3.0 rebuild - desperate!

[mickey356]

I'm sorry. I am a little short on patience right now. I tried searching and after reading a few posts there is too much info to sort through right now. I need to make some decisions over the next few days and I need info.

1. How can I tell if I have Nikasil or Alusil on my 83 SC 3.0? I see there is 10 fins on Alusils and 11 on Nikasils and something about a seam, but it seem to apply to earlier engines. Is there a number or something in the cylinder to tell me what I have?

2. I believe if I have Alusils I'm pretty much looking at new cylinders at the very least (possibly new pistons too), but I think I recall reading that Nikasils can be honed or resleeved? Is this correct?

3. How stupid would it be to buy used ones?

4. Is there any benefit to uping the compression if I have to buy new? Say like. going from 9.5:1 to 9.8:1? Or shoudl I just leave well enough alone?

Thanks for your understanding and any info is much appreciated.

[James Brown]

Did you try on the engine rebuilding forum? I think most 83 are all alusil (just depends on what they grabbed on the assembly line). They should only need maybe one or two turns with a stone hone to clean them up (just to take the crap off). And that's if there real bad. they just don't ware out. They do score so if you need one or two, used ones are a good options (provided there good ones). Changing compression won't help much without doing other mods. So take a deep breath and relax, that's a pretty bullet proof engine stock.

[don gilbert]

You can count the fins,10 for A, 11 for N, but they are going to be alusil in 83. And yea, upping the compression does stuff.

[James Brown]

Hear is a post from Wayne in 2002. As always, great info:

I fell like I have posted this at least 3 times on this BBS in the past month, but here it is again:

Nikasil vs Alusil Cylinders - In 1973 Porsche introduced a new type of cylinder used on the 911 2.7 Carrera RS. Engineered by German manufacturer Mahle, Nikasil cylinders are manufactured out of a dense, aluminum alloy that is centrifugally cast in a mold. The cylinder bore is then electroplated with a very thin layer of nickel-silicon carbide. Originally designed and used on the venerable 1971 917, these cylinders provide several unique advantages over the older-style ones. The primary advantage is that the micro-thin layer is extremely durable, and allows for thinner cylinder wall thickness as a result. As a result, the piston bores can be enlarged without changing the original cylinder head stud bolt pattern. In addition, the reduced friction along the cylinder walls combined with the surface properties of the nickel-silicon coating creates a tighter seal against the cylinder. The result is a slight increase in overall horsepower, due to the increased efficiency. These Nikasil cylinders are the most durable of any of the production cylinders and are highly sought after for engine rebuilds. These cylinders can be retrofitted to the earlier cars, however, you will need to install the updated piston squirters in to your early case (1970 and earlier) if it doesn’t already have them. The piston squirters lower the piston crown temperatures so that you can run the close clearances used by Nikasil or Alusil pistons and cylinders. It’s also important to note that Mahle makes Nikasil pistons and cylinders for 2.2L and 2.4L engines.

In 1974, Porsche introduced the Alusil cylinders, manufactured by Kolbenschmidt. The Alusil cylinders were primarily used as a less-expensive alternative to the Nikasil cylinders. These cylinders are manufactured out of a special 390 eutectic aluminum silicon alloy, and are used with a special iron-plated, ferrocoat piston. Like the Nikasil cylinders, they are plated with a special coating on inside bore. This coating is electrically etched to leave a microscopic layer of silicon particles exposed on the cylinder wall. The iron-plated piston and the silicon-plated cylinder walls operated together to create a durable dual-surface. In addition, the Alusil cylinders have the same thin-wall construction of the Nikasil cylinders, meaning that they too can maintain the same head-stud spacing pattern.

So what are the main differences between all of the available pistons and cylinders? The early biral cylinders can be honed and reused just like other cast-iron cylinders on non-Porsche cars. Starting in 1974, Porsche mixed and matched the Alusil and Nikasil sets, so it’s really the luck of the draw as to which set you have in your car. For the most part, Porsche used mostly Alusil in the 2.7L and 3.0L engines because of the reduced cost of production. The Alusil cylinders, unfortunately, cannot be honed. The honing process destroys the etching layer, and renders them useless. In fact, a general rule of thumb is that the Alusil cylinders are a one-time-use product, and should not be used again if the engine is rebuilt.

