New Porsche Owner Hot Rod questions

[Brad912]

Hello all, Just bought my first Porsche a 69 912. I am having a lot of fun with it but I know I will be tearing it down to bare metal sometime in the next 9-12 months. Minor rust only but want to make sure it doesn't get worse.

My ultimate goal will be to switch to a 6 and have a great road car that might see a little track time. I live in Southern Ca so Willow Springs and Buttonwillow are not far.

I was considering buying a 3.0SC motor but I wanted to get some feedback from you guys who have "hot rodded" their cars.

what engine would you guys recommend 2.4? 2.7? 3.0? etc...

I would like around 210-230 HP if that is realistic. Can be Flywheel HP just to clarify.
Obviously I will make sure the rest of the car is ready to take the increase in HP

Thanks

Brad

[911pcars]

Depending on your budget, I’d suggest an aluminum case as a base. Each of those engines will need the usual mods to arrive at your target. Research the many engine rebuilding manuals, websites and this forum for a wide range of suggestions. After your headache subsides, you may a clearer direction and curvature of your slippery slope.

Sherwood

[Brad912]

thanks Sherwood

[Evan Fullerton]

A lot will depend on your budget. The 901 trans in your 912 won’t survive with a lot of torque. I broke the second gear retaining boss on my early 915 trans Autocrossing with a 170whp 3.0L. The 3.0L era and later 915 trans have a stronger main shaft and other internals but have their own drawbacks. As all things Porsche, the ultimate version is a hybrid of many different years.

If you have the Budget, the higher torque of a 3.0L or bigger engine is awesome and you get an aluminum case but some expensive gearbox upgrades should be in the long term plan and that can almost double the swap costs.

Finding an early Sandcast Aluminium case or better yet, Euro Carrera 3.0 Case that both use the early 6 bolt crank can allow you to build a killer rev happy small bore motor with some longevity that won’t kill a 901 trans with lots of torque but those cases are coveted and sell for a premium.

[Brad912]

Thanks Evan I was leaning toward a 3.0 Thanks for the advice on the Trans.

[Brad912]

could you clarify on early sandcast cases?

[Evan Fullerton]

1965 to 1967 or maybe some 1968 2.0L 911s use a sand cast aluminum engine case. To save weight around 1968 Porsche switched to die cast Magnesium cases. They kept improving the strength of the Magnesium cases up through was is called a 7R Magnesium case that came out in 1972 I believe. The 7R Magnesium case is the best of mag cases and at 2.4L seem to live a good long while but 2.7L Magnesium cases, partially due to SMOG and partially due to the larger cylinders and thus less material in the case and greater torque aren't known for their dimensional stability now that the newest ones are 43 years old. The early Aluminum cases being sand cast have a little more material in them and aluminum is just a more durable metal than magnesium over time.

There are basically 3 families of aircooled 911 engines. Early engines with 6 bolt cranks (2.0L to 2.7L) with the smallest head stud spacing, middle engines with 9 bolt cranks and slightly larger head stud spacing (3.0L and 3.2L), and late engines with 9 bolt cranks and the largest head stud spacing (3.6L). There are subtle variations within the 3 families but almost all of the parts are interchangeable as long as you stay within a given family. Some parts like oil pumps can be made to fit all 3.

The 2 exceptions to these family rules are the early '65-'67ish Sand Cast Aluminum Cases and the Euro Carrera 3.0L/'75-'77 Turbo cases that are aluminum and fit the 6 bolt crank. These cases are the most desirable if you want to build a small displacement high RPM engine as from the factory the 66mm crank was only available in 6 bolt form. 2.4L-3.0L use a 70.4mm crank with the 3.0L being a 9 bolt starting in 1978.

The 6 bolt crank is somewhat known for shaking flywheels off at high RPM if special precautions are not taken which ultimately is why Porsche went to 9 bolt cranks...... 6 bolt cranks are noticeably lighter though and with proper care can be made to stay attached to their flywheels.

[Brad912]

I definitely learned somthing today

[Walt Fricke]

Take a look at what things cost. The sand cast cases can be very expensive, as they are getting rare. The 3.0Turbo/early Euro Carrera cases are the same.
A budget approach would be to buy a 2.4 or 2.7 running engine with good compression and leakdowns, no bad oil leaks, and some decent known history. Plus head nuts which hold torque. It might run fine for quite a while.

A surer bet would be a decent 3.0, costing a bit more. With some modification you can get over 200 flywheel HP from a 3.0. But you are sort of playing with fire if you don't swap in a 915 gearbox too. Shouldn't be much of an issue with a stock 2.7, or a 2.4T.

