Increasing downforce while reducing drag?

[Hermie]

Here's my spats:

http://i3.photobucket.com/albums/y93...y/DSCF0837.jpg

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Wait... Blocking airflow will cool the engine? You've got it backwards, dude. Blocking the grille makes the engine run hotter. Just ask NASCAR drivers when they pull tape off their grills during a race. More airflow=cooler engine. Less airflow=hotter engine.

The cosmetic rear spoilers don't do much of anything. However, a decent spoiler will in fact reduce lift by creating downforce. This is if they're either shaped like an upside-down airplane wing, or like the old NASCAR lip spoilers. Granted, they do generate drag.

However, a full belly pan covering the engine results in a hotter engine, reducing efficiency and lowering the life of the engine and parts. Vents/loveurs for the engine bay would be beneficial.

[Christ]

There are cases where blocking grille openings actually will increase airflow through the radiator, though I can't think of any right now.

Putting a gasket between the hood and upper rad brace is a well known way to improve cooling, as well as a tray under and around the radiator. Most of the air that goes into your front end doesn't really go to cooling your engine.

If you want to compare apples to apples, leave NASCAR out of the street car arena. NASCAR autos have tuned inlet ports on the front of the car that allow just the right amount of cooling based on the size of the opening without sacrificing aerodynamics the way street cars do.

Blocking your grille properly could allow air to flow through the radiator uninterrupted by cross-flows under the hood, which would improve cooling over stock. This is part of the reason that newer cars have radiator trays above and below, and a large part of the reason for adding fan shrouds to radiators.

A full belly pan also does not necessarily result in a hotter engine, as long as your cooling system is adequate and you have adequate airflow to vent the system into open air.

Do you have evidence to back up what you're saying about a hotter engine having reduced efficiency and less life? Seems funny, because many engines run overcooled OEM style, and end up getting better efficiency once they're allowed to run at some nominally higher temp.

[Hermie]

"By taking sumptuous amount of cold air directly to the engine it provides the engine with abundant oxygen. Cold is important too because for a given volume more air will fit in if it is cold and less will fit in if it is hot. This abundant oxygen ensures that the fuel is combusted very well and fuel left unignited due to a lack of oxygen is reduced. The fact that a higher percentage of the fuel is combusted means you get a better fuel efficiency. And the fact that more fuel is burnt in every engine cycle means you get more power. Often extra power is at the cost of lower fuel efficiency but a cold air intake manages to do both."

Cold air intake improves engine life

Cold air=dense air=greater efficiency

This isn't a secret, really.. It's common fact elsewhere, but even simple things become foreign with such fixation on MPGs alone.

Same with cooler engine parts meaning longer life. Does an overheated engine run well? Obviously not. Continuous heating over time has the same effect as one burst of heat. Look at slow cooking versus high heat. They both end up cooked, it's just a matter of when.

All engines have an optimum operating temparature. This is when they're "warmed up." Anything beyond it is less than beneficial.

"Cooling is also needed because high temperatures damage engine materials and lubricants. Internal-combustion engines burn fuel hotter than the melting temperature of engine materials, and hot enough to set fire to lubricants. Engine cooling removes energy fast enough to keep temperatures low so the engine can survive."

http://www.answers.com/topic/engine-cooling

[Christ]

1. Answers.com is hardly a technical data source, and should not be treated as anything close to such.

2. You still haven't proven that a warmer engine is necessarily going to "live a shorter life" compared to a cooler one. The problem with this statement is that it assumes that everyone already agrees that a warm engine is actually a hot engine, which it is not.

A cold air intake doesn't necessarily increase horsepower. In some cases, the same gains could be made (at WOT, obviously) by simply removing the air filter and air box.

Where exactly does a CAI make gains at less than WOT? Show me that? If colder air is really making more HP in the capacity of the CAI, then even at part throttle, there should be enough excess air density to make more power compared to the same throttle with OEM intake.

