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

[Lapkritis]

Originally Posted by blue72s

If Weissach determined that it's not possible to build 90mm cast iron cylinders to fit within the existing head stud spacing, why are the aftermarket people making them, that is the question?

With all respect due to the research team at Weissach as they were working within the materials and technology of the time, their determination on feasibility of cast iron cylinder increasing to 90mm holds little weight when we consider the inherent flaw of the magnesium case and aluminum cylinder combination that resulted. In the face of failures they could have returned to safe materials combinations and improved heat transfer technologies. This would have been a PR nightmare and done considerable damage to their reputation in acknowledging a mistake in material selection. The only viable option then would be to continue development further down this path to show the previous choice of alloy cylinder was correct. Aluminum case, water cooling, returning to the 11 blade fan from 5 and increasing diameter, fiddling with pulley drive diameters... all fixes and improvements in the state of the art that Porsche made to their production. Unfortunately you would have to throw the baby out with the bath water to apply many of those to a 2.7 magnesium case 911. This is where we have the opportunity to choose an alternate path without worry of impacting sales for the Porsche company. Imagine we are back in 1974 and know then what we know about the case failures with aluminum cylinders. We simply look back to what worked with the cast iron cylinder a year earlier and then give thought to what did we not consider would make the iron cylinder still viable because an aluminum case is not an option for numbers matching. Maybe we could take the research a bit further with the technology and knowledge gained over 40yrs. Just maybe... it's worth a look in my opinion.

[Henry Schmidt]

Originally Posted by blue72s

I agree with you but apparently Paul Frere made no mention of that in his book - Porsche 911 Story. He stated the following:-

The Carrera RS 2.7 engine differed from the then current 911S 2.4 litre only by its cylinders of 90mm bore. But to achieve that bore size, the cylinders had to be changed from Biral to Nikasil (alloy cylinder and fins with an electrolytically deposited layer of nickel and silicon carbide forming the working surface) because only the thinner walls of the Nikasil cylinders made it possible to get a 90mm bore within the maximum possible lower flange diameter [spigot].


What 90mm Biral barrels?



If Weissach determined that it's not possible to build 90mm cast iron cylinders to fit within the existing head stud spacing, why are the aftermarket people making them, that is the question?

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.
We could work around it by reducing ignition timing, twin plugs and race fuel but as the engine ran, temperatures would built in the heads, the delicate balance required to keep the 911 head cool, would disappear. We tried fan speeds and sizes, miracle coatings and even water injection all with little success.
As many of you have seen, we even redesigned the chamber on the 2.7 head to a squish / peanut head with great results but the cost was incredibly high. When all our testing shook out the cast iron cylinder were abandoned as simple a design that offered no real solutions. Nikasil cylinder were cheaper, cooled better, offered a lower coefficient of drag with meant less friction (heat) and vastly increased cylinder life. We also accepted the reality that all performance parts have a life and mag cases are no exception. Established a base line horse power number that we used to advise customers as to what they could expect from a rebuild. A street engine making around 200 hp could expect 80 to 100 thousand miles. The closer you got to 240 the shorter the life expectancy. Customers and builders alike understand this and make their decisions based on these well established principles.




BTW Andrew: I would like to take this opportunity to thank you for your continued ignorance and hyperbole. Every time a gysmo stepped into the world of professionals with the "I know something you never thought of" our business goes through the roof. Heads studs are sold out. The problem now is filling the back orders.

[Lapkritis]

Originally Posted by Henry Schmidt

BTW Andrew: I would like to take this opportunity to thank you for your continued ignorance and hyperbole. Every time a gysmo stepped into the world of professionals with the "I know something you never thought of" our business goes through the roof. Heads studs are sold out. The problem now is filling the back orders.

Spoken like a true professional. Mind posting the temperatures of the heads you found to be too hot? Aluminum v cast iron.