All the 911s were and are great road cars - you just don't get much use of a lot of extra HP on public roads. My 2.7 was about as much fun as my 07 Turbo (but no, I won't swap out the Turbo to anyone for a 1977 911). Just as easy to get speeding tickets.

All fun on the track, too - it is the cornering where our cars shine on track, and the driver has the most to learn. Anyone can plant the right foot on a straight.

If you keep the 6 bolt crank down below 7,000 RPM (and lower - upshift RPM depends on your gearing, and is often well below the nominal factory rev limit) you ought not to have issues with the 6 bolt crank. And they are easily solved anyway - careful use of red Loctite and torque to 150 lbs/ft and the bolts will stay put.

Porsche's race motors of this era developed around 110 flywheel HP per liter. But even getting close to that output puts exponential increases on stress, strain, and reliability/longevity. Your car will be pretty light to start with, so you don't need as much HP for equivalent performance as a heavier car would need.

Do you have our host Wayne's book on rebuilding 911 engines? No? Well, buy it and start reading. He goes through a lot that is very useful to know.

[Trackrash]

If you get and study Bruce Anderson's and Wayne's books, you will know more than many on this board.

BTW here is a picture of a 1750cc '68 912 that smoked most 911s at autocross.


Your homework.

[Brad912]

love the front wheel off the ground.

[Brad912]

thanks for the info Walt. I am leaning toward the 3.0.... looking at a few now.

[Brad912]

beautiful car Track. I like autocross but I prefer to race for longer periods of time

[Flojo]

3.0 with SSI is a great engine.
you can tune it to a 3.1 or 3.2

[75 911s]

Originally Posted by Brad912

what engine would you guys recommend 2.4? 2.7? 3.0? etc...

Thanks

Brad

No budget? This one:

Ed Pink 4.0L



Moderate budget? Nice 3.0 or 3.2 case to start.

Small budget? running / leaky 2.7

Redneck budget? LS Swap

Streetwise rebel? K-car or subie swap. (everyone will hate you)

[chrismorse]

To register the car, you need a smog cirt. An engine swap is doable but all the original smog “stuff” must be on the car and operational ++ you must go to a smog referee to get this done. Or you could build what you want and swap back in the original engine to get your smog, then every two years for the smog/registration.
Sorry, didn’t mean to rain on your parade.
chris

[dicklague]

Originally Posted by chrismorse

To register the car, you need a smog cirt. An engine swap is doable but all the original smog “stuff” must be on the car and operational ++ you must go to a smog referee to get this done. Or you could build what you want and swap back in the original engine to get your smog, then every two years for the smog/registration.
Sorry, didn’t mean to rain on your parade.
chris

WRONG! A 1969 vehicle is smog exempt in CA. I have had my 1973 registred in CA for 21 years and never been to a smog station.

1975 and older no smog test.

From the CA DMV web site: "Currently, smog inspections are required for all vehicles except diesel powered vehicles 1997 year model and older or with a Gross Vehicle Weight (GVWR) of more than 14,000 lbs, electric, natural gas powered vehicles over 14,000 lbs, motorcycles, trailers, or gasoline powered vehicles 1975 and older."

[dicklague]

how about hot rodding the 4 cylinder engine? It is a type II Vw basically and there is a big VW hop up market out there.

One of the best is CB Performance and I have had quite a bit of experience with them. My outlaw Speedster had a 2.2l 4 cylinder engine that had EFI and turbo built by them and it was reliably putting out over 200 HP.

Nice thing is your get light weight and lots of power.


Pat Downs at CB has been building exotic VW engines for over 25 years and he is the best. They make their own heads and lots of exotic parts. Check out their site cbperformance.com

[Trackrash]

A friend of mine has a Speedster rep. with a 150hp type 1. My bug, see my garage, has a 2110cc T1, plenty of power.

You can build a big power 4 for sure. Check out CB's web site.

BTW, the green car, which belonged to a fellow PCA member, is no more, RIP, it burned up in the 2017 fires here.

[3rd_gear_Ted]

Originally Posted by 75 911s

No budget? This one:

Ed Pink 4.0L



Moderate budget? Nice 3.0 or 3.2 case to start.

Small budget? running / leaky 2.7

Redneck budget? LS Swap

Streetwise rebel? K-car or subie swap. (everyone will hate you)

Jae Lee @ Mirage in San diego will build you a [B]4.4 L [B]