Two questions:
Are these measurements or calculations?
If they were calculations, what type of aluminum was used in your calculations.

It's my understanding that Silicon added to aluminum greatly reduces expansion.
Mahle is well known for using high Si content aluminum. Those formulas are proprietary and well protected so it's hard to judge exactly what they are using.

If I'm reading your number correctly, the difference in squish area would result in about 1.35cc change. It is not uncommon for unmolested chambers to be 2-3cc different.

1.35cc change would result in a .16 change in compression ratio.
Almost undetectable on a dyno and undetectable in real life application.

I am not sure that that is a good model - we are talking about defects that need to be measured in Angstroms and it is the effect of them piling up and interacting that causes the problem.

the relative distances between coarse and fine pitched threads are all relatively large so I am not sure that this is very significnant.

The level of stress is still the most likely cause of any difference.

There are basically 3 types of Aluminium used in piston manufacture.

2618- T61 Aloca developed alloy which has very good strength at high temperatures and is great in Turbo engines.

It has a high melting point and a wide freezing range but it has relatively high expansion.

It isn't great at scuff resistance and can be prone to ring groove wear.

Hence coated skirts and anodised ring grooves.

It is easy to forge.

Expansion 20.6 ppm per degK

Eutectic alloys such as 4032-T6

About 12% Silicon - lowest melting point of any Aluminium Silicon Alloy and a very narrow freezing range makes it ideal for the manufacture of die cast pistons.

It can be forged but is more difficult than 2618.

It has better scuff resistance and usually exhibits good ring groove behaviour.

Very similar to the material used by Mahle for 911S pistons and the like.

It can suffer from Silicon migration after extended time periods but is a good stable material that has stood the test of time.

Coefficient of Expansion 18 ppm per degK

Hypereutectic Alloys

Around 16% Silicon - some free Silicon is present as 12.7% is about the limit if solubility.

Hypereutectic 390 is a typical alloy. It has good cold strength, possibly a little better than 4032-t6 at moderate temperature.

It has excellent scuff resistance and very strong ring grooves.

Expansion is about 17ppm per degK.

This alloy is relatively modern and wasn't around in the days of Air Cooled 911s.

Thermal Expansion Metals

No huge difference in expansion rate for these alloys, range is 12.8 to 13.2. The difference may not be significant if one did not take the gap change into consideration but could play part of a cumulative effect solution.

Metal Temperature Range
(oF) Thermal Expansion (microinch/(in oF))
Aluminum 68 - 212 13.1
Aluminum Alloy - 2011 12.8
Aluminum Alloy - 2017 13.1
Aluminum Alloy - 2024 12.9
Aluminum Alloy - 3003 12.9
Aluminum Alloy - 5052 13.2
Aluminum Alloy - 5086 13.2
Aluminum Alloy - 6061 13.0
Aluminum Alloy - 7075 13.1

Chris - do you know the RS piston material rates? Is it the 4032?

Thank you for posting the 2618 rate. This is the material JE uses in their forged pistons.

Thank you for the piston material but my question was about cylinder material.
We know that Mahle used at least two different aluminum materials.
Do you have that data?

You're welcome. That list is not just piston material.

Mahle is an aluminum blend and we know the ranges of expansion for the materials class which is quite small. I can take these to a local lab for a spectro analysis and have both confirmed but I think it would be a waste of time and money if it's .2 coefficient different. If you're confident they have a magical formula then perhaps you could prove me wrong and test a set on your own.

Strangely enough, I don't have to prove you wrong nor is that my purpose. Life is too short to worry about your little project.
I have engine build formulas that has proven track records, with 28 years of constant development and improvement.
Most people are looking for just that, a formula that works.
My purpose on this forum is to ensure that the least number of DIY builders travel down the rabbit hole to never never land.

I find the whole subject to be strangly amusing.
People are at odds as to what configuration is best.
There is no one correct answer...what works for one builder may not have the results another builder is looking for.
Henry has been around for a long time...I trust his judgment...and that is because he has tried and failed at several configurations...to end up with one that works consistantly for him.
As for Andrew...I don't know...he may be a great builder...but the history is not there...perhaps in several years he will build enough engines for other people so that his rep will be confirmed.
Time will tell...until that time...I believe this discussion is moot.
Bob

That's great. I'm very happy for you, your formulas and your 28yrs of development and contribution to the community. I trust that you've helped a lot of people with their projects by providing advice and with no compensation or thanks.

