The problems of dyno testing

I did try dyno’ing GBMINI#2 last year, and repeated the experiment after the JCW intake was added; the second link has an interesting table comparing GBMINI#2 (rated 210hp by the JCW upgrades) and Greg’s car, with many aftermarket mods. In summary, the comparison is worth something, but open to interpretation.

On this same subject, NAM has had much discussion about a specific air intake from M7, culiminating in some dyno run comparisons.
Commendably, a number of NAM members fronted the dyno costs, to provide good independant data; I was in turn interested enough to send in a few $$$ and get the results.

The results make fascinating reading, if only for the difficulty of comparing one mod with another – even with the efforts made to keep everything at a similar baseline …

Some background on how we did this and the factors we used to try to match each run to get the same date base line for each intake. We met at Advanced Chassis Dyno and removed the bumper and it was off for all runs. We used a bag of ice to keep the intercooler from getting too heat soaked between runs so that the intake air temp was the same as possible. The outdoor weather was a bit hot and muggy, but stay very close to the same the whole time on the dyno. We also rest the ECU before each set of runs for the new product.

First runs: A Stock MCS
Seconds runs: a Pilo Intake
Third runs: Alta Intake w/ tube
Fourth runs: M7 AGS.

(The final AGS run was with blower fans right over Intercooler and air filter to see if they had any effect)
Over all we could see about 10 Hp from the Pilo over stock, then about another 2 Hp for the Alta. We then saw about a 4 Hp loss with the AGS when just on the dyno, but found that it liked a bit of forced air to almost keep up with the Alta. Once on the street you will get the added forced air, but at a bit more IAT. I have always liked the idea behind the AGS and thought it should make power, so I would like to see what it dynos on a car with your basic mods the most do (15%, cat-back, ECU?). But also this was a hard intake to install. It took a few hands to get things sealed and fitted, but we were also trying to install it in the air on a dyno with only a small area to work with and try not to trip over the hold down straps. With all of this said the AGS sou nded better than the Alta on the dyno. It was a lot deeper sound. But it think for the price and the ease of install the Alta C.A.I. will still be the intake to get. But if a customer wanted to get an AGS I would not try to talk him out of it as I still think there is a place for it.

Thanks,
Chad Detroit Tuned
Sid & Joel

As I said, the above indicates some of the issues with dyno measurements – the testers tried to minimize temperature effects but there is a reasonable I.A.T. (intercooler) temperature difference for different tests – the intercooler obviously cooled down while the AGS was being installed.
The “10 hp for Pilo” claim is interesting, since one of the three readings was massively worse! When you read claimed dyno results, are you reading the best performance or the average?

For me, irrespective of the tests attempt to show the AGS as best performer, it is clear from this data that the Alta gave the best results – but of course we have no value-for-money factor in the figures presented above.
The final AGS run, attempting to cool the intercooler, could have been repeated on any test and would presumably have shown gains above those for the stock, Pilo or Alta intakes.

So next time you read dyno claims, consider how useful they really are – if gains of 20+ are claimed, that is significant, but a gain of 5-10 hp is easily swallowed in real world variations …