Jadewombat wrote a really good detail list. I have some comments to add :
>My mileage actually improved too, this is another myth that more power
>means less mileage
I have had similar experiences. There are a couple of things affecting it:
- When you build an engine right and tune it properly, you have a chance
of optimizing the fuel burn. More power from the same amount of fuel.
- Better fuel efficiency gets the car moving with less effort. You don't need to push the pedal down as deep, to reach the SAME acceleration.
- if you USE the extra power, you use more fuel than before. If you continue driving nicely you will have better fuel economy.
It's all under your own control.
-Get a counterweighted crank(these help produce more torque)
No, it won't produce more torque. The main benefit is eliminating vibration and flexing. It adds rotating mass, therefore increasing torque and power LOSS. The heavier the moving engine and drivetrain parts are, the less power is left to turn the wheels. But it is generally acceptable to sacrifice a little bit of it to get better longevity and smoother running. Counterweighted cranks can safely be revved much higher than non-counterweighted.
-A mild camshaft(Engle 110 is recommended, a 120 is NOT for the street)
Another myth. 110 is a common street cam, but so is the 120. So is a 130. There is no limit to what cam you can drive on the street. I have now a custom made 310 degree cam on a street engine, and I have previously had a 1600cc engine with a 330+ degree cam in it. Both fully streetable, no need to rev them high to get the car moving, no overheating. It all depends on how well every other aspects of the engine are matched to each other. The longer the duration, the higher rpms it can turn, and the power peak narrows and moves higher on th erpm band. That doesn't mean it simply won't work outside of the powerband, it just isn't optimized for it. I have yet to see a 'race' cam in a street engine that I can't drive on the street, if I built the engine. They all idle at or below 1000rpms, and start pulling from there without hiccups. The bigger cams are somewhat weaker at low rpms, but still better than stock. The BIG difference is when they get 'on cam' at higher roms, and really start accelerating. The contrast is so big that most people think the engine doesn't want to run at low rpms. In reality, it works just fine. IF you built it to do so
-Straight-cut gears on the camshaft and crank(a little noisier than helical-cut, not much though, you pick up a bit of horsepower here too though)
Not enough for it to matter in a 1600 street engine. Save straight cuts for the race applications or engines with MUCH more power.
-Balance the internals(This makes everything smoother and lets the engine perform. The more power and engine puts out, the more everything HAS to be within specifications. You can match balance the weight of the rods with the pistons and clips, i.e. the lightest rod will mate up with the heaviest piston, etc. I went so far as to balance my engine for each component to within .1 gram)
Consider the lenght of the rod/piston combination. You don't want the weight centers to be different either. Match the rod caps to each other, then match the rods, then the pistons to each other with rings, pins and clips installed. That way the center of the combined weight is always at the same spot. 1-2g is perfectly fine variation for a street engine. factory rejection limit for rods is 8g. The higher you plan to rev, the closer the weights must be matched. 1g is easy to achieve at home with cheap tools and a cheap scale.
- You can also semi-hemi cut the heads and flycut them. I plan to do both next on my heads, hemi-cutting improves the combustion chamber charateristics and burn of the mixture,
Actually, that's another old myth and not very effective. It is also hard to build high compression with semi hemis. Don't do it. You want the burn to be concentrated on a small area, in the combustion chamber 'tub' where the valves are. The squish area (between the flat areas of head and piston) push the fuel towards the center, where more power can be extracted from it. Burn is less effective if it is spread out all around the edges of the cylinder. Tight deck and good squish minimizes inefficient, late burn far away from the spark.
-while flycutting raises the compression. I plan to bring the compression
on my engine up to 9.0 to 1(raising compression increases power
considerably), engine knock doesn't begin until you raise it 9.4 to 1.
That depends on the CAM, and fuel octane. Stock cam does NOT like 9.4:1, while my 330+ deg cam wouldn't run right at all with such low CR.
You MUST match the CR to the CAM, primarily.
-Lightened flywheel(this adds, or allows, the engine to produce more hp but at the cost of producing less torque by having less weight it has to spin. I don't do anything that sacrifices torque, again this is what you feel pulling you off the line.)
It reduces torque and power LOSSES, but does not make the engine produce any more. With lightened flywheel (and other moving masses)the engine doesn't need to waste power on getting a heavy 'useless' mass to turn faster, instead there's more left over to turn the wheels. But the engine in itself won't produce any more torque or power.
It wastes less power to get the flywheel accelerated to driving speed, but the engine slows down easier too. Upholding momentum is easier with a heavy flywheel, once it is at a certain speed, it likes to stay there because of momentum. It's good for maintaining steady speeds. It tries to keep the motor turning at the same speed even when you suddenly start going uphill. That kind of 'torque' is better.
For accelerating or decelerating, it responds slower. That kind of torque is weaker than with a light flywheel. A light flywheel is faster to accelerate and it doesn't slow down deceleration as much. Throttle response will be snappier.
-Install a windage tray(this is an option for you weekend racers to keep the oil from sloshing around, especially if you plan on autocrossing. Not necessary for just a street car.)
Well.. I have a windage tray and my pump still sucks air when braking hard or cornering hard. I mean HARD. But again this is a street car..
Granted, it's a bit more than your average 1600.