decoding serial #'s 71 project car

[kandhmfg]

Recently started on a 71T chassis project car. Gutted the interior, pulled the engine/tranny and started tearing down the motor. Trying to piece together some serial numbers that are pointing more to an "S" motor and tranny. Wondering if anyone can maybe clarify for me. Just for reference the car has Weber 40IDA's on it and heads don't have fuel injection provisions. However here are the serial numbers:

Chassis 9111100271 (definite T chassis)
Engine 6114456 (my book points to an "S" serial number)
Engine Code 911/07 (points to a "T" engine type)
Tranny 7700347 (points to an "S" 5-speed 901 tranny)

The cylinders are aluminum fins and pistions are slightly domed with valve pockets, cams are stamped "S" on the ends which points to "S" Cams... Pics below note the real deal steel "S" front spoiler.

Any help is appreciated.

Thanks,
Erik


(my weekend track/autocross car)

[70SATMan]

[i]Engine 6114456 (my book points to an "S" serial number)
Engine Code 911/07 (points to a "T" engine type)
[/B]

Which book Eric? S engine serial number would be 631xxxx not 611xxxx. Judging by the serial number and type, it is a T engine. Not to say it hasn't been upgraded.

[kandhmfg]

Book is :

The Porsche Family Tree printed by Porsche in 1980.

Shows Chassis VINS 9111300001-9111301430 had engine serial numbers 6114001-6119000.

May be a misprint knowing Porsche.

I thought the "S" engines had a "3" in the second position of the serial number also. But everything else seems to be "S" oriented so was a wierd coincidence.

[Zeke]

The pistons look too flat to be S pistons. The cams have PN on the shafts. Don't go by a stamp, IMO.

[javadog]

It's a US '71T, probably ordered with a 5 speed and S trim, which was pretty normal in those days. The gearbox on a '71 is a type 911, not a 901. The gearbox number is a little funky, as it shows to be from a '70.

JR

[70SATMan]

Originally posted by kandhmfg
Book is :

Shows Chassis VINS 9111300001-9111301430 had engine serial numbers 6114001-6119000.

May be a misprint knowing Porsche.

Does look like a misprint.
Also, the S engine type number would be 02 not 07.

[kandhmfg]

Yes engine type on case is 911/07, transmission is type 9117017700347
Thanks for your help, most likely a T ordered with S trim and 5 spd. Kind of a mixed bag of items.

Zeke-Thanks for info on pistons you are probably right, that's what I mostly what I was looking for. Will be pulling the cams all the way out this weekend so will be checking the part numbers on them.


My shop says heads do have larger than normal intakes for whatever reason and Webers have larger than normal jets.

I'm guessing someone did a few mods on the engine in the past.

Thanks for the info.

Erik

[Scott at Pelican Parts]

Erik,
Be sure to keep us updated on this project. Knowing you, it will be first class -- and faaast!

Scott

[Grady Clay]

Erik,

The ’70-’77 pretty much all have the same valve size – 46 mm intake, 40 mm exhaust.

Slide a cylinder part way up so you can see the piston skirt. That will tell if it is an “S” piston. T & E have a full skirt while the “S” is a “slipper skirt.”


Chassis 9111100271 (definite T chassis)
Engine 6114456 (my book points to an "S" serial number)
Engine Code 911/07 (points to a "T" engine type)
Tranny 7700347 (points to an "S" 5-speed 901 tranny)



Chassis 9111100271
911 – Type 911 group
1 – Model year 1971
1 – Engine type T
0 – Body version Porsche coupe
0271 – Sequential number

Engine 6114456
6 = Engine designation 6-cylinder
1 – Engine type (official) T
1 – Model year 1971
4456 – Sequential number

911/07
Correct type for 1971 911T USA version

Transmission 7700347
7 – Transmission designation, transmission for 6-cylinder engine
7 – Unknown. May be a “1” which would be a 5-speed, standard ratio.
0 – Model year 1970
0347 – Sequential number

Reference: Porsche 69, 70, 71 Models; 911T, 911E, 911S; Technical Specifications; 1st English Edition, 4210.20, IV/73.


Clearly the engine S/N is later than the VIN. The trans may have been replaced as a victim of the “Simplified” differential.

Whatever this is “transmission is type 9117017700347” Is an error – way too many digits.

The only way to know for sure about the cams is to measure the cam base circle diameter and valve lift profile every 5° and compare to original.

