jda407

In the process of rebuilding my '86 951 engine and am looking for any advice on upgrade/performance parts that I should look into for better performance out of the engine. More importantly, better reliability (if there is anything that porsche has left on the table for us to improve upon)
I'm going to do bearings and rings obviously. Is there rods that I should look at replacing my stock with? I've heard from several people that the stock porsche rods in the '86 are the best ones for this car. Should I do something with the crank? I'm obviously going to do the clutch while the engine is out and will mostlikely go for a lightweight flywheel. Any suggestions?
I know it's a very open bunch of questions...but I know there is an incredible wealth of knowledge out there that has done this before me.
Thanks

fast951

- If you plan on upping boost, O-ring the head..
- Use Wide Fire gasket
- If you plan on tracking the car, get an oil pan baffle kit. LR sells them, needs welding
- Replace rod nuts
- while there, refresh the head..

USE good parts.. stay away from cheaper alternatives.

jda407

Car is a track car. Went "boom" at Sebring several weeks ago. #2 rod went b-bye. Have new block. Where can I get a oil pan baffle kit? Because I've heard that before and it specifically relates to what happened to me already.

RMills944

Cross-drill the crank. It's well worth it.
Read this post for more info:
https://rennlist.com/forums/showthre...ht=cross+drill

jwl

John, you forgot to include a Vitesse Stage III..!

hosrom_951

Here is the link to Lindsey Racing's Oil Pan Baffle Kit: http://www.lindseyracing.com/Merchan...44OILPANBAFFEL

Dave951M

Polish, cross drill and knife edge the crank. Use only new ARP fasteners or equivalent. You'd do well to heed the sage advice from Mr Vitesse on that matter. Look carefully at the balancing of rods, make sure they're matched and check for true. If you spun a bearing, you may have rod damage, have them checked for true and cracks. Check into balancing the pistons. Balancing and checking everything is viewed by some as overkill, but 4cyl have an inherent vibration that is damped by the bal shafts, but no sense in aggravating the effect. This falls into the the "while you're in there" category. I haven't seen too much discussion on Total Seal rings on the board. That might be worth looking into.

Tom M'Guinn

I second the baffle and cross-drill suggestion, and would add piston oil squirters like the 968 blocks.

Gator_86_951

How many people have used the LR baffle? I am thinking of doing this over break along with a pan gasket and new rod bearings. I am trying to pre-plan this work, unlike when I rebuilt the top half this summer :-). No planning ended up taking forever to get done because of all the parts.

Laust Pedersen

Oh no, another one of the dreaded # 2 rod bearings.

I have a theory about the cause, namely that the connection from #2 main to #2 rod bearings is partially blocked by the plug needed to close the connection hole (2nd angled arrow from the right in the diagram). If the starvation occurred in the flow path prior to this connecting hole, then the main bearing would have been affected as well.
Porsche may not have had adequate control over the depth of insertion of the plug, so some cranks may have this ticking time bomb.

Cross drilling the journal puts a hole on the high-pressure side of the bearing lowering its load carrying capacity.

Here is a chance to verify this by measuring and comparing flow resistance between all four journal pairs (angled arrows in the diagram). If this turns out to be the problem, then the cure is just to drill the blocking portion of the plug away from the radial journal hole.

The connecting hole could also have inadequate depth, in which case cross drilling would not help and the cure would be to re-drill the hole through the plug to the right depth and replace the plug.

Laust

macnewma

Jim check out this thread: https://rennlist.com/forums/showthre...e+motor+bottom

I didn't know you threw your #2. That changes things since you probably have metal in the engine. My suggestions on the race forum were for a "refresh" not a rebuild. I would still recommend doing the things on my refresh list, but you will have a number of other additional tasks for the rebuild.

Get some of the factory manuals and it will help you figure out what you need to do. If you can't find any, I can probably let you borrow a set, just PM me.

Oh and I assume this isn't a PCA stock class car, right? If not, you can probably add some performance mods like the aforementioned Vitesse kit. If you don't want the involved process of going standalone, I would suggest a Vitesse kit from John.

Max

OriginalSterm

a few of the motors i've been looking at have teflon coated rod bearings. what is the advantage of this? and how hard/expensive are they to find or buy?

alexands

Just finished my 86 951 rebuild. All of the above advice is very good. Be sure the pistons, cylinder walls, and the crank aren't damaged by the rod bearing debris. Mine was beyond repair so I had to get a new block, crank, and pistons. The things I did include:

- Complete machining of block and head (decked, valve job, hone)
- Balanced all rotating assemblies
- Widefire head gasket
- Raceware head studs
- All new bearings, nuts, seals, gaskets, etc.
- All new vacuum hoses
- Cross drilled crank and baffled oil pan (Lindsey)

David Floyd

www.swaintech.com does rod bearing coatings

macnewma

Swain will coat my rod bearings this winter. You absolutely do not want teflon on your bearings though. Swain applies a dry-film lubricant called Poly Moly that protects against oil starvation and extreme loads...our two problems regardless of cause. Oh and it will only cost ~$30 to do our set of rod bearings!

Swain probably has the best reputation and I am going to have my exhaust manifold, x-over pipe, and downpipe coated.

HPC is another company that does this. Here is information they give about their engine coatings: http://www.hpcoatings.com/engine_coatings.htm They explain that PTFE (teflon) is not appropriate for this because it sheds oil. They use PTFE in their oil pan coating to shed oil, but not on their rod bearings. Their coating is basically identical Swains. I believe Swain's thermal coating is superior though and that is why I am going to use Swain.

Max