Saving a 906
 

The following are pictures of a 906 engine we brought back to it's previous glory.
The case was the first challenge.
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The next challenge was the crank. This project came with a stock 2.0 counter weighted crank. We searched high and low for a 906 crank with no luck.
We wanted something special so we replicated a 906 crank.

Here's a factory 906 crank:

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Here's what we made:
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Next the rods.
I wanted to build it with new GT3 Pankl titanium rods but the customer insisted we use the Factory rods that came with it. The set he had was horribly mismatched so we went on the search for more rods.
That meant, X-ray and Zyglow for cracks. Then we took the 10 rods we had and balanced them. Shot peening and re-sizing finished the job. We were also able to locate some NOS small end bushings.
The last touch was new titanium rod bolts and Supertec serrated, flanged nuts.
The same nuts we use on our head stud kits.
The bearings are unobtanium so we sent them to Calico Coating to ensure our best chance of survival.

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Awesome!

That is awesome, I can't wait to see more of the assembly. Thanks for sharing Henry!

amazing job!
 

Herry,

you said you "Shot peening and re-sizing finished the job"

I have some GT-3 rods(3 sets), but all of them are used and all show some king of wear/abnormal ovalization(egg shape) about 0.02mm (from 0.005 to 0.02mm)how do you feel about those numbers?

also I hear that those ti rods are no good for turbo charged engines even with ARP rod bolts, is it also proceed? engine will be for performance street most of time, and no more than 800hp and no more than 7500rpm

could you please tell me what you would do? use it or not, re-sized is good idea? re-coat the sides to prevent it seize with the crank? what coating would you suggest?

thank you
Tadashi

Shot peen
 

Henry:
Which process did you use for the rods?

It's my understanding that there is a standard mil spec for Ti, but then there is a different, more aggressive 'refurbshment' process as well. Chris mentioned it in another thread way back. It's supposed to 'zero hour' Ti fatigue by litterally beating the stress risers out :D.

tadd

Tadd,

I have always used these guys UK based operations. They have been in the business for a good many years and do a great deal of work on Turbine and Rotor parts for Helicopters.

Metal Improvement | Shot Peening Success Stories for Aerospace Applications

Henry:
Another question...can you give a rational for using serrated nuts on a Ti rod? This seems odd given the little I know about the properties of titanium.

tadd

I use them because they are the highest quality nuts I can find and I use them on every 10mm rod bolt in my rebuilds.

The crank and rods assembled. Note the piston squirters. You might also notice that there are no CaseSavers in the mag case. This is possible because of the additional thread engagement offered by the Supertec head studs.
We wanted to use 906 cylinders and custom JE pistons so we bore the cylinders to 81mm (stripping the Chromal coating) and replaced it with Nikasil.

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Nuts
 

Henry:
Thank you for the reply.

I'm sure they are a quality nut. The reason I asked is the notch sensivity of Ti, which you are well aware of or you wouldnt have peened the rods. Those serrations are going to damage the rod surface...right in an area of high stress.

Are you using a washer or some other way to avoid this? I can't tell from the pictures.

I apprecieate you taking the time to cure ignorance.

tadd

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The serrations do not damage the surface of the rods and the wide flange offers superior support to standard nuts with or without washers.

Henry,

You picture sequence shows the heads being assembled onto the cylinders prior to installing the cam housings. Since the cam housing to cylinder head interface is doweled and thus unforgiving in placement, shouldn't the cam towers and heads be mated before installing on the cylinders?

BTW beautiful work as always.

Thanks,

neilca

Either way works fine. Of course you can't torque the heads until after the cam towers are installed. By installing the heads on the cylinders you can check how even the heads are in relationship to each other. This also allows you to turn the engine over at each step.
This way also makes installing the head nuts and washers far easier. It also gives you a nice working platform.

You might also notice that the cylinders are installed before installing the head studs making it far easier to install the pistons in the cylinder then install the wrist pin and clip. Supertec head studs make this assembly technique possible.

Very nice work, seriously!

And very impressive case repair (welding magnesium+machining).

Thats' some impressive welding skill!

I had not noticed the head studs,, thanks for the heads up. That does make sense.

Henry, that is pure art work!!!! It apears that the top of the piston has a coating along with the skirt area. The skirt looks black. Are you using some type of dry film lube on the skirt and a thermal barrier on the top?

Pretty stuff! Thanks for sharing how you check piston & deck clearance with the red clay.

Also notice the thermostat blockoff RSR piece. That means this engine will be running an oil filter console, or will the oil cooler simply be flowing at all times?

I like how the small displacement engines have so much "meat" around the piston bores. The larger displacement engines have always bugged me with how close are the head stud holes to the piston bore OD.

Excuse my ignorance, but is this actually going into a 906?

Beautiful engine BTW!

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Sometimes fine tuning is required
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Hi Dave
Yes sir, 906 0022

There's my answer. Factory Porsche multi-screen filter console.

The pistons are coated with a thermal barrier and dry film lubricant. We also coat the bearings and rocker pads as well as the cam lobes.
The valve stems are also coated with dry Moly.

We also did the trans:


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Henry, what coating/plating are you using on the mag parts? Looks really nice.

The coating is a Dow product that was contracted by the shop doing the body restoration. Sorry I can't be more helpful.

Henry,
One more question if I may please.... Lash caps. Did you reuse what was there or did you need to replace them? If you did change them, might you share where you got them?

I will be needing to do this process myself soon.

Make that two questions...Were the tensioners for authenticity? In other words why not use solids given it's going into a 'real' car that will see maintenance respectful of use.

tadd

We were fortunate enough to source NOS valves so we needed to adjust every valve. We used what we had by dancing them around and hand lapping for precise measurements. That left us needing 4 specific sizes. With those numbers in hand we just ordered the sizes we needed from Porsche Motorsport.

We used hydraulic tensioners because they work well under these circumstances: occupational racing and short runs without warm up. IE: "check out how cool my 906 sounds".

I should probably know this, but do you test run your motors before they go back out? IF so, you REALLY need to record that sound!

Engines shipped from my shop re ship dry and untested unless the customer requests a dyno test.
In this case, his race mechanic will tune the engine.

Hello!

is there any chance to have a picture of the center lube cam to chain housing seals. They are known to be unobtanium and never saw one...

Another question, hos did you do to "replicate" the 906 crank? is that something you are able to make on order? if yes, would you send me details by PM?

Thanks a lot!

olivier.

Hello Henry,

Absolutely beautiful work you're doing. Quick question. I thought we were all supposed to use a five or six arm engine yolk to hold the engine on the stand. Yours is just four arm. Any insight?

Thanks.

Dino

Is there anything special to the 906 trans? It looks different from a 901 outside, but the gear stack looks the same. Is that a one-piece bearing retainer? In 1966?

http://i197.photobucket.com/albums/a...e/Demolish.jpg

Great picture - reminds me of a similar photograph in a very early Honda CB72 manual in a chapter titled 'How to Demolish the Engine' :)

Beautiful work! Thank you for sharing.