Aluminum head, warped on aluminum jug. See valve seat:

[Henry Schmidt]

The other interesting thing we discovered with the cast iron sleeves was the only way to run the close tolerances we want in our 911 engine (piston to cylinder) was to run a cast piston. The forged pistons wanted over .0035" clearance on a new piston or we saw excessive piston scuffing.
Cast pistons generally mean lower quality (unless you can get Kieth Black to cast up some hypereutectic pistons) which is another reason to avoid cast iron cylinders.
In a race engine, tight piston clearance is less important because they generally run for limited amounts of time often hours where the street engine must last years.
Piston slap was one noise we choose to avoid.

[Lapkritis]

Temperatures please.

Forged pistons in iron jugs is not the question and I must remind you that combination is extremely popular outside your protected little world here.

[Henry Schmidt]

Originally Posted by Lapkritis

Temperatures please.

Forged pistons in iron jugs is not the question and I must remind you that combination is extremely popular outside your protected little world here.

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?

[Lapkritis]

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?

I'm going to ignore your insults and be the bigger person.

Were these 380-400 aluminum or iron cylinder or both? I would appreciate your measurements from both.

[Turbo_pro]

Originally Posted by Lapkritis

I'm going to ignore your insults and be the bigger person.

I just about blew half a cup of coffee through my nose when I read this.

Andrew, you have insulted almost everyone who has commented on this thread. You accuse Henry of lying, suggest his costumers are "victims" and even posted a veiled threat against another contributor and you have the nerve to try and claim the high ground? What a tool.

I would say that Henry has demonstrated an amazing amount of restraint.

[Ronnie's.930]

This thread really delivers!

[Daniel930]

Village Idiot Vandalized - YouTube

[Lapkritis]

Originally Posted by Lapkritis

I'm going to ignore your insults and be the bigger person.

Were these 380-400 aluminum or iron cylinder or both? I would appreciate your measurements from both.

Still waiting. Simple question.

[Lapkritis]

Originally Posted by Turbo_pro

suggest his costumers are "victims"

[TimT]

Refer to post #53

Of course there is this

How to lose Friends and alienate People

You accuse Henry of lying, suggest his costumers are "victims" and even posted a veiled threat against another contributor and you have the nerve to try and claim the high ground? What a tool.

+1

[TimT]

I'm wondering if this is the return of Snowman?

[Lapkritis]

Cute. Again, please PM me if you wish to have words.

Tim - We're awfully close to the same market so I will be seeing you around if you're out to events and the like. Are you representing Rudtner's Racing officially with your posts here?

I would appreciate some understanding of the actual statement you guys are clinging to. I consider anyone with a failed magnesium case a victim. Sure, we may have a solution for now with case savers but victims of the magnesium case will happen once those savers begin to fail... the materials discussion leads us to believe it will be a matter of time. I'm sure the work done to place these savers and assemble the long blocks that are out there is top of the market. Just time will tell...

Edit for question.

[Turbo_pro]

Porsche enthusiasts are not victims, they choose to participate in the Porsche experience.
We are generally well educated, devoted enthusiasts that research both service providers and product limitations. To suggest that some engines have limitations
and working within those limitations makes you a victim, is naive.
For you to think that with 10 minutes on the scene, you can change those limitations, then boldly claim that all other efforts were devoid of merit, makes you a clown.
The only victim here is you. You're a victim to your own limited knowledge. A little knowledge is sometimes worse than no knowledge at all. To paraphrase Reagan "the problem is not that you're ignorant; it's just that you know so much that isn't so."

Your explanation about "victims" lacks credulity. You clearly state when responding to Henry "best of luck to your magnesium case customers. I definitely will not be of those eventual victims I mean customers." which is not an indictment of mag cases. It's your snide attempt to attack Henry's engine building capabilities of which you have less than no knowledge.

[Lapkritis]

Originally Posted by Turbo_pro

Porsche enthusiasts are not victims, they choose to participate in the Porsche experience.

I don't think anyone would get in line for pulled head studs when a solution exists. If you want 2yrs warranty then fine- go with Henry and I'm sure you'll be happy. THAT ISN'T THE TOPIC HERE.

We are generally well educated, devoted enthusiasts that research both service providers and product limitations.

Who said they weren't? I agree. This is one of the most well-read and educated enthusiast groups there is. Period. I'm sure many will appreciate reading about the materials and experience shared thus far here.

