To Gofasterfirebird: Please do take the time to disprove my thoughts on cylinder pressure. I would like to hear if you have better information/theory. That is the purpose of discussing this, after all... To TPI-Guy: Don¡¦t be likening yourself to Santa Claus just yet. #1 ¡V The link you provided should have included the top of the next page as well. Your little "soundbite" of text is taken out of context. Here is the whole paragraph: "Because aluminum rejects heat faster than cast-iron, traditional wisdom holds that an aluminum head won¡¦t make as much power as an equivalent iron head. Leaving aside the fact that there is no "equivalent" iron head to the AFR casting, Ken has revised the water jacket¡¦s circulation pattern compared to stock, :the coolant goes first to the hot exhaust valve side of the head, then to the intake side. The ¡§reverse flow¡¨ circulation pattern transfers the exhaust heat to the combustion chamber, counteracting the aluminum¡¦s heat rejection characteristics to maintain full power potential. Nevertheless, the aluminum material, in conjunction with the efficient water jacket offers more uniform cooling overall without the detonation-inducing hot spots typical of cast iron.¡¨ Keep in mind that AFR is promoting their own heads here and this bit of marketing material includes discussion about their revised cooling passages. However, another shown benefit of aluminum over cast iron is more uniform cooling to get rid of the excess, wasted combustion energy in the form of heat. Let¡¦s remember how power is actually made. In the combustion process (for an internal combustion engine), there is fuel which is ignited by a spark. This small explosion produces energy in the form of pressure (outward expansion) and heat. The pressure actually transfers the power to the piston, thus moving the piston. The combustion energy is converted into motion by the piston and then heat is created. The heat is the inefficient byproduct due to less than 100% efficiency. Remember the 1st law of Thermodynamics, energy is neither lost nor gained. This leftover residual heat is the energy left after the engine has converted as much of the combustion as possible into motion. Eventually, that heat makes its way into the heads and then into the coolant. If the combustion process was 100% efficient, then there would be no heat leftover to worry about as all of the heat would be converted to motion. The aluminum heads ARE better as they whisk away the residual heat more efficiently and it helps to reduce hot spots in the head which reduces the chances of power-robbing detonation. It also serves to keep the intake charge cooler as it comes into the head, which results in more power as well. The aluminum heads serve better to control the overall temperature of the combustion process. End result: Heat DOES NOT help power, nor does it create power in the combustion chamber. It is a waste product from the combustion process because the force of the rapidly expanding combustion cannot turn all of the energy into motion, thus the excess energy, in the form of heat is created. That is why running an engine cooler makes more power. Pressure makes the power, not the heat. #3. As for the Edelbrock base, I have been running one for about 5 months and have noticed no issues at all. Maybe the early castings had problems, but mine does not. #4. Yes Vortecs flow well, but they have some quirks to deal with that I do not want to explore. Like I said before¡K.Personal preference¡K #5. Is the different bolt up pattern a conspiracy? No Dude. It is more likely due to GM's idiosynchrocies or maybe they saved like $1.00 per assembled Vortec engine. It seems like some of their engineering is based on assembly efficiency or some minute cost savings, not practicality. Aluminum may not be as strong as iron, but there are definite advantages to using it over iron. Personal preference tops the list (yet again) as well as the overall engine package and how it is to be used. Funny, I have never heard anyone in their dream motor talk about cast iron heads. Could just be my part of the country though. I would love to hear some of the ¡§seasoned¡¨ guys respond to this as I hope that many lurkers are learning something here too. I know that for a long while (starting 4 years ago), I would just lurk on the Net and watch everyone else to get my information. Let¡¦s hope that this good discussion will provide some good points on both. This debate is a lot like the auto vs manual and 3rd vs 4th gen debates in that there are pros and cons. Lets continue to all the info out on the table.

TFS vs AFR 190...
here is the #'s I got.

lift----------TFS23----------------AFR190
-------------I----------E-----------I----------E
.050-------33.22----24.27-----32.21----26.26
.100-------61.02----49.80-----65.84----57.03
.150-------101.80---74.65-----103.36--85.52
.200-------135.28---101.90---137.56--116.92
.300-------185.00---134.90---190.92--165.36
.400-------223.77---169.80---230.38--190.80
.500-------245.00---187.60---245.68--201.93
.550-------246.80---192.3-----245.68---203.52


pretty damn close.

