100 mm Nikasil Carrera II p+c

[Wally]

For an experiment, I was contemplating to adapt a used set of the pistons and cylinders of a 3,6 ltr 911 (carrera II), which I believe are 100 mm diameter to a type 4 stud pattern. Piston pin is about 23 mm, so a bushing would be needed, but thats not the most difficult part.
Since they are nikasil parts, the condition could still be good when used, depending on the engine they came from of course and I can pick them up for about € 450,-- a set.
If it would work, I might try this for a turbo set-up, hence its important they are not expensive, since turbo's tend to be known for leaning out and/or pinging, both possibly damaging/destroying the engine. The Alu/Nikasil will of course be great in cooling the greater heat of the turbo induction.
Has anybody else tried the Carrera II p+c 's personally?
Looking forward to your reactions,
Walter

[kdanie]

I don't know what the Carrera piston tops look like. I know the earlier 6 cyl. pistons have a dome that would not be compatable with a type 4 cyl head.

How far off is the bolt pattern?
ken

[Pillow]

I have thought about it, but never really persued it.

Keep us posted on how it goes please!

[BOBTAIL]

If I remember the 911 barrels are not the same stud spacing as a T4 If they were it would make fitting Porsche OHC heads easier.
Obviously ,The pistons are designed for a full semi hemi head IE 911
making fitting to a T4 head a little tricky.http://www.centralvwaudi.com/lowres/911head.jpg

[Wally]

I will pick up a set this evening, which promised to be a very good set (low milage, owner had done a 250 to 272 hp modification 5 years back, which involved new p+c).
The stud spacing must indeed to be redrilled. I will post the difference in stud spacing when I have the set in front of me, Pillow.
Since the original stroke has been approx. 76 mm (from my calculation, could also be 76,4 or so), I should have enough room for keeping the piston from the head with my 71 mm stroke crank and. And because I might go turbo in a later stage, maximum compression ratio is not my goal, quite the opposite. 1:7,8 - 8,0 would be fine, so don't know yet how much must be taken off of the cylinders to achieve this.

The reason for the route originated from the possibility to get the extra displacement for lost cost: my set will cost about half of what I thought it would (hope the guy I 'am purchasing from tonight doesn't read this..). Even when I f#$k up some mods, there are two spare p+c to try again, haha.

Using the 911 heads would involve a very major modification with pulleys to drive the ohc's and is way beyond my intent/capabilities/budget etc. Has been done though. There is a nice picture of such an engine in the photo gallery (its the engine with the carbon inlet trumpets and dubble injectors. It used to be a Kaefer Cup car, running in a special class, soon afterwards outruled).

Thanks for thinking along with me.
I'll keep you'll posted.
Walter

[Richie]

Yep, studpattern is different and it will be a lot of work to modify a T4-engine to the correct pattern.
Only the turbo pistons are flat as far as I know, all the others have domes of some sort.
You'll have to modify the head as well because the register for the 964 head (Carrera 2) is flat. The cilinder is probably too short to modify so it'll fit in the T4 head.
I've considered this modification as well and I have measured a set of 102mm barrels (3.8) but it turned out too much of a hassle for me. Maybe a futureproject??
By the way, the 102mm barrels are still for sale (not cheap though).

Cheers,

Richard

[Wally]

Hoi Richard,
Nice to see you here again!
I wasn't planning at all to redrill the type 4 case studs, but to redrill the Cylinder holes! (maybe plug the old holes with a alu tube to reinforce the cooling fins, if it appears necessary)
Sorry for the confusion. Any thoughts on that approach?
See you,
Walter

[Shad Laws]

Hello-

For an experiment, I was contemplating to adapt a used set of the pistons and cylinders of a 3,6 ltr 911 (carrera II), which I believe are 100 mm diameter

Get ready for an expensive experiment... I'll bet that by the time you are done $1800 for a set of Nickies cylinders will look cheap.

It's been done before. I've talked to several people who've called us and said how much they'd wished our stuff existed back when they did it!

