Heads: Let's air it out

[skunk21]

Well for the sake of argument we pretty much know all about GT40s and "P" heads. The other heads that get alot of discussion for instance are AFRs & Wedge heads but what about all the others like Patriot, Brodix, Holley, Flotek, ford racing,and any others. If you are only building a mild street car and have no interest in track time what is wrong with thumper or ported E7's.Do alot of these heads get over looked due to hard numbers and facts, they are of poor quality, people use the other brands because that is all they know or everyone runs them. This is more for conversation and to shed some light is all so lets not get too crazy.

 

[Mustang5L5]

I think the issue is that once you put the money into the heads, you are several hundred bucks within range of a better head.

Prob is it never stops.

You do ported e7s and someone will say you could have gotten gt40ps

You do 40ps and someone will tell you you should have sprung for aluminum heads

You do some of the entry level al heads and someone will say to just get top of the line AFRs.

I've gotten plenty of crap alone for using "junkyard 40ps". I agree. If building a fun street car, don't need high dollar or fancy heads.

 

[NIKwoaC]

*Lurking...*

 

[Cobra912]

Well you are right. There is a lot of people that will only use a certain brand or part because of what they were told and once they use them, they share the same info as it being the only choice. Granted that same info can make you avoid costly mistakes but there is also a lot of bad info out there. I bought performer heads last time around and everyone told me I was nuts. Well my car made 475 to the wheels with the out of the box stock heads and recently ran my best times with them. No one could believe my junk runs mid 10's. So guess what......I bought another set of eddy heads despite being told I was dumb not to go with AFR's or TW's. It's what I could afford!

 

[85_SS_302_Coupe]

The problem is that, anything even close to $700 in my book is a waste of cash on iron heads because you can find very nice aluminum heads on any classified section on any forum for around that much, which are likely to flow better than ported iron heads.

In my case, i'm running ported '69 Windsor heads, but all the port work was done when i bought the heads so i saved myself money there, and my machine shop guy was so impressed with the port work that i took a chance on'em. I did end up having $800 into them after new valves and a valve job, but the numbers they're making are pretty worth it IMO as i'm only 20hp or so less than equally built 347s with AFR's (and keep in mind those engines usually have higher compression than mine which could make up for some of that 20hp). If i had $800 to shell out all at once, i'd go with used aluminum heads next time, but i bought the heads for $260, let them sit for a few years and then spent another $450 on valves and a valve job when my budget allowed it.

All that aside, it's pretty damn cool when i pop my hood and people see iron heads and i can pass it off as a cammed 302.

 

[NIKwoaC]

The problem is that, anything even close to $700 in my book is a waste of cash on iron heads because you can find very nice aluminum heads on any classified section on any forum for around that much, which are likely to flow better than ported iron heads.

In my case, i'm running ported '69 Windsor heads, but all the port work was done when i bought the heads so i saved myself money there, and my machine shop guy was so impressed with the port work that i took a chance on'em. I did end up having $800 into them after new valves and a valve job, but the numbers they're making are pretty worth it IMO as i'm only 20hp or so less than equally built 347s with AFR's (and keep in mind those engines usually have higher compression than mine which could make up for some of that 20hp). If i had $800 to shell out all at once, i'd go with used aluminum heads next time, but i bought the heads for $260, let them sit for a few years and then spent another $450 on valves and a valve job when my budget allowed it.

All that aside, it's pretty damn cool when i pop my hood and people see iron heads and i can pass it off as a cammed 302.

I'd say that you're more the exception than the rule. Most guys with ported factory irons on a 347 are going to be in the 330rwhp range. Also, I think that a lot of people automatically default to AFR 185s on their 331/347, which IMHO is short changing yourself.

Did you ever get those irons on a flow bench?

 

[90lxcoupe]

This topic has been beat to death on this site, just do a search. Aluminum heads are the way to go. 90% of the guys that port a set of stock heads will just end up with aluminum in the long run, just do it right the first time. Aluminum heads perform better, and take a ton of wieght off the nose.

For just over 900 bucks you can get a pair of GT40x heads, why would you drop 5-600 on your iron heads?

 

[fiveohwblow]

Ok I will play, but more with a question than an answer. I got EXTREMELY lucky and found a set of never used in the box and bag TW heads from a guy with the upgraded springs for higher lift for $1050 so I bought em. I was however looking for these heads since I read many of times the casting was better on them than the AFR's. Does anyone have any factual or documented information on which is better, flowtests stock for stock? Ported? I know there is a search function, and if you read my post you would know I have researched it but I have yet to find anything definitive that places one above the other.