Obviously, an engine has a limit to the amount of heat it can stand before it starts to grenade, even over a long period of time. Engines run most efficiently when they're not wasting heat, which tells one that the excess heat created either needs to be utilized, or not created in the first place. Since combustion creates heat, and ICE's aren't truly all that efficient, having a warmer engine means that less energy is sent through the engine as heat, and more as power. There is a reason that cold engines don't run well.

Saying that anything beyond "warmed up" is less then beneficial is just a cop-out statement, which shows that you're probably regurgitating information from someone else's mouth. You can't confirm that "warmed up" is an actual operating temperature, nor can you confirm that if "warmed up" were a concrete state in terms of temperature, that it would be the most efficient state for all applicable scenarios. Without being able to prove any of that, this statement needs no further review, as in the looking glass of scientific scrutiny, it holds no weight whatsoever.

If cooler engine parts mean a longer life - again, a generalized statment - why does the engine need to be warmed up? Now you're contradicting yourself...

I'm not even going to start on the non-scientific (or even considerably credible) nature of the CAI article.

Please, continue this discussion when you can find real evidence and studies to back up what you're saying.

[Hermie]

You could do the same and provide evidence instead of having none and attacking mine.

Who's contradicting themselves?

Also, removing the air filter? Anyone with half a brain knows that the particles getting into the engine from that would ruin it.

If you actually read my post, you would have understood what when I said cooler, it means relative to blocking the air intakes into the engine compartment and the vents underneath such with a full belly pan.

As I said, and I'll repeat, all engines have an optimum operating temparature, and it varies from engine to engine. There is no definite number for all engines, and it's asanine to think so.

And I'll repeat again, try overheating your engine constantly and see how long it lasts.

Dyno chart for a 2006 Ford Mustang GT, with stock intake, and CAI:
http://www.knfilters.com/dynocharts/57-2565_dyno.pdf

Same test on a 2006 Chevorlet Corvette Z06:
http://www.knfilters.com/dynocharts/63-3060_dyno.pdf

Gains all across the powerband, but more noticeable at high RPMs.


I'll lay it in common sense that even an elementary student can understand:

For gas to blow up, it needs oxygen. When air is cold, it's dense, meaning there's more in it for a given space. If cold air goes into an engine, there's more oxygen to blow up the gas. This makes sure there's a bigger boom. Bigger boom means more power.

Clear enough?

[Christ]

So - I'm not in the position to provide evidence, as I'm the one questioning what you've provided. It's a rather simple process.

I run my engine with no air filter, and it's not ruined. In fact, I've been doing this for about 9,000 miles now. While I don't recommend that others do it, because of the obvious perceived danger, I also know that it won't "ruin" your engine in any short amount of time, relative to average engine life.

If you feel that I misunderstood something, it may be because you were less than clear about it. I, however, doubt that there was a misunderstanding. I'm sure you were referring to blocking the air inlets of the grille, which, in most OEM "real world" scenarios, are far too large to allow for adequate cooling.

Once again, A full belly pan won't necessarily cause your engine to overheat, provided you have a means to vent the engine's excess heat into open air. That means doesn't necessarily have to be the bottom of the engine bay, nor does it have to be the hood.

You're correct in saying that engines have an optimum operating temperature, I didn't dissuade from that. What I mentioned was that it was very neglectful of you to say that "warmed up" was that optimum temperature. You simply cannot apply such a broad term to something so precise without further explanation, and you also cannot say that the OEM setting is always necessarily best for optimum performance or efficiency, to place the cue on either side of the scale, especially considering that such has been found to be false on so many occasions, both here at EcoModder and in most performance communities at large.

What one can be quite sure of, though, is that OEM's will make every attempt to compensate for "worst case scenario", even though it doesn't apply to the largest subset of consumers. What this means for you is: on average, your vehicle, when in OEM condition, will not run at it's best efficiency or performance, will not perform at it's peak in all conditions, and, at least in some capacity, has room (lots of it, usually) for improvement over OEM configuration.