I'm not a shop so I only plan on this one engine and one car like many DIY folks here. Relatively speaking this one engine/car is quite an undertaking for me. I guess if you're trying to protect me from myself then I owe you a thanks; your intentions are good. At the same time I should tell you I've been DIY'ing pretty successfully for quite a long time. I've picked up a few tricks and I look 10x's before I leap. If I screw this one up then it's all on me and I'm okay with that. I have a back-up plan and I would suggest anyone trying anything unproven do the same.

If the experiment here ends in catastrophe for me and my delicate magnesium case, I hope people have an opportunity to learn as I share my open book of notes, calculations, reasoning and methods.

The results of precision measurements for the cylinder bores for the QSC 92mm cast iron jugs were all out .0007" to .0008" top to bottom. You may not notice if you slapped them in and ran them at 3.622" as the margin is not that bad at all.

JE pistons part number 261665 PORSCHE 911 2.7L 92mm 9.5:1 are sized 3.6205" with a manufacturer disclosed margin of error of +/- .0005". This means you can order off the shelf from JE pistons and precision hone the QSC off-the-shelf jug to fit.

I would hold lower confidence in the QSC aluminum cylinder nickies longevity of service without analysis of the bore and the limited possibility to machine the bore due to the thinness of the coating. If you didn't mind paying out to recoat then it might not matter.

All the facts for now.

I was searching on Google this morning for anti-corrosive cylinder coatings and came across this thread ( http://forums.pelicanparts.com/911-engine-rebuilding-forum/261925-painting-cylinders.html ). Head vs. cylinder, different but just noticing.


2013:
2006:
:confused: Just caught my attention and made me curious. If you stated in 2006 you had no way to measure then where did the data you provided me in 2013 come from... if your experiments were from the 1980's?

Again, what gives?


2006:
2013:

Surely the paint that was used on the SR71 had a ceramic base and hence significant resistance to heat.

Apart from Black Bodies having good heat rejection due to its emmisivity approaching 1, most Ceramic Paints cause heat to be retained as they have relatively low heat transfer coefficients and behave as insulators.

I fail to understand the argument about increased surface area as this would inevitably increase drag and defeat the whole object on a plane that flies at the speed of a Blackbird. :confused:

Blackbird aside, I'm curious where measurements from the 80's came from that were provided this year (2013) but didn't exist in 2006.

Paint
 

What I remember in school, the primary process of the SR-71 paint was to help absorb radar waves to help lower its signature, early stealth technology. Then of course the paint had to survive the heat generated by its Mach 3+ envelope. Interesting fact, the airframe would stretch a foot in flight due to thermal expansion. I think those 9000 rpm engines Henry is building have some Blackbird DNA. :D

We can talk about the skunk works and leaking fuel until the airframe was up to temperature in flight... start up with two supercharged v8 engines.

Still curious on the data that was presented by Henry.

Andrew,your obsession with Henry is starting to look a little creepy!
Present your data and we'll evaluate your conclusions.

Of course I'll present my information when it is ready. The fact that misinformation was provided to say I don't know what I'm doing rubs me the wrong way. It should rub everyone that has read this thread the wrong way especially if they believed and supported this guy.

Glad someone said it. I applaud someone's desire for facts to benchmark progress. But it is a huge mistake for those involved in research to ignore the learning that comes with the punishing laboratory of practical experience.

Between the economy and the aging out of our cars, those who service our high performance industry are under extreme darwinistic pressure: word of failure gets out quick. Reputations never rebound. Shops are kaput. Look at all the tuning shops that have closed over the last five years alone. I can nr several just my area.

Part of science is observation of what works and survives over time and learning from that. I think the experiences of Henry, Steve and other who do a lot of this should be well heeded. Or be prepared to suffer what doesn't work.

This ongoing obsession seems up have little to do with progress or sharing information.

Sounds great. Let's accept lies as facts because of who this guy is around here. Get real.

Put yourself in my shoes for a minute - another person provides false information to further their agenda and position in an effort to discredit yours. Mentioning this and asking for an explanation doesn't make me obsessive. It makes me angry. I don't like being lied to; I'm going to confront it and call the BS out.