I saw a dyno comparo between these two heads on a 500BHP 383 with a carb, VIC JR. He dyno tuned the best power with the given combo out of both heads. The AFR's made only 3 more HP. This was on Ken Dutweiller's Dyno, I can't give you exact #'s because They don't just hand out other poeple's dyno sheets to the general public, and it was about five months ago. However that small difference did stick in my head.

Now I do believe that you might see some reasonable gain in an AFR if you were running around .700 lift or aproaching it. That is where I think the AFRs flow sig better that the trickflows. However, how many of us are running .700 lift in our daily driven cars. NOT ME anyhow, I hate rumpidy idles, poor gas milage, and sorry drivability.

All in all, I could not justify spending The extra money on AFR's and dealing with the 3 week waiting period. TFS gets here in two days from summit, tax free.

I also Agree that the TFS could use some cleanup in the exhaust (around the seat insert) and I'll bet they'll match or beat AFR's in the exhaust port. The intake already flows virtually identical.

So just my $.02, don't make a decision based solely on what everyone else says. Do some homework, compare, look at what your goals for the engine are, find your budget, and make a decision for yourself. I have found that to always turn out more pleasing results. ESPECIALLY when it comes to camshaft selection, but that is a whole nouther ball of wax.

Gasp! Sometimes I babble on like a woman, except about tech stuff!

TPI INTAKES,

I was not at all impressed with the quality of the accel base. It had really bad core shift. The ports did no line up worth a damn. I thought it might be the heads, so I put my stock intake on, and it lined up perfectly. Anyone else have this problem, or did I just get a bunk one?

On my accel base there were these long casting marks that went the length of the runners.

If I remember right, the Edelbrock base that i have didn't have any serious imperfections, nor have I noticed any sealing issues. I am sure that all major manufacturers have some quality control issues here and there.

I have just seen too much research and comparisons from people who have seen the bases. The consensus still is that they are functionally identical and no gain is made by using one over another.

The AFR flow #'s are pretty interesting, but i thought that the flow #'s at .500 were 262 cfm on intake and 211 exhaust...from the Chevy High Performance Flow-to-Go research on their website.

-Adam

Greenshamrock77:

Do you remember the huge Accel base manifold purchase not long ago. The shop that Accel contracted to cast those bases did a pretty half-@ssed job on most of them because of the huge volume they were forced to turn out. Most of the bases they did produce had to be destroyed because of quality control reasons. When Accel approached the casting house to get an explanation, they were pretty much told where to go. Some of the bad ones still got through. Accel has since switched casting houses after they lost so much money trying to build the manifolds for that group purchase.

88TPI406GTA, the pertinent information is below:

"...Leaving aside the fact that there is no "equivalent" iron head to the AFR casting, Ken has revised the water jacket¡¦s..."

Two heads identical in every way, one cast iron, one Aluminum, cast iron will win, and here's why:

"This small explosion produces energy in the form of pressure (outward expansion) and heat. The pressure actually transfers the power to the piston, thus moving the piston. The combustion energy is converted into motion…"
You are correct up until this point, although, I think your reasoning is a little off. Let's do some chemistry!

I'm sure you are familiar with Energy of Activation (EA) and Gibb's free energy. The energy of activation is the initial energy required to start a chemical reaction. In the case of the internal combustion engine, this is provided by the spark from the spark plug. Once this activation energy has been added to the equation, the oxidation reaction between fuel and air is spontaneous. That leads to an extremely fast formation of hot gaseous products (an explosion of the air and fuel) governed by the following equation for combustion for any hydrocarbon in oxygen: CxHy + (x + (y/4))O2 ----(heat)> xCO2 + (y/2)H2O +Heat

Once ignited, gasoline has the potential to expel 42 - 44 Megajoules of energy per kilogram. That energy comes in the form of heat, light, and sound. The heat from combustion is the only thing responsible for the pressure that forces the piston down.

