Sunday, November 1, 2009

Engine rebuild goals and objectives

The motor in the 'runner is pretty tired. It'll hold 80 all day long (at 20mpg no less!), but the grade up Grapevine really wore it out.  It's also not what one would call fast to 60. And I'm not sure it can spin a tire in dirt (considering they're 215 street tires, this is a sad, sad day).

Before starting an engine rebuild, you have to decide what's important. All out power? Economy? Cost? Pick any two. Ok, maybe just one!

In my case, I don't need all-out power (I have other vehicles, one of which will pull a sub-3-second 0-60). But it does need to run good. I don't expect 40mpg, but mid-20s would be very nice. I don't want to have to run premium gas, except when I want to (e.g. when I turn the PSI up on the turbo). And I have a lot of expensive things to do to the truck (long travel kit, dual tcases, convert to 5 speed, fix the AC, etc.)

So, in a nutshell I wanted a reliable engine that puts out decent power, over 200hp, and which delivers decent mileage.

Impossible? After all, in the 80s, it took at least 5.0 liters to deliver 200hp (Mustang).

Consider this - My '95 BMW M3 puts out a rated 240hp and gets 28mpg on the highway (23 mixed). The guys with slightly newer automatic and 6-speed versions (overdrives) are seeing 32mpg on the highway. It does, however, need premium. 87 octane reduces the mpg, and power has a big flat spot in the middle. I can live with running premium though (with 125K miles, I certainly have enjoyed living with it!).

The M3 is a 3.0 liter six, the 4Runner a 2.4 liter four. Certainly there are some key design objective differences BMW and Toyota faced, such as one is in a truck designed to make torque, the other is in a sports sedan.

BUT - back in the mid-90s, European companies were scared of US litigation, so we got extremely watered down versions of their sports cars.

How watered down? The Euro M3 3.0 liter engine puts out 321hp vs mine's 240hp. Pretty watered down. Even so, the motor in my M3 is a dream to drive. It pulls all the way through redline, is torquey, and very responsive. And dyno runs show these cars might be underrated a bit. Fun, fun, fun!!

So... rebuild the motor myself, or have someone do it?

Now that's a dilemma. More on that soon!

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