Drag racing raised mileage!?
 

haha so back in April before i left for boot camp i decided i wanted to take Tank out to the strip So i changed the oil and filled him half way up with the only gas i ever use Shell V power and i took him out to the strip. First run of the night was a horrible 17.6 :turtle: that was with no launch and just step on it in D I got in about 13 runs that night and i slowly got quicker and quicker with almost each run and started manually shifting it so i could get the most out of the old 3 speed and finally i broke a 15.09!!!!! amazing time for a 4500 pound El camino that's for the most part stock I thought.

But anyway ECONOMY after i left the track the car was running smoother than it ever had before and for the whole week before i left for boot no matter where i went or how i drove it jumped in average from about 19MPG mixed freeway and city to about 21 MPG in mixed driving

Haha moral of the story Take your car out to a run whatcha brung/ test and tune day with new oil and blow some of that old carbon outta there every now and then to improve mileage:thumbup:

NOTICE: Results may vary No garuntees but hey if worse comes to worse you had fun for a day:D

I've noticed that as well... all this nannying around made my car slow too and I struggle to keep fuel consumption down, BUT I drive an '87 Mk2 Jetta 1.6 Carburettor an I have a hard time getting your mileage figures. Well done!

I make a point to stand on it in the beast any time I get on the highway for that exact reason. Long highway runs can help as well, particularly if you hold it down a gear and accelerate hard up a hill once in a while.

Aha, so that's the secret behind your 1.6% over EPA. I wondered how you managed that mileage.

Seriously, full throttle acceleration will put even a Metro into single-digit FE, and fuel injected vehicles can go for tens of thousands of miles with no significant carbon buildup. Save it for those rare occasions when you need to merge from a stop in a construction zone.

with a carburetor running some gumout through it every now and again will keep things running tip top. My 83 Sentra would start dropping off on the mileage when it was time for a can of carb cleaner, then I'd be back to my steady 35-37 mpg, sometimes 40 if I was easy on it for once.

yeah back when i seafoamed it last year it picked some up too but i mean i was amazed at the difference after drag racing

sounds like you could jet a little leaner or turn your idle mixture leaner.

I was surprised how smooth my Tempo was running and that my mileage didn't suffer much after two passes at a strip. Would have done more, but I was hearing a strange sound and decided to err on the side of safety.

Robertsmalls - I don't drive a whole heck of a lot of highway, and when I do, it's usually a minimum of 10 miles, typically longer. I'm not too hard on it on the shorter runs. On the longer ones, a single WOT pass up to 60 is a drop in the bucket over say, 350 miles (such as the run to college on Tuesday). Part of the reason for me being so low compared to EPA is that until now, 90% of my driving was city driving, where the beast is only rated for 11 mpg. In that perspective, pulling 12+ out of it doesn't look as bad, especially with a lot of short trips, and some not-so-efficient routes, where the only more efficient alternative is much longer. Plus, this is just an inefficient vehicle. A Jeep with a 360 in it was never built to get good gas mileage, although it's still better than some large vehicles, or a full size truck.

I wonder if you didn't blow some carbon build up off the valves and out of the exhaust.

BTW that is one cool car. I always have had a soft spot for the car/truck combo!

Yeah quite a bit of carbon

and thanks man it was my first car and i'll be keeping it forever so it'll be m project car for life pretty much

WOW comp thats pretty bad fe i have a 97 jeep grand charokee I6 and i get 21 city 23 highway and the only thing i'm doin right now is usin the acetone at 3.5 oz's per 10 gallons the epa estimate is 16 city and 18 highway:) (oh and i also made a direct cold air intake basicly a k&n air filter directly mounted on the intake manifold and a box that only allows air from the hood scope to supply it)

This made me think of a minivan that was used as a shuttle at a plant I worked at. in normal use, it barely got to 25 mph, and was mostly driven very slow. All day it would shuttle people between several buildings. About once a month they would take it out on the highway and floor it to clean it out. This was a 1999/2000 model, with modern fuel injection. It would still get build up and other issues with all that low speed, low load driving. I remember the exhaust would start to smell bad. I think part of it was moisture in the exhaust gasses condensing on the exhaust pipes and building up.

in such an extreme circumstance as you describe, I suspect build up would become a problem. But, except for those living in a city, I suspect just driving it would keep build up down.

On the Nissan Sentra I had there would be visible buildup on the throttle plate which would wash off with carb cleaner. I imagine there is some buildup like that by the fuel injectors, but due to the higher temps that close to the combustion chamber it isn't nearly the issue it was with the carb. While I don't think it's as big a deal with a modern engine to "burn out the carbon" on a regular basis as it was with an older carbed vehicle, I would consider a good hard run 2-3 times a year a good idea. Take that thing to the hills and give it the beans. That should clean it out!

Stovie - The city driving mine sees (which up until the last few tanks was 90% of the driving) is mostly stop and go, and short trips. That was killer. In that cycle, I could get about 14 or a little more from an I6 grand cherokee. The big V8 is a killer, especially on the highway (can't break 20 stock). It's just not geared tall enough for mpg. As I start doing a few minor mods to the engine (and the rest of the Jeep), I should be able to get a bit more out of it.

My next door neighbour's father in law has a Vauxhall Zafira with 300K miles which he uses as a minicab.

He swears by a bottle of Redex one tank in very 3 - which means once a week for him - and giving the old girl a damn good thrashing occasionally.

He also recommends drving his Zafira quite hard every now and again too.

i remember when i put 98 octane fuel (in america i think you call it 92??) i took it out on the highway and put it in 4th gear pulling 4.5k rpm (only has a 4 speed gearbox atm) i remember a big puff of thick black smoke coming out the back, after that it idled so much better and got better fuel economy!!, i felt sorry for the person behind me though :)

My WAG is that your choke was sticking for some reason.

Taxicabs see daily short hop driving their entire lives, and have longer longevity than the vast majority of family cars. New York City and San Francisco hybrid taxi fleets retire their vehicles after 300,000 to 350,000 miles, typically without repairs, still using their original batteries, etc.

On the taxi-cabs antecdote, how many years does it take them to rack up that mileage? Its my experience that time weighs more heavily on vehicles than miles.

As to OP, first congratulations on your time, thats pretty good, especially for that old heavy beast. As to the rest of the post I believe most car publications and experts agree its good to blow the proverbial cobwebs out of your engine every now and then. A good full throttle romp clears carbon out of the combustion chamber and moisture out of the exhaust, etc. Plus its just good for the soul. ;)

Nice to see that you had such great results on the el camino. i assume you still have the factory Quadrajet on top. they have tiny front barrells and you can can get relatively speaking great mileage from them as long as you keep the back bores from opening up by stomping on it.


As much fun as it is at the track best way to clean carbon is via Seafoam l ike another person suggested. i wouls say that you must have more of an exhaust blockage then a carbon on the valve issue to achieve those great results. if you haven't reworked your exhaust you may want to look at your cat it may be breaking apart causing restriction.

Clean air filter, Plugs, wires, cap, rotor, a good coil and a oil change go a long way in getting you improved mileage

:thumbup: for taking it to the track and a 15.09 is not a stock time for that ride :) You should have been sporting a mid 17 in the 1/4 stock or there abouts.