Here's a list of problems you are going to have:
- wrong pin diameter in pistons
- wrong dome shape
- wrong compression height in pistons
- stud pattern is wrong. You'll have to deal with the stud enclosures on the cylinders, too.
- head register is wrong
- case register is wrong
- cylinder is too short. This is going to be your number one biggest problem! People take eight cylinders, strip the nikasil, weld them together, machine them, then replate.
- fin pattern is wrong. When installed, there will be gaps between cylinder banks and the tin won't fit.
- stock 911 cylinders are _cast_. Warning: do NOT ping! If you ever accidently detonate much with your turbo setup, kiss the cast aluminum cylinders goodbye - they'll crack.

I wish you the best of luck in the adventure, but I'd wager that $1800 for billet Nickies will be a bargain by the time you are done.

Sorry for the bad news...

Take care,

[Richie]

Oh, well! Shad beat me to it. I posted earlier but it seems to have disappeared But, he's totally right. They have THE alternative.
As a matter of fact, I've experienced a 100mm cilinder to crack under a bit too much boost. Well, actually it was 3 bar absolute. All due to a stuck boostcontrol valve. It even burned a nice round hole between the head and cilinder.
The old KaeferCup car you're referring to is probably one with the Holzapfel engine. I forgot who it was, could be dr. Gerold, but I'm not sure.
An engine like that would cost you around DM 30.000,- 6 to 7 years ago.

Cheers

Richard

[BOBTAIL]

Originally posted by Richie
The old KaeferCup car you're referring to is probably one with the Holzapfel engine. I forgot who it was, could be dr. Gerold, but I'm not sure.
An engine like that would cost you around DM 30.000,- 6 to 7 years ago.

Cheers

Richard


Which is what we did for about £6000 for the full engine ,no carbon fibre it makes the difference on the invoice!

[Wally]

Bobtail,
I think its difficult to compare both engines. Holzapfels engine used a WBX or as I believe oxyboxer as it is called here, as a basis. His engine was used to race on a circuit; yours I believe is to drag race. His heads were a one-of OHC heads, specially designed for that engine, not 911 parts.
Its a very impressive job you have done though, especially for the relatively low costs involved.

Shad,
I am very pleased to hear your expert opinion on the parts, despite the 'bad' news. I was kind of hoping/afraid you would respond to my experiment.
I totally agree with Richard that this is of course by no means a replacement in any way of the fine piece of engineering you have pulled of with your specially designed Nickies set, period. If the experiment threatens to costs more than a normal set of p+c, its stops there.

The good news is that the measurements really don't differ that much:
Stud spacing from opposite studs (accuracy little difficult):
type 4: 124,5 mm
911 100 mm Nikasil cylinder stud hole spacing: 127,5 mm, so the cylinders have to be drilled 1,5 mm closer towards the bore center, but that should be easy/still safe.
Type 4 case opening with case cleared for 103 mm p+c: 107 mm inner diameter.
911 cylinder bottom outer diameter: 107 mm !!
The case will therefore have to be opened up a tiny bit more (108 mm or so)
Type 4 head opening, machined for 103 mm p+c: don't have one of these yet, but that will probably be appr. 115 - 116 mm.
911 cylinder outer diameter at top (head location): 113 mm (6,5 mm wall thickness), so this can be made to fit as well.
The part of the top of the cylinder that goes into the head is too small on the porsche cylinder, but it could be machined down, so the cylinder would go all the way into the head.
Type 4 cylinder length (original 94 mm 914 GB engine): 92 mm . This is measured from the mating surfaces of the head to case - distance.
911 cylinder : 83 mm
So the cylinder is indeed very short looking only at the mating surfaces, but total cylinder length is 120 mm, all Nikasil plated and the wall thichness at the very bottom of the alu cylinder is still 4 mm. A cylinder spacer may just solve that problem and could also be used to counter the different piston heigth of the 911 piston.
Type 4 piston pin diameter is 24 mm
911 pin diameter is 23 mm.
Well, if 22 mm bushings can be installed in a stock 2 ltr rod, so can a 23 mm bushing imo.
Just leaves the piston top issue, which is rather domed indeed. This would require a trial install on an engine to determine at what heigth the valve will just clear the dome, so what heigth spacer to use and what compression ratio would still be left. Or I could maybe buy a new set of JE 100 mm forged pistons, since the Nikasil cylinders have not a mark on them and the bores can be cleaned as was showed to us in one of the former threads of Pillow. Locating a set of 911 turbo pistons which have flat, and probably forged, pistons (thanks Richard for pointing that out) will be very hard, I think, but still also a possibility (I only need 4 good ones, not 6).
Cooling fins on these cylinders is very limited and will leave therefore indeed an opening between them when installed on a type 4 case, but if a small insert of some form, would be fitted between the cylinders and attached to the case, I would doubt if cooling would be a problem with the Nickies.

