Thanks for the tips. Will definitely look for the Elring RMS. Notch the bellhousing? (5 minutes and a google search later) THANK YOU FOR THAT! I was wondering how I was going to index my sensors. Will definitely do my best to restore the threads before assembly. thanks again!

short note - if you have to replace the O2 sensor do it after ring break in so the new O2s does not get all oil fouled from the new rings.

Good idea. I didn't get the new sensor until the motor had about 900 miles on it. Probably not totally broken in, but the motor did not smoke even on the first run, so I think the rings were a pretty good fit right off the bat and seemed to break in very well right away. The motor uses hardly any oil now, only some out the RMS.

Right now she's got about 1500 miles and still going strong!

Just stumbled across this thread -- I've been away too long!

Fantastic writeup. Thanks alot HondaDustr.

How is the oil pressure issue? Still losing power?

Dan C.

Power delivery is top notch. I don't know if the cutting out was some corrosion on the DME connector or the O2 sensor was bad, but it resolved itself when the O2 sensor was unplugged, and also with a new O2 sensor installed.

Oil pressure seems to run a bit lower than the old one. The one thing I did not do was disassemble and inspect/measure the oil pump, so the gears may just be a little loose or something. Once warmed up, it runs a decent 3.75-4 bar below ~3500 rpm and climbs to ~4.5 bar at full rpms. Idle is around 1.5-2 bar...a little lower than the old motor, but still within spec. The guage still dips ~0.25 bar when going from coasting to throttle below about 3500 rpm, but no knocking or any other problems yet, and all the crank and rod bearings are new, crank and rods mic'd good at the shop, oil clearances plastigaged good, and I was absolutely obsessive about clenliness during assembly, so I have no idea.

It's mere miles away from turning 3000 mi on the rebuild. I'll be changing the Castrol conventional oil out and going back to Brad Penn and consider it broken in once it does. Still pulling strong as ever and still no smoking, bad noises, or other stuff indicating serious problems. I also have to say throttle response is so much crisper and quicker than the old motor and the top end is so much more useable.It made it 300 and some miles up to NY and back this past weekend performing beautifully...it pulled hard well on its way to the 7000 rpm rev limit in 3rd on the LR chip, which the old motor would have never done. Maybe the porting work and the gutted cat actually do make some difference there. :cool:

Only thing yet to be squared away is replacing the RMS, which I have a Elring seal on the way for that, and also swapping out a lifter that's been randomly liking to go flat on cyl #3 or 4. If it behaves itself after I switch to Brad Penn, I'll just let it go, but otherwise, the cam housing is coming off sometime soon, too.

There actually is a difference between Porsche and Glyco bearings besides price
 

Interesting info I came across on the 911 rebuilding forums as to the apparent slipping quality control of aftermarket Glyco bearings.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/521208-bearing-still-crap-my-oil.html

I almost wish I spent the extra $200 to upgrade to original Porsche parts in that department. Interesting thing I just figured out, there's a way you can tell the Glyco from the Porsche parts, which are still made by Glyco but are thickness and quality checked. The aftermarket Glyco bearings are smooth and the Porsche certified parts have two little marks on them from the factory thickness checks. Read through the thread above. The old mains out of my motor were original, as you can see the two lines on each edge of the center of the bearing shell perpendicular to the bearing.

http://forums.pelicanparts.com/uploa...1252647033.jpg

You can also see there's no sign of the washboard pattern on my old bearing. The rods had some, but not as bad as the 911 motor in the thread (especially the one on the second page), but that was also a race motor.

The rod bearings must have been replaced once before, since none of them had the same marks, but the picture of the Porsche rod bearings on Lindsey racing have the same two marks on each bearing halve.

Otherwise, the motor is still running great with a bit over 4K miles so far. It's running fine on Brad Penn and it's coming up on 1000 miles after the oil change and I still haven't seen the oil level light yet, despite the RMS leak. I'm waiting for better weather to deal with that job. I still need to pull the cam tower and swap a lifter or 2. I pinpointed the lifter to be most likely on cyl 3, maybe #4 exhaust. I'll probably eventually try to find a complete assembly with less miles and hasn't had the lifters swapped/mixed up so many times. There's no telling how much wear is on the camshaft, since there's pretty much literally no way to tell, plus it's had a hard life. http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/526255-help-dilemma-anybody-know-camshaft-lobe-wear-specs.html

I really need to take a compression test but I just haven't gotten around to it yet.

I am in the process of rebuilding my engine and found HondaDustR's info invaluable. I wanted to contribute my experiences to this thread to help anyone who may attempt this in the future.

