okfoz

That was rude. You do not need to post stuff like this... just move on.

no new tires

That guy bumped a thread from -2011-, I don't even really remember that far back.

blackfrontier

iTrader: (1)

Not sure why I got the rude reply. This thread IS for people wanting to know mileage so to say "nobody cares" contradicts the whole purpose for the post. Get a clue

okfoz

Seeing that you joined just shy of a year ago, you would not remember that far back. Personally, if it was my board I would delete your post and consider giving you an infraction. It was unnecessary, and personally people like you **** me off.

no new tires

Iv been a member here since about 2006.
Wow, im getting old. Wheres my medicaid and ginger snaps?

okfoz

Not under the name no new tires... the join date was 3-3-2014

Ozz1967

iTrader: (4)

Seeing this thread is one of the reasons I'm looking to upgrade from my CC Qjet to TPI/Miniram.

When I had a 305, I was getting 22mpg with my carb. With the 355, it's 19 highway. About 9 city only. 14/15 combined.

okfoz

I converted my car from an LG4 to TPI, actually purchased a wrecked TPI car and did the conversion right. At the same time I also installed the SLP headers & cat-back, and I went from a 2.73 gear to 3.73 gear IIRC all at the same time. I did not notice a huge change in MPG...

oddly enough, when I went from the stock Formula Wheels & 245 tires, to the 17" ROH wheels with the 275 & 255 tires, I actually noticed a change in MPG. Never could figure out why... but it seemed to happen at the same time... Of course I have messed with my PROM and made it more on the end of performance, over the original 87 PROM that was for economy...

Ozz1967

iTrader: (4)

Nice! That's pretty much what I'm looking to do. I already have 3.73's, they came factory. If I can pull the MPG's into the 20's, I'll be happy. I'm just not sure if I should start with TPI, then get a miniram, or just wait until I can afford a miniram...

I do find it funny, my carbed 84 still gets better gas mileage on the highway than either of my other two DD vehicles (Avalanche/Explorer).

okfoz

The car with the 4BBL really was not that bad for fuel economy... If I was really worried about it I would stuff the 86 PROM I found in a junkyard... Buuut I like pull too much...

no new tires

That is correct. I can't remember how many accounts that I had.

IROCgiraffe

iTrader: (3)

Last figures I recall on my 305 TPI A4 ... 18 mixed and solid 25 hwy, no AC as it currently doesn't work. Driving gingerly with a few spirited bursts here and there.

1MeanZ

iTrader: (9)

The 383 powered GTA in my sig gets 26-28mpg on the highway depending on weather and status of my windows and T-tops. T-tops being out has seemed to cost me nearly 3 mpg at times.

Mixed city and highway I'm 18-22 depending on the mix. As others have mentioned the T56 helps. Also helping me is a good combustion chamber, 10:1 compression, .040" quench, and a mild cam.

Ozz1967

iTrader: (4)

Your gearing also helps with that. Additionally, many people don't consider the transmission itself, not just the transmsission gears. Auto's use more gas than manuals do. 1-3 less for an auto compared to a manual usually.

1MeanZ

iTrader: (9)

It's a '93 T56 with a .62:1 6th gear, which mates perfectly with my 3.27 gear. Final drive is basically identical to a later T56 with the standard 3.42 gear.

okfoz

The reason why the manual is more efficient than an auto is how the auto works. There are more internal frictions and that leads to more losses of power thru heat. A Manual is more or less direct drive once you let off on the clutch.

Also with an Auto, you are still spinning the torque convertor when you let off the gas, they do not coast quite as well as pushing in the clutch. I know at first my torque convertor Stall was stock, I could barely stop the car, I had to stand on the brake. I changed the stall to 2000RPM convertor and it really made it easier to drive...

Mscarter40

what speed were yuo running at and which octane fuel 87 89 or 91+?

Michael

Mscarter40

What speed exactly were you running at and which octane fuel 87,89, or 91+ ????

Michael Carter

Fast355

iTrader: (2)

Something off on that Q-Jet? I was averaging 18-20 on road trips with a 305/700r4 and 3.08 gears with the M4ME Q-Jet in my old heavy box of a G20 van. Purely city was 12-13 mpg. Stayed roughly the same after adding a cam, tri-y headers, deleted the EGR and put a performer rpm q-jet intake on it. Stayed about the same when I switched to the old Weiand 7525 single plane and put the EGR back on for smog reasons.

My cammed 305 Tahoe with a 4L60E and 3.42s rolling on 85 lbs each 305/50R20s on 20x9.5 wheels would knock down 22-23 mpg highway and about 14 in-town.

My Express van with a cammed 5.7L vortec with tri-ys consistantly saw 18-19 mpg running 80 mph on the highway with 30.5" tall 20s, 4L85E and 9.5" 14-bolt with 3.73s. 350 was spinning about 2,500 rpm @ 80. About 12-13 in-town. I ran a Holley 650 double pumper spreadbore carb on the L31 in that van for a year as well. Roughly the same fuel economy as the EFI setup.

Fast355

iTrader: (2)

My heavy vans and my Tahoe have all gotten better city mileage with a converter in the 2,400-2,800 rpm range than the factory converters. Hard to get 5,000-6,500 lbs rolling lugging the engine down at 1,200-1,400 rpm off-idle. Less load at idle means the engine will idle with less throttle or IAC opening and then it keeps the carb or EFI out of fuel enrichment accelerating normally from a stop. Stock torque converter causes the engine vacuum to drop off very sharply even with a small throttle opening.

ULTM8Z

2nd gen Camaro here.... ZZ4 350 with a Miniram, 212@.050 cam, AFR 180 heads, putting out about ~400 hp, TH700R4, 3.42 axle ratio, and highway mode lean-cruise activated, I was getting ~27-28 mpg highway cruising along at 75-80 mph. After I added the Gear Vendors overdrive unit to the transmission, the double overdrive increased my mileage to 29-30 mpg highway.

Around town if I drive normally I can get ~14 mpg.

When I had a carb set up in the early 1990's and the TH700R4, I could pull down 21 mpg on the highway, but was only getting 10-11 around town. It was a mild setup though.. Edelbrock Performer manifold, 600 CFM carb, and a cam about the same size I'm running now.

Fast355

iTrader: (2)

I lean pretty heavily into the lean side of the APT on Q-Jets. To the point, tested my 383 at approximately 2,000 rpm on a quart of fuel. I started with empty float bowls and cranked it over until it started with both a Q-jet and a 1406 that had both been recalibrated to run my 383 well. Q-Jet ran 8:26 and the Edelbrock 7:24 and that is not counting the last 20 seconds the Edelbrock ran on 4 cylinders where the Q-Jet ran on all 8 to the end.

Was running at about 2,000 rpm and roughly 40° of timing advance. Q-Jet is way more efficient at light part-throttle. At 2,000 rpm no load the Q-Jets primary main metering is atomizing fuel very nicely in a fanned out mist similar to what a TBI looks like and the edelbrock is merely drizziling huge droplets in.