Thanks tmyers. You are correct sir. I read the links before I responded, as well as some other interesting reading I found on my own. It is not I who needs more education, or whom needs to check with an engineering school. I am over this subject, and will not respond again. <! Debating with one who has a superiority complex is futile>

 

The full aluminum motor, head and block with iron cylinder liners like in the 95 Rover Discovery, (hell it's a reworked Olds / Buick) will go the distance. I have seen many Rover motors with proper maintenance that have gone over 240, 260, 285,000 miles without any internal repairs. This is offroad as well as highway use. When running at 50 mph you have 20 seconds MAX and the temperature will be in the red zone from a normal temperature zone with a stuck thermostat. That motor will heat up alot faster than an all iron motor. From a cold start they will be up to temperature alot quicker than an iron motor which I believe results in less cylinder wear. Motors should be all iron or all aluminum, not the thermal expansion gasket testing mismatch. Just my opinions. Manufactures have bean counters, what makes the most profit to them they will manufacture. I may sound like i'm defending aluminum or Rovers motor but that 278 ci acts just like a 289 Ford. The next motor build will be a 482" all iron FE motor. Had to vent.

Carl....=o&o>....

 

There are many more papers and books out there. The thermal barrier information did have some information that was interesting and did relate to various engine materials and heat transfer rates. The Instrumentation paper gave some interesting information on instantaneous heat transfer rates and how that varies during the combustion cycle. Nice work that is better than the older bulk thermocouple methods that did not have the response time necessary to instrument the phenomena. They are just two examples available on the web I found with a few minutes searching and are not intended to be the "end all" of an explanation. They are merely a beginning from which to work following the references given etc. There is a lot more information out there but much of it costs big $$$ or is available in engineering classes which again costs $$$. I have presented a summary of information I have found from a number of sources over the years that is fairly common knowledge among automotive engineers. Keep reading and looking. Sorry, -I don't have a lot of time to look it all up for you.

I notice Steve did not produce any background reading or references at all for his "theories" of engine operation.

My problem with aluminum is that it is very easily damaged by any cooling system problem, even a McD's wrapper. Much more easily damaged than cast iron.

 

Eric you make it sound like there is a larger problem out there. There is not. Almost every modern motor has aluminum heads if not an all aluminum engine's with steel sleeves. Little Honda 4 bangers, all aluminum last 200k plus langer than most american all iron engines. The Duramax runs aluminum heads and I see no major problems with them. In fact the only Ford engines that are still all iron are the 3.0 used in the Ranger and the 6.0 PSD.

Beemer Nut even if a termostat gets stucked close it will take much more than 20 sec's before you overheat. Even when stuck, water still flows through the engine either through a bypass or through the heatercore. With out this bypass it would take the water in the block forever to heat up.

 

That's OK. I have just experienced or witnessed a number of problems with aluminum head engines. There are also numerous posts here that detail the problems with aluminum heads etc. Personally I won't have one in a vehicle and if that limits me to diesels that is OK by me.

People can buy whatever they want as long as it is available. Most people are clueless and will buy whatever the advertisers and marketing department tell them to. As far as new vehicles go, if Ford does not make what they want some other manufacturer might. I am not in the market for a new vehicle at this time so I can care less.

There are many aftermarket aluminum head manufacturers that want to sell their product so it is marketed heavily. I think they are great for racing applications but not for a daily driver.

Just my opinions based on experience, nothing magic -oh well.

 

The Porsche 928 had a sleeveless AL. block and ran fine also. NOTHING wrong with an AL. setup...........As already stated; the older Cobras, the current GM LS1's, the ULTRA high HP motors like my 180HP ZX12 motorcycle engine.

Remember all the freaking out over the Duramax AL. heads?........No problems.

 

tmyers, congratulations and hats off to you as you seem to know more about the aluminum 215 which grew to 278 4.6 litres in Rovers. We at the club as well as a factory mechanic, from the factory not your local oil changer have gone from normal to pegged hot in less than 30 seconds with Limey crap thermostats. We install modified U.S. stats ( 180*) that fail in open mode. No heater cores, hard core offroad, no radiator cooling, nothing but a 195 degree block and a completly shut stat, yes they get hot fast. Never into steam if we can, steam means death with Rovers motors. I'm Done.

Carl....=o&o>....

 

When I was going to school (which was only 3 months ago, as a ME [Plug: Haven't found the job I want yet either, so feel free to ask for a resume, ME, minor in math, focus in hydraulics and gas jet turbines]) we took a road trip from Montana to Vegas...

On the way back, shrapnel from a vehicle ahead puntured the radiator...in the amount of time the driver said "$%*@" and I said "@$#%", he hit the brakes, pulled over, and the aluminum engine and block in his Honda accord were gone. The vehicle was scrapped after being towed to the nearest town. Understandably, the engine was not in premier condition, and had had a rough life, but I don't think it was more than 30 seconds before the engine was ruined (could have been longer, it was a bit of a situation).

