New Hesco heads

[XJZ]

Hesco suggests NOT going with the bigger valves with their aluminum head or any other 4.0 head. Bennie @ Hesco was saying that there's just not enough room for the bigger valves and it causes back draft (I think that's the term he used), therefore actually hurting performance.

I'll take the Hesco head any day. I'm sure it will be second to none. I have no idea what Accurate asks for their large port head, might be a good deal for the price however. :dunno:

Edit: A good price if the large valves don't hurt perf.

 

[ROBZ95Xj]

Hesco suggests NOT going with the bigger valves with their aluminum head or any other 4.0 head. Bennie @ Hesco was saying that there's just not enough room for the bigger valves and it causes back draft (I think that's the term he used), therefore actually hurting performance.

I'll take the Hesco head any day. I'm sure it will be second to none. I have no idea what Accurate asks for their large port head, might be a good deal for the price however. :dunno:

1k for the acurate head last time I checked.

 

[Bloose]

Hesco suggests NOT going with the bigger valves with their aluminum head or any other 4.0 head. Bennie @ Hesco was saying that there's just not enough room for the bigger valves and it causes back draft (I think that's the term he used), therefore actually hurting performance.

I'll take the Hesco head any day. I'm sure it will be second to none. I have no idea what Accurate asks for their large port head, might be a good deal for the price however. :dunno:

Edit: A good price if the large valves don't hurt perf.

With the small bore of the 4.0 large valves could indeed be a problem. But some unshrouding of the combustion chamber and possibly the cylinder should be able to make them work.

A cast iron head may not be worth it for them. It is unlikely the cost would be much lower than aluminum and then they would lose their performance image. Fact is a iron head, with all things being equal, will make more HP than aluminum. Aluminum require more compression to make equivilent HP to iron. But you lose the the weight savings and aluminum is repairable and easier to machine and port.

B

 

[FUNKYTEE5]

With the small bore of the 4.0 large valves could indeed be a problem. But some unshrouding of the combustion chamber and possibly the cylinder should be able to make them work.

A cast iron head may not be worth it for them. It is unlikely the cost would be much lower than aluminum and then they would lose their performance image. Fact is a iron head, with all things being equal, will make more HP than aluminum. Aluminum require more compression to make equivilent HP to iron. But you lose the the weight savings and aluminum is repairable and easier to machine and port.

B

Ya, many V-8 guys don't go past 1.94's unless the bore reaches 4.00" or more, or if they have special reliefs cut into the cylinder itself. Like B said, the reason being is that large diameter valves in a small bore tend to get very close to the cylinder wall. This causes more actual restriction of flow in or out of the chamber past the valves. Where as if you had smaller/less shrouded valves you would get more equalized flow around the whole valve head, contributing to better flow and overall performance. The 4.0 head can definitely use alot of chamber work to allow for unshrouding the valves but, going 2.02/1.60's would probably not be worth the effort due to the bore size.

FUNKYTEE5

 

[XJZ]

1k for the acurate head last time I checked.

I just checked the pricing on Accurate's Big valve Head (now that their site has been found and they're not out of biz ); $1,349-1,449 depending on year.

I guess Hesco's Aluminum head can be had for $1,490 (@Rusty's, even though it will be enroute for 4 months or more after you order it. )

Off the Accurate site: "ACCURATE POWER Big Valve heads are the perfect compliment to your stroked or blown engine's heavy breathing. Dyno tested power gains of 16hp on a stock 4.0. Gains are even greater (25+ possible) on stroked or blown engines".

Hesco's head is said to produce 30 h.p. on a stock 4.0.
+14 ponies over the Accurate Power head for only 41 bucks more. This is a no brainer.

 

[ROBZ95Xj]

I just checked the pricing on Accurate's Big valve Head (now that they're not out of biz ); $1,349-1,449 depending on year.

I guess Hesco's Aluminum head can be had for 1,500 (@Rusty's, but it will be enroute for 4 months or more after you order it. )

Off the Accurate site: "ACCURATE POWER Big Valve heads are the perfect compliment to your stroked or blown engine's heavy breathing. Dyno tested power gains of 16hp on a stock 4.0. Gains are even greater (25+ possible) on stroked or blown engines".

Hesco's head is said to produce 30 h.p. on a stock 4.0

I've been thinkin about building a stroked and blown XJ sleeper next winter and the hesco head is on my list.

 

[explorer]

Fact is a iron head, with all things being equal, will make more HP than aluminum. Aluminum require more compression to make equivilent HP to iron. But you lose the the weight savings and aluminum is repairable and easier to machine and port.

B

Could you elaborate on this? I thought aluminum heads generally allowed higher comp. in the first place due to better heat transfer in the head. And while aluminum may be easier to machine, there is still the necessary skill/knowledge to create good port design. In addition isn't the raw material more expensive?

 

[REDXJ4FUN]

Fact is a iron head, with all things being equal, will make more HP than aluminum. Aluminum require more compression to make equivilent HP to iron. But you lose the the weight savings and aluminum is repairable and easier to machine and port.

