gas saving tips?

[Gas Guzzler]

hey guys new poster here.
just wondering if you guys could give me some tips to improve my gas mileage in my vehicles.

my daily commute is around 80 miles round trip with about 70% being freeway driving.


Thanks

[theholycow]

Welcome. Which of your vehicles do you drive to work? That's quite the collection you have.

Do the cars have manual or automatic transmissions?

[Gas Guzzler]

the navigator is my wifes daily driver.

currently my daily driver is my viper. i usually drive the vette but ive got it torn apart to put in a new motor and twin turbos.

i have a set of 55lb injectors i could put on the viper instead of the 72's that are currently on it. do you think that would help any? i wouldnt think it would as when im just cruising there not going to be squirting the max amount. or maybe my thinking is wrong.


edit: there manual transmissions in the cars. i try to shift them around 2000rpm

[theholycow]

I don't think changing your injectors will affect FE (fuel economy), just maximum power. Your car's computer monitors air/fuel ratio and adjusts injector duty cycle to make it right.

Your MPG figures seem low if you're shifting at a reasonable 2000RPM, which is probably where the EPA tester shifts too. Even with moderate modifications I'd expect better than that.

I bet that Z06 will be a BEAST with the new motor!

So, some strategies for what you can do...shifting lower may help. I shift my economy car at 1200-1500 and on average I keep up with traffic (sometimes I have to back off, sometimes I have to let it run up a little higher); your torque beasts ought to be plenty fast shifting like that too, though turbochargers change the game a bit. Except when a turbo is involved, it's usually more efficient to step on the gas more at lower RPM. You'll sacrifice a little bit of engine/exhaust noise that you probably enjoy with those cars, though.

You may be able to increase your tire pressure. However, those cars tend to come with some pretty large tires, and since they're hardcore performance vehicles they may come specified with high pressure for good handling instead of the usual lowest safe pressure for comfort. Never exceed the maximum stamped on the tire sidewall, never go below the car's recommended pressure. Experiment in that range and see if anything works.

Aerodynamic modifications would be a crying shame with those cars.

A warm air intake would slightly reduce your top-end power, which I imagine is not an acceptable compromise for someone who's putting a ballsier-than-stock motor in a Z06.

I'd guess that you have custom tunes on the cars? Can you get them adjusted? The only adjustment I can think of would be aggressive DFCO (Deceleration Fuel Cut Off) that kicks in immediately and stays on until almost idle.

So, we're back to driving style. I bet those cars handle really well. Within the limits of legality, etiquette, safety, and visibility, go ahead and enjoy that handling; don't brake for turns.

Red light coming up? It might be fun to blast up to the red light in your cars and stop short, but it's a waste and doesn't get you to your desination any faster. The most efficient way to do it is, as soon as you see the red light, guess the speed you can coast to coast right through as it turns green and adjust to that speed immediately.

How do you feel about coasting in neutral with the engine on?

[Gas Guzzler]

my problem is ive built all these cars to have fun in but since i moved and have a bit longer commute id like to try and squeeze a bit more economy out of them.

i think ive got 45psi in the fronts and 18psi in the rears on the viper. the rears are drag radials.
my fuel pump controller is set to have the pump only running 1/2 the capacity it can as long as im under 2500rpm.
in 6th gear i can cruise along with traffic at around 1300rpm, i just dont get why my mileage is still so sucky though. im not sure on shutting the fuel off during coasting on the vette or viper but i do have that set up on the mustang.


I am my own tuner on all my cars and there all tuned dang near perfect. 14.7:1 a/f all the time unless throttle goes to the mat then they go to what i have set in the base fuel map which is 11.8:1.


coasting in neutral is cool with me, usually ill just clutch in though as for soem reason when i put it in the neutal and let the clutch out it wants to fast idle around 1300rpm while if i just clutch in it drops right to its 850rpm idle i have set in the tune.

im hoping the vette will be fun when its all done, it had a vortech blower on it before i decided to go with the twins. the mileage on that car didnt change 1 bit when i did the heads, cam and blower compared to when it was stock. im hoping it stays like that once the twins are on it.

[theholycow]

Hmm, tough case here.

Coasting can help, especially if you're willing to Pulse & Glide. P&G is pretty much as it sounds - you accelerate and then coast in neutral, letting the engine idle while coasting. This works especially well for me with short rolling hills; I pulse up the hill then glide down, which keeps my speed somewhat steady and avoids extreme differences in speed that would bother other traffic.

I used to have difficulty doing it on the highway (I had trouble rev-matching with my car's DBW throttle and low gears), but lately I've tried again and I'm much better at it...and it's really increased my highway fuel economy.

A more extreme technique, which is illegal in many places and only safe under certain circumstances is Engine-Off Coasting (EOC). As part of P&G or just any random time that you might coast, kill the engine - once it settles down to idle, key off and then back on. You will have a reasonable amount of power braking left, but without power steering I imagine those cars may be difficult to steer (does the Corvette have electric power steering, by any chance?). When you're ready to apply power to the road again, bump start (I can point you to instructions for doing it gently without causing much clutch wear).

I don't recommend it under most conditions, where it may be illegal, unsafe, or uncomfortable for the driver. Anything you read about on this site should be limited by those issues (as well as concerns about accelerated wear on the car and road etiquette).

[Gas Guzzler]

killing the engine is no problem. i dont think the vette has electronic power steering but id have to check on it to be sure.

most of the downside of hills where i could kill the motor are straight as an arrow so steering shouldnt be too much of an issue hehe.

i guess i could swap a different pulley on the blower and drop it down to 6psi but then again im wondering if it would really make a difference as it doesnt really get into boost until 2400rpm which im under 99% of the time when im driving to and from work.


i used to say i didnt care about gas mileage but dang my gas bills have gone through the roof since i moved out of san antonio and have to drive there everyday.

im gonna check the max i can put in the drag radials and prolly pump them up to the max. i never thought id be using a dang viper as a daily driver. i need to buy a normal car to drive everyday

[theholycow]

Straight roads don't negate the need for power steering. There's always evasive maneuvers to consider. If there's not kids or entering traffic then there's wildlife.

I thought that modern computer-controlled adjustable turbo systems will boost at almost any RPM, when the throttle is opened far?

It is pretty tough to come up with much for you to do, you've got great cars that just don't deserve to be modified for fuel economy (nor would you want to). If you're willing to drive something more efficient then go right ahead. 2010 V6 Camaro 6MT as a daily driver, maybe?

How many miles are you putting on, anyway?

[GasSavers_BEEF]

why not buy a piece of crap car. even a not so economy car from the 80s should yield you better than 15mpg and they can be had cheaply.

buddy of mine just bought a truck for 500 bucks. it runs and is perfectly legal on the road (1983 I think) he hasn't ran an entire tank in it but I think it will do pretty good for a truck.

if you were to do the same with a car (cavaliers are cheap BTW) and get better mileage and leave the drag slicks along until you want to really burn them.

[Gas Guzzler]

im putting right around 80 miles a day for my commute and the wife does about 70 a day.

my problem is that if i were go buy a say a base camaro/mustang id be inclined to start modding it.

ive been leaning towards maybe buying a new fusion as a DD since it gets decent mileage and has enough room to haul the wife and kids around if i need to.


the turbos that can boost right off idle are a variable geometry turbo, but mostly you will find them on diesels like the ford 6.0L.