Is it possible to gain 350 hp 400 ft lbs of torque and have 20 mpg?(With a carb?)

I know with the LS engine family it would be possible but I don't have the money to sink into it to have it done RIGHT and not to mention it would take me years to get it done...

With that said I know I do want a T-56 so I am sure that can help with the mpg and I know the rear end ratio will also play a major factor so I wouldn't want anything outrageous. Maybe 3:23 or at most 3:73 although I am almost sure that would defeat my mpg.

While I like the ZZ4 cause its the exact power I am looking for I don't know how much gas it would drink and all the searches I have found look to be 16 at the most.

I would really like to go to carb simply because I have read and read how to burn chips for my TBI and I still am completely lost. I have done quite a few searches and read the thread on 20mpg carbs on this but couldn't get any good opinions with the specific amount of power I am looking for and all so feel free to throw your ideas out.

Now here comes the phrase that don't go together...

I would like to do this as easy as possible without breaking the bank haha

 

Some years ago Hot Rod magazine bought an '82 Camaro, and did the following to it: '91-'92 ground effects, ZZ4 crate engine, Edelbrock headers for '89-'92 dual-cat TPI 350, 700R-4, 3.42:1, 245/50R16s on 16x8s, and a few detail items, but they got 22 mpg. Based on a similar build of my own, I'm inclined to believe it. You may still be able to find the info somewhere on their website.

 

System: '86 LG4. Carb rebuilt, DR rods and H hanger, otherwise stock. Stock distributor with Accel Supercoil and 7-pin ignition module. Otherwise stock.

Engine: ZZ3 shortblock rebuilt .030" over with Speedpro 12cc dish pistons, moly rings. Stock ZZ3 crank. ZZ4 cam, intake, oil pan & oil pump. Self-ported World S/R Torquer 305 heads with 1.94"/1.50" valves, "Z28" valve springs.

Transmission: Rebuilt '83 TH700R-4, shift kit, 2500 RPM restalled converter.

Gears: 3.23 posi.

Tires: 235 - 60 x 14 on Berlinetta rims.

MPG: 22 highway (recent 350 mile one-way trip, average both directions, done twice in the last month).

 

Its very possible. Head design is the key - you want heads with the most efficient chamber design you can get. This is why the LT1 and LS1 guys can make that much power, or more, and get incredible fuel mileage too.

This is the build I would suggest for a Gen 1 350ci:

- '87+ roller cam 350ci block
- LT4 hotcam (or other hydraulic roller cam of similar specs)
- 906/062 Vortec, or 180cc/195cc AFR Eliminator CNC ported cylinder heads
- Flat top pistons/head gasket to get compression in the 10.25-10.50 range
- High rise dual plane intake (Weiand Stealth or Edelbrock RPM would be good choices)
* an intake that allows to keep EGR will help fuel mileage with no effect on performance*
- 1-5/8" or 1.75" headers and free flowing catback.
- Accurate, high powered ignition system, like the MSD Pro Billet dissy and matching coil and box.
- Holley 3310 (750 vac sec 4160) or Quadrajet.

You also have to match the rest of the car to the engine though too... match up the converter stall speed, rear end gears, etc. For the above engine or something similar, I'd suggest a 3.23 or 3.42 gear set.

 

Yeah I have been debating on whether or not to go for crate engine or to build. I have also been looking at alot of other crate engines to get an idea of the cost for the power I am looking for. I wont be doing any swaps for a while (156,xxx and still running strong knock on wood) but I want to have all the details planed out ahead of time to be prepared.

 

Just remember that GOOD heads are the key... the more modern head design you use, the easier it will be to reach the power/economy goals you set. Once you have a basic shortblock bought/built, spend the money for GOOD heads, the best you can get, and go from there.