GM is running a 9.4CR on their 3.8 liter V6 - with IRON heads, 2 valves/cylinder and 87 octane fuel.

Aluminum permits a ~ 1/2 point increase in CR for a given head/combustion chamber design. I've already posted that.

But it also GIVES UP the heat faster. So the aluminum head HAS to run a higher CR in order to produce ~ THE SAME power as the (otherwise identical) iron head running a slightly lower CR.

I'll check my text book on Monday @ work on pressure velocity issue.

Either way, lowering velocity INCREASES pressure. And a scoop in a "ram air" system DOES lower velocity (thereby increasing pressure @ the intake manifold).

http://www.boscobel.k12.wi.us/~schnr...lli_effedt.htm

 

Sorry, gyp board is short for gypsum board and it is just good ol' drywall.

http://www.ammolab.com/Test%20Results.htm

 

First, who told you that aluminum permits only 1/2 pt in compression? Whoever told you that is full of crap.

Of course lower velocity increases static pressure. That is what you were arguing against for the first 4 pages of this thread and what those dorks in the articles you've been posting don't understand.

Higher velocity is why ram air doesn't work. You can't compress air at automobile speeds and that's the only way you're going to increase static pressure over the environment. (That is you aren't going to get static pressure higher than static air outside the car)

 

Show me where I "argued against" the fact that a reduction in velocity results in an increase in pressure.

GM is running 9.4:1 with 2 valve, cast iron heads and 87 octane fuel.

The aluminum/4 valve heads in my Accord permit a .6:1 increase with the same octane fuel.

 

Skeed,

My department actually dropped our HK MP-5's and went to suppressed, 12 inch barreled AR-15's as our entry weopon. It just boils down to basic common sense, if you are on a search warrant or SWAT entry and you get in a fire fight, the last thing you want to do is kill your team member in the next room. There are numerous studies like the one below but basically, I think there is a common thread to all of them and that is that a hard target interferes with the expansion of a hollow point round causing it to behave like ball ammo. The energy of the 55-grain .223 round is quickly lost into the first obstruction and it frags fairly easily, meaning, if you don't hit flesh, the chances of it going through 4 more walls are greatly diminished.

http://www.olyarms.com/snoco.html

 

http://www.hughesengines.com/general..._head_tech.asp

 

Dude, are you my wife??? You can't win this one so now you are bringing up the past??? (If anyone rat's me out that I said that, I'll hunt you down.)

 

<---made my statements from a layperson's standpoint, completely outclassed by people who know what they're talking about

 

Holy crap...EVERY ARTICLE you posted made the claim that higher velocity resulted in higher pressure. That's why these dumbasses call it Ram Air.

Comparing GM to Honda doesn't show anything.


You just just have ZERO clue as to what you're cutting and pasting.

Do you actually READ the articles before you copy them?

 

Can YOU read?


http://www.hughesengines.com/general..._head_tech.asp

"Aluminum heads dissipate (get rid of) heat much faster than iron heads. The rapid heat loss from the combustion chamber results in reduced combustion chamber pressures (heat equals pressure); similar to the effect that lowering the compression ratio lowers cylinder pressure. When switching to aluminum heads you MUST raise the compression ratio to prevent a power loss....

Aluminum heads will not automatically create more power than iron heads unless they flow more air and are installed on a higher compression ratio engine."

 

So what you are saying then is aluminum would make a good intake pipe material????? Like, say, on the Injen?

 

No, that's not what I'm saying.

AT ALL.

Plastic heads would be better than aluminum and iron if they wouldn't MELT.

Aluminum is good at conducting HEAT away from hot spots and into cooler areas.

That's exactly what you DON'T want on an air filter assembly.

 

But you are saying that it gives up heat very fast, right???

 

I agree with this statement, but I would add that aluminum permits the building of more power by permitting more than enough compression to offset the loss of heat.

 

The point he was making (although wrong in concept) was the the aluminum CAI would take heat from the motor and give it up to the air charge. A plastic CAI wouldn't easily take any heat from the motor nor easily give it up to the air.

However the air charge isn't in there long enough to absorb heat so it doesn't matter.

 

And I agree with that.

The slightly higher CR allowed by aluminum OFFSETS that material's heat transfer properties.

The net result isn't more power.

The cheif advantage of aluminum heads is that they are lighter (~ 55 pounds in a SBC and ~ 75 pounds in a BBC).

They are therefore the perferred material for performance heads.

 

This is where we must agree to disagree. The increase in CR permitted by Al heads isn't slight.

 

Wrong in concept?

Aluminum is good at transferring heat (from hot areas to cooler ones).

Transferring heat from the engine compartment INTO what is supposedly a "cold air" intake system is just plain stupid.

 

The highest CR production cars are running ~ 11:1...with 4 valves per cylinder/pentroof chambers, premium unleaded and aluminum heads...

GM is running 9.4:1 with iron heads, two valves per cylinder and 87 octane.

How much power (as a percentage) do you think is gained by jumping from 10:1 to 11:1 (assuming the same mead material)?

 

It depends on the impact of the heat transfer. The transfer is so small in the TL application that it doesn't matter.

 

Again, GM is running 9.4:1 in their 3.8 liter V6 with 2 valve, iron heads and 87 octane.

Pentroof/4 valve chambers, aluminum heads and premium fuel (to support the higher CR) COMBINED are only good for a ~ 1.6 point jump (~ 11:1, like the Honda S2000).

