engine choice

hello all ,new member .soliciting input .we are building a 74 gremlin for my currently 15 yr old son . the enormous 232 six is on the lift cart having been pulled after 192,000 miles . since gas shot up the six is not my first choice anymore.so i have considered 4 cylinder or newer v6 engines . it needs to get good mileage ,over 30mpg highway. car is light 2,400 lbs rear drive .was an auto but i want manual 5 spd. choices 2.3 turbo ford 5spd,2.5 amc/gm 4 cyl,v6 sho ford ,volvo 2.0, and maybe 215 buick aluminum v8 2 barrel. any suggestions or experiances.I do have an 87 maserati biturbo v6 in my garage but it is too powerful for the boy to have ,that goes in my next project,caterham,locost,spitfire,gt6,alpine,datsun roadster,still thinking about it .any help appreciated. regards jeff

Hmmm. I don't think 30 mpg is attainable in that car while still having adequate power. Mid to upper 20s is reasonable. Touching 30 would be a challenge. Exceeding that...good luck. I'm curious what the mpg was with the 232. The autobox probably hurt it the most. You'll also want to check the rear axle ratio. The Gremlin is going to be limited by it's aerodynamics.

My peripheral experiences with many of your choices would also say you're not heading down the right path. The Ford 2.3 does not get tremendous mileage, even without the turbo. It is a heavy engine, for one thing. The 2.5 GM Iron Duke is an outdated pig of a 4 cylinder. You need only look at the abysmal mileage of Jeeps equipped with it to get an idea of what you might expect (and that's with modern fuel injection).

Decent economy is attainable in a car of that weight. BMW manages to do it quite well with the 2.7 eta six found in the E30 as well as the 318i engines. Hondas are the mileage leaders while still providing good power. RWD can be had with either a CRV or S2000 transmission.

Consider again the gearing...look at the amazing highway mileage a late model Corvette can accomplish with 400+ hp. But, remember the cd will be low on that also. The frontal area of a Gremlin will never be slippery. I think you need to look at quite a few more alternative powerplants, consider the difficulty of installation, and then weigh that against just how awful a simple AMC six would be (which you could have on the road in short order). BTW, my American car book pegs the Gremlin six's weight at 2855 lbs for 1974, 400 more lbs than your estimate.