random technical question

[TGstring]

Hey guys,
I'm new here and new to trucks in general.
Recently picked up an '02 RCSB with an LR4 and MG5
it's in pretty good shape and I'm slowly turning it into the truck I like with a few small odds and ends updated to my liking.

the one bit of information i have never been able to find is what the Cd is for this truck?

that is, coefficient of drag spec seems to be unnknown, where as the Cd of trucks seemed to surface in 2005 or 2007 a lot more.

does anyone have this spec?
I'm guessing somewhere closer to .40 as a mandated design element, but I just can't find it anywhere.

I'll leave this here for now as I continue my search. I found a lot of really good technical threads in here which suggests a cut above the typical "how high can I jack my truck" threads found in other corners of the truck enthusiast forum world.

Cheers,
Tom

 

[djthumper]

I am not sure that they posted that stuff back then. Unless you get lucky and find it on wikipedia or some place like that.

 

[Reprise]

It's probably going to be close to .43

Your truck is a GMT800. GM gave the trucks a slightly revised front clip in '03.
The '06 2500HD CCSB was rated at .43 Cd

Since you have the 1500 (4.8L and NV3500 M/T makes it such), it will sit lower than the 2500HD (at least 2")
Thus, you could be a tiny bit lower -- if I were to guess, perhaps .42 But not lower than that. It takes a lot to move the number, given the similarity in both models. Vehicle height is a big reason the Cd is so high.

For more info: Click Here
(took me about 10min to find the raw data and confirm.)

PS: I didn't realize you could get a short bed in a regular cab -- I thought only the 8ft bed came with a regular cab -? But thinking about it, GM had a lot of variations back then -- much more than now.

GM started really improving the Cd with the 900's forward - IIRC, they were somewhere in the .38x area, for the 1/2 ton during that generation ('07-'13). The 3/4 ton started getting bigger & taller then, so you'd see more differentiation between the two, as well.

 

[TGstring]

first, thank you for your input. that GM '99 - 02 number is elusive.
The '03-07 number quoted sounds about right-ish to me as the referenced HD version would have a few things working against it: bigger rad/grille area, higher ground clearance, the HD hood as we know is about 2" higher than the non HD hood, along with the bumper/tow hook lower bumper openings.. I could see that increasing numbers by 10% which takes me to....
I don't know why but the .40 "design element" is knawing at me for some reason... I could be completely wrong here. It sounds silly but I was wondering if the documentation existed online to support why this idea is in my head. Perhaps 25 years after the truck was designed, memories tend to fade
The closest I've gotten to finding out directly from GM documentation refers to the tahoe/yukon changes and working backwards from the given numbers, calculating something like a .397 or literally just under .40

maybe some day I'll cross paths with a GM design team member who was part of the team 25 years ago and remembers what the numbers are although they're likely retired by now.
Who knows