MasonsGTA

How to

KG427KG427

iTrader: (1)

What can you do to get better gas mileage on a stock l98 5.7 automatic?

I need a new complete exhaust what should I get?

And what cam should I get for better gas mileage?

What else can I do ?!

Convoy25

iTrader: (3)

Biggest thing is don't floor it, you don't need to be the first person across the intersection.

Make sure everything is tuned up, its running well.

Do you do more city or highway driving?

KG427KG427

iTrader: (1)

Freeway driving 65 miles a day. What exhaust set up should I get?

Cam?
Heads?
Intake?

Convoy25

iTrader: (3)

an exhaust really isn't going to help you get better fuel economy, power yes.

Engine mods you can do are electric fans, maybe an underdrive pulley. There isn't one mod thats going to give you 2,3,4 MPG.

The mods that will help the most are aerodynamic mods, and weight reduction mods. Fiberglass hood, aluminum pieces over steel. getting rid of the back seats. every 100 pounds affects fuel economy by 1-2%.

aerodynamic mods, headlight covers, partial grille block, lowering the vehicle. A belly pan could help as well.

you could also swap in a 5 or 6 speed, and get taller (lower numerically) gears.

KG427KG427

iTrader: (1)

True could take my back seats out and lower my car.. I need a new exhaust what would u suggest ?

Atilla the Fun

RamJet 350 cam, swap your 3.42:1 axle for 3.08:1, slow down, be sure the rear isn't sitting lower than the front, switch to 225/55R16 tires. If that doesn't get you 27 MPG @ 60 MPH, then there's a problem with the computer / injection / electronics stuff.

Convoy25

iTrader: (3)

you have a 305 or 350 now? if you do and you plan on swapping it out i wouldn't bother with headers and a y pipe, just get a cat back that you can reuse. Hooker and Magnaflow seem to be decent.

Tom 400 CFI

All of the 'Tuning'/set up of a car possible can be blown out of the water, by stupid driving. Llikewise, thoughful driving can make even a gas sucking sow, be frugal. When I had my TA, (305CFI/T5/3.23) it got 24mpg hwy. When I sold it (400CFI/T5/3.45), it got a high of 25mpg hwy. Same conditions same driving. So I don't personally feel that "305/tall gears" etc. those types of changes make meaningful differences. They make differences, but I feel that they are marginal differences...and easily obliterated by driving style.

So what about driving style? How impactful can that be towards savings? Huge. Here are my vehicles and their current hand-calc'ed results:
'88 Acura Integra: (EPA hwy rating = 31) 40.3 - 40.9 mpg
'96 Silverado xcab/shortbed/350/4x4: (EPA hwy rating = 19) 23.5 mpg, last tank.
'92 Corvette (stock): (EPA hwy rating = 24) 31.2, last trip.
'05 CST-V: (EPA hwy rating = 21) 29.9 last time I drove it. Wife gets about 24.

So driving is really where the "money" is at, for improving fuel economy. You can make significant and meaningful improvements there, and the "mod", costs you nothing. Obviously, if there is something wrong with your vehicle, that needs to be repaired to obtain efficient/normal running. But performing "mods" to improve fuel economy is almost always a money-losing proposition. Drive smarter. What is "smarter"?
*Don't use your brakes
*Don't use your gas
*Smoooooooooth everything
*Draft
*Shut the engine down when not needed
*Drop your average speed.
*Don't use cruise control (unless you're a terrible driver...then it can help)
*RPM = heat/friction, waste. Run it like its a diesel.
^A few to get you started. Basically, pay attention to what you're doing.

Tom 400 CFI

Sorry, I feel that there is more to say here. TO underscore the point made above, let's look at an example. I think it's fair to say that most decent running V8 F-bods get low-mid 20's for gas mileage I'll use 24 mpg since 4 of my F-bods got that. Let's take that typical car and add some things that "typically improve fuel mileage"; UD pullies ($250), Exhaust ($300), K&N filter ($50), roller rockers($250), and gears($400+install). What does that cost us? In this example, we're looking at ~$1300.00. What improvement are we going to see? In MY experience, basically none. But averaged out across many users, maybe we see a 2-3 mpg improvement. That is optimistic I feel, but lets say 3 mpg.

At three mpg, you're going to have to drive ~12,000 miles, or about a year, before you save a penny.

Atilla suggested a roller cam ($250), gears ($400 +install), and tires ($600). Again, we're looking at ~$1300 for a ~3mpg improvement?

HOW TO GET BETTER MPG's; take the money that you'd spend modding your car for better mpg's and spend it on an '80's econobox like the Acura I bought two months ago, for $1000 (I'm actually partial to Civic HF's and VW Golf's from the '80's but couldn't find any around here). Compared to my truck, the Acura will pay for itself in gasoline alone, in 5 months. Compared to the 'Vette, 12 months. That doesn't include tires (14" tires are cheap), brakes, 4 qts of crap oil compared to 6 qts of synthetic...and on and on. If you want to "economize", take your "mod money", buy a ****-box and save your fun car, for fun.

TreeFiddy

Type of driving plays a big part too. Spend as much time cruising in OD as you can, to get the maximum miles per rpm.

My work situation changed about 6 months ago, and I'm no longer driving across the city every day and using the relatively fast ring-roads and freeway sections. I'm mainly hanging locally now in a stop-light suburban area that has 40-50 km/h limits (25-35 mph) for many miles around, so daily OD and often 3rd is a pretty much a thing of the past.

Fuel consumption has gone up 30-40%. Then again I'm going nowhere near as far, so it's way longer between fills.

KG427KG427

iTrader: (1)

In my old 3.1 Liter v6 engine I would milk it and I could only get like 29mpg and I had new fuel injectors and spark plugs / wires caps. With a 3.08.

So I will be happy if I can get 25 with the 5.7