Porsche 2.5 litre

billyboy · 05-30-2004, 03:59 PM

Is there any info available on a 2.5 litre engine that was made for 914 racing cars? I am looking at a 911 that is supposed to have this engine in it.This is the first time that I have used one of these message boards so please forgive me if I screwed it up!

Grady Clay · 05-30-2004, 05:28 PM

billyboy,

Welcome to the Forum. You found the right place to ask these important questions.

I have several of these engines I used in SCCA CP and GT-2 914-6 that were built in about 1983.

They were built on 7R cases with good virgin 66 mm cranks and lightened, shot peened and polished steel rods.
They have 91 mm Mahle Nikasil P&Cs originally set at about 11:1.
Weber 46 IDA carbs and C6 intakes. C6/910 cams, with both center oiling and spray bar oiling.
935 rockers, shafts, and securing parts. Factory Titanium retainers.
Modified 2.4 MFI heads, single plug (required).
Largest 930 oil pump of the day.
I was able to successfully use the 906 (215 mm) flywheels and the ‘69S clutch parts.
This was into a ’71 911 trans with a welded solid differential and 3rd gears welded on input shafts. It used the large CVs on long axles.

The HP peak was about 8100. I would turn them 8300 regularly with occasional quick runs to 8800 if it saved a shift. They had maintenance rebuilds every 25 track hours and never had any problems. The rebuilds consisted of bearings, rod bolts, rings, flywheel bolts, seals and gaskets, and proper touch-up of the perfect valves.
At races in hot weather I would change the fan pulley ratio to get more air cooling. It has a huge front cooler but a 935 oil filter in place of the engine oil cooler.

What to do if you get one of these type engines in a street 911?

First make sure of what you are getting. You need some experienced people to help you with a Pre Purchase Inspection (PPI). The 2.5 engine can be a worn out old race engine built from junk parts or a great race engine. Why is that race engine in that street car?

What are you going to use it for? It is a good track engine in a lightweight (<1900#) car. It is not suitable for normal street driving. These don’t run very well at all below 4500 and will be very, very expensive.

Find out more info about the car and engine and report back to the Forum.

My favorite street engine for an early car is a 2.8S MFI twin plug.

Best,
Grady

billyboy · 05-30-2004, 05:55 PM

Thanks for the info. We are going to take it to a good Porshe mechanic in this area and have him determine just what it is,(engine wise). There is some question about it since the original owner is long gone and the car has been sitting in a body shop for about 10 years under a tarp.The 2.5 is what it was reported to be, but not sure at this point. thanks again and I'll report back when I know more. I did want the car for a driver but not if it is going to be a life of grief. My dad had a 1962 356 Carrera 2 and he had nothing but trouble trying to drive a racing engine on the street. I wish I had that car now, in the bank!

Grady Clay · 05-30-2004, 06:18 PM

billyboy,

Post where you are located and perhaps some California Pelicans can give you a hand.

Give the owner some money, say $100, to secure your right to thoroughly inspect the car. Agree on a price up front where you can always back out; but he is committed. You can always walk off and come back with another offer.

Try this thread.
the buying process

Above all proceed carefully.

Come on guys, give him a hand.

Best,
Grady

BTW, For many years I had a 1962 2000GS/GT coupe with the 587/2 engine and two 1964 356C 2000GS Cabriolets (587/1), one with additional hardtop and original 12v sunroof.
G

Grady Clay · 05-31-2004, 05:21 AM

Guys,

I know we have Pelicans in the Morro Bay, SLO, Pismo area. Atascadero is just north on 101.

Billyboy,

You are going to need to do some serious prep prior to attempting to start the 911. DO NOT JUST TRY AND START IT.

First, drain the oil and inspect the sump plate.

Use the Search function on this forum with the keywords “storage” and my name.

Best,
Grady

jluetjen · jluetjen's Garage

billyboy;
Near as I can tell, Porsche never made 2.5 liter race engines for 914's. They did make 2.5 liter race engines for 911ST's, and there were two versions; short-stroke and long-stroke. The HP and performance of both was very similar, but the short-stroke model was an interum measure by Porsche until they could get the long stroke crank figured out.

If you can post pictures and/or the serial and model numbers off of the case, you'll be able to get some additional information.

If I were you, I'd try to determine the following:

1) Is the engine a "factory" race motor or a street motor that was converted? If it is a converted street motor, the value will be significantly less then a factory race motor. You should be able to tell this (or at least get a good idea) by the engine model number and serial number on the case.

2) No matter what the answer is to question 1, the other question is the condition of the motor. This will be far more difficult to ascertain and Grady's advice is good. Unless the motor is running, from a negotiation perspective it is a big unknown and to be treated very skeptically. In other words, it's only worth what the seller can prove about it, and most of the key parts of a race motor are not obvious without disassembly and careful inspection. Lots of people know how to say "Race motor", but very few really know what it means.

Grady Clay · 06-01-2004, 10:12 AM

John is right on. It would be very unlikely, but not impossible, to find a Factory racing 2.5 engine. Even Empi made “2.5” P&Cs for early 911s in ’68.