Alusil cylinders cannot be reliably reringed. This indeed is a common misconception in some Porsche circles. There are no replacement rings available that are specifically designed for the Alusil cylinders. Of course, throwing out your current pistons and cylinders can lead to the large expense of new ones, so a lot of people reuse them anyway. In some cases, the new set of rings seat fine, and they indeed can be reused successfully. However, you cannot hone these cylinders, nor predict whether the rings will indeed seat properly. The correct action to take is to purchase new pistons and cylinders, otherwise you may be tearing down your engine again in less than a mere 1000 miles. These Alusil cylinders typically have a ‘KS’ Kolbenschmidt logo cast into their base, although for a time, Mahle also made Alusil cylinders. The coating on the Alusil cylinders is non magnetic, so you should be able to tell the difference with a simple refrigerator magnet.

If you are tearing apart your engine for reasons other than worn out rings or valve guides, then you might opt to reuse your Alusil cylinders. This would be the case, for example, if you were tearing down your engine to replace broken or pulled head studs. If this is the case, I would recommend that you take your pistons and cylinders off of the engine, put them high up on a shelf, and don’t touch them until you are ready to reassemble. Don’t pull the pistons out of the cylinders and don’t dislodge or disturb the rings. Of course, you are taking a risk here that you will have worn rings in the near future. However, if your engine is a 3.0L, with 100K on the odometer, then there is a good chance that you can get 100,000 additional miles or more out of your set of rings, cylinders and pistons. I don’t necessarily recommend playing the odds like this, but if you’re rebuilding a good running engine with excellent leak-down numbers for the purpose of replacing head studs or some other non-wear problem, then it might be a good bet.

The Nikasil cylinders can indeed be honed and reused. They typically have a ‘MAHLE’ stamp on the lower side of the cylinder. The nickel-carbide surface needs to be lightly honed with a special silica impregnated tool, or what is commonly known as a grape or flex hone. The surface properties are too hard for normal tool steel honing machines. The Nikasil coating will be ever so slightly magnetic when you place a magnet next to it. The honing process is performed using special tools – either a specific tool designed to hone the cylinders, or a grape hone. Either way, you should only have an expert familiar with the Nikasil cylinders perform the honing process.

-Wayne
__________________
Wayne R. Dempsey, CEO, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines
Coming Eventually:
101 Projects for Your Porsche Boxster & Cayman (2010) • 101 Projects for Your MINI Cooper (2010) • 101 Projects for Your Porsche 996 / 997 (2010)

[mickey356]

So if they're Alusil I'm pinched. Nikasils can be honed with the right tool and pistons reringed. I'll be looking at the cylinders tomorrow morning to find out if I can determine what I have. I'll keep my fingers crossed that they're Nikasils. Both my "Wayne books" and my bently man. are with my car so I can't even reference my references tonight.
James, Thanks for posting that.
Anyone got a nice set of used Nikasils and pistons? I'm desperate so you can take advantage of me, but please be gentle.

[Ray_G]

You have a lot of decisions to make about them. But, do yourself a favor and go to the engine rebuilding forum and read, read, read and then decide what to do depending on what cylinders you have. A couple of notes, if you buy a set of used Nikasil cylinders do not hone them! Prep them with red scothbrite. If they are in spec and in good shape you will see the cross hatching no problem. Just use the scotchbrite to clean them up. The rings will seat fine. On my 2.7 being a noob at this I thought if they were marked Mahle they were Nikasil. That could not be farther from the truth. I bought boxes of used Mahle alusil cylinders before someone on the forum that actually knew what they were sent me a set (Nikasil that is). If you buy used there are a couple of guys on the forum that might have a set and I would trust them if they say they are in spec. Otherwise look out. If you have Alusil cylinders they can be chromed and reused. In fact some of the chrome shops will buy them from you if you don't use them. But do a lot of research on them before you start making expensive mistakes.

[steely]

mickey356

Maybe Dan Pechtel (carsincnj.com) in Bordentown might have some.
Sometimes I see Tony (boyt911sc) has parts for sale in Philly.
Don't know anyone closer to you (like in Chester or DE/MD)- I guess checking out the Hershey swap next Saturday 24th could be an option.

good luck - hang in there.

[FL911]

The alusil cylinders are reusable if they are checked out and are within spec. I do not care what anyone says about them. My 1981 had 95,000 miles or so on it when I bought it and upon adjusting the valves I discovered numerous head stud broken........long story.
My machinist, which is hands down the very best in the Midwest in my opinion (AMT Racing Engines), new all about the felt pad with the Sunnen AN-30 paste to reintroduce the silicon particals in the cylinder walls in the Alusil cylinders. Rather than me spend countless thousands of dollars on new Nikasils and new pistons bla bla bla, we simply reconditioned my OEM alusils and my engine is 100% proof positive that this can and is successfully done.
My engine has a lot of nice mods on it and it will run with the best of them.
So, like the other man said take a deep breath and read up on this before you go blow the wad on all new goods. You can and will save a lot of money if you are confident in your machinist!
Good luck.
Frank

[James Brown]

I think Mercedes uses Alusil cylinders in there engines with no sleeves, manufactured that way, and there is a procedure for reintroducing silicon into old blocks. So, it can be done.