I did't realize the original Porsche pistons were cast though. Pity. Turbocharging them is therefore not a good idea, I agree. But hey, with 100 mm bore and 71 mm stroke, I would still have a N/A 2230 cc T4 engine with nickies!

All in all, I can even more understand Shads love for nikasil cylinders, as this nikasil set is excellent technology and thrills me! As for now, I will proceed with it (slowly) and keep you posted on the forum if even only one of you is still interested in this route.

Walter

[Alex]

If I remember correctly the engine Holzapfel sells is based on a T4 with 993 heads.

There is also this engine from Parts Obsolete....but I do not know if it will fit in the engine compartment.

http://www.partsobsolete.com/4_cylinder_911_motor.htm

[Richie]

These engines are cut and welded 911 engines. I believe some guy with a greek name which I've forgotten was one of the first who did such a conversion. I've seen one fit into a rather special 356. Chances are that it will fit in a bug after some mod's. And a healthy amount of cash ofcourse!

Wally, I can sell a used set of five 965 (964 turbo) P+C's. Please mail me when you're interested!

Cheers

Richard

[Type 5 Joe]

A cast cylinder is actually stronger than a billet cylinder, talk to a proffesional metalurgist
- Joe

[Shad Laws]

Hello-

A cast cylinder is actually stronger than a billet cylinder, talk to a proffesional metalurgist

False.

That statement is impossible to make, as you haven't specified _which_ casting alloy (three-digit number) and _which_ forging alloy (four-digit number) you are talking about.

I won't tell you the exact alloy we use in our Nickies, but I will say that after extrusion, the tensile yield is over 400MPa. Additionally, the alloy is pretty ductile and has a relatively high impact resistance.

Porsche used an alloy with a decent amount of silicon in it for their cylinders. All of these have lower strengths than our material. Plus, these alloys tend to be more brittle and less impact resistant, making detonation _much_ more of a potential disaster.

Joe, I ask that you do a little more research before making strong accusions like that. Thank you.

[Type 5 Joe]

Sorry but your totally wrong Chad,

I wasn't refering to your exact product, but extrusions are always weaker than castings.

Thats why we use alot of castings to produce our Aerospace and Medical Components. These could be Whittled out of billet alot easier.

The molecular structure of extrusions can be compared to a slice off of a log, you give it some stress from the side and it fails...

Cast material has multi-lateral matix, grain structure, Thats why Porsche used it then and does today.

But what do they know compred to you, nothing I guess.

Good Luck to the Gentleman who is inovative an adapts the Porsche Jugs, don't let someone beat you down, so the might line their wallet W/$$$

- Joe

[Alex]

Shad and Joe,


please no punch lines. There is nothing wrong with a good debate.

:tisktisk:

I also heard that the shop (Wahl I believe...can not remember anymore) that does all the race stuff for Kolbenschmidt (or was it Mahle....brain fade) said that casts are stronger generally.

But Shad has a point when he says that it depends which casting and which forging you are comparing with each other.