Henry, Andrew and Scott (aka: Winders) ought to bring some of their banter over to the ". . . hurt by Motor Meister" thread in the 911 Forum and help give that clown, SuckerFish, what for!

Jokes eh? Try this one on: In addition to being a renowned engine builder, Henry is also a great fabricator... of misinformation that is.

Here's where we are with the cast iron cylinder. Oh heavens be, they aren't Mahle AND they're using those magical coatings!

Ceramic coated JE pistons/chambers/inside SSI header ports; exhaust ports and exhaust valve are also coated but can't get a good picture:

http://i458.photobucket.com/albums/q...psaa923223.jpg

http://i458.photobucket.com/albums/q...ps5c1846f0.jpg

http://i458.photobucket.com/albums/q...psf52205fb.jpg

SmileWavy

My guess (not that it matters in any way) is that when one is doing something as a business and to other the same thing is hobby, there is always a biased opinion/protecting the business principles etc and that is what is taking place here at the moment.

I'm all for true data gathered by testing and pretty sure that there is not one correct way but several: what works for the owner is correct for him.

I understand Henrys position also, because experiments with engines will not pay the rent but in technical forums he could sometimes just relax and talk about these engines like he is no businessman :)

Personally I don't get the bashing when someone thinks differently, for example when I dared to mention that there are other ECU's than Motec that can really do the same job and do it at least as good for less money and using bike ITB's.
And then comes a person who uses Megasquirt and he is praised for DIY? I mean, are you kidding me? Only two options, Motec or MS? Give me a break, world is so much bigger.

But, as I've always said, everyone can do what they want, just don't assume that everyone else who does things differently is automatically doing it wrong. Well, with Motormeister we perhaps agree that they represent what is truly wrong in this world.

Andrew, I like your approach of measuring and knowing, not guessing, though I personally am a guy who is in somewhere middle, sort of educated guess-guy.

Andrew - no, I did not mean that as a joke. You should check out that tread. The guy, SuckerFish, needs an internet pounding if ever anybody did, and I can only do so much on my own.

Lapkritis,
Seems like you are now just pulling Henry's tail,
I am also building a 2.7, unlike yourself I am going with the masses, case savers, Mahle cylinders, while following "How to Rebuild and Modify your Porsche 911 Engine" etc. A Tried and proven rebuild, I can't afford to gamble on something new.
I think Henry is there for guys like me who just want to know what time it is without building a watch.
I look forward to your new angle and will be following your progress with these cylinders and studs.
Take care

This has gotten just ridiculous.
To suggest that Supertec as a team doesn't explore new concepts and experiment with new ideas is wrong on every level.
If you look at the 3.1 SS recently posted on this forum, you will see an experimental engine that challenges most preconceived notions about Porsche engines.
Everything from the parts we used to the very engine concept are experimental.
80% of the engine utilizes experiential parts.
Water cooled 911 Porsches have been around for years and to this date we still experiment in an attempt to improve the 50 year design. Some claim it's about the "money" but anyone who knows anything about business will tell you that the fastest way to go broke is to get an ever increasing percentage of an ever shrinking market.
It's not about money for us it's about a love for the product and the process.
Even my head engine builder has built what could be considered the most challenging of engine modifications. The Polo engine. Why? For the money? Please.....Because he saw a niche for something one step away from crazy.

Now we have a guy who thinks he's figured out something new and when confronted with "it's not really new" and "we've tried it" he challenges past conclusions with accusations of lying. What a shame.
There's nothing new about trying to save money by using inferior parts. We have all done it. I tried over and over to use cast iron cylinders in performance engines with no success. Why: because cast iron cylinders won't dissipate heat well enough to cool the heads when you try to make horse power. If you can't cool the heads 911s will detonate. But when I state that the factory even concluded that cast iron doesn't dissipate heat as well as aluminum so they limited the horse power, I'm met with "you're lying".
This has become tedious and frankly ludicrous.

The lie is yours, the shame is yours. This is all besides the point of whether we can make reliable power with the cast iron cylinder. The moment you put out misinformation for all of us to consume is when you will have to answer for it and the answer isn't your vast experience or $20k engines. Integrity shouldn't have a price tag.

