Specific Question - ARP Head Studs on 2.7 Magnesium case - Insane?

[Henry Schmidt]

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.

[chris_seven]

Originally Posted by Lapkritis

Chris, I'm curious to know more about the diffusion and mobility of the crystal defects. I won't be able to use proper terms so I'll have to ask in the form of a story/hypothetical. Say we have a magnesium case engine and are studying two cylinders side by side on this single engine. One cylinder has the case saver of maximum size and the other has simple early timecert. The case saver has larger thread and from what I understand different pitch so the profile of the single thread is taller and the overall thread is more coarse relative to the timecert. Given the same pressures that would initiate the mechanism for crystal defects to become mobile, should we conclude the finer thread will always fail first because the physical distance is actually somewhat shorter for that failure to travel? Rate * Speed = Distance... the train going further at the same speed shall arrive later. All other factors being equal for the simplicity of this exercise. I believe this might be the case but am interested in how that actually works.

Thanks for the reply,

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.

[chris_seven]

Originally Posted by Henry Schmidt

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.

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.

[Lapkritis]

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.

[Henry Schmidt]

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?

[Lapkritis]

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.

[Henry Schmidt]

Originally Posted by Lapkritis

...edit..... 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.

[HawgRyder]

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

[Lapkritis]

Originally Posted by Henry Schmidt

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.

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.

[Lapkritis]

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.

[Lapkritis]

I was searching on Google this morning for anti-corrosive cylinder coatings and came across this thread ( painting cylinders ). Head vs. cylinder, different but just noticing.


2013:

Originally Posted by Henry Schmidt

The temperatures we saw were in excess of 350 degrees. In the race engine we would regularly see 380-400 but as I stated before, we could deal with those numbers using twin plug and race fuel.

When you say "protected little world" you mean the "real world with real results" where we build hundreds of high quality Porsche engines as apposed to the unicorn world of half theories and hyperbole, you live in?

2006:

Originally Posted by Henry Schmidt

There are coatings, TechLine sells them, that actually increase surface area with a the use of a crystalline formation. The theory is that increasing the area that cool air contacts will increase overall cooling. These products were produced to reduce radar signature, drag and heat that formed on the surface areas on the SR71 "Black Bird" spy planes. This coating (offered by TechLine) is black.
The formulas for these products became available through the "freedom of information act".

It seems unnatural to coat something in order too help it cool but it works.
That said, we used it on two race engines and saw no temperature reduction. It is important to state that we really had no way to measure cylinder temperature.

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?

Originally Posted by Henry Schmidt

We made both 89mm (IMSA 2.5) and 90mm (2.7) Biral barrels back the the 80s. With the help of the engineering staff at LA Sleeve and some great machinists at Q&E (an aircraft maintenance machine company) we achieve a pretty nice product. The problem was horse power. Every time we tried to produce reasonable horse power numbers we kept running into the same issue. Detonation with street gas. The hemi head in the 911 is prone to detonation.

[Lapkritis]

Again, what gives?


2006:

Originally Posted by Henry Schmidt

There are coatings, TechLine sells them, that actually increase surface area with a the use of a crystalline formation. The theory is that increasing the area that cool air contacts will increase overall cooling. These products were produced to reduce radar signature, drag and heat that formed on the surface areas on the SR71 "Black Bird" spy planes. This coating (offered by TechLine) is black.
The formulas for these products became available through the "freedom of information act".

It seems unnatural to coat something in order too help it cool but it works.
That said, we used it on two race engines and saw no temperature reduction. It is important to state that we really had no way to measure cylinder temperature.

2013:

Originally Posted by Henry Schmidt

No Andrew, I didn't use 90 mm cast iron cylinders because I learned from earlier experiences with cast iron cylinders (2.2 & 2.4) just like the factory did.
The earlier cast iron cylinders were never used to produce an engine that generated real horse power. More horse power always means more heat.
All of the early engines with cast iron cylinders were limited in horse power to less than or around 140.
What we discovered (I assume the factory as well) was that most of the cylinder heat is concentrated 20 to 30 mm from the head and with cast iron incapable of dissipating the heat efficiently, cylinder head temps went up. Since the heads are primarily cooled by air, the addition of the external cooler had little effect.

[chris_seven]

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.

[Lapkritis]

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.

[Daniel930]

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.

[Lapkritis]

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.

[Turbo_pro]

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

[Lapkritis]

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.

[Geneulm]

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.

[Lapkritis]

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.