10#'s Boost=what mph?

[Bluebird]

I know this will be a variable math question, but I sure some can shed insight. Since I don't have gauges I would like to know what miles per hour you are traveling in 3rd or overdrive (auto) that equals 10#'s of boost? I know many factors apply... I usually go empty w/passengers (daily driver) or carry no more than a 500# load. My next purchase will be guages, EGT/BOOST. I hope to get some numbers to create mathmatical formulas. I ask this 'cause I just read in the lastest TDR issue that 10# of boost is the fuel mileage 'sweet spot'. I average 20. 05mpg right now. Thanks in advance to anyone who replys Oo.



Patrick

 

[Philip]

I don't know what the MPH would be for #10 pounds of boost. I run 4 PSI at 60 MPH, 6 PSI at 80 MPH.



If 10 PSI is the sweet spot. They better raise the speed limit some.

 

[JLEONARD]

I agree with Philip... .

With a manual trans and 3. 54 diff I think I'd have to maintaining close to 90 on a flat road to be at 10 psi.

I would say the sweet spot mileage wise would be about 3 to 5 psi... that would be 60/65 ish and perhaps 1800/1900 rpm for me.

Engine sounds like it's in its sweet spot about there... kind of loafing along, ready for action to defy that mathematical formula that says strokers are faster!! :-laf



Jay

 

[paccool]

At 70MPH on level ground, no extra weight, I run just a little over 2psi which is where the gauge starts to register. Any little rise will bring the boost up to 4 -6 psi. Now, getting on the freeway is a different issue! Thats when I check my gauge to be sure it is working. 32-35 psi is the norm then.

 

[dpuckett]

I am going to simplify this a great deal, no offense to anyone intended. It takes fuel to make boost and EGT. Keep them both down as low as possible (within reason) to get max MPGs. I can sometimes drop nearly 100deg EGT @ 60 by dropping 2mph; other times, 5mph doesnt seem to matter. Wind speed, direction, and humidity will all affect what pressures/ temps you run at a given speed. Once you get the gauges in, pay attention to what conditions make the best EGTs/boost, and learn to drive with them, making the speedo a secondary ticket preventive device.



Daniel

 

[phillips5]

I agree with Daniel the swamp monster. The with 2 psi at 65 is using less fuel than the guy with 5 psi at 60

 

[hdm48]

Aw heck, I just push the tall skinny peddle untill the guage reads 45 then just throw it into neutral, shut it off, and coast till I get where I'm going. I get great milage this way. :-laf :-laf

 

[bgilbert]

Aw heck, I just push the tall skinny peddle untill the guage reads 45 then just throw it into neutral, shut it off, and coast till I get where I'm going. I get great milage this way.

Bet that turbo doesnt like those shutdown temps when you do that lol, but hey I bet that vibration you were getting goes away when you do that? Did you ever find that vibration critter's location?

 

[JLEONARD]

I did an "experiment" yesterday on the way home from work, and this morning on the way in... ... ...

I tried to get to a speed on a flat where I needed to stay at 10 psi to maintain speed.

Even at 90, once I got there I was only producing about 6 to 8 psi to maintain speed.



I guess my truck didn't read that TDR article..... :-laf

Jay

 

[bmoeller]

Going by the EGTs would be a better gauge for finding the "sweet spot". I get the best mileage at between 5-600* (pre-turbo). BOMBed or not.