There are several ways of making free horsepower on most older cars. In the older days, before EFI and high output ignition systems we used to shut the alternator off. When an alternator "energizes" and begins charging, it loads down and can suck up about 10 to 15 horsepower. Don't believe me? Fine. Just listen to your engine lug down 100 RPM or so when you hook-up some jumper cables to jump start a friend with a dead battery. That my friend's is the alternator lugging the engine down under a load. Just how much power do you think it takes to force an engine to drop in idle 100 or so RPM?
If you are racing at night with your headlights on, the electric fan on, or your battery is a little low... then your engine is being put through the same "load" as trying to jump start someone with a low battery while you're racing down the track. You can gain this HP back by simply installing a switch in the "field" wire to shut it off. The field supplies the alternator with electricity which energizes it, or basically, "turns it on". Alternators need electricity to work, unlike old generators, so if you don't allow this field wire to energize the alternator, then you've gained a few more ponies. To do this though, you MUST turn the engine off first and make sure the key is off when the alternator kill switch is turned off, otherwise the alternator will NOT "de-energize" if the engine is already running. Once the engine's running and you want to re-energize the alternator, simply flip the switch while you're driving and it instantly turns-on.
Now, (as I stated above), a BIG down side to this is if you have a high energy ignition system, ESPECIALLY something like an MSD box, and/or an EFI system! Those boxes and EFI injectors, the ECU, and high pressure pumps need full power to function properly. If you try this alternator trick when you have anything other than an old points type ignition system and a carburetor you'll end up LOSING power because the poor ignition and EFI system isn't going to like it. The battery alone is barely enough to run an MSD system. You REALLY need the additional current and voltage from the charging system if you are running these. I said this was free horsepower, I didn't say it would be a great idea for all vehicles :-)
Side gapping your spark plugs is another way to make a few horsepower. What is side gapping you ask? When you look at a typical spark plug, the ground strap covers the entire center electrode, such as what you see with the plug on the left. This is fine for 99.9% of the vehicles out there, but that full length strap covers, or "shrouds", the spark and initial flame travel. By taking a fine grinder or a good file to that ground strap and removing about .025" or so of material from the very end of it makes the ground strap only cover about half of that center electrode, such as what you see with the plug on the right. Now the spark is more exposed to the open cylinder and chamber which promotes better flame travel rather than shrouding it. Believe it or not, this is worth a few horsepower.
Indexing your spark plugs is another way of gaining you a few extra horsepower. The object is to get the open-end of the gap facing the intake valve, or at least facing the open area of the cylinder. If a spark plug's ground strap is facing the intake valve or the cylinder, it shrouds the spark and blocks the flame travel, which impairs the burn path, causing a loss in power. By facing the open end of the gap towards the intake valve, it faces the open-air spark right at that fuel charge and promotes a better burn. It can be a 6 - 8 horsepower difference in some engines by indexing the plugs. Index a set of side gapped plugs and instead of a 6 - 8 HP gain, you just made an additional 10 - 12 HP gain (in many cases)... for free. Little things like this is what makes one guy faster (or quicker) than the others. It all adds-up! You can click the image to the right to enlarge it to see what a decently indexed plug looks like.
Another thing you can do is to not run a high volume oil pump. Most street and street / strip guys believe you just HAVE to run a high volume oil pump. The reality is, you don't! Standard oil pumps pump plenty of oil and have plenty of pressure to support most mild performance engines up to 6,000 RPM. By installing a high volume oil pump you increase the drag on the engine while it is trying to turn that pump to push that additional oil which robs you of power you didn't need to lose. Also, try running a thinner oil. Most guys run too thick of an oil in their performance engines anyway. Thicker oil is harder to pump through the engine and requires more power, much like trying to blow a mouthful of milkshake through a straw is harder to do than blowing a mouthful of water through a straw. Instead of running something like a 20w-50, try a 10w-40 or something. And remember; it's the first number that indicates the thickness of the oil, not the second. The second number just shows what viscosity equivalent it'll have when it's at running temperature. It doesn't mean that a 20w-50 oil is 20 weight when it's cold and 50 weight when it's hot. ALL oil thins down when it's hot, so how could it become a higher (thicker) weight after it thins down? It can't, BUT it can have the protective viscosity of a thicker oil when it's hot, which is why there are straight weights and multi weight oils. Multi weight oils change "viscosity" protection, not their weights. Besides, a thinner oil gets to where it needs to go quicker upon start-up and when the engine is cold, so it'll help keep the wear and tear that you get with thicker oils down as well.
Another way to gain a substantial amount of power is to remove your power steering pump and convert your car over to manual steering. I don't recommend this for daily drivers because the steering will become harder. Most stock power steering pumps can easily suck-up 20 to 30 horsepower. Don't believe me? Turn your steering wheel side to side while your engine is idling and hear the idle drop a hundred or so RPM. How much horsepower do you think it takes to lug your engine down that far? Yeah... about 20 or 30. So you say you aren't "steering" while you're driving down the drag strip? Well, every time your car gets squirrelly off the line, you have to "correct" it by steering, and there went 20 to 30 horsepower. If your car doesn't get squirrelly, maybe you should call us and order a BAD-ASS Engine and then you’ll be fish tailing! LOL
Another way of gaining about 8 to 10 HP is by draining about 1 quart of oil out of your oil pan. Most cranks dip into the oil a little which is why windage trays and crank scrapers work so well and get you more power at RPM. They keep the oil away from the crank which makes less drag. When the engine is full of oil, it is like wading through knee deep water. Try to run while in knee deep water. It isn’t that easy because of the drag the water puts on your body. When you drain out 1 quart, this makes the crank less deep in the oil as it spins. It’s now like walking in ankle deep water. Try to run now, it’s a LOT easier than it was when it was knee deep, right? Well the same principals are at work here as well and will make you free power. Again, switching to a slightly thinner oil is another way of gaining power because it puts less drag on the crank as it dips through it in the pan as well as makes the oil pump spin easier and much more free which in turn, takes less power to spin.
