I'm running at 70 mph at 2000 rpm, boost fluctuates at that range. So I am wondering if more boost equals more fuel? Thanks

 

Yes. Boost allows more air, which allows you to burn more fuel which makes more power.

 

I'm on a long trip and seems to be burning more fuel, so that makes since then. It must be the new waste gate I installed. I was just worried and couldn't figure it out, Its a long trip with high fuel prices. Thank you for confirming that.

 

In case anyone is interested :

Boost is the result of higher exhaust gas density from more diesel being injected, The higher density exhaust gas spins the turbocharger faster (more mass pushing on the turbine fins), which in turn causes the intake side to "suck" in more air (creates a low pressure area that draws in more air which in turn creates pressure in the intake manifold), which increases intake air density and consequently further increases exhaust gas density. However, more fuel at lower RPMs will not, in and of itself, substantially increase boost pressure (we have all experienced this - black smoke and no torque). Even though it is higher density due to the fuel, there still is less exhaust gas hitting the turbine in any given moment compared to higher engine RPMs (more combustion cycles per second and consequently more intake air sucked in and then pushed out the exhaust at any given moment).

Further digression: in short, yes, more boost means more fuel being injected at that moment. However, the overall energy or work you get out of that fuel is dependent on all kinds of things, such as engine RPM and the parasitic losses due to friction and rotational inertia dependent on it, air filter and intake flow, etc., etc. With an automatic, the transmission will shift for optimal engine speed in most cases. However, with a manual transmission, proper shifting can reduce fuel usage. Furthermore, under heavy load more boost will result in increased engine efficiency which can result in better MPG in some cases versus operating at lower boost and RPM under equivalent load. This is all in regards only to fixed geometry single turbocharger diesel engines. Gas engines further complicate the discussion with different stoichiometry, compression ratios, throttle plates (excluding GDI), and other factors.