Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
Re: HP or MPG and what would you do?
Since you asked... I'd do an MT15, shift at 5500, and call it good. The stock valvetrain isn't THAT bad. But that's only because I don't do a whole lot of highway driving.
Since you seem to, the MT3 and cyl. deactivation doesn't seem like a bad idea at all. Although I gotta say you're almost assurredly going to fall short of 25mpg. In my 95 ETC, which is 3800lbs, sequential injected, much more aerodynamic, and about a Honda short of your displacement, I get about 27-28 doing 70mph. Adding a couple hundred pounds, a brick wall nose, over a Honda worth of displacement, a carb, that's going to cost more than 2-3mpg.
The MT15 on stock valvetrain? I was told I would run into problems if I wanted to use the MT10 on the stock valvetrain....
With the 2.28 gears, I think the MT3 would actually greatly improve the driveability and assumed power of the car in day-to-day life.
The 25mpg was just a quick guesstimate.... really even if I got a sloid 22mpg, that is still pretty darn good for the car.... free miles on the highway is how I see it.
Still pondering the idea... we just got the AC working, but now all that will have to be done over since the condensor would have to come out... not looking forward to that.... I just don't know if it is worth my time, it isn't like I drive all over everyday.... but it would be nice until I build up a 500 for the car.
Well, the problem with doing any exhuast on the 425, is it would be a waste in general, since I would be doing it again the future for the larger, more built 500.... which is why I don't really want to do a whole nice dual exhaust on the car right now.
If I could go big enough on the 425 that would still be good for the 500, then maybe I would.