okigot a 97 with slight mods to it.im lookin to go alot farther into but dont wanna kill my mpgs. lookin to get into the mid 400hp range what, from the sounds of it alotta guys on here are at that hp range whats the mileage at?

 

I may be wrong - but a plate and injectors will get you to 400 or close to it.

Your MPG might stay the same or drop a little bit at long as you're not always on it.

 

plate n injectors only = a bunch of fuel but no air... u need air too in order to make power.. anywayz my truck is at 18mpg right now w/o being all economic doing the speed limit

 

I was around 18 mpg, now closer to 16 thanks to winter fuel. Thats going 75-80 mph on the highway.

 

The important thing to look at here is how your mods affect the efficiency of your engine.

Compression is very important in this respect and if you drop it due to cutting pistons or using a thicker head gasket, your economy will drop. Luckily, you don't need to do this for 400hp.

Fuel delivery is important as well. If you put a more aggressive plate in, you have the ability to dump more fuel into the engine which is inefficient. The good thing about this is that you can refrain from using lots of throttle and maintain your old fuel economy. If you decide to change injectors, the important thing is spray pattern. An injector like a DDP1 won't be able to dump tons of fuel but does have very good atomization which will help with economy. Generally, the larger the hole, the poorer the atomization. The timing of the injection event is important as well. A mild timing increase like 16 degrees will help with highway mileage(our trucks come stock with a timing setting for a lower rpm than we see on the highway).

The final important thing to look at is airflow. Opening up the intake and exhaust will help since the engine won't have to work as hard to move air. Putting a different turbo on will have an effect because it will change the air to fuel ratio. If you have black smoke, that is inefficient. Both spool-up and total flow are important. As far as airflow goes, you could get important gains with a good head porting job and a new cam maximized for mileage.

If you drive it right and set it up right, it would be possible not to hurt your mpg's and have a truck that dynos around 400.

 

My truck calculates around 350 flywheel HP and I go around 22MPG on the interstate. That's at 70 MPH too.

 

if you have the money buy a set of ddp stage 2 injectors for 75hp gain and 1-2mpg' and a bd super b turbo. or something like this, because everyone says they only want 400hp and they get close to that and they always want more. http://www.puredieselpower.com/catal...ins-p-762.html
not cheap but very nice. and you can have a 600hp truck and still get whatever you were before the mods in most cases if you can drive the truck slow enough.

 

yeah i deffneed to do the turbo with the injector. thanks for the info.im just startin out at this so i appreciate the help