I have the dreaded Alusils!!!

chrisp · 02-26-2004, 08:53 AM

I went into this rebuild preparing for the worst but hoping for the best. My nightmare came true today. Got a call from the rebuild shop. I have Alusils. However, the motor is in "excellent condition" according to the mechanic and we are going to forge ahead with a felt hone and re ring of these parts. He wanted to fully disclose the risks and let me make the call but was pretty confident it would not be a problem, especially since they are in such good shape. He's done "several" of them and it works well.

What's market value for a set of excellent condition used Alusils from a stock 3.0? I may be better off selling them and upgrading to Nikasils since it's a race motor and the lighter pistons would be better.

Leland Pate · 02-26-2004, 09:50 AM

Who said Alusils are dreaded?

I don't think they are "dreaded". You can't run sloppy JE pistons in them which is a drawback, but I don't think they are inferior to Mahles by much of a margin. Both Nikasil and Alusil have their ups and downs. If it is a full blown race engine and you are planning on installing aftermarket pistons, you may want the Mahles. I'd say for a set of "in-spec un-refurbished Alusil cylinders you could get $400 +/-??? I paid $900 for a set of refurbished alusil pistons and cylinders from EBS in '01.

I just don't think the Alusil cylinders should get a bad rap for street cars.

douglas robbins · 02-26-2004, 11:00 AM

I can't say if this sort of phenomenon has afflicted 911s but in the BMW community the alusil blocks are the ones sought-after and the nikasil blocks are considered unreliable and defective.

This is because, as BMW found out in the mid-90s, the nikel in the Nikasil V8 engines reacted with the high sulfur content in certain American city gasolines, eroded the blocks, and caused compression failure in short order. In response BMW extended its powertrain warranty for Nikasil engines in the mid 90s to 6 years/100,000 miles and used Alusil blocks as a replacement fix for the bad engines. For more details see http://www.koalamotorsport.com/tech/misc/v8shortblock.htm

BMW did not have this problem with its Nikasil motorcycles and perhaps, like them, the 911 engines are secure. It would be interesting to hear anyone who has some additional input on this.

Doug Zielke · 02-26-2004, 11:15 AM

Alusils? Not the end of the World (although I'm glad I replaced mine with new Mahles....the motor has never run stronger).

You can have them re-plated to Nikasil. That's what I'm doing with the spare set I have.

Superman · 02-26-2004, 11:31 AM

I re-ringed my Alusils at 182K miles. Now at about 240k miles. This engine is so tight, I should do a leakdown test to have the numbers ready when folks post threads like this. Darned close to 0%, I'll bet. I can tell you it's a waste of my time to check the oil. The level does not change. The most wear I could find on any of my six Alusil cylinders was .0015". That's right in between "none" and "miniscule." closer to "none." Do what you want with your Alusils. I may just re-ring mine in another couple hundred thousand miles.

AZ1977911 · 02-26-2004, 11:52 AM

See the LONG... thread in the Engine Rebuilding Forum on this issue. It has responses from OEMs and acknowledged experts. Bottom line was there is a lot less to worry about than you may think.

AZ1977911 · 02-26-2004, 11:59 AM

Here is the URL for the above mentioned thread.

chrisp · 02-26-2004, 12:08 PM

I knew I would pull the positive thinkers out of the wood work.

I don't see the link but I'll do a better search now that I know it's there.

You guys are making me feel better. I think I will pursue re-using these parts especially since the shop says they are in such good shape.

89911 · 02-26-2004, 12:28 PM

As far as a price, I sould 3.2 Alusils last year on Ebay for $150-180? and have another set to sell from my car. The really don't have much value except for a spare set or such. Reringing issue aside, most would rather go with the Mahles.

AZ1977911 · 02-26-2004, 12:34 PM

Ooops,

Windoze on one mouse UNIX on the other...
http://forums.pelicanparts.com/showthread.php?threadid=137346

Zeke · 02-26-2004, 02:15 PM

Quote:

Originally posted by Leland Pate
You can't run sloppy JE pistons in them which is a drawback, ......

