Performance Myths...

[Jonathan]

The more I look at the ridiculous claims from the performance parts camp, the more I feel like debunking some of the typical myths spread about the car performance arena. Import builders, you are the most susceptable to these false claims, mainly because the import trend makes you the current target of the aftermarket. I'll start with a couple:

1. Virtually any exposed open air filter, or any kit designed to give you big power gains from such a setup. The "restrictive" stock plastic box pulls relatively cool air from outside the shock towers. To solve this "horribly restrictive box", we put an open filter in the middle of the engine compartment so it can suck 200+ degrees worth of header, engine, and radiator heated air. Do you think that for the last 20 years manufacturers would waste the money to manufacture a plastic box if it weren't necessary? A ten degree increase in temperature loses one horsepower. You can be assured that any "proven" dyno runs with these kits did so with an engine compartment that's cooled down enough to avoid revealing the truth. The rest is in perception, the open intake is louder, which may make it "seem" faster. A 10hp increase (assuming they actually provided it) isn't really seat of the pants unless you're driving a car without any power to start with. But even in that case, one of these intakes will be even worse on a transverse 4 cylinder car since the intake is that much closer to the exhaust header.

2: High horsepower ignition systems. A "hotter" spark is NOT going to give you more horsepower or better gas mileage unless the car is misfiring to begin with. With most every engine, you could light the compressed mixture with a match should you wish to do so. Keep in mind I'm not referring to ignition consistency, a proper timing curve, or anything along the lines of proper tuning. Just the fact that a street car isn't going to gain anything from a 50,000 volt ignition coil if it isn't having problems to begin with.

3: More of a point than a specific problem, in reference to the newest vehicles.

Upgrading the heads, camshaft, induction and exhaust on an older small block or big block will result in huge power gains. With a newer vehicle, which benefits from computer aided design, flow testing, and more emphasis on power and efficiency than in the past, you won't experience anywhere near that degree of a performance gain because the stock stuff doesn't have as far to go. That isn't really the problem. The problem is that there are established "typical" gains that you'll get from these upgrades on an older engine. For example, it's typical to see a 50-100hp gain with a head and induction swap on an older small block V8. The aftermarket would like you to believe (and will/does claim) that you'll experience the same from your newer, more sophisticated performance vehicle, which isn't true by any means

On a more specific note, performance mufflers leave little to be gained unless you're upgrading the entire exhaust system (from the header all the way back). The catalytic converter(s) will restrict more than a muffler will ever dream of, with the header being second worst. Point: Better to have a slow vehicle than a slow obnoxious one. Leave the fart cannons on the shelf and let somebody sleep in peace.

Most induction upgrades aren't going to amount to much of anything by themselves. Shift the powerband around, sure, but in terms of average power there is little to be gained until you work the heads over. The cylinder head is still the biggest restrictor in every engine.

The reason that so many manufacturers are looking to power adders for their performance vehicles is because that's where the performance is to be had. Manufacturers are already reaching the limitations of the power they can make while being streetable (and emissions legal), so power adders (superchargers, turbos) are naturally the next step up.

4: Horsepower. Not a bad thing, but often misused in order to wow a potential customer/victim.

Horsepower is calculated from torque and RPM. Increase either (or both), and you increase your horsepower. Point is that most upgrades aren't really giving you more power (torque). Most just shift power to a higher RPM range. That isn't a bad thing, but you need to have power where you can use it. Before you buy, look at the torque curve. In many cases more horsepower doesn't equal an increase in speed. More times than not it's done incorrectly and the end result is a mismatched combination that isn't much better than what you had to begin with.

5: Performance parts are "ready to go" once they arrive on your doorstep. Not true. Most parts, even CNC machined parts, still need quite a bit of cleaning up even from the most respected aftermarket manufacturers. Cylinder heads are a big one on that point, intakes are second.

Keep it going, contribute your $.02, guys.

[smoker]

i like the bit about fart cannons....i drive a 93 alitma 2.4 dohc 5 sp.....anyway in the car audio business a lot of younger guys come through and some of them have heard my cannonless car and have suggested i get one cause they really noticed a big difference after they got theirs and openend up the exhaust system.....well last week the stock pipe just before the muffler let go...hell its 13 years old and the car has 183000 miles on it, except for the noise i didnt notice a thing, in fact it has a slightly deeper tone to it but the cat is so restrictive,and there is nothing more opened up than that when compared to fart cannons.... nothing gained except now i need a new muffler....

