Aluminum Heads For The IDI

[jaluhn83]

There is so much more to it than that, especially when an alloy is made for the purpose of having a higher melting point than the base metal. Example: iron melts at 2300, while medium carbon steel melts at 2700.

You're backwards. Pure iron is ~2700*F. This is why wrought iron was used for so long because it was very difficult to get hot enough to truly melt pure iron. Also part of why the blast furnace works - you're dissolving carbon in the iron as it's reduced thus creating liquid high carbon (and thus lower melting point) cast iron.

Alloying is very very complicated. Most of the time you're not trying to raise the melting point, but rather trying to extend the working temperature range or increase strength in some way.

Really, the melting point is meaningless from an engineering point of view, because long before you get to that temp the metal has softened to the point of having no strength.

Most likely the bulk temp of the pistons isn't much over 300-400* since you've got constant heat flow out of the piston into the cooling oil and the cylinder walls. Anything over that and you start getting serious problems, not just due to metal softening, but also thermal expansion.

Steel pistons may actually be worse due to the lower thermal conductivity - they may loose strength at a higher temp, but will run hotter since they woln't shed head as easily.

Ceramic coating the crowns is certainly a good idea period just to reduce the heat load going in.

The myth of the 1200* EGT being based on aluminum's melting point is just that - a myth. Really it's based on the heat flux through the head, piston, chamber, cylinder, etc and damage due to piston overheating, thermal stress, scoring, etc.

Also, are not hyper-eutectic. Hyper-eutectic don't really get you that much. If you read the article that was linked, you'll see that it's mainly to reduce thermal expansion allowing for a closer cylinder fit to minimize cold emissions. The additional silicon also makes the alloy more fragile which is obviously not a good thing. Said article stated that most diesel pistons are a 2613 alloy with low silicon levels. 99% are cast as well due to the need for a steel top ring groove insert.

 

[tbirdfiend281]

So you say porting the idi heads is a waste of time or are you saying its not going to change any flow in or out... Hmmm OK.. I'm all ears. You probably have no idea what the exhaust ports look like in the idi head. I have spent plenty of time porting several sets of idi heads. Those that have seen the before and after ports know what it is. But many that have seen my work go to the ralleys or look at my porting pics. Am I offended by you comments... Nope... Not at all. My job here is to get the correct information out there for all to see. I have never nor will I ever hide any information. No secrets here. So now lets discuss some carectrustics of our diesel heads. Do you know we don't really need an intake manifold on the na engines.... All we do is allow air into the cylinders by being directed thru a manifold. Thats it... Now add a turbo to that mix and now you need a manifold. So we are boosting to say 13 lbs... Thats 13 lbs of compressed air waiting on top of the intake valve to rocket into the cylinder. As long as the boost stays at 13 lbs we have an infinant supply of this air at that pressure. We don't care how open the intake is. We loose nothing if its made wrong by porting it. We are not a gasser head where porting them wrong kills the flow. So now you have all this pressure in a cylinder and then its compressed and goes bang. Now get it out of there fast as you can when the exhaust valve opens. If you have ever seen the exhaust ports you may have noticed and felt the floor of the port as it turns towards the exhaust manifold.. That inside radius is to sharp. It needs to be cut down so the flow is smoother. Again we can smooth out this area as much as we want. Actually the smoother the better the flow. Opening up the port works great. Now we are out of the head into the exhaust log.. Sorry but thats going to be a problem. Its a log jam of hot air usually under pressure because its working to spin the hot side wheel of the turbo as much as 120,000 + rpm... Now simple math will tell you thats oh... Around 2000 rpm per SECOND... Did you blink... That was probably 4000 rpm you just missed.. Bowl work is important too. Unless you were able to see what I did it hard to explain.. But its smooth flowing in every way. Give Barnett machine shop a call about the porting they do. I did my porting before I read about what they did. So I used some of what they do... But I port everything. Not just some of the ports. I was lucky. I worked in a power plant machine shop that was the size of 2 football fields. We had every kind of hand grinder and burrs available to man or beast. Every sanding roll made too. I had 6 differant air grinders in my tool inventory and if I needed or wanted more they were free for the asking. We could even check them out for home use.. Same with the actylene and oxy bottles... Bring them back mt.. Not a problem... Steal anything and your fired. Porting idi heads a waste of time.... Well only for those that think its so...

