to “prove” their product produces more HP/TQ. Dyno sheets are often “my dic$ is bigger than your dic$”, but the numbers are so all over the place as not to be useful in anything but benchmark comparisons; however, very few think of or pay for the benchmark pull, and as I've stated above, if using the factory HP/TQ numbers instead of a benchmark pull the "gain" with a performance pull is simply inaccurate. There are a couple of members here who know the only real value to a dyno pull and result is if there was first a comparison "benchmark" pull and done in close proximity to time/day/engine temps/air density/etc. and on that same car, NOT the factory published #s. Those members (and I) will always suggest a benchmark pull first before the mod is added and run.

So when an aftermarket performance vendor who makes intakes, exhausts, other trivial components claim their "dyno results" show 5hp to 30hp gains over stock HP, with a car in the 500HP range, 5hp to 30 hp can be had simply by moving the cooling fans on the dyno or changing the ambient conditions of the second pull. Aftermarket companies know not to get crazy with claims and the "marketing pill" of 5hp to 30hp is an easy one to swallow and likely not challenged. They also know they don't have to convince everyone. They'll make enough money on the naive, and in a strange way, I applaud that, as long as it is not my money. One advertiser (who will go nameless) who posts his wares here occasionally, advertises his "CAI Intake product" increases HP over stock WHEN USED IN CONJUNCTION WITH A TUNE...yeah...no kidding...