B

I'm just wondering where you get the idea that if all things are equal that the iron heasd produces more power. I've been in to hot roding for almost 20 years and have never heard this.if that was the case why would there be somany alum headsouthere besides the weight reduction.

 

[Bloose]

The more heat that stays in the combustion chamber during burn the more HP you make. An Iron head absorbs less heat than aluminum so they make more HP (all things being equal). Aluminum heads actually REQUIRE more compression than iron because of the amount of heat they transfer out of the combustion chamber. You may not believe it but it's just plain physics. Heat is energy, the more heat that is in the CC the more power you make (until you get preignition). You make the most HP just before parts start to melt.

Why do so many aftermarket places use aluminum? Not exactly positive but I have some non scientific guesses.

1) The cost of the raw materials is small compared to other factors of manufacturing when dealing with relatively small production runs.

I would guess the cost of getting going on a new head would be very large and the cost of the raw material is small in comparison. When dealing with mass production just the opposite would be true as the initial start up costs would be amortized over a huge amount of heads but the cost of raw materials would be added to the bottom line with each head produced. The difference in cost between a set of aluminum heads and a good aftermarket iron head is only a couple hundred $$, if even.

2) Less weight.

When putting a new race motor together you can pretty much select whatever compression you want so aluminum or iron really makes no difference. If you run aluminum just bump up the compression a point or two. But there is no denying the at least 50 lbs you will save. When it comes to racing, you take every advantage you can.

3) Because aluminum is used almost exclusively in race motors (except where class rules prohibits them) they must be better, right.

I think this mentality has lead to the fact that people are willing to pay more for aluminum, or more correctly, not willing to pay as much for iron. Because of this there is not much money to be made making iron performance heads with the exception of guys that must run them.

4) Aluminum is easier to machine.

Again in limited production I think this can really make a big difference in cost.

I personally run aluminum on the 289 in my '68 Fairlane. There was no way I was going to pay $900 for iron when I could get aluminum for $1100. Plus I bought AFR which come CNC ported right out of the box. Just bolt on and go.

If there was a choice of aluminum for the 4.0L it would be a tough choice. There would likely be a huge weight reduction with the aluminum but the rock solid dependability of the iron would be hard to pass up. If the heads were otherwise identical I think I would have to save the $$$ and go aluminum.

There you have it.

B-loose

 

[MudDawg]

Pretty good explaination....aluminum does transfer heat much better than iron. Lose heat, you lose cylinder pressure...less pressure, less power. On technical merit I agree that aluminum should make less power than iron.

The other side of the coin is that by far most of the heat energy is wasted out the exhaust.

 

[thecozmo65]

I could well be mistaken but Hesco has both a CNC Iron Head: http://www.hescosc.com/HES40CNC.html
And a CNC Aluminum head: http://www.hesco.us/catalog/aluhead.html
If I understand correctly, I could be wrong though.

 

[REDXJ4FUN]

I could well be mistaken but Hesco has both a CNC Iron Head: http://www.hescosc.com/HES40CNC.html
And a CNC Aluminum head: http://www.hesco.us/catalog/aluhead.html
If I understand correctly, I could be wrong though.

I don't see why they wouldn't if they allready have the programing for their alum head they can mod a stock head.

 

[Bloose]

The more heat that stays in the combustion chamber during burn the more HP you make. An Iron head absorbs less heat than aluminum so they make more HP (all things being equal). Aluminum heads actually REQUIRE more compression than iron because of the amount of heat they transfer out of the combustion chamber. You may not believe it but it's just plain physics. Heat is energy, the more heat that is in the CC the more power you make (until you get preignition). You make the most HP just before parts start to melt.

Why do so many aftermarket places use aluminum? Not exactly positive but I have some non scientific guesses.

1) The cost of the raw materials is small compared to other factors of manufacturing when dealing with relatively small production runs.

I would guess the cost of getting going on a new head would be very large and the cost of the raw material is small in comparison. When dealing with mass production just the opposite would be true as the initial start up costs would be amortized over a huge amount of heads but the cost of raw materials would be added to the bottom line with each head produced. The difference in cost between a set of aluminum heads and a good aftermarket iron head is only a couple hundred $$, if even.

2) Less weight.

When putting a new race motor together you can pretty much select whatever compression you want so aluminum or iron really makes no difference. If you run aluminum just bump up the compression a point or two. But there is no denying the at least 50 lbs you will save. When it comes to racing, you take every advantage you can.

3) Because aluminum is used almost exclusively in race motors (except where class rules prohibits them) they must be better, right.

I think this mentality has lead to the fact that people are willing to pay more for aluminum, or more correctly, not willing to pay as much for iron. Because of this there is not much money to be made making iron performance heads with the exception of guys that must run them.

4) Aluminum is easier to machine.

Again in limited production I think this can really make a big difference in cost.

