Every picture tells a story.....

[emcon5]

In the beginning....








Ted at German Precision did his magic:

[emcon5]

Add 6 of these:



Plus some a big pile of stuff shat out by Wayne's rebuild wizard, some pretty hardware from ARP and a distributor from Steve Weiner, and some chewing gum



Bolt on the heads, some of the ancillary stuff, plus some artwork from Novato,



Put it all together and bolt it in the car:





Put fire to it the first time Saturday, breakin underway.

The details:

82 911SC, 111K miles, rebuilt due to excessive oil consumption.
98MM Mahle Cylinders with RSR Pistons, measured at 9.8:1 CR.
Cam reground to 964 profile by Elgin.
Twin plug with Rennsport 964 distributor conversion, 2 Bosch CDIs and coils.
ARP rod bolts, 993 steel head studs.

915 transaxle freshened by Paul at German Precision, (who has since closed his doors, a huge loss to SF Bay area Porsches and Audis)

New Bilstein shocks, sport (rear) and HD (front), Turbo tie rods, 86 Carrera sway bars.

Probably some more stuff I can't think of.

Huge thanks to Steve Weiner, who spent hours on the phone keeping me pointed in the right direction, Wayne for writing an excellent book, without which I never would have managed this. Ted at German Precision did great machine work, and helped me with CCing the heads/piston domes to measure the CR, and loaned me cam timing tools.

No leaks, pulls like a freight train to 4K.

Still breaking it in, will post dyno results in a few months when it is ready.

Tom
(Pretty damn happy....)

[Shuie]

Congrats, that sounds like an awesome motor.

Any advice you can give to someone thinking of building a similar engine? Anything you would have done differently?

I sent you a PM with a few more questions.

[Wayne 962]

Weird - why do the spark plug holes look backwards in those pics? Optical illusion?

-Wayne

[ChrisBennet]

Originally posted by Wayne at Pelican Parts
Weird - why do the spark plug holes look backwards in those pics? Optical illusion?

-Wayne

They must be British RHD spark plug holes. ;-)

The 2nd plug hole is on the other side of the head from the "top" plug so they holes are angled the other way.

-Chris

[emcon5]

Originally posted by Wayne at Pelican Parts
Weird - why do the spark plug holes look backwards in those pics? Optical illusion?

Maybe because they are upside down in the picture?

Tom

[jpnovak]

Do tell... Where'd you get the 98mm pistons? I am starting my search. I think I will with a hotter cam since I will run carbs not CIS.

Pretty engine. Now you just need to clean the fan to match the heads and case.

[emcon5]

Originally posted by jpnovak
Do tell... Where'd you get the 98mm pistons? I am starting my search. I think I will with a hotter cam since I will run carbs not CIS.

I bought a low mileage Mahle Max Moritz P&C set, and then sold the Moritz pistons. The RSR pistons came from Andial, they were the correct size for my cylinders, and they had them on the shelf.

They are listed as 10.3:1 with RSR heads. With my 90cc SC heads they came out to 9.8:1. I measured the dome volume at 37.3cc.

Pretty engine. Now you just need to clean the fan to match the heads and case.

Probably true, but I didn't build it to look at.

I forgot to mention, I also added VDO cylinder head temp and volt guages, and clubsport engine mounts.

Tom

[Bill Verburg]

It's about time!! Nice job!, why did you decided to ditch the M/M pistons(not that there is anything wrong w/ the RSRs)

[emcon5]

Originally posted by Bill Verburg
It's about time!!

Agreed. I tore it down at Christmas. Took forever.

Part of the problem is that it was in my in-laws garage. If it was at my house, I could have done a little bit each night when I got home from work.

Nice job!, why did you decided to ditch the M/M pistons(not that there is anything wrong w/ the RSRs)

Thanks. Long story on the pistons, I had a line on a 20 hour set of 98mm 10.x:1 race Mahle Pistons from a local shop, but he was having a hard time finding matching cylinders. By this time, planning on using these pistons, I had commited to twin plug, and had bought the distributor and had the machine work done.

The Moritz set came up for sale from a customer of the machine shop, and faced with waiting for a potentially mismatched set, or buying a known complete set I jumped on it.

Unfortunately, I didn't do my homework. I had assumed the Moritz pistons were standard Euro 9.8:1 compression. I was wrong. When we measured the dome and calculated the C/R, it came up as just under 9:1.

Doh.

Looking in the piston chart in Bruce Anderson's book (which I should have done first), I discovered that the M/M sets were only 9.3:1. To compound things, the previous owner had the valve pockets machined a little deeper so he could run a hotter cam with carbs.

By this time, the low hour race pistons I had planned the engine around had gone away, sold to someone else.

Faced with having a low compression twin plug engine, I called around and found Andial had the RSR set, so I sold the M/M pistons to help pay for them.

The funny thing is that this started out as a budget top-end only rebuild, and sort of snowballed out of control.

Had the low hour race set come through, the price, plus the added cost of twin plug would have still been less than a new stock set of P&Cs.

Tom

[Chuck Moreland]

I can't wait for a ride!

What is it about twin-plugging that gives me wood?

[Bill Verburg]

The funny thing is that this started out as a budget top-end only rebuild, and sort of snowballed out of control

Imagine that

Interesting story

[beepbeep]

First picture:

Is that a hole in your piston or you are just glad to see me?

Very nice engine, btw.

[Wayne 962]

Originally posted by emcon5
Faced with having a low compression twin plug engine, I called around and found Andial had the RSR set, so I sold the M/M pistons to help pay for them.

$3600 bucks...

-Wayne

[aigel]

Why did you twin plug? Do your pistons have big enough domes to make it necessary?

Cheers, George

[emcon5]

Originally posted by aigel
Why did you twin plug? Do your pistons have big enough domes to make it necessary?

The pistons are measured at 9.8:1, which is marginal at best with the piss-water 91 octane California calls "Premium" gas.

Wayne, it ended up considerably less than that because I had low mileage Mahle Nikasil 98mm cylinders from the M/M set. All I needed were the pistons. All in all, they ended up costing less than a new stock set. When I sold the M/M pistons, the cylinders only ended up costing $550.

Tom

[smokindav]

Hey, Emcon5, how about those dyno numbers you promised?

[emcon5]

Probably in the next week or 2.

Tom

[Grady Clay]

Tom,
Good for you. This is the benefit of twin plug. We are spoiled here in Denver in that we can buy up to 116 octane “street” fuel legally, road tax paid.

Will the Pelicans in Bezerkeley (Oakland, Albany) please e-mail me. I need some help with my car at my mom’s house in North Berkeley Hills, up near Tilden Park.

Best,
Grady
gradyclay@hotmail.com
Denver, CO

[emcon5]

Finally made it to the dyno, results over in the Technical forum:

Dyno results

Tom