Shock Hawk

I've seen some of the more recent GM LS-based engines with some kind of multi-displacement/cylinder shutoff mechanism. Can it be used on an LS1? What do you guys think the extra mpg off it will be?

gametech

iTrader: (1)

It doesn't work on ls1, but if it did, I would still ignore it. The new DOD motors have different lifters and oil passages, and the DOD doesn't work worth a damn. If MPG is your goal, buy a bike. You can get 9sec 1/4 times and 45+MPG out of the same bike. I you want a good car, forget the EPA gimmicks.

2002_Z28_Six_Speed

iTrader: (19)

It works but recent body styles have decreased aerodynamics and bad programming makes the DOD switch on and off too much.

It isn't a bad idea because increasing the load and decreasing the number of operating cylinders, yea that sounds more efficient to me. You can crunch the math yourself. Still. You have to exert so much power just to move down the road and every time you hit the pedal your MPG drops like crazy so don't expect a huge increase in fuel efficiency.

LS1s can see 30 MPG on the highway under good driver habits and modifications. Buses and tractor trailers can see 10% difference just because of the driver according to CAT!

3.4camaro

iTrader: (1)

DOD should be a user controlled function. Like a switch next to the radio to shut down some cylinders.

Shock Hawk

I'm not crazy about gas mileage, just a tinkerer. I'm not even sure DOD is even a good idea because a stock M6 f-body does 70 at about 1600rpm... and the engine struggles a bit. That's why people report better gas mileage on 3.73s over stock 3.42s. The rpm raises and the pedal pressure is reduced. Having less power would make it worse in this scenario.

3.4camaro

iTrader: (1)

I don't think my engine struggles at all at 1000 rpm in 6th. But I have a healthy h/c setup.

Your people who see better gas mileage drive in the city mostly. For highway driving, it doesn't matter what kind of gear, a lower rpm, down to about 1200, will get better gas mileage. This is because the pcm will keep AFR at 14.7:1 while cruising.

2002_Z28_Six_Speed

iTrader: (19)

Been wondering about that alot. The higher RPM you go you use less load. It is surely a balancing equation. I have changed my gears and gotten the same or better MPG. I know it sounds impossible. I swear it is true.

What's the math say though? On my other PC I did a simulation of fuel consumption vs load vs RPM and it says lower RPM was still better despite my real world findings. I put in the cell I was cruising at before and after the gear change BTW.

So, either the math I did is wrong or possibily when you feel the engine is more peppy you don't have the need to bury the throttle all the time further decreasing your MPG! Who knows.