To combat your previous non-sensical assessment of CAI's with more non-sense:

Most OEM's won't cover engine damage that could even remotely be associated with intake stream modification or manipulation. Go ahead and verify it.

[Hermie]

OEMs won't cover ANY modification of the engine that isn't replacing OEM parts. I'm quite sure your lack of an air filter isn't covered either, so what you said is pointless.

Also, here's a challenge for you- Take apart your engine, especially in the air intake, and wipe it down. You'll see how much gunk is getting in there.

Give it another 10,000 miles or so. Without an air filter, you're going to need an overhaul. I'd bet money on that. It's recommended air filters are changed every 12,000 miles.

"I'm sure you were referring to blocking the air inlets of the grille, which, in most OEM "real world" scenarios, are far too large to allow for adequate cooling."

That makes absolutely no sense. Go ahead and pull off your front facia. I'm sure you'll be running plenty cool from all that air hitting the radiator. If you said "small," it would make sense.
Unless the engineers are complete idiots, a large grille allows a large ammount of air into the engine compartment and through the radiator, thus allowing better cooling than a smaller grille. Common sense.

[Christ]

As if it hasn't been made painfully obvious, the engineers are covering "worst case scenario", and yes, you can easily OVERCOOL your engine by removing the fascia from the vehicle, which would put it outside it's efficient range, which is apparently not what you're going for... so that statement is pointless. Were you going somewhere with this discussion?

You'd bet on my engine needing an overhaul, and you'd probably lose. 10,000 miles is a very short time.

In case you'd like something else to under examine, I also don't change my oil on a schedule. If overhaul was imminent based on my lack of air filter, I should see buildup in the oil, correct? I'll take a pic for you tomorrow. Hell, I'll even text it to you. It's just starting to lose it's golden color - and it's been in there, with the same filter, for ~9,000 miles as well.

A large amount of air doesn't necessarily afford more cooling capacity, either. I'll let you do the searching to quantify that - you might begin to understand how a grille block could make an engine operate more efficiently.

When you really want help, we're here, but you've been afforded plenty of solicited advice/information, and you don't seem to accept it, both here and elsewhere, as I've been informed by others.

Once you figure out whatever it is you really want, please, by all means, show us the Nobel prize in your category.

[2000mc]

first off, click on the "65+ Efficiency Mods" at the top of the page and spend time reading through them, might find some new ideas, or at least the logic behind them.

i thought the overcooling thing was about having more air flow over the radiator than needed, not the actual coolant temp which would be controlled by the thermostat. on most stock vehicles in most conditions there is much more air flow to the radiator than needed to keep the vehicle running at the temp regulated by the thermostat. so grill openings, or part of openings can be covered to make the car more aero without making it run hotter.

if your cold air intake is working properly and your getting that extra oxygen, anything with an oxygen sensor will adjust the fuel mixture. now you can make more power for any given throttle opening. sweet right? but it still takes the same amount of power to hold your car at any given speed going down the road, so you dont need to use as much throttle. this car has to be efficient now right? well wait, closed the throttle more...crap thats where the oxygen gets in.... what were we trying to do again?

[NeilBlanchard]

Hi,

Thanks for posting the pictures -- I would call them deflectors.

With a fully ducted cooling system, you can cool the engine with a LOT less air. NASCAR has found that 16 sq. in. of intake for each 100HP is adequate. That is an opening 4" x 4" to cool 100HP engine. Small opening = less drag.

Not all of a large grill is necessarily taking IN air! If the lower part of the grill is more efficient at taking in air (as it is), then on some cars at least, the upper part of the grill has air flowing OUT. That air does not flow through the radiator, and will not cool the engine -- it only adds drag.

Have you read the Hucho book "Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering"? I have started to read it, and you should check out the chapter on the internal engine bay air flow.

Also, see my xA build thread, dude: http://ecomodder.com/forum/showthrea...mods-2969.html