Shooter_Jay

If you laid out the math in an equation and maybe a schematic diagram, you can solve for whatever variable you want, including how much fuel.

We have two motors, identical except one with a 100% efficiency intake, the other 50% efficient. You accelerate each vehicle to the same speed at the same rate, above the 50% rate, in the same conditions. More energy is spent pumping air in through the restricted intake, than energy used to pump air in through the unrestricted intake. The power to pump that intake air in, is subtracted from the total power to the crankshaft. So the restricted car does more work to reach the same rate and distance as the unrestricted car. More work means more gas, so for the same distance, you get worse gas mileage in the restricted vehicle.

My initial response to the article was that, he might have clarified more, that you're burning 99% of the fuel, but your not using 99% of the energy to move you forward. Some of it is used to pump in the intake charge, as well as spin the valve-train and crank, trans, rear, wheels, friction/heat etc.. Even oil on your crank-shaft wastes energy so gas-mileage, that's what windage trays are for.

Shooter_Jay

That's where I thought the article was unclear, I thought he made it sound like there is no way to improve your gas mileage. You can improve it by letting your engine flow more efficiently.

I'd be willing to bet that better heads with the same cam and all, gets better gas mileage.

Shooter_Jay

my ls1 has all these parts...

YoungGunLs1

could you say what kind of truck it was? reason I ask is I am going to be getting a 99-04 silverado or sierra and am curious as to what you did to the settings to pick up the MPG on the highway, as I will DEFINATELY do that if it works!!

bww3588

iTrader: (49)

your not getting facts straight here, the motor is not working harder to do anything, which goes back to my original point where the motor is not sucking air in, the atmosphere is pushing it in. the motor is going to create a vacuum in that intake behind that throttle plate no matter what size restriction is on the other side of it. the atmosphere is going to suffer the parasitic loss of the smaller "less efficient" intake rather than the motor.

Shooter_Jay

Sucking works, it's just not pulling. When you "suck" through a straw, it works because you are putting lower pressure in the straw, the atmosphere pushes the drink through the straw. Your engine "sucks" air through the intake by pumping air out the exhaust, lower the pressure in the intake manifold, so the atmosphere pushes the air into the intake. That initial pumpin air DOES take energy to do, and that is parasitically taken off the output power. If you don't get what I'm saying there, I give up and agree to disagree.

mycamaroSS

iTrader: (4)

haha k thanks, glad i didnt than

slow

iTrader: (7)

you also have to consider pumping losses, with a more restrictive intake, or intake track. There is a huge reason, why Variable Cam Timing is used on vehicles such as the 5.4 3valve F-series motor used in that test. During part throttle cruise the cams are retarded to allow the throttle body to open more, reducing pumping losses, and increasing fuel economy. Ford would not have spent millions of dollards in R&D and designing the 3 valve cylinder heads to allow this functionality


Ryan

miamifan3413

iTrader: (1)

I think they both are right for the most part but why doesn't a ls1 with 85mm tb/ls6 intake and full exhaust get better gas mileage then over the "smaller" stock setup It didn't give me better gas mileage

Shooter_Jay

Not sure you're right that it wouldn't. A cam "upgrade" could decrease you mileage, but not opening your intake I think. You sound pretty sure, but how are you so sure that the scenario you suggest wouldn't get better gas mileage over stock?

miamifan3413

iTrader: (1)

I was getting 23 mpg mixed driving when I was stock......I have the same driving patter for a while now from home to job to friends house. Once I got all my breathing mods done, my mileage dropped. I edited my earlier post because I shouldn't have said more air = more fuel, cause to be honest i'm not totally sure about that statement, but I know my gas mileage has went down a little. I was getting 300 mi. a tank stock. Then my mileage dropped to about 270, then gears it dropped to about 260.

Shooter_Jay

Interesting. You may be right, or there may other unnoticed factors contributing to this. Either way, I've been curious about all this lately.

I have a question for you about your driving style. Do you tend to have a heavy foot, or like a grandma, or normal or what? The PM guys had the right idea by using the same amount of gas on a dyno to be as consistent as possible.

I think all this is nearly impossible to prove 100% due to all the variables, but it's interesting theory for consideration and discussion.

miamifan3413

iTrader: (1)

This has always been an interesting debate topic for me....but i'm a person who goes by what I see for myself to be happening to be true. I drive fairly normal. I will step on it from time to time but my driving pattern hasn't changed for a good 3 years or so. I get the same gas and I have fairly new o2 sensors just for the record. Your right, there are alot of variable's that can make a difference, to be sure is hard to say. I do know that my mileage dropped.

its turbo time

iTrader: (3)

Then why do most people report better economy with less restrictive intake an exhaust?

miamifan3413

iTrader: (1)

What do you report??? I hear people say alot of things, some are true and most isn't.....all I know is I can speak for my own result's. I never saw better gas mileage.

its turbo time

iTrader: (3)

for me my mileage was going up with every mod until i put the stall in. I was averaging like 25-26 with all my intake and exhaust mods, now im lucky to get 21.

miamifan3413

iTrader: (1)

What are you basing your mileage on? You could have drove more highway miles.....who knows, this topic just has tooooo many variable's to contend with to draw an ultimate conclusion.

vaticano

iTrader: (8)

I took an 1800 mile trip N.J. a few years ago and averaged 30 mpg every fill up but one where I got 31. This was with H/C exhaust and untuned. Dynoed at 383. I just took a trip up north of me, 165 miles round trip all highway, and did 2 dyno pulls, and used just under 8 gals. Average is about 21 mpg. On E-85 no less with over 600 rwhp.