anyone here add the right side air deflector that the srt10 has to move more air into the fenderwell and ultimately into the airbox area? I looked at my co-workers srt10 and look at his ducts, he's got some diverter pieces that force air into the fenderwell where it feeds the stock airbox area. this piece may be a cheep way to improve airflow to the CAI on 3rd gen trucks. I'm going to look into getting one for my CTD to feed the massive 7x9 AFE stage 2 filter (proguard)

has anyone added it yet?

 

I have seen block offs on either side of the SRT10 Radiator
but I always thought those were there to improve aerodynamics
by reducing un-necessary air coming through the grille...kinda like
how NASCAR teams duct tape up the grille during qualifying runs.

 

they actually divert air to the left & right of the radiator into the fenderwell. pretty interesting setup actually. what also would be a good setu would be to have a functional hood scoop directing air into the CAI area, pressurising it of sorts to keep the turbo heat out.

Hank, in your mpg threads that you have, is there any data on how much drag can be reduced by using underbody panels?

 

I haven't yet experimented with underbody panels
but I have thought about making some from those
foam boards at Home Depot with aluminum foil on one side
that would be held in place with
"marine grade" velcro fasteners that are 3 to 4 times as strong as normal velcro.

A few years ago this post was on one of the Cummins Ram boards:
---
Im a 3rd gen'r but figured i would throw a little something in the mix here.
When i was in college a few years back we took a scale model of a
1999 Dodge ram and did some wind tunnel testing on it
our results were as follows. (wind speeds at 70 knts)

Aerodynamic drag changes were:
.43 base

.51 with windows down and tailgate open
.49 windows down tailgate up
.43 windows up tailgate up
.37 windows up tailgate up tonneau on.
.32 windows up tailgate up tonneau on, and underbody sheeting in place.
The "underbody sheeting" was basicly like advertised on the new lexus. Only we didnt dimple it like a golf ball strictly out of lack of desire. But we found it interesting that if you were to do a large "skid plate system" under the vehicle how much drag you cut down. to go from .51 worst to .32 is a 37% increase in aerodynamic efficiency which should account for a 18.5% increase in fuel economy.

Another thing is that based on drag to run the AC compressor you would get better mileage with the windows up tailgate up and AC on than with the windows down in the same configuration.

I am currently working on a lightweight aluminum underbody sheeting unit for my truck to see if i notice any increase on a couple of 1200 mile trips i have coming up. Should be interesting.

Barrett_Fodder
Senior Member

Registered: Jan 2004
Location: Rapid City, SD
Posts: 115

 

the 37% is more like 25% from the base, not the worst case, realistily 99% of the time the windows are up on the freeway. I hadnt thought of the foam board thing... I was looking to do something temporary with wood if I could secure it well enough. that way I could test it on the longer trips... well, even the weekly route is pretty consistant int he mileage area.

according to a CTD whitepaper I have, it says "Every 2% reduction in aerodynamic drag results in approx. 1% improvement in fuel economy" so if that's the case here and there is a max of 25% reduction in drag then it should equal approx 12% improvement on the diesels... I currently average about 15~15.5 mpg to & from work... 15*1.12 = 16.8, 15.5*1.12 = 17.36... that's quite a change... I might have to prove it...

 

I have also thought about buying stainless steel mesh screen cloth
(like Chicken Wire but smaller holes)
and trying to make an underbelly pan from that.

I want a design that does not:
1. rattle
2. catch mud
3. catch on fire near the catalytic converter
4. add too much weight

The 'rule of thumb' that a 2% improvement in aerodynamics
gives a 1% improvement in MPG
is true in the 65-75 mph highway driving range.

Of course, it isn't true in mostly city driving.

ex-Chrysler vice president
and head of the 2nd gen Ram design team
Bob Lutz, now chief 'Car Guy' at GM
claims that the underside of the new 2007 Silverado pickup
has had the components re-arranged so that it is 'almost' as good as a belly pan.

I have not been able to crawl under one yet to look.

 

yeah that might look a little on the odd side crawling under a new truck...

I like the foam board idea... I may give it a shot...