mymaur

On a recent Hot Rod TV show they took a 2002 3500 dually with a CTD, put it on a dyno and got various horsepower figures.

They eventually got the HP up 204hp above stock by adding propane, huge injectors, changing the computer settings, gee whiz air intake and a 4" exhaust with low restriction muffler.

What was so interesting to me was that the exhaust system gave them a whopping 4 hp and the air filter gave them 1 hp.

For a long time I have been reading about guys spending big bucks on all this stuff and imagining they are realy getting something. THe dyno does not lie. Exhaust systems and free breathing air intakes help, but if you want real power you have to play with the fuel system.

They did not discuss mileage. Of course it's not rocket science, more HP = lower mileage.

Ryan

The air and exhaust systems do not typically add power to a diesel but they do let you use the fuel that you have available by allowing for improved air flow to both fill the cylinders on intake and empty the cylinders on exhaust.

More HP does not necessarily mean worse milage. The first 5 months I have my truck I was getting 18.2 MPG stock, now at 505/ 1052 I am getting 18.2MPG. There was a time in the middle when the milage dropped to around 17 MPG.

dodgeman01

I have dynoed one time and every run ewas a different HP/TQ with the same set up. I gained 10 HP by the last run so I don't know if it really got anything from the 4" and air filter but who knows.
DM01

Haulin_in_Dixie

Everyone says that there is no power increase so the five makes sence. My truck picked up a little power and a little mileage gain with the Scotty II and straight pipe.

PistolWhipt

MYMAUR,
You should know by now that you don't get HP and torque by air, exhaust and fuel .... it's the DTR window sticker that gets the most bang for the buck !!!

PISTOL

DieselDaze

The bigger the sticker, the more horse power gain.... of course.

Rich

Shovelhead

I think the Exhaust & Air Cleaner mods are more geared toward EGT control, than actual power increases.

Ed
JMHO

RustyJC

I'm not surprised at the dyno results since, generally speaking, more BHP in a diesel requires more fuel. Intake & exhaust modifications help in providing the extra air to burn the extra fuel as well as in controlling the EGTs.

Rusty

BIG&BAD

my air and exhaust changes were only to help with EGTs
i didnt think of them helping out with power
oh and more HP does not = less MPG I still see 19 - 20 mpg
and 15mpg pulling 20,000 lbs worth of cows last weekend
and my truck is waaay more powerful than stock

mymaur

I always knew the air filter and exhaust mods had very little to do with HP increases. It probably gets you mileage up a tad. Maybe .5 mpg if your lucky. Those mods probably help keep turbo temps down more than anything. And thats a good thing. I've always gotten a kick out of the guys that invest hundreds and even a few thousand bucks into exhaust and air intake mods thinking they are getting some huge mileage and power increase. But that just my 2 cents and I know there will be a thousand posts from guys swearing they really did get huge improvements from air and exhaust mods.

As far as more power not effecting mileage. Re-read the original post guys. I said they installed HUGE injectors. Now I am probably wrong. But in my average intelligence tells me if you install a set of fuel injectors the size of your fist it will likely result in a lot more fuel being pumped into each cylinder. Which will give you a pretty good boost in HP and likely lower your mileage.

Maybe I'm wrong. Just seems to me that if you dump in a lot more fuel your mileage has to go down. But my wife tells me I'm wrong about 20 or 30 times a day. So, I'm probably wrong here.

If I am, then I'm going to get a set of these monster injectors, get my ponies up significantly and get better mileage to boot.

RustyJC

Fuel mileage will depend on how much of the newfound BHP you're actually using with those bigger injectors. I dropped about 1 MPG towing our 13,500 lb 5th wheel when the DD2's went in, but my average speed went up - in other words, I'm using more BHP (thus, fuel) to hold speed on grades, etc. At steady cruise/steady load conditions, there probably won't be a lot of difference in fuel economy unless the atomization of the new injectors is especially better or worse than the stock Bosch injectors. The DD2's, being extrude-honed, are probably not quite as good as the stock injectors in that department.

Rusty

mymaur

Thats interesting. I wish those guys on that Hot Rod TV show had done a mileage comparison and not just a HP comparison. Would have given a much more complete picture of their end result.