As you may well know, gasses behave (ideally) according to the ideal gas equation (PV=nRT), where p=pressure, v=volume, n=number of moles of gas, R= a constant, and T=temperature. By rearranging the equation, you can see how the increase in temperature retained in the exploded gas will result in the increase the volume of the gas. If heat from the exploding gas is lost to the atmosphere, it does not contribute to the volumetric expansion of the gases that force the piston downward.

So, why is it, then, that we want our gasses hot and our components cool? The cylinder head does not retain a constant temperature throughout. The middle cylinders are often subject to hot spots that cause detonation. Also, increasing engine temperatures causes the intake charge temperature to increase, increasing the chance of pre-ignition.
http://inventors.about.com/gi/dynami...tern%2Dco.html

The mixture on burning becomes a hot, expanding gas forcing the piston down on its power stroke. Burning should be smooth and controlled. Faster, uncontrolled burning sometimes occurs when hot spots in the cylinder preignite the mixture; these explosions are called engine knock and cause loss of power.

http://chemistry.about.com/gi/dynami.../gasoline.html
7.5 What is the effect of temperature and load?

Increasing the engine temperature, particularly the air/fuel charge temperature, increases the tendency to knock. The Sensitivity of a fuel can indicate how it is affected by charge temperature variations. Increasing load increases both the engine temperature, and the end-gas pressure, thus the likelihood of knock increases as load increases.

"…by the piston and then heat is created. The heat is the inefficient byproduct due to less than 100% efficiency..."
As stated above, explosion requires the expansion of gasses, expansion of gasses requires heat.

"Remember the 1st law of Thermodynamics, energy is neither lost nor gained. This leftover residual heat is the energy left after the engine has converted as much of the combustion as possible into motion. Eventually, that heat makes its way into the heads and then into the coolant. If the combustion process was 100% efficient, then there would be no heat leftover to worry about as all of the heat would be converted to motion."

No. Let me break it down for you in terms of total thermal energy:
http://www.cs.ruu.nl/wais/html/na-di...faq/part1.html
For a water-cooled SI engine with 25% useful work at the crankshaft (self explanatory)
Of the remaining 75%, energy losses may be comprised of:

35% (coolant)
The piston rings account for about 40-50% of engine friction. The drag on the cylinder wall creates heat. The heat is transferred through the sleeves and absorbed by the coolant.
33% (exhaust)
The heat does not sit around in the chamber until it eventually makes its way into the heads and coolant passages. It is in there for a fraction of a second and is expelled as exhaust heat.
12% (surroundings)

"#5. Is the different bolt up pattern a conspiracy? No Dude. It is more likely due to GM's idiosynchrocies or maybe they saved like $1.00 per assembled Vortec engine. It seems like some of their engineering is based on assembly efficiency or some minute cost savings, not practicality."

I believe they raised the runner .100" from stock location allowing a more gentle short side radius, but maybe I'm wrong. They eliminated four intake manifold bolts. I could not ask for more out of a production head. In my opinion, they are better than the Trick Flows on the basis of flow numbers vs. runner volume, straight up volume under .400'' lift, cost effectiveness, and ability to pick up chicks.

First off, ...... Me? Chill out? Ummm.... you are the one tossing around ideas that you are all-knowing and that the rest of us (or maybe just me) are 'reactionary'...... I have to say it again, you have some kind of ego there, ace.....

Ummmm..... Nope. The thought process that you use here is your whole problem. You do not have some kind of authority here on what is being discussed - and nothing is assumed unless stated. I agree, most of the time we are talking about L98s here since that was what came in most of our cars. But that doesn't mean that we are talking about a stock one - or even the lower end at all. I am inclined to think that a reference to an L98 is more indicative of what style intake is on the engine.... but I don't just assume it since it is convenient for my argument and throw it out there as if I have proven some point over the ones I am argueing with.

The part that you forget in all of that chemical reactivity stuff is that cooler air is more dense and that means more oxygen content which is also a 'fuel' for the cumbustion process. So if we look at it your way and assume everything else is identical, the iron head WILL NOT make more power.....