[mickey356]

Does the Bently have the "usable specs" on cylinders? Where can I get this info? I'll do a search.

[Wayne 962]

I was going to add my input, but it looks like I already did!



-Wayne

[James Brown]

Bentley recommends replacing alusil pistons and cylinders with nikasil's.

[T77911S]

i may be wrong, but i think other manufacturers tried to use thesecylinders and failed. i think jag was one of them.
a friend had a v8 jag. his lost oil pressure due to some lining on the cylinder walls coming off and clogging the oil pump. jag gave him a new motor.

says a lot for porsche

BTW, i am planning on reusing my alusils. if it fails i will back up and punt.

[Groesbeck Hurricane]

Go to the re-build forum.

Don't panic! Take a good hold on your towel and read some more.

I re-used the Alusil after re-ringing. Many people have. It can work. I used the (I hope this is correct) Groetz (SP) rings. Pelican can get them, they did for me. Just make sure your cylinders are in spec, measure, measure, measure. If they are in spec and are not scored/damaged... I have north of 30,000 miles on the re-build and do not appear to have anything blowing past the rings.

[JMH82SC]

Originally Posted by Groesbeck Hurricane

Go to the re-build forum.

Don't panic! Take a good hold on your towel and read some more.

I re-used the Alusil after re-ringing. Many people have. It can work. I used the (I hope this is correct) Groetz (SP) rings. Pelican can get them, they did for me. Just make sure your cylinders are in spec, measure, measure, measure. If they are in spec and are not scored/damaged... I have north of 30,000 miles on the re-build and do not appear to have anything blowing past the rings.

I did the same re-using the Alusil with new rings. I do not have quite 30K on engine but after 2 years and MANY miles engine has perfect numbers. The key is measure everything.

[cashflyer]

When I re-sealed my engine a couple years ago, I found one of my pistons had a cracked ring. Rather than leave it in and wait for it to fragment into the engine later, I changed the ring on that piston.

Groetz rings and Alusil cylinder. I have been driving it and tracking it since with no problem.

A lot depends on the condition of the cylinder wall. Check for wear... if a cylinder shows wear, re-ringing will not work.

YMMV

[mickey356]

They're Alusil (non-magnetic). If you run your fingernail along the top part of the cylinder wall you can feel the wear (there's a tiny ridge). The pistons look good, but need to be cleaned up. Everything else looks good (cams, etc... now visible wear) So I guess I'm faced with new cylinders or used. My buddy can get me a set of Mahle P&C's for about the price of a new set of Nickies but either way I'm looking at @ $3k just for those, not including the rest of the work (heads redone, studs etc...). I'd like to avoid any issues in the future, essentially build everything to spec, basic 3.0SC and be done with it. Is it too risky to buy used cylinders and use my exisiting pistons with new rings?

Thank you everyone for the input this far, and the deep breathing advice, it works.

[Groesbeck Hurricane]

Clean and measure before you drop $3K. You might be surprised what happens with a good cleaning. And then you can measure.

[Gunter]

Originally Posted by mickey356

They're Alusil (non-magnetic). If you run your fingernail along the top part of the cylinder wall you can feel the wear (there's a tiny ridge). The pistons look good, but need to be cleaned up. Everything else looks good (cams, etc... now visible wear) So I guess I'm faced with new cylinders or used. My buddy can get me a set of Mahle P&C's for about the price of a new set of Nickies but either way I'm looking at @ $3k just for those, not including the rest of the work (heads redone, studs etc...). I'd like to avoid any issues in the future, essentially build everything to spec, basic 3.0SC and be done with it. Is it too risky to buy used cylinders and use my exisiting pistons with new rings?

Thank you everyone for the input this far, and the deep breathing advice, it works.

Pistons may look good but they need to be miked to be sure.
The first land on any piston gets the hammering; it, and the other lands, have to be within spec.

Only measuring will tell if you can re-use your P/C's; they may still be usable.
Be careful about buying used P/C's; they have to be within specs and a lot of people don't have the skill or tools to measure.

If you're spending $3k on new 95 mm P/C's, you might as well go with 98 mm Max/Moritz 9.5 :1 CR for that kind of money. Keep the CIS and re-grind the cams to a 964 profile (~$300.-).

You'll be very happy with the extra HP and torque in a SS 3.2.
Plus, it gives a higher resale value.

Whatever you do, do it right or you'll be sorry later.

"Haste makes waste"

[T77911S]

does anyone have a current source for the compound and pads and which pads to use?