I decided to have my pistons ceramic coated and bore my cylinders out to accept the enlarged pistons. Information on the ceramic coating and related cylinder size issues is contined in this thread http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/541623-piston-cylinder-clearance-piston-coating.html so I won't repeat it here.

I do want to go into some detail on the process I used to enlarge and finish the cylinders. First off, for the enlarging I used a cheap 3 arm hone from Harbor Freight. For honing oil I used WD-40 which worked ok but I would not recommend it to others. I found that the actual cutting rate of the hone was dramatically influenced by the amount of WD sprayed. Lots of WD meant very little cutting, and very little WD meant very fast cutting. In general, I recorded cutting rates of 0.0003 to 0.0006 inches (increase in cylinder diameter) per 60 seconds of honing depending on the amount of WD sprayed. Obviously, purpose formulated "honing oil" would probably be the best thing to use. If you failed to plan in advance and are impatient (like me) I'd suggest trying mineral oil, vegetable oil, or automatic transmission fluid instead. I think any of those would result in more consistent cutting rates than the WD.

After honing the cylinder walls had a fairly deep cross-hatch pattern and a rough textured finish.

Immediately following the honing I tried finishing with AN-30 as described above but found that the deep cross-hatch pattern from the honing was barely reduced. I then tried red scotch brite* wrapped around the hone as described by HondaDustR above and that did a great job of knocking down the depth of the cross-hatch and resulted in a noticeably less rough finish.

*I recommend using standard green scotch brite as it is a little more agressive than the red stuff. I had already used up my green scotch brite with my original finishing proceedure (before I realized I'd have to enlarge my cylinders) and only had a sheet of red SB handy.

After the SB treatment, I returned to the AN-30 which was now able to do a great job finsihing the cylinders resulting in a dull grey finish with a very light cross-hatch pattern that was smooth to the touch but not "polished smooth".

Between my original cylinder reconditioning and post-honing reconditioning I used up an entire can of AN-30. I also experimented along the way and learned some things. I have to admit that when I first read HondaDustR's experience, I thought that he was making too big an issue about thinning the AN-30 and didn't understand why it wouldn't produce good results straight out of the can. After all my experience I now understand exactly what he was talking about and wished I had listened to his advice from the start.

When I first opened the can of AN-30, the paste on top was nice and thin. The original refinishing of the frist cylinder went very well. After that, the paste got thicker and thicker. You should definitely stir the can of AN-30 well before starting to use it. To thin out the remaining thick paste I added automatic transmission fluid. This mixed well with the paste and did thin it out but I only had a little ATF left at the bottom of my bottle and it wasn't enough to get the consistency I wanted. I then tried spraying WD-40 into the paste. This also did a good job of mixing with the paste and thinning it out. From my experience I'd say that both performed well as thinning agents. HondaDustR used mineral oil and it seemed to work well for him. FWIW, I added the cutting agent right into the can of AN-30 and stirred with a paint stick.

The problem with using thick AN-30 is that it cakes to the walls of the cylinders and the felt covered hone rides on top of that caked layer of AN-30 without really rubbing the AN-30 along the cylinder wall. Once thinned you could actually see the AN-30 being pushed along the cylinder wall by the hone. Without this pushing / rubbing action you don't get much "lapping" done.

I bought my felt from JoAnn Fabrics. They had about 20 different colors of felt available. I chose dark gray and ended up wishing I'd picked a lighter color so I could see if I was getting any staining and/or material deposits on it. I did use thread to sew it around the stones on the hone.

On my original attempt, I covered the stones with duct tape then sewed a double layer of felt on. In retrospect, I think that created too much "padding" on the hone and probably contribued to the hone riding over the caked layer of AN-30. After I honed out the cylinders I sewed a single layer of felt directly over the stones. I think the single layer provided a firmer surface and better lapping. The felt held up just fine after two 90 second runs in every cylinder. The first run I did clockwise and the second run I did counterclockwise. not sure if this is necessary but it seemed like a good idea to me. I had some issues with hone coming apart (it uses a threaded connection for the flex drive) when I initially tried to go counterclockwise, but I tightened it up with a couple pairs of pliers and it worked fine after that.

Oh yeah, I almost forgot, I used the highest pressure setting on the hone for all work performed. I actually tried the low pressure setting on the very first cylinder and felt that it was not enough. With the cheap 3 arm hone the pressure is easy to adjust just by screwing down the big threaded knob above the spring as far as you can wihtout preventing the arms from moving through their full range of travel.