 

[NIKwoaC]

Ok I will play, but more with a question than an answer. I got EXTREMELY lucky and found a set of never used in the box and bag TW heads from a guy with the upgraded springs for higher lift for $1050 so I bought em. I was however looking for these heads since I read many of times the casting was better on them than the AFR's. Does anyone have any factual or documented information on which is better, flowtests stock for stock? Ported? I know there is a search function, and if you read my post you would know I have researched it but I have yet to find anything definitive that places one above the other.

What heads in particular? TW170 vs AFR185? Both Trick Flow and AFR post flow numbers on their websites. I've heard a few people say the AFR advertised flow numbers are "inflated", and if you look at their flow bench setup for some of the heads, they use 4.125" bore, which would lead to higher numbers than testing on a 4.030-4.060 bore...

 

[90lxcoupe]

You cant just rely on flow numbers to compare heads, theres also port velocity, valve angles, etc etc. Flow numbers are one piece of the puzzle.

 

[skunk21]

This topic has been beat to death on this site, just do a search. Aluminum heads are the way to go. 90% of the guys that port a set of stock heads will just end up with aluminum in the long run, just do it right the first time. Aluminum heads perform better, and take a ton of wieght off the nose.

For just over 900 bucks you can get a pair of GT40x heads, why would you drop 5-600 on your iron heads?

I'm not really debating iron vs aluminum. all I stated was what is wrong with them for a given type of build, nothing so I guess I stand alone. I'm aware of flow #'s and weight. I was also looking for the sake of discussion reasons why other aluminum heads are overlooked and hoping people who run the other types of heads would jump in with info, facts, pro's & con's, real world stuff we could use. Patriot heads can be had for less than a grand the flow #'s don't look all that bad but I'll admit I know very little about them. How is the quality, etc. What about Brodix, Holley,etc. Tons of info on afr's, TW, etc. I'm not knocking any company I'm opening up a topic about different available heads and if anyone has info they can add.

 

[85_SS_302_Coupe]

I'd say that you're more the exception than the rule. Most guys with ported factory irons on a 347 are going to be in the 330rwhp range. Also, I think that a lot of people automatically default to AFR 185s on their 331/347, which IMHO is short changing yourself.

Did you ever get those irons on a flow bench?

No and i wish like hell i did. Next time i have a reason to pull them off that's first thing on my list. I basically just went by the machine shop guy's opinion of what the port work looked like. They had a couple bent valves in them when i bought'em, and this guy is pretty reputable for what he does so i asked him straight up if he thought the port work looked good enough to dump money into, and his words were "i haven't seen hand porting like this in decades" so i ran with it. The kid i bought them from told me he bought them from a guy in NC who ran them on a 600hp Windsor in a dirt track car...which i didn't believe until seeing the dyno results.

 

[85_SS_302_Coupe]

You cant just rely on flow numbers to compare heads, theres also port velocity, valve angles, etc etc. Flow numbers are one piece of the puzzle.

Ahh...something i forgot to mention about the P vs. non P heads, the P's actually have smaller exhaust valves than the non P, which is funny because everyone knows Ford heads are lacking on the exhaust side. So why would Ford do that? Because they revised the exhaust ports and by using smaller valves they picked up port velocity

Also on another note about my heads, i read years ago before i even got them that the '93-96 GT40 iron heads were based off of the old Windsor heads, with the biggest change being smaller combustion chambers...but i think i read that on the internet so who knows how true it is.

 

[85_SS_302_Coupe]

Here's a few pics of mine after getting them back from the machine shop. The white stuff is grease they put on there to lube the valves on the first start up.

 

[NIKwoaC]

I know this is going to stir the pot, but I have to say it- The more I learn about cylinder heads and engine design, the less I believe the hype about flow "velocity".

Look at the heads that GM uses on it's LS engines... Notice how big the ports are... Do you think they're worried about "velocity"?

Look at the Coyote. It has huge ports in its heads, but does it struggle to make torque? Would anyone consider the Coyote a dog, even at low RPM? Does the TiVVT by itself really make up for the big ports and "low velocity"?

Sure, the GT40P has a smaller exhaust valve, but does the exhaust port itself really have a smaller cross section? How does the exhaust flow compare to a standard GT40P?

I'm not a pro engine builder, nor do I claim to even be close to that level of knowledge. But I can tell you that when I venture into my planned engine build this winter, I'm not going to be too concerned with "velocity" when I'm buying my cylinder heads.

Just food for thought, fellas, keep up the good conversation.

Oh, BTW, 85_SS_302_Coupe, those ports do look good!

 

[90lxcoupe]

I know this is going to stir the pot, but I have to say it- The more I learn about cylinder heads and engine design, the less I believe the hype about flow "velocity".

