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

[Lapkritis]

Ah, external water mist to cool. Hadn't planned on it as goal initially is to achieve stability without an additional consumable.

[Lapkritis]

Hope you guys don't mind me sharing a few other steps on this that aren't necessarily iron cylinder related.

Noted the bell housing inside the transmission was fully caked in oil/grime indicating rear main or trans output shaft seal. Decided to replace both.





As you might gather from this photo we are no longer considering any book at this point in the repair; brand new trans seal and some foreshadowing:



As you can see, this is the trans with the trapped seal and a guide tube without mounting screws. After confirming it was possible to see between the original seal and output shaft we determined it was necessary to replace or deal with the inevitable leak. Trans build isn't in the cards so cleaned everything up and slid the new seal in.



Seated tight.

[Lapkritis]

Fresh powdercoat perimeter tins



Going up:





Fit is perfect... found one of my dozen jegs hats.









Finished up last night with it ready to turn key with the exception of taking the battery off the trickle maintainer and reinstalling.

[Henry Schmidt]

Now that your engine is in, I was wondering about how you dealt with the low Rockwell condition of the cylinders.
Early on you spoke about the desire to build a 911 engine (mag case) that would out last the expectations of previous engine builders.
One of the things we noticed in the early 911 years (64-70 or so) was that the cast iron cylinders had a very short life.
We would rarely see an engine with cast iron cylinders that would be in spec after 60,000 miles.
One of the big reasons stated by Porsche for the advent of Nikasil was cylinder longevity. That has proven true in Nikasil engines with 200,000 miles plus, showing little or no sign of wear.
The reason I ask is because in our testing of Chinese cylinders we discovered the low Rockwell numbers and have been dealing with a solution ever since.
Heat treating cast cylinders helps but not much. It still leaves the Chinese cylinder 15-20% off.
With the Biral barrels (cast liners with aluminum fins) heat treating is impossible so we started using Cryo. Tests show good results but we were still not satisfied. We are now having our Biral cylinders Nikasil plated and the product has proven phenomenal.
So what about it Andrew: how did you deal with this glaring quality issue?

[Lapkritis]

This came with dinner on Sunday night. Big fan of the white rice and sweet n' sour chicken... mmm.



The big picture answer here is I would much rather replace a worn cylinder set a decade down the road than have a pulled stud ruining my numbers matching engine case because I stubbornly stuck with a materials mismatch. I know there are folks out there loosey-goosey stamping blank engine cases to get back on the road but I'm not playing that game.

Cylinder wear is definitely an uncoated cast iron concern that can be managed within reason. This isn't exclusive to Porsche; had a Jeep Wrangler in the family years ago with the larger straight 6 that was carbur'd. Bought it running rich and the bores were toast; huge lip at the top where the piston travel ended. Overbore, retune = fine; has since left the family but still in the area and running around. Detroit iron, chinese iron, brazillian iron... all subject to the same wear.

Solutions for you to poke holes in:

1) Run proper air to fuel mixture to prevent washing of the bores which would remove the oil layer and dramatically increase cylinder wear. This will mean dyno tuning and careful carb tuning. This is the most significant concern of mine at this point.

2) Managing the temperature of the piston with proper ring gap is of high importance. In simple terms, the hotter the piston, the tighter the piston to the bore and the increased probability of piston scuffing and ring wear which will slowly(or quickly) remove material from the cylinder wall. Careful consideration has been taken to move heat through the gates of materials in the engine with insulation layers to move the hot gases.

3) Synthetic oil after break-in is complete. Superior ring life improvement over most conventional oils. I understand there is a lot of hoopla around running high zinc in these engines but I'm not completely sold on it not being just a fantastic sales pitch. I've had great experience with various synthetic oils in engines with uncoated cast iron cylinders albeit non-Porsche ... and approaching 160K miles with an add-on turbocharger.

[Henry Schmidt]

I guess the short answer is that you never checked the Rockwell and don't care that huge wear will occur with extremely soft cylinders.
The rings will live (maybe) but the chance of long life of the cylinders is almost nil.

I thought this was an engineering exercise, charting unexplored territory (comparing yourself to Columbus) designed to extend the life of mag case engines not shorten it.

Do you seriously believe that this a compromise most Porsche owners want to make?

Really? This is a compromise justified by the nonsense about matching numbers?

