Quote:
Originally Posted by SenorFunkyPants
Have you run the car on a dyno to see if there is any bhp gain with the valves open?
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Actually, yes, what a timely post of yours. I just got back! While at the dyno, I installed a MS air filter. I read that this gives some gains, and I thought it would be interesting to do a comparison with the valves open and closed with the MS installed vs the OEM filter. I did two runs in each configuration, data is as follows:
DynoDynamics Dyno
2 runs
HP/TQ
87.4 deg F (Hot!
)
Closed w/stock air filter:
1. 347.7/262 (the operator made some change after this run, so I'm not sure these values are accurate, but I'm posting it anyway)
2. 350.8/257
(Just want to interject and say that at roughly 351HP, that is almost exactly 414HP as claimed by BMW, minus the 15% tranny loss - nice to know I don't have a lemon!
It also shows that our dyno setup was pretty accurate.)
Open w/stock air filter:
1. 347.3/254
2. 354.0/258
Closed, MS filter:
1. 352.5/256
2. 356.3/254
Open MS filter:
1. 358.4/255
2. 358.5/259 <-- best run
I said this back in an earlier post, but I never went into this project expecting massive gains from a cat-back exhaust. I knew that aftermarket cat-back exhausts provide little by way of gains (maybe 10-15hp), so my main goal was for a great sound. I was not happy with the quietness of the oem exhaust coming from a Corvette Z06, and I wanted a little more excitement and driver-connection back there.
But I was really happy to see that the exhaust and MS filter did give some gains. There was quite a bit of variation, but this is to be expected I guess - Dyno testing has many variables. Overall though, it is clear that the exhaust and filter do show gains. I was worried initially that perhaps I was ruining either the HP or power curve of the car by modifying the exhaust, but as you can see, the Bates just enhances it a little (about 4HP up top). Adding in the filter realizes another 4.5HP for a total gain of about 8.5HP. I think under proper testing (lower temps/humidity, stronger fans), or on a less conservative dyno, the #'s would be closer to 15HP-20HP in gains that many others promote.
Onto the pics..
This was our setup. I was a little bummed about the fan we had access to, a small one from Lowes. I have read that proper airflow into the three vents of the M3 can massively increase observed HP. I think it was Dinan who showed that they could gain as much as 20% (yes percent) just by adding in fans. As you can see we just aimed it towards the front. In retrospect, I should have aimed it at the lower driver's side vent.
BTW, it was also quite a warm and humid day!
Here is the dyno graph with all of the highest HP runs posted for the day. Note that the Bates does not significantly change the curve of the graph and does not show the common dip below 3K with some other aftermarket exhausts.
Stock air filter:
MS air filter:
Overall it was a great day. I took some video, maybe I'll post it later.
Cheers!
