Fireball

iTrader: (21)

yeah...you're talking a bit more binary of an approach (shutting off cylinders vs reducing volume) but its in the same ballpark

427

iTrader: (3)

GM did some cool testing years ago with the inline 6 cylinder with twins with integral wastegates driven by the ECU. The engine was reduced to around 3.0 litres and still produced 400hp with 500ft lbs available on 93 octane fuel. They were rolling the ex cam to reduce power and still using a traditional tb for idle.

Kurt

Ericmck2000

Hell, my full sized silverado got 20-25mpg

Then again, it was a stock engine 4.8 with bigger injectors and only 10-15 lbs of boost.

1320

iTrader: (6)

years ago.....their was a turbo buick, that made around 450 rwhp probably, but I think it used a thumbwheel chip with one program that cut fuel entirely to three cyiinders. It got around 40-45 mpg under easy driving conditions I think.

It ran high 11's low 12's

old motorhead

iTrader: (10)

40 to 45 mpg is pretty special with anything heavier than an econocoupe. You need to save that recipe! It takes power to move the load...no matter what size the motor is.

stock48

iTrader: (17)

Check out the new Ford Eco boost; I think they are on the right track.

427

iTrader: (3)

My truck will only get around 16-17 driving without the trailer, probably due to the 4L80E drag and the AWD box coupled with the heavy tire/wheel combo. Towing the trailer it seems to stay between 7.5-8.5 running 75mph. I can't really see a difference between 3rd or 4th gear most times, but on level ground I normally run 4th. I think the reduced size engine has merit because it should reduce pumping losses and have slightly lower internal drag. The downside will be increased cylinder pressure required for the same power as the larger engine. Someday I would like to test a little, but that will probably be a ways out for me as the first engine went 107,000 miles and I am hoping for another 100 out of this one!

Kurt

slangegger

Kurt,

How heavy is the trailer your towing? Expressway or around town? Enclosed or open?

427

iTrader: (3)

The trailer is 5-5500 empty and I have had a few different cars in it. My guess is between 8500-10000 going down the road. I have been doing highway at 70-80mph, running in mountains a bit. It is a 24 ft enclosed trailer.

Kurt

gnx7

iTrader: (28)

Find something very aerodynamic and light. That is why current cars being heavy pigs struggle to get the economy of cars from the 80's/90's even though their engines are more efficient.

RX-7 with an LS1/T56 and 3.90 factory gears making 450rwhp+ still achieves high 20's MPG. .29 cd and 2800-2900lbs wet with a/c

I have a '99 Jetta TDi with 5speed that gets 50mpg+ highway.

427

iTrader: (3)

I don't think that would pull my trailer!! Mine made 600 at the tires and ran 11.4X at 5500 pounds. It would be better lighter for sure, but might not do the work I need done. I would be really happy if I could get 9 towing at 75mph. The only way it will do that now is at 60mph, but that drives me nuts!!

Kurt

TurboS10

iTrader: (12)

cam and gears are the key - need to match-
GM can't get a V8 to work at 1300.......might want to plan on a little higher.

2.73's, 80e, 28" tires are about 1600. -6262's for the power-

On a side note - I know someone who got 24mpg in a hot cammed LT4 with 6spd vette. So cam doesn't need to be near as small as previously commented.

I thought Kurt's buddy with the 6spd LT1 fbody w/ twin 61's got 20+ w/ 218/218xe HR 355 and about right HP. Intimd8 or something on TTF.

Beaflag VonRathburg

iTrader: (176)

I think compression, DCR, and valve events would play a lot into non boosted efficiency. I think something like an NA engine on 8 injectors and then a boosted setup with an extra 8 full of something else would be nice. If you're going to run all the time on E85 though you could probably do it on 8 larger injectors.

99Z28LS1

iTrader: (4)

Prob the wrong thing to say to one of the most known engine builders on tech, but you should have gone Duramax

kmracer

iTrader: (1)

22+ MPG on GASOLINE is doable. e85? good luck. i dont see why you wouldnt be able to get 22+mpg in a light car with good aero, a mild cam, 10.5:1+ compression (torque out of boost), and some good heads. i really dont think backpressure is gonna be a huge issue. obviously the tune will need to be spot on.

kmracer

iTrader: (1)

i think you need a diesel, or something with incredible part throttle torque.

99.9percenter

iTrader: (2)

Real Americans don't spend money on foreign crap Duramax=rice

kmracer

iTrader: (1)

you're driving a socialist built camaro... LOL.

427

iTrader: (3)

I have something with great low speed tq, just like Jim I seek more mpg. My truck will pull a 5% grade with 9-10,000 on it's back without unlocking the converter at 75mph. You just hear the whistle and when you look up at the boost it's reading 4-6psi.
On my way home Sunday night with the trailer empty I ran a Ford diesel dually from a stop light. I was able to stay with him in first and move in front in second gear on 9psi. I don't mind my power, just find the mpg interesting to try and increase. The one thing that should work is keeping the engine in boost at lower rpm for fuel mpg, but mine starts going to fast under those boost conditions on level ground. Would be interesting to kill cylinders to keep the engine out of vac and control speed, I may experiment with this someday.....

Kurt

427

iTrader: (3)

Not sure if you are talking about my truck, but I have 3.73 gears in the axles. I am right on the threshold of my turbo: 65mph locked up will only make 2 psi. Can make 6 psi at 75mph. It will make 9psi in third gear locked with the boost set at 9psi, more if I get brave and turn it up.

Kurt