Quote:
Originally Posted by milo9
it is a 4.2L engine that evolved from an old Chevy tractor design, low compression, good low end torque.
|
Although counter-intuitive, I'd advise you to install a turbocharger on your engine: a small turbo would spool up since lower rpm's and would increase the engine efficiency by compensating on the standard low compression ratio and increasing torque on the low end.
See, any Diesel-powered car/truck nowadays comes with an OEM turbocharger - because of the increased efficiency and better fuel economy. Gasoline-powered vehicles (at least in Europe) are going the same way: anyone seen the Abarth edition of the Fiat 500? It uses a turbocharged 1.4L engine that outputs 162hp AND still makes 28/34mpg.
I can't tell which one should you use, but as a rule of thumb, for selecting a turbocharger you should aim for the output on hp, not size of engine. Since you probably don't want to go past the standard ~200hp your SUV does, you could use a very small OEM turbine (like that from the 1.8L Audi/VW's) that spools early and gives you plenty of torque for overcoming hills at slower rpm's, while keeping the engine on it's preferred FE rpm range.
Of course, as mentioned before, proper timing and increased fuel injection for "un-leaning" the extra air coming in is mandatory. Too lean burn or too much knock = heat on the piston heads which can eventually melt them.