Best,
Grady

[kandhmfg]

Well I pulled the camshaft out tonight and it is a Webcam grind cam 104/102 on a 911T cam p/n 901.105.133.0R.

Cam is set up for carbed engines for mid-range and top end for street/offroad. Which makes sense for a car with 40mm Webers and ported intakes.

Valve lift is .450/.408 with duration of 270/254 and duration @.50 of 250/236. Anyone have any comparison to what that might equate to in a stock grind if that is even comparable??

Still need to pull the cylinders to figure out the pistons. If they are truly T pistons will obviously have to swap for high compression pistons for that extra umph in the rebuild process.

Car is going to be set up as a street/auto-x car and want it to be snappy. Any suggestions that don't involve displacement increase? Any experience with a similarly set up 2.2L motor?

More photos below.

[Mad Mike]

I think you might need to lose the snappy idea and go for a real fast idea. bigger engine.

Cheers,

[jluetjen]

Originally posted by kandhmfg
Well I pulled the camshaft out tonight and it is a Webcam grind cam 104/102 on a 911T cam p/n 901.105.133.0R.

Cam is set up for carbed engines for mid-range and top end for street/offroad. Which makes sense for a car with 40mm Webers and ported intakes.

Valve lift is .450/.408 with duration of 270/254 and duration @.50 of 250/236. Anyone have any comparison to what that might equate to in a stock grind if that is even comparable??

The 104/102 is comparable to an S cam, most likely happier on the track then pounding around cones. Much like an S cam, it doesn't pull it's hardest until about 5500-5600 RPM, and then the HP peaks out close to 7000 RPM. Hardly the kind of a rev range that you'll be using around an Auto-X course. You'd most likely do better using something more in the range of an "E" cam or one of the aftermarket cams with a similar rev range like Solex, 158R or maybe a GE40. Camgrinder has a "Mod-E" cam that might be a good choice.

In general, an E-spec engine will out-pull an S-spec engine from idle up to about 4500 RPM. This is critical when you're auto-X'ing around slow corners in 2nd gear trying to avoid downshifting into first.

Still need to pull the cylinders to figure out the pistons. If they are truly T pistons will obviously have to swap for high compression pistons for that extra umph in the rebuild process.

Car is going to be set up as a street/auto-x car and want it to be snappy. Any suggestions that don't involve displacement increase? Any experience with a similarly set up 2.2L motor?

Using something similar to an E cam, 93 octane and single plugs, you're most likely going to want to target a CR of no more then 9.9:1. What sized venturi are in the carbs? Have the heads been ported? Hopefully the intake ports aren't much bigger then the stock 32 mm's.

The other two things that you might want to do is pitch the AC, and consider re-gearing the gearbox with a 2nd gear that is picked to match the speeds that you'll be covering around the Auto-X course. That way you'll be able to do most courses without shifting after you've launched off of the line.

[Scott at Pelican Parts]

Originally posted by Mad Mike
I think you might need to lose the snappy idea and go for a real fast idea. bigger engine.

What Mad Mike said. I have a 2.2L E -- and snappy it is -- between 5000-7000. Below that, I get beat by minivans at stoplight drag races...

[kandhmfg]

Pulled the cylinders off of one bank tonight. Need some more help if possible.

They are 90mm Mahles with number 902N2W5 p/n stamped on them. Pistons are the slipper skirt style with valve pockets. Did not pull them all the way off, but cleaned them up and there is a "1" stamped in the top of the cylinder, what this means I don't know. Also some other numbers around a M shaped insignia that are stamped 113 on top and 019 on bottom?? Any idea what compression that might be?

I have included photos below.

Connecting Rods are p/n 911.103.105.0R. Can someone tell me if these are the shorter or longer stroke connecting rods?? I can't seem to find these part numbers in the porsche parts PET catalog online at the classic section of porsche.com? Unless the writers of the parts catalog were dislexic compared to the engine stampings and the 105 in the rod p/n on the actual part translates to an 015 p/n in the catalog??

Could possibly be a short stroke 2.5L or a 2.7L if the stroke has been increased as well to the 70.4mm if I reference the Bruce Anderson book??

Other parts I can't seem to identify, heads 911.104.306.0R and cam housing 901.105.111.0R any help??

Its a journey of discovery definitely.

See pics below.

[Mad Mike]

Here is the car behind us!







I know it is in better shape now!