I personally run aluminum on the 289 in my '68 Fairlane. There was no way I was going to pay $900 for iron when I could get aluminum for $1100. Plus I bought AFR which come CNC ported right out of the box. Just bolt on and go.

If there was a choice of aluminum for the 4.0L it would be a tough choice. There would likely be a huge weight reduction with the aluminum but the rock solid dependability of the iron would be hard to pass up. If the heads were otherwise identical I think I would have to save the $$$ and go aluminum.

There you have it.

B-loose

I meant to say I'd likely go iron not aluminum.

B

 

[JeepSpeed]

The more heat that stays in the combustion chamber during burn the more HP you make. An Iron head absorbs less heat than aluminum so they make more HP (all things being equal). Aluminum heads actually REQUIRE more compression than iron because of the amount of heat they transfer out of the combustion chamber. You may not believe it but it's just plain physics. Heat is energy, the more heat that is in the CC the more power you make (until you get preignition). You make the most HP just before parts start to melt.

B-loose

Wrong. Heat is not energy, heat is a byproduct of energy production. If an internal combustion engine was %100 efficient, it would make no heat and a buttload of power. You are wrong. You don't make the most HP just before parts start to melt. Maybe best fuel efficiency, but for power production on the 4.0L ideal is about 195-200*.

 

[explorer]

Wrong. Heat is not energy, heat is a byproduct of energy production. If an internal combustion engine was %100 efficient, it would make no heat and a buttload of power. You are wrong. You don't make the most HP just before parts start to melt. Maybe best fuel efficiency, but for power production on the 4.0L ideal is about 195-200*.

While I'm still digesting what Bloose had to say, I'm not sure your exactly right either. Heat, while being a byproduct of combustion, is energy. It does work, right. If your engine was %100 effecient, it wouldn't waste any heat. Thats entirely different than not making heat. I'm not a physicist or engineer, but I'm pretty sure I could find data to back up the fact that heat IS energy.

http://www.nyu.edu/pages/mathmol/textbook/energy.html

For 4th grade no less.

 

[XJZ]

As mentioned earlier, an aluminum head allows you to run a higher comp. ratio than an iron head so you more than make up for any h.p. loss. Moot point.

 

[corbinafly]

As mentioned earlier, an aluminum head allows you to run a higher comp. ratio than an iron head so you more than make up for any h.p. loss. Moot point.

Yeah.

 

[Bloose]

As mentioned earlier, an aluminum head allows you to run a higher comp. ratio than an iron head so you more than make up for any h.p. loss. Moot point.

No, they REQUIRE more compression. If more compression is available, i.e. different pistons, milled head etc, it is a moot point like you said. But with some motor and head combinations making more compression is tough. My little 289 is a good example. Because it has a very short stroke it is hard to make compression. I have 10.5:1 running the smallest cc head available and a piston with a healthy dome. To get more compression I would have had to go with custom pistions. A 302 will have 1/2 point higher compression than a 289 just because it has more stroke (they use the same piston). Anyway, in the case of the 4.0L if you can get more compression from it by all means save the lbs and get aluminum. For me it would be a tough call.


Jeepspeed,

Sorry, but it is true. Iron heads make more HP than aluminum (all things being equal). And it is because of heat being removed from the combustion chamber. There are huge advancements going on right now with engine part coatings. Right now many engine builders are coating combustion chambers and piston crowns. This is to reflect more heat into the combustion chamber and thus make more power. BTW, there is a huge difference between combustion chamber heat and engine temp. Though they may effect each other they are definitely not the same. When I say you will make the most HP just before parts melt, I mean internal parts. Ask any big dollar drag team, they run thier motors on the hairy edge. They want them to run just outside of melt down for the most power. These are not guys like you and me who have to pay for broken parts out of thier own pocket but they get paid the big money to win. Running a motor too fat reduces heat and HP, running lean makes more power but melts parts (lean detonation) the key is finding just the right mix to make the most HP without melting you internals.

B

 

[XJZ]

But with some motor and head combinations making more compression is tough. My little 289 is a good example.

But we're talking Hesco heads and the Jeep 4.0

Anyway, in the case of the 4.0L if you can get more compression from it by all means save the lbs and get aluminum. For me it would be a tough call.

30 h.p. head and -30 lbs. That's a tough call?

 

[JeepSpeed]

Jeepspeed,

BTW, there is a huge difference between combustion chamber heat and engine temp. Though they may effect each other they are definitely not the same. When I say you will make the most HP just before parts melt, I mean internal parts. Ask any big dollar drag team, they run thier motors on the hairy edge. They want them to run just outside of melt down for the most power. These are not guys like you and me who have to pay for broken parts out of thier own pocket but they get paid the big money to win. Running a motor too fat reduces heat and HP, running lean makes more power but melts parts (lean detonation) the key is finding just the right mix to make the most HP without melting you internals.

B

I see, yeah, I knew that. I think I just misunderstood what you were trying to say.