Well, I really don't have much to add to this since the numbers speak for themselves and the TFS 23* heads do outflow the Vortecs in most tests, they are aluminum which has advantages over iron in power potential and weight savings, and they are cheaper to impliment on the engine than the Vortec heads are. That pretty much means they are the best bang for the buck out there...........

Do I need to separate you two?...........three?............here, play with the little puppy!
That's better, know everyones happy.

Matt, Matt, Matt. I think Sir Francis Bacon said it best when he said "No pleasure is comparable to the standing upon the vantage-ground of truth."

Once again, what's your deal, and why do you people always seek me out? If you have a point, for love of all things holy, please make it. Perhaps for the less literate readers, when I say:

"Gofasterfirebird, it is just the curse I am forced to live with everyday."

I should put a footnote [sarcasm]

In regard to my reverting to the bone stock L98 as a basis for discussion ... what is wrong with that? If you were to take a cross section of the tpi engine population, I am sure the average Joe would have the rough equivalent of an L98. In order for us to have a discussion, we must first have common ground on which to base it. Let's say you and I were to have a discussion about gravity, only you wanted to talk about the moon's gravity, and I assumed that we were talking about the earth's gravity. If you're gonna talk about the moon's gravity, Just say it, don't dance around the fact that it's the moon's gravity, just make your d@mn point.

Here's you:
"The part that you forget in all of that chemical reactivity stuff is that cooler air is more dense and that means more oxygen content which is also a 'fuel' for the cumbustion process. So if we look at it your way and assume everything else is identical, the iron head WILL NOT make more power....."

Here's me:
1. Aluminum dissapates heat faster than cast iron.
2. That means the rate of dissapation of AL (dy/dx)AL >(dy/dx) Fe.
3. An intake charge running through the intake tract spends x amount of time in the runner. If aluminum can tranfer more heat to air in X amount of time than cast iron, there will be more heat in the charge running through AL than a charge running through FE.

Even though AL dissapates heat faster, I am going to have to say that AL heads are either as hot, or hotter than identical cast iron heads due to their propensity to act as a heat sync during operation. Maybe I'm wrong, but I'll pretend I'm right until someone convinces me otherwise.

I am no chemistry or physics major...but I do follow TPIGuy's theories...for the most part.

I guess this still comes down to the actual world environment and how the engine works as a compelete unit, not just the heads.

"3. An intake charge running through the intake tract spends x amount of time in the runner. If aluminum can tranfer more heat to air in X amount of time than cast iron, there will be more heat in the charge running through AL than a charge running through FE."

Let's follow this....why then is the intake system not made of cast iron? After all, if aluminum acts as a heat sync, wouldn't that make it a 2nd choice as the heat would pass through the heads into the intake tract and heat the incoming air charge hot enough that it would sap power too much with an aluminum setup?

My answer to this is that the aluminum head may act as a heat sync...until you look at the cooling system which is designed to act as a medium to take the heat from the head through the coolant to the radiator. So wouldn't the aluminum head still be more efficient overall? I still don't think that the ability for cast iron to "capture" more of the heat in the combustion chamber is a better thing. Correct me if I am wrong on that...

TPIGUY, I think that your theories are good for combustion, but still the concern is the excess heat leftover and the time in which to get it out of the CC into the surrounding areas, as too much heat causes pre-detonation...as well as the fact that excess heat in an engine causes a shorter engine life. Also take into account the average engine with miles that has carbon buildup.

Maybe that is the compromise that we make for reliability and engine life, that the combustion process isn't as "efficient" in the chamber with aluminum, but it acts to transfer the heat to the coolant to keep the intake charge cooler and longer engine life. And almost all of the aluminum heads out there still offer a better design that most of the cast iron heads. I wish AFR would make a copy of their aluminum heads in cast iron to answer this question once and for all.

It also occured to me that I haven't answered the original thread. I would go with AFR 190cc heads for the overall combination and if budget was an issue, then look at the Trick Flow budget heads.