Look at the heads that GM uses on it's LS engines... Notice how big the ports are... Do you think they're worried about "velocity"?

Look at the Coyote. It has huge ports in its heads, but does it struggle to make torque? Would anyone consider the Coyote a dog, even at low RPM? Does the TiVVT by itself really make up for the big ports and "low velocity"?

Sure, the GT40P has a smaller exhaust valve, but does the exhaust port itself really have a smaller cross section? How does the exhaust flow compare to a standard GT40P?

I'm not a pro engine builder, nor do I claim to even be close to that level of knowledge. But I can tell you that when I venture into my planned engine build this winter, I'm not going to be too concerned with "velocity" when I'm buying my cylinder heads.

Just food for thought, fellas, keep up the good conversation.

Oh, BTW, 85_SS_302_Coupe, those ports do look good!

Velocity has everything too do with it, the problem is that people dont realize(even some professional shops) that you can still use a big head and have plenty of velocity.

 

[TrophyHead]

I'm not a engine builder....maybe Rick91GT will chime. I always listen to that guy.

I beileve the stock pistons are an issue. It really hinders on your cam and head selections. Unless you flycut them. So with that said if your going to invest in really expensive heads I would start with a block with correct pistons to get a nice camshaft selection and heads. IMO

Or flycut the stock pistons. But then again how crazy do you want to go? Maybe start with a aftermarket block then the skys the limit. It all depends on goal. Nothing wrong with Thumper heads or Gt40 if you want a nice fun street car. Now if you want the fastest car in your area.....that a different ball game and will set you back about 20g's to do it right.

 

[85_SS_302_Coupe]

Well, like you said i'm no pro engine builder either...it's all in what i've read. I know flow velocity is a huge deal in carbs and intakes, seems like sound logic with heads too. I know the straw theory is basically fool proof...imagine drinking from 2 glasses through 2 straws, one straw is 1/8 inch while the other is 1 inch. You have to work your ass off to get a drink out of either glass...it takes just as much force to pull a drink out of the tiny straw because it's restrictive as it does the huge straw because it takes that much extra force to pull such a huge drink. With heads, if you throw some 300cfm heads on a stock 302 short block, the engine just doesn't pull enough air through those heads to make good power. Port velocity is more about the shape of the ports rather than the size..you can't just hog out a runner and expect it to flow...air will move faster through different shapes because of the venturi effect....if a runner is simply hogged way out, air won't move as FAST as it will through another runner that's designed to be *just* restrictive enough to force the air to move faster through it. It's a science that i can't really explain better than that but everything i've read about porting says that velocity is a huge deal.

 

[NIKwoaC]

Well, like you said i'm no pro engine builder either...it's all in what i've read. I know flow velocity is a huge deal in carbs and intakes, seems like sound logic with heads too. I know the straw theory is basically fool proof...imagine drinking from 2 glasses through 2 straws, one straw is 1/8 inch while the other is 1 inch. You have to work your ass off to get a drink out of either glass...it takes just as much force to pull a drink out of the tiny straw because it's restrictive as it does the huge straw because it takes that much extra force to pull such a huge drink. With heads, if you throw some 300cfm heads on a stock 302 short block, the engine just doesn't pull enough air through those heads to make good power. Port velocity is more about the shape of the ports rather than the size..you can't just hog out a runner and expect it to flow...air will move faster through different shapes because of the venturi effect....if a runner is simply hogged way out, air won't move as FAST as it will through another runner that's designed to be *just* restrictive enough to force the air to move faster through it. It's a science that i can't really explain better than that but everything i've read about porting says that velocity is a huge deal.

Not sure that I've ever heard that straw theory.

Consider this straw theory:
Plug your nose and breathe through your mouth with nothing but a coffee stirrer straw. Can you do it for a minute? Two minutes? Uncomfortable, isn't it?

Now do the same thing with 1.5" diameter by 12" long PVC pipe.

Post pics of you doing the second one, BTW.

 

[NIKwoaC]

Velocity has everything too do with it, the problem is that people dont realize(even some professional shops) that you can still use a big head and have plenty of velocity.

If you can still achieve plenty of velocity in a big head, then why are we even concerned with losing velocity by moving to a bigger head?

This is what I'm saying, if we can get all the velocity we need, even when using a big head, then why do we worry about velocity at all?

I think what happens is people switch to big heads without paying attention to the cam. They run big heads, big cam (lots of overlap and duration), and the car is a dog at low RPM. They assume heads must be to blame, not enough "velocity", when the issue is really the cam. The big cam was necessary when they were running small heads, but not needed with the bigger heads.

<-- This is a thinking face, not an angry face, haha.