I'm a VW guy and I know lots about 4s, but whilst I'm a quick learner I need a bit of help with the 6s

What engine would street and race /6s have had in 1970? Am I right in thinking it would have been a 2.0 litre "T" engine? What's the difference between a street engine and an 'average' period race engine apart from the twin plug heads/ignition system?

Are there any specific weaknesses on 2.0 litre engines?

What is the bore and stroke?

What is the difference between a 911 and 914/6 2.0 litre motor?

Are there 'other' 2.0 litres that are different (so I end up with the right one!)?

Are the 2.0s worth more or less than the later, larger displacement motors?

Sorry for all the questions, it's wierd being a newbie again after years of being a VW know-it-all

Street 6's came with the 2.0T motor. It was basically the 1969 911T motor. They can, and sometimes are, warmed over by building them with a larger displacement, etc.

The stock 2.0 engine was (is) a workhorse. Some cheap horsepower is available with rejetting of the 3C-40IDA Webers. Most cars have already had this done. Many stock 2.0 motors are still running strong.

Because the 2.0 wasn't built up as much as some of the larger displacement engines, it runs cooler than many of it's younger brothers. Like the T-4, heat is a killer to the flat-6 engine as well. Some people feel the smaller /6 engines aren't worth the time and trouble when going to the expense and effort of doing a conversion. Generally, the larger the displacement on the motor, the more it's going to cost, both to buy and to rebuild.

I don't have the bore and stroke information handy, as I'm at work, but I think it was 80x66mm. The 916s were fitted with a 2.4 and 2.7 engines, 84x70.4mm and 90x70.4mm respectively. Of course, pretty much any aircooled 911 engine will fit in the engine bay.

There are two books I'd recommend:

- Pick up the How to Rebuild Your 911 Engine (68-89) by Wayne Dempsey of Pelican Parts. It should be mandatory reading for anyone who own's a 6 cylinder engine. I learned a HUGE amount from it.
- Bruce Anderson's 911 Performance Handbook (http://www.911handbook.com/) is an excellent book as well. I own two copies.

Hope this helps,
Rusty

That's great, thanks! I've just ordered the books from Amazon. I always feel a bit guilty when I don't know stuff!

What identifying marks/codes do the engines have?

street, yes.
race, no -- the 914.6GT was basically a 906 engine. the 1970 911T was a 2,2 liter engine.


in 1970 - the 906 engine was based on the aluminum crankcase. after that, it's your standard "cam, compression, and carburetion" differences - with the appropriate 'details'...

not once you realize that there is a big difference in preparation for a race engine. shot-peened and polished forged rods, forged crank, porting, exhaust, some oil system tweaks...

80x66mm


a 914.6 street engine was a continuation of the 1969 911T engine (110DIN HP) there were also 2,0-liter 911E and 911S street engines - 'S' was rated at 180 DIN HP. cams, compression, carburation - E and S had MFI that was good for another 10-15HP.

911T - basically the same with detail differences (oil cooler, carburation, flywheel. 911E and S, as covered above.

depends. you won't win a national-level concours d'elegance with the wrong engine. 2,0's cost at least as much to rebuild as the bigger engines, and the newest is 35 years old.

If you really want to research this stuff, in addition to the other suggested references, read Paul Frère's "Porsche 911 Story" which covers all the detail differences and evolutions across the development of the 911 engine.

The Type Number (911/xx) tells you what the engine started as - assuming nothing changed when it was rebuilt somewhere in its 40-year life (never a good bet). There is also a serial number that can sometimes be used to track back the production data, but only a few people keep all the production serial number data close at hand, and lots of people have a reference of the Type Number. Type Number will be to the right of the fan housing on the horizontal surface of the case.

There aren't really an differences in the engine itself, but the oil coooler on the -6 is different, and the -6 had timing marks on the flywheel becasue it's nearly impossible to time it by the pulleys without cutting a hole in the firewall. Please don't ask if you should cut a whole in the firewall

-Justin

Haha, I read that thread already

Was the "stock" 914 six based on a magnesium case?

yup.

