FWIW - Always seemed to me the Scotty II has a disadvantage on the dyno due to no "Ram Air" benefit. I had asked Scotty if it makes any difference dynoing with cover OFF the Scotty II....He had not tried it, but said he too was curious.
Made possibly(?) sense to me, that without the "Ram Air" effect (due to sitting still on the dyno) that the Scotty II might suck more air with the plastic cover off. And with the hood up...no big deal on sucking under hood warm air!
After doing my main test...new VP-44, comparing with & with out H2O/Meth....we did a test (#2 diesel only) with and without Scotty II cover.

Results - Gained 3% (16 hp) with plastic cover OFF. Went from 526 hp to 542 hp. Does dynoing with the cover off equal the ram air effect on the road? I have no idea. Anyone know how to calculate this???
If your interested....give it a try guys...lets get more data!

Now if we could just figure a way to test the Ram Air effect on a dyno.....we'd know how big a stable we really have under the hood.

RJ

 

I wonder if every truck running a scotty 2 would see that kind of difference or if it's just the big boys. I highly doubt that my measely 371 ponies are gonna sucking in that much air.

 

A friend of mine tried this on his 450hp truck. He didn't gain anything with the cover off.

 

Restriction does play into the HP numbers. I gained 6hp by removing a 6x14x5" filter element on the dyno. I don't know how stupid that was, but the 6hp was worth it to me.

I think I remember Scotty saying that the ram air effect only takes place >50MPH. Wouldn't that be kinda hard to reproduce on a dyno?

brandon.

 

That's one reason dynos used in R&D are done in a wind tunnel.

 

You have to have a breeze for the cowl induction effect to take place.
Good feedback on the testing. Makes sense to me.
One test I did do was idling with my 01...housing on...egt cooler by 50F
Housing off...add 50F. What I did was idle the truck for 20 minutes with the housing on parked in the yard with an ambient temperature of 84F. This was after a short run of about 10 minutes in traffic. I left the truck running, removed the entire Scotty, slipped off the housing and put the turbo inlet hose and filter back on. I then closed the hood. Next I waited for another ten minutes in the cab before I began my 2nd test. I noticed that the egt changed on the gauge before the ten minutes and after another 20, it stayed where it first rose to.

What can I say...I was bored.

Scotty