As for aluminum, my graduate project involved finding the rate of burn inside a cylinder...an aluminum engine does lose some heat transfer to faster cooling, the reason being as fuel is sprayed into the cylinder, it will get forced against the wall of the cylinder and head. Aluminum will remove heat from the fuel faster than iron, causing it to cool from a vapor to a liquid state, where it will not combust completely. This does happen in the blink of an eye, as the flame inside the cylinder can move upwards of 40 fps at only 4000 rpms.

Part of our design was an attachment that spread spark (or sparked a small amount of fuel well advanced) throughout the cylinder. This allowed us attempt to burn fuel faster throughout the cylinder, instead of the 70% that was not blocked by the spark plug diode. We thought this was a great idea, until ten minutes of driving (this was in a SAE competition snowmachine) got the engine hot enough to semi-fuse (semi because they were not the same metals, and I don't know another word to describe it) the plug attachment to the aluminum block.

The moral: I try to use Iron on anything that I think might get damaged or run hard...I use aluminum to brag to my friends that "Yup, got me a new set of dem der trick flow heads *spit*"

PS No amount of schooling can make up for old guys who have done it before!!

 

Did not know you where talking about a special purpose, hard core, off road vehicle. That was not clear in your first post. How many people here have any experience running any vehicle with anyout type of cooling system other than maybe a VW or a motorcycle. And I was not speaking about your vehicle anyway but in general. Anyway I'm sorry if you took that the wrong way.

PryoBob I agree with most of you statements. I think this is the primary reason that most aluminum engines run iron sleeves. Any system can have a catastrophic failure. One thing we see with todays engines is running higher temp tstat's. Part of this is no doubt improve combustion efficiency to reduce emision. I also think that this is the reason they can't run iron. But at what point does the heat of the combustion chamber hurt volumetric effiency. I think this is what Torq's post was elluding to.

Please everyone understand I have nothing against Iron. Last year I spent $1400 to have my DOVE heads ported. This year I moving up to Trickflows. Out of the box they almost outflow the DOVE's and ported will out flow them. The biggest improvement for this head is flow at mid lift giving me a wider powerband. This is something I could not do with the old heads at all.

 

Bob, good luck with the job search. Hydraulics are fun. Have you checked into tank design? -hehe

 

tymers, were cool no problem. On iron liners on early Rovers up to 2002 had a problem of them shifting if you drove into steam. With this motor you add a new awareness at keeping and eye on your temp and oil gauges, a good life insurance thing. More to add on aluminum, they are real sensitive to the type and manufacture of coolant used. Eat away at the aluminum to having everything white or tan coated inside. Later.

Carl....=o&o>....

 

Well I don't for sure, but I am sure that theory is sound. The more heat the chambers and heads retain, the less dense the air charge would be. Most of my studies we used a theoretical 100%, for the sake of accuracy. It would be interesting to find if anyone has done that study, to see at just what point making the switch from iron to alu or vice versa would be beneficial.

 

Considering the speed at which air enters the engine and combusts, does the temperature of the surrounding metal make a noticeable difference in air charge temperature?

 

Several years ago dyno testing was done on an engine comparing cast iron to aluminum. The heads were identical other than material. The iron made more power by 1-2%. If the design was changed on the aluminum heads to allow more compression they made more power. The test may have been done by David Vizard, but I really don't remember for sure. Iron is more thermally efficient than aluminum. Aluminum heads are used for performance applications because they can take more compression, are more easily machined, and save considerable weight off the front of the car.

In the early days of aluminum head use there were gasket problems due in part to things already mentioned. Another factor was the headbolts, which were the same as those used for cast iron. After the heads were torqued down the gasket was cruched x ammount. After heating up, the heads would expand more than the block and head bolts which overcrushed the gasket. The next time the engine was started cold the gasket did not have enough crush and blew.

I've put together several LS1's and have never had any trouble because of block or head material. These engines have been on the road for almost 9 years and have not developed problems.

The real issue with overheating isn't necessarily temperature, it's the formation of steam pockets that results in cavitation inside the engine. This will destroy aluminum in seconds, but iron will stand up to it for a while. There have been plenty of all iron engines that are destroyed by overheating easily. Anybody run a Cleveland or a 400 SBC?

An aluminum engine properly designed and assembled will live a long and happy life as long as it is well maintained and not abused. I agree that aluminum has no place in a truck where detonation is likely to pound it to death, but it is nothing to fear in automotive applications.

RC car engines are the most powerful engines in the world when it comes to specific output making about 15 hp/ci. They are made of aluminum and usually run about 250 degrees. Some newer designs run at over 350 degrees.

 

I believe this thread started by asking about longevity differences between aluminum and iron blocks. In my opinion, they're not different any more. Look at the miles on the older Lincoln Mark VIIIs (4.6 aluminum block and heads), they're getting up around 200K miles. My '94 has 165K miles, runs great, and doesn't use oil. I've had the valve covers and pan off, cylinders still show crosshatching and everything is super clean. The '93-'99 Teksid block (Mark VIII and Cobra) can handle 1000hp without being modified, but the iron parts (crank and rods) need to be upgraded to forged pieces.

Just my personal experiences.

Greg