Scratching my head on this one... math might not be your strong suit. If you've been following along I'm not trying to save money and in fact I'm spending a ton more considering I have the Mahle RS parts in perfect condition with new rings etc that I have chosen to sideline. This is not a cost-saving endeavor; this is getting the expanding aluminum jug out of the equation.

http://i458.photobucket.com/albums/q...ps054bb3a3.jpg

Henry, Bob and the rest - please view this from CEO Porsche NA:

http://www.youtube.com/watch?v=aU7ZZ0yrWGs

Wow...this post thread has gone on for ages!
My take on it all?
When you have built more than 1000 engines...come back and we will have a meaningful conversation.
I have run into many "know-it-alls" in my time...and I now take them with a grain of salt...(I guess getting old gives you a different perspective).
Many a young buck has suggested modifications or off beat ways of doing things...some work...some don't...I am now to the point that I just look at them and wish them luck.
Experience cannot be bought...it has to be earned...and unfortunately....mistakes are a better teacher than triumphs.
My $.02
Bob

No ofense but this is a sort of attitude that makes ma shake my head. There is a big difference in just building a 1000 engines without getting into them deep (like deep in scientific and maths perspective, not a folklore-grandpa type) and building few that actually work and are built right.

For example, you think Formula Student guys who a re building their 1st racecar ever are bunch of noobs just because they haven't done those cars/engines 1000 pieces? Perhaps, but they are doing it properly on 1st-2nd time.
For me personally this counts much more than a engine shop in my neighbourhood who are doing engines (and expensive ones at that) daily but can only read manuals and honestly nothing else.

Every guy brings something to the community, some guys bring innovation, some guys not and it is up to the community to either learn something from everything new to them (which requires analytic skills, again, not everyone has those) or ignore/bash them. Unfortunately this community here is not too tolerant to new ideas to say politely.

Bob,

Here's my final take on Henry and his little lie that there is no explanation for: Using lies about your own experience to chase out new ideas is shameful and embarrassing ... even when you've built 5,000+ engines. One does not reserve the right to preserve ego at all costs, including lying, to bully someone they perceive as not as experienced into submission on a topic of discussion. Instead of simply saying "Cast iron cylinders never worked for me and I don't know why but I assume it's due to heat" he had to say he had data on cylinder temperatures that was refuted by his own previous posts on this forum. You reap what you sow. My $.02.

More updates coming shortly on the original topic; possibly this afternoon or tomorrow.

More pictures to do some talking - I'm sure people would like something other than words at this point:

BIG THANKS to Mark at Hargett Precision and a couple friends in VT for the help on these. The host here has these for sale as well; Mark has the file for the flat top as well through special order.


http://i458.photobucket.com/albums/q...psf2c9f8d7.jpg

http://i458.photobucket.com/albums/q...ps4c0d110f.jpg[/QUOTE]

http://i458.photobucket.com/albums/q...psfd66d36b.jpg

http://i458.photobucket.com/albums/q...ps62e25f08.jpg

http://i458.photobucket.com/albums/q...ps86e17f57.jpg

http://i458.photobucket.com/albums/q...psfbcdc5ff.jpg

These are in my other thread but relevant here:

http://i458.photobucket.com/albums/q...ps41832725.jpg

http://i458.photobucket.com/albums/q...ps8d6e0f43.jpg

http://i458.photobucket.com/albums/q...ps7139ae08.jpg

http://i458.photobucket.com/albums/q...ps32a972f4.jpg

http://i458.photobucket.com/albums/q...psaee42515.jpg

http://i458.photobucket.com/albums/q...psbaf24745.jpg

http://i458.photobucket.com/albums/q...ps56e77520.jpg

http://i458.photobucket.com/albums/q...psf96ace73.jpg

Henry Rollins, is an under-appreciated modern lyricist; volume down a bit and enjoy his poetry:

Rollins Band - Liar - YouTube

There should be some QA/QC inspections done, those welds look ugly!

Agreed they're not the prettiest intercooler-like welds given the very thin material of the cover. The penetration is there for both materials and that's what our goal was. With extruded sinks this large they're normally bolted or epoxied down so the welding was just added for conduction. And they're not quite done yet...