TIMING! Making sure your timing is at its optimum is absolutely KEY for an engine to make the most power it can possibly make. Not just where the timing is set, but just as importantly, WHEN that timing (advance) comes-in, and 90% of the time guys have it all wrong. Most engines like around 36 degrees of "total advance". Total advance is your base timing + your mechanical advance in the distributor. if your base timing is 10 degrees and you have 20 degrees of mechanical advance in your distributor, then your total timing will end-up being 30 degrees, which isn't enough. An engine that doesn't have its full timing (between 34 - 38 degrees 99% of the time) it will be sluggish, will have low idle vacuum, will run warm and it won't have good throttle response to get it up and off the line hard. Too much timing however will cause detonation, and that's NEVER a good thing so stay away from that. Always remember, detonation (pinging) happens WAY before you hear it, so for you guys who say you can time an engine by advancing the timing until you HEAR it ping and then back it off a couple of degrees, you very possibly might still have detonation going on in the cylinders which not only loses a great amount of power, it changes the "push" on the piston to a hammer-like smack on the piston, which usually blows head gaskets and can easily damage or break pistons, hammer the upper rod bearings, beat-up main bearings, etc. Just know that a typical performance engine can lose anywhere from 10 to upwards of 40 or more horsepower by only being ONE degree of timing off! I have dynod race engines over the years where ONE degree of timing made as much as a 50 (FIFTY) horsepower difference! Obviously most of you won't have that experience, but a 10 - 25 or so HP difference for every degree of timing (in the critical area close to 36 degrees of total) IS common on typical high performance engines, so if your engine isn;t timed right where it needs to be, you just might have anywhere from 10 to upwards of 50 or more horsepower hidden in just your timing. WHEN that timing comes-in is every bit as important! You need advance to get the engine going. In other words, you need ful advance by about 2,500 RPM. Most distributors (including ALL MSD's and other aftermarket distributors) come out of the box with the complete OPPOSITE for what you want as far as performance timing. This is why you get in the box with your new distributor a set of springs and bushings to "re-curve" your new distributor. They don't sell them that way for "safety" or rather "warranty" reasons. They leave that up to you. Most distributors don't give you full mechanical advance until upwards of 4,500 RPM or more. By that time it's WAY too late! Your engine will be a slug until it gets full advance, so you want it as soon as you can get it (within reason), which in most cases is right around 2,200 - 2,500 RPM. having full advance at low RPM gets that engine to react and launch! This is one of the reasons why race distributors are "locked-out" and have no mechanical advance in them at all. I go into much more detail on timing an engine, as well as "total timing" in a Tech Tip titled "Where Should I Set The Timing On My Performance Engine? So be sure to check that one out.
And lastly, your air/fuel ratio. We hear a lot about "tuning" these days with EFI cars and how much more power they are able to get out of them with an optimal tune. The only thing you can really "tune" on something like that is the fuel delivery and the timing. By being able to maintain a perfect air/fuel ratio and optimum timing throughout the RPM and load range is KEY for your engine making the most "free" horsepower it can make. It's harder to do with a carburetor than EFI because you don't have as much control or as many ways of monitoring the A/F ratio, or the timing, over a spectrum of RPM and loads.
We always hear the guys bragging that their engine is SO powerful it only gets 4 or 5 miles per gallon. I always have to laugh at that because what it's telling me is that it's a complete MESS of a tune and for sure a complete TURD of an engine because it is running way too rich. Too much fuel in pretty much ANYTHING is never good. Internal combustion makes that even worse! Get a good camp fire going. Now toss a half dozen logs onto it. It smothers it and it'll start to smoke and will take a while for it all to catch and start putting-off heat (energy) again because you put too much fuel on it. Your engine isn't much different except that the burn is captured inside a void, so air and fuel are REAL critical, and combustion will only take place within a VERY narrow window of fuel and air. Too much fuel doesn't burn very well, not to mention the fact that you are probably washing down your cylinder walls with raw, unburned fuel which causes piston skirt and cylinder wall scuffing, and the rings to not seal. Too much air makes a lean burn which is like adding oxygen to an Oxy-Acetylene torch. The fuel (Acetylene) burns yellow and warm. Add oxygen and it goes from a warm yellow flame to a super hot blue flame that'll cut steel with no effort. Not ideal to have inside your engine! By having the right A/F ratio it frees-up horsepower you didn't even know you had. This is why good tuners can get that extra power out of an engine. Trust me, getting 4 or 5 miles per gallon in almost ANY street car is nothing to brag about. 1,000+ HP blown big blocks get better mileage than that, so for guys who have small blocks, or 600 HP or less big blocks who get 4, 5 or 6 MPG, your tune is WAY off and your power is WAY down! You can get some free horsepower by spending some time on getting a better tune!
A shameless plug: If you'd like to learn more about this kind of stuff, in great detail, be sure to check out our Auto Shop Videos by clicking HERE
Show your love and support by sportin' a cool Bad Ass Cars T shirt! Click HERE