I just got back from my Trip to Vermont, from CT. I finally got a true, or as close as I can to see what I would get in optinum conditions.

Here is my previous post. The Trans-Am wasnt getting the best as it could be getting but bear in mind the car had a honest 50/50 mix of freeway and stop and go and it was intermittent at best.

https://ls1tech.com/forums/eastern-members/729343-gas-milage-tip-skipping-gears.html

Just to recap the T/A...

M6
4.11's
Moser rear w/ 3" steel DS
SLP Flow Pack
Dynatech headers, their CATS and Corsa exhaust
No Weight reduction (but it couldnt hurt)
Untuned

Since then I did a fresh oil change, cleaned the MAF (which was a lil dirty), a bottle of injector cleaner.

On the way up, I gassed up right before the highway and it was pretty much a straight 230 mile trip, one stop. It was hilly, but I kept it 65-70mph, more towards 70mph. In 6th revs just about 2,000 rpms. I had the A/C running for the 1st 1/2 of the trip and the windows open and A/C off. 205mi for highway and 25mi for in city. I proceeded to drive in city for another 70mi and when I filled I had 300 even on the odom and filled 12.8 gallons. Which is 23.4mpg

I know I could do better so I filled up and when I hit the freeway I had about 30mi on the odom and drove about the same, 70mph. Windows up, vent on, No A/C at all (much cooler), I read that windows being down allows air in and puts drag on the car. I tried to on steep hills put her in Neutral and coast her.

When I got home, I immediately gassed up 250miles and put in 10.061 and I came out to 24.84 mpg.

I could have driven slower but I was following someone else and I go their speed. Either way I improved. But at the same time the car needs a tune. Like my last tune on the LT1 had a higher A/F from idle till like 2500 rpms and when It went to WOT it would dip to 12.8 to 1 +/- 0.1 Since the car is probably rich, I think I can eek out the extra 3 mpg even with the 4.11's Or Drive 60mph but then if the A/F is still as rich down there the diff will be neglible.

 

Here is a link to my old LT1 Dyno, the A/F is there in the graph. If I could have something similar, I think I would get all that great milage that people rave about, even with H/C's

http://www.mainstreamtopics.com/~scr...sLT4Hotcam.JPG

 

Not trying to be wise, but wouldn't you be better with a different car if gas mileage in a LS1 is a concern?

 

I have 2 cars.

I like driving the Trans Am, but @ 3.40 a gallon, I like to see I can get the best I can.

This is just an experiment and I am seeing what gets best milage and still be modded.

Oh and the Hyundai did get a best of 36mpg, which isnt bad for 105k on the clock.

I have a position that I am in the running for and I will need to drive farther away, although the Hyundai is the DD, The same technique should be able to yeild similar results.

 

good job man. i wish i got near that much in my car. im only getting about 150 out of my tank.... no joke. my tune is messed up though too. my DD is a neon and im getting 39mph out of a tank, so it makes up for it.

 

I think you can get even better mpg if you get that thing tuned! But great research so far!

 

Thanks NVR and Tracer.

I definitly think a Tune will get the average 50/50 use MPG up as well. I think I can honestly do 27-28 with the mods and weight. I also was doing the math, and if I am losing MPG, I am essentially losing money, money that can be put toward the tune. So Its going to be a sooner rather then later. Plus I wanna see the #'s since the headers.

Also on a side note, I need to get a oil catch can, my intake got a film of oil. Good o'le PCV system at work!

 

hey aaron none cares about your gas milage LOL j/k whats goin on for sat. nat anything good

 

Sean what happened... I heard you had a problem with the car, take it to PM if need be.

 

I'll give yea a call. Definitly a turnpike night.

 

That's great MPG with your gears. I drive about 27k miles a year, work commute. About 3/4 highway driving and I get 23 MPG average per tank with the stock 3.42's.

 

When I drive my car all highway at a steady 65 mph with the cruise control on (CC helps mileage) I consistenly get about 23 mpg. I'm at about 2000-2100 rpm at that speed. I did a trip one time that was all back roads going between 45-55 mph and got 25 mpg. If you want to know how speed affects mileage take a look at this chart:



A catch can will do wonders for that. I could show you mine tonight, different setup since it's an LT1 but the results are impressive.

 

i think i get around 18mpg

 

I have that, whenever you want it it's yours. Hell I'll even install it

 

My car is basically stock, and I get great mileage.

 

LOL Mileage.

Actually I probably get 20-22 on the hwy. Don't even ask around town. I can stomp it and watch the needle move down.

 

Damn that is some bad mileage when I had the same mods as you and Don tuned my car I was getting around 32 mpg highway

 

I checked mine once this year... 8 mpg LOL, with 6.50 a gallon 105 unleaded.

And now 112 is going in the tank..... and people wonder why I don't drive it around

 

And some people ask me why I still sport a 4l60E

JL, why do you run 105+ on the street? Whats your CR?

 

wish i still got in the mid to high 20's , best so far on the new motor is about 21-22 i average 18-20 around town/,mixed though

good research though man