[Lapkritis]

Originally Posted by Henry Schmidt

I guess the short answer is that you never checked the Rockwell and don't care that huge wear will occur with extremely soft cylinders.
The rings will live (maybe) but the chance of long life of the cylinders is almost nil.

I thought this was an engineering exercise, charting unexplored territory (comparing yourself to Columbus) designed to extend the life of mag case engines not shorten it.

Do you seriously believe that this a compromise most Porsche owners want to make?

Really? This is a compromise justified by the nonsense about matching numbers?

I don't appreciate your snide comments. Your conduct is unbecoming of such a professional as yourself. I'm embarrassed for you and your blind belligerence.

Yes, I'm aware of the benefits of nikasil. With everything else remaining equal will it reduce cylinder wear? Of course. There's no point in arguing it. Temperature control and synthetic oils also will return an extended life which is not "nil" as you state (that's a load of horse *****) .

[manbridge 74]

I would think EFI would allow for longer cylinder life as there is no fuel injected under throttle off conditions which, I believe, is what happens in all carb designs.

Also, it should be noted that documentation of one having a numbers matching engine from 1974 is almost always inconclusive when trying to determine if the car has an engine installed from the factory.

[Henry Schmidt]

My friend , you called my customers victims, suggested I had my head in the sand, lied about testing iron cylinders, you said I'd eat crow and insisted you didn't want my help.
That's all fine but many people read these threads and I need them to have the information you find irrelevant. Like I said before, my propose here is to guaranty that the greatest number of people see the best results possible.

BTW: your distortions of my statements don't go unnoticed.
I said "the chance of long life of the cylinders is almost nil."
That is an accurate statement when "life" is defined by Porsche norms and is beyond any contrary information you can offer.

[Lapkritis]

Originally Posted by manbridge 74

I would think EFI would allow for longer cylinder life as there is no fuel injected under throttle off conditions which, I believe, is what happens in all carb designs.

Also, it should be noted that documentation of one having a numbers matching engine from 1974 is almost always inconclusive when trying to determine if the car has an engine installed from the factory.

That's exactly correct. A solid efi install with sequential control for each cylinder is the best solution. Nikasil is an alternative that will allow you to run sloppy fueling without paying in engine wear. Synthetic oil achieves much of the same result. EFI control is much more precise... warm up, different climate conditions etc... far more adaptable. I would like to swap my PMO kit out for ITB eventually. Maybe this coming winter when looking for more projects.

[Lapkritis]

Originally Posted by Henry Schmidt

My friend , you called my customers victims, suggested I had my head in the sand, lied about testing iron cylinders, you said I'd eat crow and insisted you didn't want my help.
That's all fine but many people read these threads and I need them to have the information you find irrelevant. Like I said before, my propose here is to guaranty that the greatest number of people see the best results possible.

BTW: your distortions of my statements don't go unnoticed.
I said "the chance of long life of the cylinders is almost nil."
That is an accurate statement when "life" is defined by Porsche norms and is beyond any contrary information you can offer.

You're refusing your crow and it hasn't even been served yet. Any result here is irrelevant to preserve your reputation. Wow. Seems you have a horse in this race.

Your statements about not testing cast iron cylinders are in this very thread typed by your own fingers. If you then say you did test and had data then I don't have to say you lied even. You would be served better to just not pick fights, period.

The results here will be available shortly. You don't need to attack to try to salvage reputation if by chance it goes well. Your current body of work speaks for itself. Let these results speak for themselves too. It very well may scatter to pieces on the first drive.

Just sit back and relax. Your engine building practice isn't in jeopardy because someone 3000 miles East went a different direction based upon their calculations and called you on BS they saw.

[304065]

what rms did you use?

[safe]

Well, this is a fun thread....

I really think there is a very good reason Porsche only used cast iron cylinders for the low output T engine and then stopped using them altogether when power rouse above ~130 hp.
Pulling away heat from the heads is crucial.

[Lapkritis]

Originally Posted by safe

Well, this is a fun thread....

I really think there is a very good reason Porsche only used cast iron cylinders for the low output T engine and then stopped using them altogether when power rouse above ~130 hp.
Pulling away heat from the heads is crucial.

Just a barrel of monkeys in here.