To my knowledge, you can buy pistons different ways. In spec, oversize to the measurement or "fitted." If JEs are "sloppy, you should be able to tell them how you want them sized. I've always sized the bores or cyls to the piston. But, when using existing nickies or alusils, if you want .003 clearance, they should be able to help you out.

chrisp · 02-26-2004, 02:16 PM

Just spent 45 minutes reading the long thread on the engine rebuild forum. What an awesome discussion. Felt like the old days (16 mos ago) brainstorming about engine related design stuff at my previous job.

I think there's a lot of value to the Alusils and feel comfortable that they are reusable given they are in good shape and the resurfacing is done correctly. People refer to them being risky but no one who has had a bad rebuild has come forth. Either they're embarassed, not on this BBS, or it hasn't happened in years.

89911 · 02-26-2004, 02:22 PM

Both sets of Alusils that we removed, one from an 87 with 105K and an 89 with 70K where in perfect working condition. Both were swapped out for high compression euro 3.2's and Mahle big bore kit 3.4l. No, there is nothing wrong with them at all.

Leland Pate · 02-26-2004, 02:26 PM

Sloppy probably wasn't a good word.

It just seems I remember reading that JE piston clearances are tighter or looser and expand differently than the original pistons... I'll try to dig it up.

Rondinone · 02-26-2004, 03:14 PM

You've obviously not heard of the 'alusil revolution'.

¡Viva la revolucion!

By the way, I'll hopefully be starting her up on Saturday. We'll finally get to see how this home Sunnen procedure works.

350HP930 · 02-26-2004, 03:38 PM

BMW's nikasil problem is purely a quality control or metalurgical problem.

Lots of other vehicles that use nikasil and US gasolene have had no problems.

Early_S_Man · 02-26-2004, 03:57 PM

Guys,

Alusil has worked well enough that is was used for 944, 928, 968 engines with no apparent serious problems ... and Mercedes and Ferrari have used the process in several high-end cars' engines, too! From a rather inauspicious start at GM ... it has made quite a bit of progress throughout the world's auto industry in the past 35 years! Had Porsche not taken a rather big step in 1973 ... the Vega engine might have been the end of the line, and a rather nasty footnote for the Reynolds 390 alloy and engine cylinders!

Some of you may be fixated on myths and racing history ... the 917 Turbo-weapons used Nikasil cylinders, and knocked the McLaren Reynolds 390 alloy Chevy engines from 430 - 494 CID range off the Can-Am podiums ... but the 917 didn't accomplish that fact until a couple of KKK turbos were hung off the tail!!!

john70t · 02-26-2004, 05:13 PM

The alusil sounds like it has two good properties in its formula: aluminum base material that transmits heat well, and a good spattering of sand crystals which act as an ultra-hard wear surface.

Some questions:

-do the cylinder materials wear from top to bottom in a good, repairable shape with outwards pressure , or does it even matter with fresh rings ?

-do alusil cyls need to be used with a specific piston that matches its (AL) expansion rate, and what are the o.k. range specs?

350HP930 · 02-26-2004, 05:14 PM

Turbos Rule . . .

pwd72s · 02-26-2004, 05:31 PM

Quote:

Originally posted by john70t
The alusil sounds like it has two good properties in its formula: aluminum base material that transmits heat well, and a good spattering of sand crystals which act as an ultra-hard wear surface.

Some questions:

-do the cylinder materials wear from top to bottom in a good, repairable shape with outwards pressure , or does it even matter with fresh rings ?

-do alusil cyls need to be used with a specific piston that matches its (AL) expansion rate, and what are the o.k. range specs?

Just trying to learn here...and I think these are all damned good questions. I also recently read an article in a domestic car magazine...okay, it was HOT ROD, that explained some of the differences between domestic V-8 cast pistons, forged, and hypereutectic pistons. Forged, it seems, are the strongest, but they need to be "slappers" when cold because of their high expansion rate. Hypereutectic, developed by Keith Black for use in the old "slingshot" dragsters, are nearly as strong as forged, yet allow for much closer engine assembly tolerances because the have such a low expansion rate. A local mechanic, who does engine rebuilds for the local dirt trackers informed me that most of the alcohol burning "outlaw" engines here have KB hypereutectic pistons in them. So...does anybody make hypereutectic pistons for the 911? If so, how have they worked out? In a normally aspirated engine, I would think this compound could offer some advantages over forged???