88TPI406GTA, I am glad you asked the following question, because I was thinking the same thing:

"Let's follow this....why then is the intake system not made of cast iron? After all, if aluminum acts as a heat sync,wouldn't that make it a 2nd choice as the heat would pass through the heads into the intake tract and heat the incoming air charge hot enough that it would sap power too much with an aluminum setup?"

I think the answer to this question resides within the fact that there is a greatly increased surface area the manifold can employ to dissapate heat. You are correct in the assumption that you want to keep the intake manifold cool. Notice the oil splash shield located beneath the manifold for the purpose of keeping hot oil from heating up the intake charge.

The difference between the heads and the manifold is that the heads are directly connected to the block, they absorb a lot of heat from combustion, and, in the case of aluminum, absorb heat from the block. I agree that the manifold, on the other hand, must be used as a medium to transfer heat between the coolant passages of the head. There is no way around it apart from significant design change (The revised version of the smallblock, the LT1 coolant flows from heads to the block, no coolant runs through the manifold itself)(see http://members.home.net/millicanga/Bolt_pattern.htm)

"TPIGUY, I think that your theories are good for combustion, but still the concern is the excess heat leftover and the time in which to get it out of the CC into the surrounding areas, as too much heat causes pre-detonation...as well as the fact that excess heat in an engine causes a shorter engine life. Also take into account the average engine with miles that has carbon buildup."

The excess heat is in there for a hundreth of a second and is expelled as exhaust gas. There will me a marginal, let me stress how marginal, amount of excess heat absorbed in that short time duration ,but not significant.

I believe AFR makes the PRO Action lightning heads in cast iron???

The original question, I think, was "Trick Flow vs Vortec heads". Both heads can make decent horsepower if you know what you are doing. I personally wouldnt go with either of them! I am also not on a budget, so to speak, due to the fact I have all the time in the world to eventually save the money to do it right. I recently sold my new, never been used Trick Flow 23* heads at a $50 loss for many reasons. I have done ALOT of research on SBC cylinder heads over the last year and I decided to go with GM Aluminum Fast-Burn heads. And no, they wont be bolted on as they come from Chevrolet. They will be ported, polished, 3 angle valve job, and springs will be upgraded to match my cam. In my "personal" opinion, these heads will make the most power with the combination I have picked. For all of you thinking of buying TFS and Vortec heads, again you can make power with both sets of heads, but if you are like me in the fact that you can only afford to build it once and want to make the most power you can from a long tube runner TPI setup, then I would choose the Fast-Burns. Criticise me if you will, I'm just trying to let you guys benefit from what I learned. To all the people at Thirdgen.org, have a SAFE and Merry Christmas and Happy Holidays!

Just got off the phone with Mike from AFR.
Advantages of AL vs cast Fe:
1. Weight Savings
2. Repairabilty - cast iron is difficult to weld, it is easier to replace the seats in AL
3. Machining costs - Al is much, much cheaper. As a point of comparison, it costs $350 dollars to angle mill their Pro Action heads, and $250 to angle mill their Al. Cast Iron takes twice as long and chews up twice the tooling.
4. Al is cheaper to heat treat

Disadvantages:
All things being equal, an identical cast iron head will make more power due to the heat retention during combustion.

As a side note, I didn't buy the vortecs a year ago when I pulled a rocker stud on my 882's because the castings are too thin. I also did not buy the Trick Flows because of durability issues and the fact they are Aluminum. I did, however, buy the Dart 180's ... cast iron, good flow numbers, and chicks dig them.

So did he say that their pro action heads were basically their aluminum heads in a cast version?

Or are these the seriously flowing race heads that are cast iron?

The pro actions are really only for big cubes or racing check their site out http://www.procylinderheads.com

True true.... but you certainly are not ALWAYS the one 'standing' on said ground

Geeee....... You don't think that your HOR$E$HIT 'I am ALWAYS right - you are wrong' attitude and connotative 'tone' are what get you into trouble here, do you? [sarcasm] Along with the fact that you are actually NOT always right and still assume this 'tone' in EVERY one of your replies that you are all-knowing.......

Ummm...... I think I already pointed out what was wrong with what you originally posted and how you used it.

