Quote:
Originally Posted by Ecky
I'd be concerned about the 4's torque - it would require a different rear-end, and likely there isn't a 4 that bolts up to the existing transmission. A modern 6 can out-torque an older V8. But, it's certainly worth considering. A 4 is far more efficient than a V6.
I'd be concerned that a V8 with a bank removed (or even just two cylinders at the end) would have terrible balance and would vibrate a lot.
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I think there are two things to consider.
- What is the intended purpose of the vehicle (not everything needs a lot of power and torque)
- What is possible with a 4 cylinder? There are 3 cylinder engines now with over 300hp (I think there's one with 600hp IIRC). I'm sure getting 150 or 200hp out of a 4 cylinder is perfectly possible. But could you get that and better fuel mileage and not cost a lot?
The V8 to 4 cylinder idea would require a lot of work, that's for sure. For one you couldn't use a crossplane crank, you'd have to use a flatplane crank. And yes, even then the thing would not be balanced for only 4 cylinders.
Quote:
Originally Posted by Solarpowered
I actually have some experience with extrude honing, and it's got nothing on plain old hand porting. Extrude honing is a very expensive service and the process doesn't remove a lot of material. Forcing a media thru a port/runner is not going to re-shape the port/runner for better average flow as if you were hand porting it. The media removes more material in areas of high flow better than areas of low flow which is not effective when compared to hand porting. At best, extrude honing can save a bit of time for the hand porter. But he's still going to have to go back in and get everything that extrude honing missed, which will be quite a lot.
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And there's no need to port. Just as was said that you want small (but long) exhaust primaries, you want small (but long, if possible) intake runners. The same with exhaust and intake ports.
Intakes and exhausts are not an "open it up and you get better flow" type system, although the majority of people seem to think so. Air, fuel and exhaust are constantly speeding up and then being forced to stop. This creates pressure waves (harmonics) that bounce back down the runners to the plenum and then come back. If things are way off, including too big, you actually get less flow in and out of the engine. The lower the RPM target, the longer and narrower the intake and exhaust should be.
Nice smooth intake ports can also lead to more fuel condensating and accumulating on the port walls. A rough surface should, in theory, help keep more fuel in the air.