The car still may be a “good buy” if you consider it doesn’t have an engine at all.

The other very important issues are general condition, originality, rust, and previous crash damage.

Best,
Grady

techweenie · techweenie's Garage

All of this advice is good, but assumes a 6-cylinder engine.

Garretson made some 2.5 liter 4-cylinder engines in the '70s. They were not endurance engines, but were impressive as hell on autocross courses.

Grady Clay · 06-01-2004, 10:46 AM

techweenie,
Yes, I’m assuming a 6-cylinder. I don’t think anyone suggested this was a Garretson engine. If it were (and documented), that would change the picture dramatically.
Yes, and Jerry also built some great 4-cylinders that won Pike’s Peak Hillclimb – no fan, lots of methanol.
Best,
Grady

sundaypunch · 06-01-2004, 02:54 PM

Quote:

Originally posted by Grady Clay
...... The 2.5 engine can be a worn out old race engine built from junk parts or a great race engine.....
My favorite street engine for an early car is a 2.8S MFI twin plug.

Pardon my lack of experience on the various spec. engines Grady....
If someone were to have a 2.8 MFI engine built would you start with a 2.4L? I primarily see people going with 2.7's and don't know what the advantage of some of the others (like a 2.5, 2.6, 2.8) would be.

billyboy · 06-01-2004, 06:56 PM

Hopefully, tomorrow, I will know much more about the engine. Could somebody give me a quick tutorial on where to look for the engine numbers? I do know at this time that it is a 6 cyl. with a 4 speed I belive it is called the 901 gearbox. I have not seen the car yet and that is whyI appear to be so much in the dark. I am going on a short description given by the owner. Thanks Bill

ttweed · ttweed's Garage

Quote:

Originally posted by billyboy
Hopefully, tomorrow, I will know much more about the engine. Could somebody give me a quick tutorial on where to look for the engine numbers?

Back by the fan- on the right side vertical upright will be the engine serial number. The Type number (format will be xxx/xx) will be below that on the horizontal surface of the case (stamped in small characters- may require some cleaning and good light to read it).

In all likelihood, the Type number will not correspond to what the engine is in reality. If this is a 2.5 custom engine, it could be built with a number of different cases. The only way to know what is inside is to check bore and stroke and compression, etc., which require either a teardown or some pretty sophisticated tools which can measure these parameters non-invasively.

If it is a Type 911/70 or 911/73 engine with MFI, you have found nirvana. Conceal your glee and pay the guy anything he wants. Those were the real, factory 2.5 liter racing engine type numbers.

TT

Grady Clay · 06-04-2004, 06:36 AM

billyboy,

You have PM.

Please give us an update. What did you find?

Best,
Grady

billyboy · 06-04-2004, 03:53 PM

I am,unfortuately, quite familiar with PMS, but what is PM? With the car, I did an inch by inch inspection yesterday,it's a 1968 911T with 901 gearbox with a shortshift mod.Very little rust, one little blister on the right door and just surface rust on the underside of the floor pan, more brown stain with no flakes, pitting, or holes.Battery tray looked the worse of all but could not poke through, mostly a lot of dirt and debris.Car needs lots of cosmetic work inside and sandblast and recoating of the wheel wells and undersides. As far as the engine, it is at least a 2.2 as documented on an old invoice for service done in 1988. We are going to drop the engine out and take it to a good mechanic (Guy's Service in San Luis Obispo) to have it gone through. I believe it has weber 40? carbs and a "S" cam according to the invoice The owner said it has as malfunctioning chain tensioner which is hydraulic. He said that he engine is a high compression engine. The 2.5 idea came from the previous owner who said it was 2.5litre so I will wait and see what the mechanic thinks although we don't want to take it all apart if not necessary....will be continued

Jim Richards · 06-04-2004, 04:22 PM

PM = private message. Look at the bottom of Grady's post and click on the button marked "pm" just right of the button marked "profile."

Grady Clay · 06-05-2004, 10:04 AM

billyboy,

You, with the help of Guy’s and Pelicans, will have to determine if this is the right 911 for you.

The pro:
It sounds like it is relatively rust free (a real find for a ’68) and a good base for a nice hotrod 911.

The con:
It will take a lot of effort and parts to make back into a really good 911.

With your effort and the right lubricant ($) you can turn this into a really cool lightweight early 911 for street, DE/auto-X, or café racer. It sounds like it could also be restored to original. A great deal depends on your willingness and skill in lighting into a big project. Please post some pictures.

You may be able to find someone’s partially un-completed project 911 and spend less overall.

If you decide to not buy it, you should feel the obligation to find it the right owner.

Best,
Grady
gradyclay@hotmail.com

billyboy · 07-30-2004, 05:10 PM

The engine turns out to be a 2.2 litre with "E" cams and 84mm. E pistons. It was built on a 1967? sand cast aluminum crank case.It has Weber carbs. The engine is getting a complete rebuild due to somebody using a heater hose for an oil line back in 1986 when it was last rebuilt and parked. The hose disolved and sent bits of rubber throught the engine and that is why the chain tensioners were not working.