What exactly are you taking the derivitive of there? The atomic mass? Looks like one of those 'reactionary' statements to me?



Now, I am no Chem major (I made it through two semesters but found most of it tedious and uninteresting), and I am NOT saying that I am right, but it would make sense to me that the AL head would never get as hot to begin with - especially in the area of the intake port - as the FE head since the rate of dissipation of the AL means it will always shed heat faster.... Now, since you are a chemistry expert, I would appreciate your input on this so tell me what you think........ but do it civilly....

Matt, I swear you have sand in your vagina or something. I'll reply when I get some more time.

Well, upon seeing that reply, I revoke my earlier request for your ideas on the rate of dissipation. I don't want to hear any of your ideas anymore.........

Just shut your friggen C0CK Holster.......

Man you are a tool..........

Why don't you just do us all a favor and dissapear......

Matt

"and I am NOT saying that I am right, but it would make sense to me that the AL head would never get as hot to begin with - especially in the area of the intake port - as the FE head since the rate of dissipation of the AL means it will always shed heat faster.... Now, since you are a chemistry expert, I would appreciate your input on this so tell me what you think........"

We typically refer to heat dissapation as taking place in air. We are trying to move air into the combustion chamber through an aluminum head. Aluminum dissapates heat faster than cast iron ... that is to say it transfers more heat to air in a given amount of time than cast iron can. Therefore, the incoming air charge will contain more heat energy when travelling through AL intake port than a cast iron intake port.


"That means the rate of dissapation of AL (dy/dx)AL >(dy/dx) Fe."

Matt, herein lies the magic of mathematics. The X variable is the independent variable. Time is the most common independant. The Y variable is called the dependant variable. This is because it's value is dependant upon the independant variable. A good example would be the amount you complain. It increases exponentially as a function of time. If we were to plot this on a typical cartesian plane, we would set the independant variable (x) equal to time and the dependant variable (Y) the amount that you complain. Now above, I used (dy/dx) to avoid typing "the rate of dissapation of Al" and " The rate of dissapation of Fe" . I'm sorry if it frightened you.

"ALWAYS right - you are wrong' attitude and connotative 'tone' are what get you into trouble here, do you?"

Matt, If I'm saying something that you think is incorrect, call me out and cite some sources. I know I'm not right all the time, but you are going to have to show me some numbers to convince me otherwise.

Now, is that so hard??? You did a really good job of just talking tech in that part and keeping your ego out! Good Job!!

What I am getting at is that the material of the head is a heat sink for the rest of the material of the cylinder head. And since the rate of dissipation of the iron is slower than the aluminum, and the temperature of the head casting is not uniform throughout, and you have what are called 'cooling jackets' that contain what we call 'coolant' (a mixture of ethylene glycol and di-hydrogen monoxide) to keep the critical areas of the head cool, the iron head will 'hold' the heat longer in a given area and transfer that heat to the rest of the casting which means the intake port area of that FE head, which is generally not exposed to extreme heat, get to a higher temperature than the intake port of the AL head. Now I certainly could be wrong here........

Do not speak to me as if I do not understand what Calculus is. Do you think I would be able to identify your notation if I didn't know what it was?

Listen, this is your problem. The rule here, and pretty much anywhere in life, is that you do not run your friggen mouth and assume the position that you are correct about something until others proove you wrong. You just don't do that. People will identify and think of you as a tool, which many of us have. Do you walk around in your personal life and just rattle a bunch of crap off and than turn to who you are addressing and say "Now prove me wrong or I am going to believe with my entire being that I am the greatest mind to grace the surface of this planet," ????????? Because that is what you are doing here. And at that point it, how correct you are really doesn't mean $hit anymore.

Ahhhh.... So I'm just complaining..... That makes it much more palatable for you doesn't it.... Well I really can't blame you I guess.

Enough of this. If you wish to respond to me with tech, than by all means, post it here. If you wish to continue flaming, use my email address.

Matt, you just took the bait. This guy obviously enjoys pushing peoples buttons. He's a troll. Just let this post die, it's worthless.