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

[Ronnie's.930]

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!

[Lapkritis]

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:

[Raceboy]

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.

[Ronnie's.930]

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.

[vhs]

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

[Henry Schmidt]

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.

[Lapkritis]

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.

[Lapkritis]

Originally Posted by Henry Schmidt

There's nothing new about trying to save money by using inferior parts. We have all done it.

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.



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

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

[HawgRyder]

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

[Raceboy]

Originally Posted by HawgRyder

When you have built more than 1000 engines...come back and we will have a meaningful conversation.
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.

[Lapkritis]

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.

[Lapkritis]

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.




[/QUOTE]

[Lapkritis]

These are in my other thread but relevant here:

















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

Rollins Band - Liar - YouTube

[Daniel930]

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

[Lapkritis]

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...

[Henry Schmidt]

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.

[Flieger]

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.

[Lapkritis]

Originally Posted by Flieger

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:

[Flieger]

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.

[Lapkritis]

Originally Posted by Flieger

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: