Sequence of adding new parts
We would put parts into 3 categories:
1) Below $1000, mostly external work
2) Below $1000, internal parts
3) Above $1000
1) would contain carb, intake manifold, exhaust manifold, camshaft, ignition, cylinder heads
2) would contain crankshaft, connecting rods, pistons
3a) would contain blower, turbo, nitrous
3b) crate engines
On 1): Assuming current ignition and carb work fine, most bang for the buck on a V8 will be freeing up the exhaust. Stock exhausts are quiet, don’t get excessively hot and lasts forever, just what the car factories look for. But they’re restrictive, replacing them with headers produces a lot of power. Intake manifold is all about shape and design. Stock intake manifolds aim to produce most power in 1500-5000 rpm band, a good dual plane manifold moves to 2000-6500 rpm. Carb is not necessary if the stock one is working fine, but often on cars with mileage they’re dirty inside and throttle shafts are worn, making finding a good idle difficult. Ignition parts are great to add, because they create power and at the same time improves economy and drivability. The camshaft is the brain of the engine so to speak. A different profile camshaft totally changes the personality of the engine, from mild mannered to fire spitting. Heads are the most expensive in this group, and their benefit is depending on the how bad the old heads were with regards to valve size and flow characteristics in general
A suggested list could be:
-headers
-ignition
-carb
-camshaft
-intake
-heads
On 2): These would be parts that would require the engine be taken out of the car and dismantled. And these would also be parts where it wouldn’t make sense to only do some of it. If you buy and install a stronger crankshaft, you need to install stronger connecting rods and pistons, valve springs etc.. An engine is truly not stronger than it’s weakest link. These parts will in themselves not produce much power, unless the new parts change the compression ratio, they will more likely enable other parts to be installed. Using forged low compression pistons allow the use of blower and turbos, and a strong bottom end (crankshaft, connecting rods) allow the engine to go into a higher rpm band, enabling using the radical camshaft, single plane intake and large carburetor.
With these parts you probably get less fun for the buck, but you do get peace of mind, knowing that when you go to the track, you’ll also be able to drive home is definitely worth something. Besides if you want to build the absolute fastest car in town, these parts are necessary.
On 3a): Serious power! And serious risks. We’ll start with blowers: (Turbos are in principle the same but while we’ve had plenty of experience with blowers, no turbo engine yet. On the intake side they are the same, main difference is how fast the pressure comes on when flooring the pedal). A good blower actually requires up to 100 HP just to run (!), but it also produces 250-500 HP, so net it’s a serious power addition. Blowers producing up to 5 psi boost can be added without upgrading the internals like in 2), unless the engine has a compression above 10.5:1. So that’s a simple bolt on. Blowers that produce more than 5 psi require the internals to be stronger and the pistons should deliver a lower compression.
Note though that when you live with a car that has a blower on it, it’s a totally different ball game (see section Tuning with a blower), the tolerances for error in for example too early ignition, too lean mixture, too hot combustion chamber are very small. If all is tuned perfectly, a blower engine can survive and make gobs of power for many years, we’ve seen that in reality. But we’ve also seen a 7 psi blower marine big block converted to an anchor in 10 seconds because something was not adjusted right. Big gains and big risks.
Nitrous is fun to play with. It can produce just as much power as a blower and in a sense Nitrous is easier than a blower to live with, because when you don’t use it, the engine is a normal engine. We’ve run Nitrous engines, back when nobody really knew about it, and boy when you hit that button and the extra 150 HP comes in, it’s a sweet feeling. The problem with Nitrous is that it’s only there when the bottle is full and open. And it just like a carburetor has to be mixed with fuel, too little fuel and your engine will quickly melt. To avoid that see section Tuning with nitrous)
On 3b): This is the easy way. Of course you have to install it which requires tools and place to do it, but besides that. The parts are mixed as they should be from the start. And when you can buy a 620 HP Chevy big block that runs on pump gas and has warranty, then I doubt most of us could build something more powerful for the same money. So if you got the money and the will to go all the way, consider crate engines.
As mentioned these engines will have most of the right parts already installed, but they of course still have to be tuned to get all the HP they can deliver