To suggest that some engines have limitations
and working within those limitations makes you a victim, is naive.

I think you're using fancy words and not knowing what they actually mean. Every engine on planet earth has limitations. Wanting to push those limits further back is part of the hobby and enjoyment. I'm not talking about 1000hp from these engines. We're not all driving stock factory 911's here and to be satisfied with limitations as they currently exist is more naive.

For you to think that with 10 minutes on the scene, you can change those limitations, then boldly claim that all other efforts were devoid of merit, makes you a clown.

Thanks for the name calling. You're quite passionate and I'm not sure where your attitude is coming from. It sounds like you're guaranteeing that I can't make power with this setup. I'm not sure where your confidence in such a claim comes from other than what you're read on the internet. That's great, keyboard racing.

The only victim here is you. You're a victim to your own limited knowledge. A little knowledge is sometimes worse than no knowledge at all. To paraphrase Reagan "the problem is not that you're ignorant; it's just that you know so much that isn't so."

I'll be the first to admit I'm trying something I haven't done before. That doesn't make me ignorant. Sitting on the sidelines heckling is a real class act.

Your explanation about "victims" lacks credulity. You clearly state when responding to Henry "best of luck to your magnesium case customers. I definitely will not be of those eventual victims I mean customers." which is not an indictment of mag cases. It's your snide attempt to attack Henry's engine building capabilities of which you have less than no knowledge.

Let me be clear here. I expect the guys that assemble engines for Henry are truly some of the most experienced air cooled 911 engine builders on the planet outside of Germany. That isn't in question so give it a break.

[911 tweaks]

ahhhhhmmmmmmmmmmmmmm...henry does the assembly along with an assistant when I visited him a few yrs ago...wow...more mud slinging of what you don't know...

[Lapkritis]

You're splitting hairs going off topic. Henry does fine work is the point.

[Lapkritis]

Trying to capture all considerations on setting this up properly. I noticed we hadn't considered expansion of the piston in a cast iron jug as a mass such as the piston will grow in all directions including up into the combustion chamber when heated. Here are the numbers, same assumptions as p1 with fastener stretch and growth but with a piston element added and cast iron expansion of 5.8:

Mahle RS Piston is the static subject and assuming 350F temperature (the hotter the piston, the worse it gets).
1.2" + .425" = 1.625" from the center of the wrist pin bore to the highest point of the dome.

13.1 x 1.625 x 350F = 7450.625 or .007450625"

This is how much the growth of the stack is lifting the head away from the piston:
Growth of all aluminum cylinder (13.1x3.367x350): .015437695 inches
Growth of iron cylinder (5.8x3.367x350): .00683501 inches

This is how much the growth of the piston is growing back into the space:
Growth of piston (13.1 x 1.625 x 350) = .007450625"

For me this is easier to look at back in the metric system that we use for setting cylinder height and piston clearance around these parts:

Growth of all aluminum cylinder (13.1x3.367x350): .392117 mm
Growth of iron cylinder (5.8x3.367x350): .173609mm
Growth of piston up (13.1 x 1.625 x 350): 0.189246 mm

If we assume 1mm piston to head clearance (and ignoring the head expanding) then we find the operating temperature gap for piston to head with the two cylinder materials to differ, with all else being equal.

1mm cold assembly gap by builder
+.392117 lift from heated cylinder
1.392117 gap of heated cylinder alone
- .189246 expansion of piston when heated
1.202mm heated gap with aluminum cylinder

1mm cold assembly gap by builder
+.173609 lift from heated cylinder
1.173609 gap of heated cylinder alone
-.189246 expansion of piston when heated
.984363 heated gap with iron cylinder

So with that taken into consideration we have a difference in gap between the two at the same operating temperature of 1.202-.984363 of .217637 millimeters.

If you're a builder assembling an iron cylinder engine with the same gap technique as an aluminum cylinder engine then this could potentially cause problems due to compression ratio. I would recommend setting the cold assembly gap between piston and head on the cast iron engine .217637 mm greater than that of an identical aluminum cylinder engine. The cylinder base gaskets used for setting this gap are available from the host in .2500 mm incremental thickness.