Maybe you feel you just gotta have/do a 6-cyl conversion. But if you look at Jake Raby's sites, Massive Type IV and Aircooled Technology, you'll note that you can stay type IV and get close to 200 hp. Yeah, its 5 grand and you do the work, but you were going to do the work on the six project, and spend more by the time you were done, right? Not sure if you can keep it to 2.0L and get really great power, but Jake's 2270cc motor he claims is as long-lived as the factory, and gets 180+ hp and more than doubles factory torque. It's a bit lighter than a six, needs no long lines to a front oil cooler, and appears almost stock --depending on the fuel system. As an old transporter van man myself, I find it an elegant solution to the power question.

i will side step that one.....
you will need oil tank , modified engine cooler, six engine tin , engine mount, oil lines, an oil cooler, (some say optional) and a few other incedentals like throttle linkage...etc etc...oh yes and money, and time, two months of weekends....

You didn't specifically mention that you were interested in a conversion... but since the thread has turned that way.

Pete's right about the parts list. Most of that stuff is readily available from Rich Johnson and other various sources. There's a vast amount of information available about doing the conversion.

Having owned both 914-4 and 914-6 cars, I like both. Both have their own character.

As far as the argument about a "hot 4" or a "6 conversion"... it's your car. Do what makes you happy. My personal opinion is that I will buy an engine that was originally built for the power I want. I want 180hp? I'll pick out something that came from the factory that way, and I won't need to worry about what special tricks someone else did or customized parts that might be NLA in a few years, etc.

Cheers,
Rusty

If looking for a lower cost 6 cylinder, maybe Corvair is a good choice. They are aircooled and develop lots of oomph and still reasonable. Adaptor needed though as the tranny sits in the front end of engine on the Corvair and rear on the 914. Some have done this and were happy with the results.
IMHO:
Corvair is to Corvette as 914 is to 911.
Lots of bang for the buck.

Thanks guys The car is going racing, and to do what I want it to do it has to have a 2.0 litre six. In its previous life it had a big 4 (a 2.7 on DRLAs)

Vintage racing? Sounds like fun.

There are original /6 motors available from people upgrading... or you could go with a 1969 911T motor. Check your rule book.

yes - check the rulebook very carefully... unless it restricts you to an original production run case number, the hot setup would probably be to build up as close to a 914.6GT engine as possible - those were 210DIN HP engines. The 906 and 904/6 racing 2,0 engines used titanium rods, twin ignition, and right around 10,3:1 compression producing rated power at 8000 rpm via MFI or Weber 46's.

for those levels, I'd try to find an aluminum-case 911S engine with the forged, counterweighted crank and build up from there. I believe I saw that Mahle had re-issued the 906 P&C set due in large part I'm sure to the resurgence of vintage racing.

None of this stuff is cheap.

Is the 911 S ally case the same as the 911T magnesium one apart from the material?

basically. detail differences, that 911 Story and Anderson's book will lay out for you. For instance - in the aluminum engines, the intermediate shaft can and did run directly in the aluminum case. in the very early (1967?) mag cases they tried that, but discovered very quickly they needed bearings. probably a good idea to have even an Al case bored for intermediate shaft bearings nowadays. There was also a change to the oil scavenge circuit made somewhere around the 2,7's - that mod should be retrofitted to early cases.

The Al cases are regarded as stronger and stiffer - but they're also 10Kg heavier so choose your poison...

Another possibility is the 1973-1/2 'small bore' "7R" mag case. produced 1/2 year only, it was the latest & greatest mag case, still made with the 92mm cylinder spigot holes. I sold one of those about a year ago - they're still out there if you're patient and have ready cash...

I run a 2.0/6 in a vintage race car
you have to read the rules very closely about what is or is not allowed.
every club is different.
for example, rich's GT spec motor above would put you into a higher class than other 914/6's in my club (one guy has one!)

I'm in the middle of gathering parts for my next motor and it will be hotter. but my car log booked and started running with a 1966 aluminum case filled with all 1967S internals. 160hp is the stock rating for this motor and the only "performance" items in mine are the oil updates and oil pump. I dyno'd at 142 with 5000ft of altitude, so I figure about 170hp at the flywheel after much jetting. This seems realistic since I'm running headers, bigger venturi's, and alot of jetting/dyno time on it.