Note Harley Davidson/Buell HP capability per liter with cast iron cylinder... in competitive racing for porsche the weight savings may have been a major consideration given the level of competition. I imagine you would not want to share your reasoning with competitors so you might realize the benefit of discovery longer. That is imaginative speculation.

[Henry Schmidt]

Originally Posted by 304065

what rms did you use?

If this is a question about the Rockwell tester and measuring scale,
we used a Rockwell 3R and measured on the B scale.

[Walt Fricke]

Andrew - I think you were not as unlucky with your model of 915 as you could have been. If I have this right, the first 915s had the output shaft seal on the diff side of the guide tube and up against a lip. This meant the only way to replace the seal, at least in the stock location, was to disassemble the transmission to the point of pulling the output shaft out. Mucho trabajo.

Next generation had the seal on the engine side against a lip. The factory had a tool for pulling out the old, and then you could insert the new. This must be what you have? How did you pull the old seal out?

Finally Porsche went back to what the 911/901s had - a removable guide tube, and all was much easier. I've not seen any factory explanation for why they did what they did in 1972. Even saving money by casting the tube in (assuming there were savings) doesn't explain where seal went in relation to lip.

[Henry Schmidt]

Originally Posted by Lapkritis

....edit...
Your statements about not testing cast iron cylinders are in this very thread typed by your own fingers. If you then say you did test and had data then I don't have to say you lied even. You would be served better to just not pick fights, period.
....edit.....

Originally Posted by Andrew

Seems pretty safe to say if those original cases with steel are fine without savers then the later such as mine would benefit from an iron cylinder retrofit as well especially given the cooling tricks we've since learned. I'm curious if Henry has tried this on the 2.7 and await his response.

You seem to be basing your attack on this statement: Which clearly states I didn't use 90mm cast iron cylinders. Nowhere does it say I didn't test cast iron cylinders or use smaller cast iron cylinders to evaluate the possibilties.

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.
JB racing cast cylinders (a nice product BTW) uses aluminum fins to cool the cast liner thus limiting the heat build up.
Considering the Porsche is a performance automobile designed for an exhilarating driving experience, we always felt 140 horse power in the flat six was droll and undeserving of a place in the rear of one of these gems.
So thank you but you can keep your million mile motor and I'll keep helping people build the heart pounding performance the "real" Porsche enthusiast seeks on a budget they can afford.

[piggdekk]

Originally Posted by Lapkritis

Just a barrel of monkeys in here.

Note Harley Davidson/Buell HP capability per liter with cast iron cylinder...

Harley/buell cylinders are actually more similar to biral type. I believe they are made with a cast iron liner with aluminium fins. Aren't they?

[Henry Schmidt]

Originally Posted by Walt Fricke

Andrew - I think you were not as unlucky with your model of 915 as you could have been. If I have this right, the first 915s had the output shaft seal on the diff side of the guide tube and up against a lip. This meant the only way to replace the seal, at least in the stock location, was to disassemble the transmission to the point of pulling the output shaft out. Mucho trabajo.

Next generation had the seal on the engine side against a lip. The factory had a tool for pulling out the old, and then you could insert the new. This must be what you have? How did you pull the old seal out?

Finally Porsche went back to what the 911/901s had - a removable guide tube, and all was much easier. I've not seen any factory explanation for why they did what they did in 1972. Even saving money by casting the tube in (assuming there were savings) doesn't explain where seal went in relation to lip.

Walt you're right, the 72 915 trans had an absolutely stupid main shaft seal requiring a complete dis-assembly to replace it.
At the dealer during the warranty period it was not uncommon (company not technician policy) to just drain a pint from the gearbox to alleviate the leak with the hopes that the transmission would survive the warranty period.



The factory tool.

[Lapkritis]

Originally Posted by piggdekk

Harley/buell cylinders are actually more similar to biral type. I believe they are made with a cast iron liner with aluminium fins. Aren't they?

Believe it or not... it's cast iron for the real performance over there.

HAMMER PERFORMANCE - High Performance for your Harley Twin Cam, Evo Big Twin, Sportster or Buell! 208-696-1250

But shhh... don't want to let the cat out of the bag.

Note 3: 1250 kits are also available with AXTELL full cast iron cylinders on a special order basis. Axtell cast iron cylinders offer the ultimate in bore stability and ring seal but have a weight penalty of approximately 6lbs per cylinder. They are highly recommended for maximum effort engines.