Fuel Consumption

[Helmar]

How about Fuel Consumption ??

I have been toying with this idea and I am sure others have too.

History.
Small block chevy such as the 350ci engine for example.
I have a 1979 350 in a chevy truck, 10mph no matter how you drive it.

I have a 1988 350 in my GMC with the TBI (Throttle Body Injection) that gets 19+ mph with over 170k on it.

I have been using several other Hot Rod forums that talk about the Conversion, but most are for V8 engines.

This site shows Marine applications for most of the Inboard/Outboard engines.
Hope this link works.
http://www.affordable-fuel-injection...on=show_detail

Most of us motor heads know that after 3000rpm you suck more fuel for very little more horse power (on a street application)

My little Volvo B-18 with the dual Webers does better than the old Solex carbs but the interesting thing was, I got Much better fuel economy by keeping that engine down to 3000rpms as well.

I have one boat with the small block ford in it that I am thinking of converting in time too.

Anyone been playing with this concept ?

[ChuckB]

Joe:
Years ago i had a horozontally opposed 6 cyl GM engine that I had a friend machine a Nissan 240/280Z MPI system to. It changed all the performance characteristics and economy exc for the +/- 3K rule. I think this has to do more with 4 strokers and how they develop torque peaks and all. But even when i look at all the various Boats that Honda has done fuel/speed work with, the below 3k at plane is usually the best bang for the buck. Mine was on my little Glasspar. The 19 Sabrecraft is not really dialed in yet so no good info on that. And, Honda is now fuel injecting their OB's. No more carbs. I'd go for it. ChuckB.

GMC BoxerMotor???

When did GM make a "horizontally opposed 6 cylinder?"

Ohhhh. I just realized: Corvair. :eek:

So you had a Z-car fuel injection system grafted onto a 'Vair? Cool!

The 2 main things that affect effieciency are throttle opening (in relation to engine vacuum) and proper gearing (in relation to peak power)

Too small an engine will run at a wider throttle opening than a larger one (properly sized for application) resulting in lower engine vacuum due to load and throttle position. I beleive the early Boeing 767's came with engines that were underrated and because of this, spent more time at WOT resulting in reduced economy and shorter overhaul intervals. These were retrofitted with larger engines which solved both problems simultaneously (and at the same time even).

Running an engine faster OR slower due to gearing (or in marine applications, prop size/pitch) will will burn more fuel. I run into this all the time on Harleys, in the last couple of years replacing 5 speed transmissions with 6 speeds has become all the rage but more often than not fuel economy suffers even though the engine is turning slower...it's outside it's power band unless you increase the bike's speed, but then aerodynamics conspire against you and overall the efficiency STILL suffers.

And then there's the charging system that won't work as well at the slower engine speed. There's no free lunch!

Fuel injection violates the KISS principle! Although more efficient than a typical carb (assuming closed loop system with oxygen sensors and integrated ignition) they require proper set up and the hassle of installing extra wiring/plumbing. Plus they demand a good charging system for smooth voltage with enough oomph to run the fuel pump and the computer etc.