My reasoning for that specification was that I needed something reliable that would give me 5 seasons of worry free performance and allow me to focus on driving/set up.

many of the 2.0 cars (911's mostly) in my club kill me on power.
many of them are over 200 hp. In fact I have guys in 1.8L mgb's that out pull me on the straight. So an all out horse power race is futile, since I personally will never be able to outspend the guys with 20K into their motors.

the factory rated 2.0/6's started at 110hp and went up to 160hp
(the mfi of 1969 was actually 170hp, but most vintage groups would not allow an mfi on a 914/6 since they didn't come this way)

always great to see another vintage 914/6 being born
good luck with your project and feel free to ask any questions that I might have learned the hard way

brant

That's the key for me - I can worry about screaming about when I've got a handle on everything else.

I'd recommend something in that stock range then..
a T motor is cheap(er) and will run fine for a couple of years
you don't have to spend the whole budget on motor that way and can always upgrade the next year.

but something used and with records, or good condition...
building a hot race 2.0 can be VERY expensive

for me I needed to get the chassis/paint/suspension/gearbox/safety gear/tow vehicle/trailer/entry fee's/and about 20 thousand other items done before I worried about having the hottest motor!

plus its a good excuse if you don't take 1st place at your first race (something rarely ever done!)

check out the thread linked in my signature to see what we did with a metal car
I actually think it may be the lightest 6cylinder metal race car out there
brant

good advice, although I think I'd suggest something in the E range, with S crank and rods. The counterweighted crank is heavier, but it is forged and stronger - I have known a couple of guys who've broken cranks in 2,0 classes - usually at the #2 crank throw. the soft nitrided S rods are getting rare due to the guys in classes that must use them. I think - especially if using a mag case - the counterweighted crank might alleviate the need for shuffle pins and keep the case from getting too beat up (although I'd probably shuffle-pin a mag case 'just because' if it were legal in the class...)

1mm over P&C are not too pricey if you can start with a stock E Biral cylinder set and use 9,8:1 JE pistons. check class rules for this, but "040-over" (or its metric equivalent 1mm) was a standard SCCA-legal mod "in the day."

But the whole area is all about tradeoffs and balance. and reading the rule book :-)

I personally wouldn't consider anything less than a 2.2, as these engines have the oil squirters which spray oil on the back side of the piston, which helps cooling. We all call these engines air cooled, but in reality the flat sixes are oil cooled as much as they are air cooled.

I'm in total agreement as far as building the engine to the class you plan to compete within. Diligence and careful interpretation of the rules will prevent future trouble. I'd be sure to consult some local enthusiasts prior to spending any money on an engine.

The labor cost to rebuild a flat six isn't going to be much different on a 2.0 or 3.2, but there will be a difference in the parts expense.

I'd say get the latest model, lowest mileage engine you can afford. The 3.2 Motronic engines with Mahle P&C's are probably the best choice of that lot. The injection will require some special wiring, but you won't be diddling with Weber idle jets every three months, and you can just turn the key and it starts, no snappity pop pop.

Good luck! You'll find lots of good advice here, and of course as any internet entity lots of keyboard experts with no real world experience. Talk to guys who have done this sort of stuff and see what really works. Limit your "Star Trek" (going where no one has gone before) adventures and you'll finish the project much quicker.

Competition Engineering can install squirters (even Turbo ones) in the early cases I believe. Presumably a race engine would also uprate the oil pump too... The 73.5 "early 7R" case also has squirters and can built as a 2,0.

I believe the engine in this thread is limited to 2,0 by class rules; a protest/teardown will ruin a race weekend - especially if the engine is found to be nonconforming...

It is - some of the races are a looooong way (as in another country) from where I live so I don't want to get there and get bounced! When I used to drag race my bug that was my ultimate fear. It never happened to me but it did to plenty of others, usually for cage problems.

This is the set of rules the car has to conform to - I'm about halfway through learning them

http://www.fia.com/resources/documents/895...AppK_2006_a.pdf (those are last years - this years aren't working for some reason)

They are without a doubt the most complex rules I've ever read, mainly because there is a lot of things that don't apply to me.