cold air intake - Page 3

**Killerbee** · 06-04-2008, 06:36 AM

post your IAT observations.

You are on the mark.

**Hook'em_Horns!** · 06-05-2008, 10:40 AM

Well, I burned thru a tank and while I feel an increase in power similar to an extra 20+hp, under load my mileage dropped 1.5-2mpg, yet it increased pulling empty by 2mpg.

I’m thinking I need to go ahead and cut and open up the front side of the box. Lowering my IAT has resulted in more power but I think this alteration has decreased airflow resulting in higher consumption.

So, soliciting some thoughts from the mod-ers/racers here, am I on track with this line of thinking?

**Killerbee** · 06-06-2008, 07:20 AM

How did your fan activity change?

If you really want to find a place to improve your trucks mileage, heat, and performance, pull off the compressor mouthpiece, and then picture that an entire 8x10 roomful of air has to pass through it every minute at max throttle.

**gr8shot** · 06-06-2008, 08:22 AM

Ya x2 on that ^^^ Killerbee, I read the whole 20+ pages on thermal feedback and oil cooling... FASCINATING!!!!!!!!!!!!!!!!!! I tell you what, you sure got some time on your hands!!! Great stuff!! I am an engineer myself, so seeing facts and numbers presented in a logical, sensible manner is everything. If everyone would read that stuff, then there'd probably only be half as many ?'s on this forum!!! GOOD WORK!!!!

My only ? is why don't you get rid of your LLY and get an LBZ?? LOL!!!

**n0useforaname** · 06-06-2008, 10:05 AM

Don't wana sound stupid...but does my LBZ have a compressor mouthpiece? And if so, where do I pull it off at?

**Killerbee** · 06-07-2008, 07:11 AM

The LBZ mouthpiece has a significantly better design, less issues.

It connects the airbox tube with the compressor. Very easy to remove, there is a v-band clamp that must be removed on the compressor.

Thanks for the compliment.

**Hook'em_Horns!** · 06-07-2008, 08:27 AM

Quote:

Originally Posted by Killerbee

How did your fan activity change?

If you really want to find a place to improve your trucks mileage, heat, and performance, pull off the compressor mouthpiece, and then picture that an entire 8x10 roomful of air has to pass through it every minute at max throttle.

Actually, the fan activity has decreased, along with the engine and transmission temps under load on steep grades.

That Thermal info explains why the LLY coolant is trashed at 70k miles.

formula455 · 06-07-2008, 11:42 AM

I installed the s&b, it is my first duramax but I have a cai on everything i own, and s&b system is the best I have seen, well thought out design and excellent quality

**Killerbee** · 06-08-2008, 07:30 AM

Having been around intake companies for a few years, I have a reply to that.

None of the intake companies, including SB, have tested a stock LLY for where improvement could be made. If they did their jobs, to find flaws, and significant areas of improvement... this discussion would not be necessary. There is no defense for it, yet not one of these companies will confess, they will only argue and defend, in blind marketing moves.

The resistance that can be found in the LLY intake box, element and tube, combined is only 16% of that found in one simple piece that these companies ignored altogether. That means that 84% of the intakes restriction was left in place, unattended to. It's pathetic actually, and a waste of a "million dollar flowbench facility".

**Hook'em_Horns!** · 06-09-2008, 04:56 PM

Okay, I used a handy little palm size offset air tool with a tapered plunging router bit, and cut open the lower side facing the front, without having to remove the intake box. I now have an unrestricted passage thru to this intake area down and between the front bumper and the inner fender. Looking thru this new inlet, to the right you can see the intake drop area.

I went ahead and cleaned the K&N, it had a few bugs but nothing major.

The result thus far is:

Limiting the intake to outside air with just the weather-stripping dropped my mileage from 9.8 to 7.8-8.3 under load but, more overall power with somewhat less fan activity and a bit cooler engine temperatures.

Opening the front now has me up to 10.3 under load, in the 13s when unloaded, and with much better performance, even cooler engine temps than after the weather-strip and the biggest change…fan activity only every now and then and much quieter when it does engage.

This was while driving in the mid 90s outside, AND it was an overall quietness that I’ve never experienced before except while driving in winter. Running long grades, the Allison is running cooler with much less shifting also, it has yet to reach 200*, and engine temperature is now staying constant with no fluctuations.

Oh, and my dog complained about the A/C being much colder, so I had to back off the temperature a few degrees.

I’ll report any additional gains, if any, when and if I’m running empty and trailer-less but now it is: up .5mpg under load and up 2mpg unloaded. (Note: Unloaded=13.5k lbs gcw, Loaded (today)=25.5k lbs gcw)

Not a whole lot, but every little bit helps at $4.50+/gal., I guess…and it runs better.