I had no intention of offending. I was just commenting, the large majority of those of us on the forums are not going to invest into that kind of motor work. That is all.

 

[tbirdfiend281]

Some of these posts have made me scratch my head. I will attempt to straighten out some things I think I know about.

1) Aluminum OHV heads have been on gas engines for at least 50 years, some with better results than others. They aren't new.

2) Aluminum melts at 1280 f. It will not magically stay solid at 1600. That is why the crucial number on anyone's exhaust gas gauge is 1150, since it is downstream from the event. Any higher and you are looking at pistons with holes in the top.

3) The galvanic reaction can happen to some extent, depending on several variables. There are millions of aluminum heads on cast iron blocks that have a useful service life of 200,000 miles and more.

4) Aluminum and cast iron have a very similar expansion rate. At normal operating temperatures it insignificant. Molten aluminum has a shrink rate of .007 per inch, cast iron is about .010 (Iron melts at almost double the temperature of aluminum). Those numbers change a little in the casting process depending on shape and length, but are close enough that all of the automobile manufacturers have decided it is OK to use dissimilar metals in engine construction.

5) There is a significant difference in head porting and polishing. What Gary does is an aggressive polish job that undoubtedly helps air and exhaust flow, especially for the turbo engines. A port matching job is not necessary for the IDI simply because we do not have the concern the gassers do about atomization and fuel pooling. A smooth airway is all we need.

6) What good does it do to talk about not ******* in other people's cheerios and then go ahead and do it anyway? Your opinions count as much as anyone else, but don't wrap them in a **** sandwich. They lose their taste.

I will rephrase in a PC way. There is no reason to get upset about something a large percentage of us are not going to do. A large percentage of IDI forum people are not going to port there heads, an even larger percentage will not seek out and acquire AL heads.

 

[tbirdfiend281]

you owe me a new monitor!!!!!! dang!!

Well Mike.. I may have to borrow that quote.... I really didn't need a reason to clean the screen on this side of the computer.. But it sparkles now.. I'm not pointing out a failure or falsehood in someones posts. But looking at the number of posts we both have and we joined this board about the same time. It appears I have over 14,000 more posts. Validation for what I post.... Maybe Angry about the posting about wasting time porting an idi head.. Nope. Just sad that someone can't see the usefullness in it. Sometimes I feel I failed to help others to understand whats known to work and work well. Moving on now..

I had an IDI, then got rid of it. I recently got another IDI. Voila, post count. Simply having posts on a forum means nothing in the amount or lack of knowledge one person has. That being said, you have done a lot of work with IDI's so I assume you do know a lot, as to not insult or take away from your own knowledge. Also, why not call me out specifically?

 

[icanfixall]

Tbirdfriens.. I amd not calling you out so please don't go that direction. I simpley know what I know but continue to learn here all the time. I do not know everything. I certainly wont post a false statement about something or any member here. Thats not my style nor many others here. My post count is what it is. Nothing inflated either. At this time there is only one member with more posts than I. I may or may not pass him someday. Thats not a goal of mine. I post to help others. Nothing more. I have no ego to get hurt either. This is a friendly family forum that I'm happy to be a contributater of. I own a 1938 Cord beverly sedan and am a member of the clug.. Auburn Cord Duesenberg clug. We are a world wide clug. I talk with and help members all over the world but... Thats a very slow forum. Those owners are not fast answering questions like we are here. This forum has members all over the world too and we like to help them also. Not every country has a mention on this forum and niether does the ACD clug. There are only about 700 cords, about 400 duesenbergs and around 500 Auburns out there so parts are tuff to locate especiaaly for the Duenbergs. During WWII some big cars were found in barns over in Europe. So during the mid 50s a group of members went back over there searching for these cars. Some were found.. Others not found but the search goes on. The Cord historian lives about 8 miles from me and the Duesenberg historian lives about 34 miles from me. He has helped Jay Leno get his Duesenbergs running again... I have met and talked with Randy and hes a great guy. Have not met Jay yet but will someday... So am I someone special.. Not.. I put my pants on one leg at a time just like everyone else. Some hav called me a celeb just because Diesel Power mag has done three articles with me in them. My truck has been showcased too but that imbarrassed me some. Jason the publisher of the topics is a friend of mine and I have helped him with what he has needed too.... Still I'm just a member here doing what I can for others. I'm really uncomfortable being placed on a pedistal by some members. I feel thats for other more worthy than me...