A 1.6:1 jump equate to a ~ 1.6% increase in power. That's good for ~ 5 HP in a 300 HP engine.

http://www.wallaceracing.com/crpower.gif

 

I agree with that.

I agreed with that ~ 4 pages back.

But it's fundamentally wrong to use aluminum tubing in that application.

Plastic would be better (mainly in theory) and FAR less expensive.

 

Sorry Skeed, I was just messin' with him based on his other thread on the Injen.

Check this out:

http://thecurmudgeon.freeservers.com...ocacy-pg1.html

 

I just ran these changes through engine analyizer and tt depends on the motor setup, cam specs, valve size, etc. The results were 5% in a very mild cammed 2V V8 with typical iron wedge heads with no other changes you would normally associate with higher compression.

But all your examples are apples and oranges.

 

Cheaper true. Had plastic been an option, I would have chosen it.

 

I'm fool enough to weigh in on the air filter discussion. My experience with them comes from 5.0L Mustangs and it is a bit dated - but here is some of what I remember...

K&N consistently produced slightly more power (3-5hp range) than stock. There are a lot of dyno pulls that support this. An interesting effect was that cars would produce more power with a K&N than with no air filter. One theory, that I agree with, was that the K&N created less turbulent flow through the MAF meter. I have no idea how applicable this would be to other cars including the TL. It is clearly dependent the air intake design.

Another commonly known benefit of the K&N filter, at least back in the 80's, was that the flow gap between K&N and paper increased as the filters got dirty. The K&N would lose some flow, paper would lose more. This resulted in cars making more consistent power over the life of the filter (between cleanings).

As for efficiency, I have seen several motors torn down after 100K+ miles running with K&N's that looked great. No unexpected journal or bearing wear.

Cost-wise, the K&N is a pretty good call. They will last for years, are easy to clean, and cost less over the long haul than a stack of disposable paper filters.

Am I running out to buy one? No, but I'll think about it when the first change is due. With all the attention Honda paid to the air intake on the new TL, I'm betting the factory filter is probably a pretty good one.

Oh, and in the combined gas law, V is volume. Skeedatl is right on that one.

 

If you really have to check a text book to quote Bernoulli's equation or verify a statement pertaining to it, one would have to wonder what were the two fluid mechanics courses you took. Forgetting it is equivalent to forgetting something like F=ma. Even otherwise, this equation can be derived without the aid of a text book on a sheet of paper based on energy balance considerations in a control volume or Euler's equations of motion by someone who has had exposure to a fluid mechanics course.

 

My only remark to this thread is that with a K&N filter in place my Mustang gained about a tenth in the quarter mile averaged over 10 runs with paper and 10 with the K&N to get a baseline.

There are people who got more but there are other reasons why it only got a tenth out of it and those reasons aren't important to the fact it did help.

I ran that motor for 7 years HARD at the race track and never had a problem with anything getting dirtier because of the K&N. Making sure you follow the recommended cleaning and oiling of course helps. I doubt I'll get one for the TL though.

 

@harddrivin1le:
Just curious: do you know what a Pitot tube is and how it works? Are you familiar with how you compute fluid velocity using a Pitot tube?

Without running off to your text book, consider why the equation as you state fails when the fluid velocity is zero. You would have to have infinite pressure in order to bring a fluid at motion to rest according to what you posit. It is complete nonsense.

 

Plastic would not be cheaper. Aluminum intakes take a stock 3" aluminum tube and bend it to specification. A plastic intake would entail making a blank, making a 4-part mold from the blank (top outside, top inside, bottom outside, bottom inside) then pouring the plastic into the mold, and finally waiting for it to set. Then after it comes out of the mold it must be cleaned and deburred before being assembled to the rest of the intake system to test for fit. If it doesn't fit on the first try you have to start all over again. Aluminum goes to the mandrel pipe bender, gets cut, then gets fitted.

You have to keep in mind that aftermarket applications are NOT high volume. Plastic only becomes cost effective for OEMs because of the high volume. You have to cover the cost of tooling for medium-to-high volumes because you need a mold that is going to stand up to repeated moldings. Aftermarket companies simply can't afford the high cost of these toolings (which for an intake would run about $10k).

 

And aluminum takes a CNC bender and most likely 3D scanner (to scan the welded up prototype) which is only cost effective at volume.

 

I think we have already established that he has no practical knowledge of fluids (or even the mathematical background to understand what you're saying about evaluating his "magic math" at V1=0 if V is velocity which of course it isn't).

 

If they used a jig and bent it by hand they were cost way more than they do then you have the welding (and welding aluminum is pretty hard).

 

I danced a jig tonight...

 

I wasn't talking about the combined gas law.

I was talking about the relationship between PRESSURE and VELOCITY:

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

 

Where have I mentioned bringing the fluid velocity to zero?

Answer: Never

But as the velocity of a fluid deceases, pressure increases:

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

 

True or false:

V is velocity here, where a decrease in velocity = an inrease in pressure:

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

 

Higher velocity DOES result in higher pressure....IN THE AIRBOX and the intake manifold (of a "ram air" system)!!!!

 

That page does not support your ludicrous claim that pv = const is Bernoulli's Theorem. For anyone that has a smattering of fluid mechanics knowledge, your statement is absolutely and astoundingly wrong (before you question credentials, let me mention that I have a doctorate in Mechanical Engineering and I do know what Bernoulli's theorem is).

 

True or false:

A drop in fluid velocity causes a rise in fluid pressure.

"The qualitative behavior that is usually labeled with the term "Bernoulli effect" is the lowering of fluid pressure in regions where the flow velocity is increased. "