Alex

[Type 5 Joe]

That would be a good point, if we were talking about forging compared to castings.

Actually extrusions are generally weaker the conventional Billets, and far weaker than cast, due to the stresses created in the extrusion process.

No punch lines, just facts.

- Joe

[Shad Laws]

Hello-

Sorry but your totally wrong Chad,

(it's Shad... I wasn't blessed with an easy-to-spell name :-).

I wasn't refering to your exact product, but extrusions are always weaker than castings.

Absolutely false. It depends on all the specifics!

Extrusions, at their _finest_, are essentially open-die forgings, and are just as strong, too. 400MPa is a VERY high yield strength for aluminum alloys - go to the reference books and find a semi-common casting alloy that's higher. There aren't any.

Our extrusion is essentially a tube. Rather than just bore out the metal in the middle, we force it to the outside. This results in a stronger piece, and an organized grain structure in the axial direction. Given that the highest single component of stress for 99% of cylinder applications is the axial one caused by compression of the studs (because the aluminum wants to expand), this is a good thing!

And yes, I have done all the Finite Element Analyses on the structure and know that what I just said is true, unless you have 50 bazillion pounds of boost :-).


Thats why we use alot of castings to produce our Aerospace and Medical Components. These could be Whittled out of billet alot easier.

The geometry is likely different, which can yield different results. Also, in decent quantity, casting is a lot cheaper than machining one by one.

Another thing in aerospace and medical stuff is metal matrix composites. Here, casting is even more common because CTE is low as is machinability, making casting even a better bang-for-buck option.


The molecular structure of extrusions can be compared to a slice off of a log, you give it some stress from the side and it fails...

This isn't a 1/32" extruded wire, this is a 6" tube. Big difference.


Cast material has multi-lateral matix, grain structure,

Actually, the grain structure from casting aluminum is mostly random. The only time it takes shape is when dissimilar cross-section thicknesses cool at different rates.


Thats why Porsche used it then and does today.

Not for their prototypes, but for production, it's quite a bit cheaper.

But what do they know compred to you, nothing I guess.

That's not true.

If I were Porsche, I'd use billets in testing (before I dialed in the turbo and computer and whatnot to make sure there was no detonation, etc.), then swap over to casting to save the piles of money there is to be had in even making 100 engines identically (i.e. even their racing engine production runs).


Good Luck to the Gentleman who is inovative an adapts the Porsche Jugs, don't let someone beat you down, so the might line their wallet W/$$$

EXCUSE ME???

With all due respect Joe, leave me the hell alone. You've challenged my character before. You even told me that I crafted the truth around my desire to get money.

I see these actions as very unethical, and respectfully ask that you remove this behavior from here immediately.

Good day.

[Type 5 Joe]

Calm down chad, your very exitable aren't you?

I will not post any further here in this matter, if you won't frequent the STF and talk down my Oxyboxer motors.

People will believe what they want, I'm not trying to get rich off of any of it.

Good Day there Junior, - Joe

[Shad Laws]

Hello-

Calm down chad, your very exitable aren't you?

For the second time, that's "Shad." My name is spelled right there in front of you, and I'd appreciate it if you copied it correctly.

Yes, I do get pissed off when people directly attack my character. Don't ever do it again.


I will not post any further here in this matter, if you won't frequent the STF and talk down my Oxyboxer motors.

The oxyboxer is _not_ a bad idea! However, you were selling it as the best thing since sliced bread, immune to all the defects of OEM cases and the whole lot, and I simply stated what it really is. It's good for what it is, but it only is... what it is. Sounds kinda zen-esque, but you know what I mean.


People will believe what they want, I'm not trying to get rich off of any of it.

Neither am I. With my resume, I can walk into a $100,000/yr. job in a snap. Yet I'm here trying to innovate new products for aircooled engines. That is _not_ a move made in the interest of money, and I do NOT appreciate the insinuation.

Grow up and leave my character alone. Thank you.

[Alex]

Thread closed.

Alex