Just because you don't understand time lines doesn't mean I lied.
What misinformation?
Give it a rest.

In the 80s we worked with oil and head temps. We couldn't measure cylinder temps (no equipment) and to be quite honest I'm not certain we cared.
In the 90s we bought an ACT 7000 (?) thermal probe and added that to our data acquisition equipment. This tool made cylinder temp part of the equation.
Sometime in the early 2000s we bought a Fluke infrared. This makes isolating temperatures easier.
In the future I hope to acquire a thermal imaging camera, but for now interested parties will have to take my word on test results.

The important thing to remember is that our testing is on going. We have built cast iron, Biral and Nikasil engines for more than 3 decades and data spans all 3 decades as well as years of training gleaned from Porsche experts like Bertil Weir and Walt Adrience. Both legends in their time.

Late to the thread, but I hope some heat transfer calcs were done on those fins. They look entirely too large to me. The longer the fin, the less efficient it is. Those look rather heavy.

Welcome to the party. :)

The sink we're working with is a tapered fin extrusion which we interrupted for both stud access and air flow relief as we are not forcing convection. To answer your statement of hoping for transfer calcs, we did not design the sink extrusion specifically for this application if that wasn't apparent from the chop saw; we researched natural convection heat sink designs and modeled after common production examples from outside the Porsche circles. They are certainly visually striking in height due to scale which is a side effect of intending to extend far enough to catch more of the cool air wash behind the wheel.

Longer fin, less efficient draws my attention because that's obviously false. The inverse test of shorter fin, more efficient doesn't hold because you end up with nothing being more efficient than something and heat sinks exist for a reason. You may be able to find models of an uninterrupted extruded sink that did not perform as well as an interrupted shorter finned sink but we made an effort to avoid that here.

As for the weight, there is some added which is actually desirable for this application. When you increase the mass attached to the head you will be able to draw more energy (kW); more extended loading from the engine before you reach an overheat (similar to boiling a larger pot of water vs. smaller on the same sized burner). I suspect the issue of detonation that Henry mentions as unsolved may not be from the head alone and is possibly from the cylinder that is much hotter than the head in his experiments. We'll be using a thermal conductive gasket material from the cylinder to the head to draw the heat into the head from the cylinder and away from the magnesium case. This shouldn't be a challenge given the thermal conduction of aluminum is about three times that of cast iron at room temp and only increases as both heat.

Thermal Conductivity of Metals

Some natural convection heat sink examples to help understand normal dimensions and flows:

http://assets.hardwarezone.com/2009/...h_heatsink.jpg

http://assets.hardwarezone.com/2009/...6/heatsink.jpg

http://upload.wikimedia.org/wikipedi...-fluid-WBG.jpg

http://www.ixbt.com/cpu/cpu-coolers-...forged-fin.jpg

http://upload.wikimedia.org/wikipedi...h_a_z-clip.png

Fins get less efficient as they get longer because they are cooler near the end. Less temperature differential means less heat transfer per unit area. A longer fin dissipates more heat than a smaller fin because it has more surface area, but if you look at total heat transferred per total surface area of the fin, the smaller is more efficient.

So, more numerous shorter fins would be preferrable to a few longer fins.

I would think forced convection would dominate here once the car is moving. Even stopped it seems the flow around the cylinders would tend to cause secondary air circulation around the heads (not as much as the fan flows, of course).

If you want to "catch" flow around the wheel, why not use a duct like a brake duct? That way you can get out of the low pressure area behind the wheel. Now that would really increase heat transfer.

You don't want more mass behind the rear axle on a 911. The mass of the heat sink would only help in transients, much like brake rotor mass. You need to be able to dissipate heat to reach a lower steady-state temperature. That means better brake ducting or in this case better heat sink design, not just mass. Otherwise you could bolt hunks of lead to the valve covers and have a very cool engine. :)

Ah, unit of efficiency- I gotcha now. If we've gone too large and don't have maximum efficiency per unit then that's okay as long as we attain our goal of temperature control. We maximized the space available with this header; there are some headers without heaters that would allow for a multiplane extrusion and more surface area yet.

We had been considering some ducting to direct air across these eventually and have a few other tricks that might be fun for you to guess at. Here's a hint:

http://cdn2.armslist.com/sites/armsl...ever_f_640.jpg