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Supercharging is really easy --no black art involved, however other avenues should be explored first, if only for cost purposes. I have no wish to explain the obvious to you or teach you to “suck eggs” but for this to make sense and be useful to other people who may read this i have to include some basics.
Here we go
using your 502, or any other engine some questions need to be answered before you can choose your configuration, or more to the point is just rebuilding your motor with performance parts to gain horsepower a more sensible way to go.
My background on engines is from drag racing-- all it has to do is fire up and run long enough to get it down the quarter mile, it can be rebuilt during rounds. You i imagine would like a reliable powerful engine that requires minimum maintenance.
Before we address superchargers which require a purpose built engine, the performance capability of bolt on or in components to your engine should be entertained, certainly for reliability.
Let’s take a stock 502 and assume the crankshaft is a heavy duty one (most are the 502 is based on a truck engine) and it has four bolt main caps --four bolts per bearing on the crankshaft, if your engine does not it is not a problem as it can be easily modified and regardless of which way you go this is a must-- the last thing you want is a big bang in the cylinders and the crankshaft removing itself from the bottom of the engine.
Again let’s assume the piston rings and cylinder bore are in good shape.
Now we can start to play or spend money dependant on your outlook.
Basically the more fuel and air you can get into the cylinder (there is no substitute for cubic inches!!)And ignite it, the more power you get.
It would be great if you could just bolt on a huge carb, small problem tho -- fuel rich does not burn explosively --air in is the key (and exhaust out but that comes later). Proper fuel/ Air supply to the engine is primarily governed by the intake manifold as this “feeds” the engine. What we really need to happen here is a good mix of fuel and air delivered to the engine but keeping the airflow as smooth as possible, to achieve this distance is required between the carb (air /fuel intake) and the cylinders, a good after market manifold helps, start thinking of an rpm or similar from edelbrock or a tunnel ram style from other suppliers.
You now have a good smooth fuel air mixture heading for the business end of the engine, here we have a few problems that need to be resolved. The way in to the engine is via the cylinder head, now unless you are going to buy some race cylinder heads (mega bucks) you need to get theses “ported” there is no point having a great fuel air flow thru the carb and manifold if you are going to mess it up at the intake point. “porting” is basically machining the intake and exhaust holes “ports” to maintain a smooth flow of your fuel air mix.
The next thing that your fuel air arrives at is the intake valve, common sense hear dictates that if it is bigger it will offer less resistance to the air flow, big valves are good, but the valve has to be open long enough to get a good charge into the cylinder, this is where the dark art of camshaft choice comes to play, it controls how much the valve will open and for how long, utopia would dictate that it is maximum open when the cylinder starts on its down stroke and immediately closes when the piston reaches the end of its travel (suction) this is where fuel injection become vastly superior to carburetion
We now have a quality “charge” within the cylinder. Horsepower is how big the bang is, the bang forces the piston back down once compressed and ignited. The bigger spark and more powerful spark you can supply to the spark plugs is a key point, you need to set fire to all the stuff you have in the cylinder quickly, think of a 20w light bulb versus a 150w bulb.
To keep the engines rhythm waste gas has to be expelled easily or the engine will rob power pushing the exhaust gases out, the same principle applies here as to the intake, smooth in and smooth out.
With all of the guff above taken into account it is easy to take your standard 502 engine rated at around 400-450bhp to upwards of 750bhp while still maintaining a rev limiting reliability of around 5400-5600 rpm, should you wish to alter the piston shape and turn it into a high compression engine 850-900bhp can be achieved but at cost of reliability---she will blow up eventually!!!
As we are talking petrol engines (diesel is a whole different ball game) supercharging can be a real good hit in the horsepower league,however the engine needs to be built to suit – you can not-i repeat can not just bolt on a supercharger.
A supercharger is a pump, forcing air/fuel into the cylinder “super charging” trebling if not more the fuel air volume that a carb engine would ingest, a low compression engine needs to be built to take account of the extra air that is being squeezed during compression, a standard engine will basically detonate into a multitude of parts. If you add in the longevity of the extra parts (think drive belts to the supercharger, yes mechanical ones are available but the same applies) if the drive fails no engine no power, the engine can not aquire air.
Putting the negatives to one side tho, a well built 502 supercharged engine is well capable of turning out in excess of 1500bhp, its life time however is limited, i am talking using the 6v or 8v 71 truck superchargers tho, i have no doubt that messrs whipple will have a bolt on unit should you wish.
The fact remains certainly in the drag race arena reliable engines are carburated or fuel injected, add some extra wind and things go “mammary upwards” at the most inconvenient moment.
I love building engines, should you want something built to your spec , no problem, just remember that boat engines sit at max rpm most of the time, if it can break it will, the more simple you keep it the less that can go wrong. All things change tho if you can afford to replace or rebuild the engines on a regular basis (race to race).
Hope this helps
Budweiser
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