Starting next semester I'm going to have to drive 120 miles a day so I would like get better gas mileage. I have 3 different combos to choose from and need some advise deciding.

First
283 bored .06 ~9.2 CR
Second
305 stock ~8.7 CR
Third
350 bored .02 ~9.9 CR

All would use
Vortec heads 62cc 1.94/1.50 valves
Performer Intake
Hooker LT Headers 1 5/8th dual 2 1/2 exhaust
Holley 600 VS
CompCam XE250 for the 283/305 206/212 @ .05
CompCam XE256 for the 350 212/218 @ .05
3.73 gears with a 27.4 inch tire ~2200 RPM @ 70 mph
700R4

This will be going in a 3700 lb w/driver S10 Blazer so I understand I need some torque. From a money standpoint all three combos just need gaskets. I would like to get as close to 25 mpg as I can and still be able to run in the 14s. Currently I get 21 mpg on the highway with a 350/XE268 combo/4.10 gears.

I also have a set of #416 heads 1.84/1.50 and an Edelbrock SP2P intake manifold. Does anyone think that would provide better gas mileage with the 283 or 305? If so would it be worth the tradeoff in power?

Any suggestions or criticism would be greatly appreciated.

 

Id go for the 350 with the XE250. Might also consider some form of fuel injection if you want to get a good boost in fuel economy. 25 on the highway would be feasible, but if its all city then itll be tough. Another point is that an S10 is about as aerodynamic as a brick wall. I used one for a bit and the fuel economy with a vortec 4.3 was only so-so. Youll probably want the most torque at reasonable rpms as possible. One problem the 4.3 had was it didnt have much low end torque so Id have to give it some gas to ho at 75 or 80 mph.

 

Strictly for mileage and reasonable power I'd go with the 305 and XE250 cam. Get a QJet tuned up properly (see the site's Tech Articles) and you should hit 25 mpg on the highway with ease. Plus you can burn regular gas and save money.

 

Unless you already have the 3.73 gear in the car, I'd go higher (3.23 etc.). Top gear in modern cars gives a cruise rpm of like 1800 if I remember right. That's one important key to gas mileage.

Also, you're better off putting this combo in a more aerodynamic vehicle. The thirdgen Firebird is one of the best when it comes to low drag coefficient. That's probably the biggest factor in highway cruising mileage, next to gears/rpm.

(oh yeah, and get a good ignition too, MSD amplifier or something like that)

 

I'm not to sure the XE250 would be a big enough cam for a 350 with ~9.9CR which is why I chose the XE256. I understand FI would probably give better street/overall mileage but it's not really a route I want to take.

I really want to use the 283. My thinking is that I could try to get the CR as close to 10:1 as possible and still be able to run on 87 octane due to the shorter stroke/longer dwell time and Vortec heads. That would make up for some of the lost torque compared to the 305 and at the same time make the engine more efficient.

I already have 4.10 gears in the vehicle and a set of 3.73s in the garage so that's what I'm going to use.

 

I would throw that 14sec factor out and focus on gas. Run the 283 with a cam maybe a tad smaller than the 250, unless you have it laying around.

 

Getting a nice mix of economy and power from an engine usually requires alot of patience and very specific component choice. A 305 would be much better all around and a lower compression ratio will help keep the fuel cost down. Theres no real gain if the compression ratio is too high to run off of low grade fuel without detonation. I personally would use the 305/250 combo toped off with a qjet, I think someone also mentioned this combo above. This way with the gearing you should have plenty of tire shreading power and the ability to cruise down the highway saving enough fuel to realize the price your paying for fuel will rent you an aparment closer

 

I also vote for finding an apartment in that area. I worked with a couple of guys who commuted an hour each way every day, and they hated it. Aside from the fuel and maintenance costs of the car, it's also a waste of two hours that you have to spend sitting in the car. That's two hours that you could be working or two hours of free time.

On the engine, I also vote for the 305 with the small extreme energy cam (206/212? duration). If I remember the catalog, this one is rated from idle to 4600 rpm or so, perfect range for a 305, with good fuel economy, and should give lots of torque, especially with the longer stroke of the 305 versus the 283.

The 283 will be a better top end motor, but for low end driving and cruising, the 305 should be the better bet I'd think.

 

Another option is car pooling.
If I car pool to work, I get a discount on my insurance plus the obvious.

I vote for living closer to school. I bought a house as close to work as I could since I have to drive to work everyday.