I know this is the motor swap area but I dont know where else I would put this question.

I have a 1986 Camaro sport coupe with the 2.8 MPI and auto tranny.

Right now I get 230 to 250 highway miles to the tank and thats with a new fuel filter, plugs, wires, cap and rotar, and air filters along with fresh oil and all of that good stuff.

A lot of people have told me that the fuel injected 2.8 had a much smaller gas tank and that is why my mileage stinks and with gas prices at $1.20 I can fill it up for about 15 to 18 bucks from a quarter tank.

Soon I am droping a ZZ4 350 crate in and I am porting the heads, boring it .30 over to put forged pistons in, electric water pump, no A/C or smog, a better torque converter, NOS, and better gears in the back so it will will eat a lot more gas then the 2.8 so can I put a bigger tank in like out of a 350 IROC or will I have to get one custom made???
Thanks
David

 

Nope. Everyone got the same sized tank. There might be slight differences because the in-tank pump displaced some as opposed to a block-mounted pump or in-line pump.

Besides, carrying more fuel doesn't increase your mileage. Mileage is usually measured in miles per gallon (or kilometers per litre). That's a function of how far you can go per gallon of fuel burned. You only being able to go 230 to 250 miles highway, is called "range". e.i. how far you can go on a single tank. A bigger tank would increase your effective range, but not mileage, since that's determined by your engine/driveline's efficiency at turning chemical energy into kinetic energy (power output, transmission, gear ratio, etc.).

I'm not sure why, but a lot of the V6 guys here get the same or worse mileage as V8 guys, which is just another excuse to go to the bigger engine.

Next time you fillup, take note of the "gallons pumped" reading. If you were running on fumes when you pulled in, you should be able to squeeze 13.5 to 14.5 gallons in. The tank is rated at 15.5 gallons, but you can rarely scoop up that last gallon, nor should you, since it'll be a concentrated suspension of all the crap from the bottom of the tank. The rating also takes into account the top part of the tank, which you can't really fill with gas since most station pumps shut off as soon as it gets a little backpressure in the filler neck.

 

WOW thanks for the great info man.

I was unsure about the IROC gas tanks but at least this will save me from wasting some money
I just dont see a point in having a slow and small v-6 when I will have the same mileage with a V-8
Now that you mentioned it I do remember filling it to 13 gallons but in a week I am going back to Indiana for the summer so I will run it to under a quarter tank and check it.
David