Higher-Octane Gas Could Improve Fuel Economy

[1project2many]

No torque, but the anemic 4.3 was available with loose converter in one ton applications. We're in town, stop and go, so not much help no matter what size engine or where torque production is. BSFC is maximum at peak torque so I'll take a loose converter and power vs torque to move along.

I will say that shop truck with 6.0 pulls stuck buses all day long without breaking a sweat. I can get reasonable mileage on the highway if I keep it below 70. But as soon as I hit a couple of lights there goes the economy.

Currently rebuilding 5.7 engine for bus and trying HT383 cam. Nice experiment for an otherwise stock vehicle.

[Fast355]

No torque, but the anemic 4.3 was available with loose converter in one ton applications. We're in town, stop and go, so not much help no matter what size engine or where torque production is. BSFC is maximum at peak torque so I'll take a loose converter and power vs torque to move along.

I will say that shop truck with 6.0 pulls stuck buses all day long without breaking a sweat. I can get reasonable mileage on the highway if I keep it below 70. But as soon as I hit a couple of lights there goes the economy.

Currently rebuilding 5.7 engine for bus and trying HT383 cam. Nice experiment for an otherwise stock vehicle.

Just my $.02, I would try a set of 1.6:1 full roller rockers rather than the HT383 cam. The HT383 cam has a bit more overlap than the L31. But it will be interesting to see what happens.

I have the 4.3 converter in my 4L80E in my G1500 with the 5.7.

Not sure where you have seen that BSFC was highest at peak torque??? BSFC is often LOWEST at peak torque and falls off on both ends. Take the project Vortec TPI built for the something old, something new article.

It peaked in BSFC between 3,300 and 5,000 rpm and was relatively flat between .4 and .43 lb/hr/hp, which is a stellar number for an old 5.7

http://www.gmhightechperformance.com...ck/page_3.html