trying to cut down drag. right now im getting 25 mpg, i need to find a tonneau cover and ddp2's. im shooting for 30. my driving habits are still 70-75 mph.

 

I am curious as to whether you have tried covering over the openings in your bumper or whether the engine will run too hot if you do that?

As you mention, running fast is the real killer. That darn drag equation with that velocity squared term in there.

 

sheesh, I don't think I could get that many mpg draftin ya at about 1 foot back.. consider yourself lucky. Sigh, but by all means, go for it. hear the toneau cover does help a good bit.

 

hey if you really want to up your mpg get a flex-a-lite electric fan. make a work of difference

 

i was thinking about a electric fan but i do alot of towing during the summer months and dont want to overheat anything

 

crabbelle

I'm a retired Coastie (30 years...). You stationed at the Yard?
I just put a Extang Express tonno on mine. I like it. Extang claims a 10% bump in mileage. To early to tell. Is the air dam commercial or home made?
Any other aerodynamic work planned?
Take care.

 

i had a bed tonneau cover on a gasser and it helped allot i heard some of those electric fans will actualy keep things cooler. ive been thinking of getting some to

 

i believe that flex a lite even says that they are not for use with towing.

 

cwoflyboy no im not at the yard im stationed on 175' bouy tender WILLIAM TATE out of Philadlephia, but i live in Baltimore. im hoping to get the yard when i transfer ANT Baltimore or Station Curtis Bay.
The air dam is home made a piece of stainless steel , i just plan on adding a tonneau cover, set of injectors and bump my timing to 16 maybe get a set of land speed wheels and less aggressive tire. but thats later down the road

 

heres a link they claim if you are over 18000 combined gross vehicle weight, you need more help to cool.
http://www.flex-a-lite.com/auto/html/262-diesel.html

 

bobby...you're at 25 mpg already...slow down a bit more and you may be at your goal. One word of advice, don't run the flexalite if your gonna tow heavy or close to it at all...I called them before I ordered the kit and that's what they told me (actually Summit Racing who is their prefered largest vendor)...since you tow and already have great mpgs I wouldn't risk it if I were you. Do you have a tonneau cover already? Put it this way, you have a 2wd manual with GV already...that's already way ahead of the curve.

 

About the only thing I can see as an improvement is slowing down- the faster we go the higher the engine rpm- either drive slower or add a US Gear unit. Get the engine rpms down in any case. It will offer a much greater improvement then electric fans.

 

There was a great article in the August 07 DIESELPOWER magazine about getting 30 mpg out of a 1 ton dually. They duct taped the body seams and streamlined the rig as much as possible. Folding in the mirrors greatly reduced drag but isn't advised for towing or highway operation! I know smooth disc wheel covers also help but may increase rotor temps. The toneau should help a lot too. My rig likes about 1900 rpm with stock tires. That's where I'm getting the best mileage so far, about 21.6 highway. Not too shabby for a 4X4. Kurt

 

Ive been involved with speed/aero tests at superspeedways with racecars. Yes, do plug up your front bumper! During the winter, you can run fanless. There is a considerable amount of turbulence around the wheel openings too. Dont run wheel arch flares, dont run wide tires or aggressive tread patterns. A flat-faced wheel with an offset that makes it flush with the fender and quarter is best, but wont be good for brake cooling. As mentioned in another post, taping up your body seams is good. Keep your surfaces clean and waxed, including your windshield. Even cab lights create turbulence. I remember seeing a post on TDR about 10 years ago about some grad students testing topper shapes in a wind tunnel...very interesting! The bed cover will help a ton! Do some research on photos of nascar trucks to study wing shapes. At speed, a vortex is created just behind the tailgate and just sits there and tumbles. This high-pressure area keeps new air from comming over the top of the cab and sliding off behind the truck..essentially, it's a wall of wind! The purpose of a wing is to reshape that tumbling air so that it only makes one revolution and then trails off behind the vehicle quickly so that the new air comming up over the hood can take it's place and leave quickly. I guess, you could think of it as the flat bow of a barge pushing through water. Again, go check out wing shapes, sizes and angles of nascar trucks that are trimmed for superspeedways. You dont want downforce, just slippery speed! Yours is a very cool project!!

 

I already have a gear vendors, im running 285 tires and so far ive never seen over 2000 rpms unless im hotroding. i cant slow down my driving is from 65-75 on 95 any slower and im going to get ran over. i got my timing bumped to about 16.5 by brett at tnt diesel. VERY NICE GUYS. next in order is a tonneau, then a clutch, then ddp2. after that im done. maybe ill look in to nascar trucks and stuff like that but it cant interfer with a 5th wheel trailer. thanks for all the info.