I'm tired, so I hope I did a decent job of explaining this. Feel free to ask any questions If anything is unclear.

Damn, great post.

Nice explanation on the finer points of the AN-30 consistency. I kind of just boiled it down to what did work and not so much exactly what didn't work and why. Valuable info and 100% consistent with my experience as well. ATF is probably a pretty good choice, but if it were me, I would use a thin weight non detergent oil...don't know exactly why, other than honing oil is mineral based and not highly detergentized like ATF. ATF is a good weight, though...very similar to the vintage 20 weight oil I lucked out on finding. API SA,SB is the spec for non detergent straight mineral oil.

I cringed a little at the part about the honing with stones, as I saw many many posts saying don't do it, but maybe the scotchbrite and AN-30 smoothed out whatever surface it may have produced. Honing is almost a molecular science, as matching the abrasive material, pressure, speed, lubrication, etc. to the metal and type of honing done has everything to do with obtaining the correct amount and type of roughness (Ra), especially with a soft finicky metal like aluminum that tears easily. With the scotchbrite and AN-30, it's probably pretty good in the end. It's all about producing a surface that's rough enough to wear the rings in and retain an oil film but smooth and consistent, not having been torn or "shredded" by incorrect abrasive stones.

Good luck with the build and keep us posted on how it turns out. Mine's getting very close to the epic 10,000 mile mark and it hauls @ss and doesn't smoke or burn any appreciable amount of oil. Just 700 miles to go and I'll do the first official compression test to celebrate the milestone.

cjpacitto

Yes, very nice followup to the detailed information HondaDustR described.

The last post in the link gave me the information as to what size ring set is needed.

John

I would be so nervous to do this myself. I wouldnt mind saving he money and doing it myself but,.... it just seems risky to me. This is perfectly safe for these alusil blocks? I thought a special honing machine was needed?

Just read this thread and I spotted a major potential problem.....are you using this OPRV? Because it is not supposed to have that groove machined into it...that is a sign that the housing was not aligned and it became stuck and started spinning, which is what caused the groovehttp://forums.pelicanparts.com/uploa...1277365880.jpg

I guess we'll see, right? The factory service manual discusses the proceedure for boring out the cylinders. Remember, oversized pistons are available, so boring and refinishing would have to be performed to fit those.

The Porsche manual says:
1. Rough Turning to 0.1 mm before finished size
2. Dressing to 0.02 mm before finished size
3. Polishing to finished size
4. Lapping with Sunnen silicum mixture

Sunnen also has this technical artile on honing Alusil bores Honing Options for Hypereutectic Aluminum Cylinder Bores - Sunnen which says:
1. Boring
2. Honing
3. Finish Honing
4. Exposure

Here is some more info from the Sunnen article:
Kind of weird they are using an elastometric stone instead of AN-30.

I used the honing stone to take off 0.001 to 0.002 inches of material.
I'm sure the scotchbrite took off at least 0.0001" as it reduced the depth of the honing marks considerably. (and 0.0001" is freaking tiny). I guess we'll know for sure when I get it all back together, but I'm pretty comfortable with it.

FYI, the manual does say you MUST bolt the crank girdle to the block and torque the nuts before doing any honing/finishing work.

[QUOTE=944CS;5420902]Just read this thread and I spotted a major potential problem.....are you using this OPRV? Because it is not supposed to have that groove machined into it...that is a sign that the housing was not aligned and it became stuck and started spinning, which is what caused the grooveQUOTE]

No, I'm running a 1 piece valve now. That's weird... It did seem to function correctly when I did use it.


It's also interesting that Sunnen says you can cut the Aluminum silicon cylinders with regular abrasives. I think the scare was caused by people on the 911 forum suggesting a deglazing hone alone on Alusil to prep for new rings. It's ok on Nikasil, but not on Alusil! Following up with scotchbrite and the AN-30 should be just fine to produce the proper finish.

I would love to do this myself to save the money but I'm afraid things will go terribly wrong.

The rest of the confusion comes from 911 guys who have nikasil cylinders. Nikasil is just a coating on the cylinder wall where as alusil is what the entire block is made of. If you hone nikasil you'll go right through the coating and need to get them recoated. You don't have that issue with alusil.

These two posts contradict each other----I think.

John

Argh im 50/ 50 on whether I should do this,... not sure. Things have changed her a bit and I really need to kind of watch my budget now. Cant do EVERYTHING i wanted. I have to try and do as much as possible without seriously going over the top.

I may mess around and try to drop the short block before any money gets thrown around,

Still got the old one? I would love to get a look at that spring.