[CaptainPioneer]

Cold air induction kits whats your say on those... I know alot of ppl advertise that you will get a 5 to 15hp gain in power and some claim greater mpg... If my logic is wrong tell me but when u push more air into an engine do u not also increase gas consumption? Maybe the cold air induction just means that it is going to give the same amount of air to the engine just colder resulting in less thermal loss of power, i guess forced air induction would result in both greater hp and loss of mpg... Am i wrong here.?

[Jonathan]

"Cold air induction" kits often stick the filter in the hot engine bay as described above. They do little to nothing to improve power or mileage.

A higher flowing filter that does suck in cool air (via fenderwells, under the apron, etc.) does improve power and mpg. You're increasing the efficiency of the engine.

There are a lot of performance parts that improve power and mileage simultaneously. In fact, any vehicle gets it's best mileage at peak power (torque) output, because the engine is most efficient at that point. So you can achieve better mileage and power with intelligent choice of camshaft, induction, and exhaust, basically optimizing the setup to work at a given RPM range and increase efficiency at that point.

Forced induction doesn't have to decrease mileage. When they're producing boost, sure, but most of the time they aren't. Sometimes a turbo/supercharger will improve mileage a bit because with either the turbine is spinning just enough to help air flow better through the restrictions (filter, throttle body, mass air meter, etc.).

[Jonathan]

"Cold air induction" kits often stick the filter in the hot engine bay as described above. They do little to nothing to improve power or mileage.

A higher flowing filter that does suck in cool air (via fenderwells, under the apron, etc.) does improve power and mpg. You're increasing the efficiency of the engine.

There are a lot of performance parts that improve power and mileage simultaneously. In fact, any vehicle gets it's best mileage at peak power (torque) output, because the engine is most efficient at that point. So you can achieve better mileage and power with intelligent choice of camshaft, induction, and exhaust, basically optimizing the setup to work at a given RPM range and increase efficiency at that point.

Forced induction doesn't have to decrease mileage. When they're producing boost, sure, but most of the time they aren't. Sometimes a turbo/supercharger will improve mileage a bit because with either the turbine is spinning just enough to help air flow better through the restrictions (filter, throttle body, mass air meter, etc.).

[CaptainPioneer]

Ok very good so i guess my friends idea of putting a Cold air kit in is really not worth it

[smoker]

the only drawback toa supercharger is parasitic losses through the belt drive but they are more than made up for

[Jonathan]

Also, Turbos lose through higher heat discharge (compared to a supercharger). Made up for w/ an intercooler, though. The impeller tends to increase efficiency enough at part throttle (when not making boost) to make the engine more efficient since it helps combat the restriction of filters, TBs, MAF sensors, etc. Basically the gains and losses tend to balance out and it acts as a normally aspirated engine would when you aren't dropping the hammer.

Turbos tend to produce more overall power while superchargers like twin screw or roots types tend to be able to give bigger gains at lower RPMs.

[solacedagony]

These little threads and posts you make on car enhancements are very informative. I always love reading them when you post, so thanks! Wish I had the time/money to put into learning more about cars and automotive performance.

[Ryan from Ohio]

1
Ive read a few about them "electric turbo's" that you see all over for $150+ EACH...

All that deal is, is a blower of some sorts off a boat.

Like the one on E Bay said. "If anyone thinks that one of these little blowers can actually boost the air intake than you are an idiot". I cant agree more. Engines when running a HIGH RPM suck so much air its pathetic.

If anyone disagrees please take off everything from the throtle body forward. Start you car and put you hand about 4" in front of the TB... Be careful that your hand doesnt get sucked in, otherwise it will pull the skin right off ya...

NO WAY IN HELL can any little electric blower force more air in there than needed, period...

2

The "chip" in the sensor, AKA RESISTOR... I looked at about 8-9 pictures and was able to decipher the colors on the resistor and went to Radio Shack and picked 5 up for $1...

All I can say is wow, what a waste of $1!

Did absolutely NOTHING... And if it did it was so unoticeable I tried 3 more resistors just to see if I was doing it wrong or if one was bad...