1977 911 S 2.7L Motor

[axvel]

1977 911 S 2.7L Motor, what can be done horse power wise, i'm currently in the process of rebuilding it so everything is apart, how can i make more of the performance engine, like the RSR 2.8 300 hp? in historic races?


1) Changing the Pistons?

2) Turbo? - Can 2.7 handle it?

3) leave it as is?

P.S. I KNOW I KNOW IT'S NOT THE BEST MOTOR TO START WITH BUT YOU WOULD HAVE THE ENTIRE MOTOR WHAT WOULD YOU DO.

PLEASE HELP ONLY

[RoninLB]

I wanted a 2.7 that would be able to position on fast highways and that's what i built.

A street engine needs torque not total hp. Torque is a function of displacement.

btw.. a good 2.7 rebuild is big bucks.

[Steve@Rennsport]

Axvel:

Ron in LB told you a key fact: a correct rebuild of a 2.7 costs plenty and you should budget appropriately. Their magnesium cases need about $ 2K of machine work to make them reliable.

To your questions:

1) Use OEM 90mm 8.5:1 Mahle pistons & cylinders

2) 2.7's are poor candidates for turbocharging. Keep it N/A.

3) Install SSI's and a good sport muffler like a Monty.

4) Have your cams reground to SC grind and time them to 3.0 Carrera spec.


The 2.8 RSR motor was really VERY VERY different and quite expensive to replicate, even in carbureted form. Your CIS fuel injection prevents the use of high compression, aggressive cams, and big displacement changes due to limited fuel delivery capabilities.

[SLO-BOB]

Most of those in the know will discourage you from turbocharging a 2.7. However, there are a few out there. Do a search under "turbo" and see for yourself. There is a lot of info out there so it'll take some time. Most use a BAE type kit at low boost. No doubt turbocharging will reduce the longevity of your motor, but maybe that's okay if you are completely dissatisfied with your car. If and when it fails poney up for a 3.0 motor and toss the turbo on that car.

[axvel]

Steve, could you possibly switch out the intakes? Let's say i have 3.2 intake instead of CIS would this be better is it doable?

Sorry if this sounds newbish

Originally posted by Steve@Rennsport
Axvel:

Ron in LB told you a key fact: a correct rebuild of a 2.7 costs plenty and you should budget appropriately. Their magnesium cases need about $ 2K of machine work to make them reliable.

To your questions:

1) Use OEM 90mm 8.5:1 Mahle pistons & cylinders

2) 2.7's are poor candidates for turbocharging. Keep it N/A.

3) Install SSI's and a good sport muffler like a Monty.

4) Have your cams reground to SC grind and time them to 3.0 Carrera spec.


The 2.8 RSR motor was really VERY VERY different and quite expensive to replicate, even in carbureted form. Your CIS fuel injection prevents the use of high compression, aggressive cams, and big displacement changes due to limited fuel delivery capabilities.

[axvel]

bump

[Steve@Rennsport]

Originally posted by axvel
Steve, could you possibly switch out the intakes? Let's say i have 3.2 intake instead of CIS would this be better is it doable?

Sorry if this sounds newbish

No worries, mate. Ask away; thats how we ALL learn.

The 3.2 Carrera intake doesn't fit the 2.7 due to large differences in intake port sizes. With some serious mods, it could be made to fit but the intake runner diameters are too big for that displacement and converting to Motronic is neither easy nor cheap.

[flash99]

axvel-

when i rebuilt my 2.7 two years ago i used the following:
40mm webbers
solex cam
9.5:1 JE pistons
SSI heat exchangers

it's certainly not a 2.8 rsr, but it is a great daily driver that keeps up nicely w/ the newer SCs and Carreras.

good luck with the rebuild.

[Cory M]

Steve-

I'm in a similar situation as the original poster. I have a 1977S 2.7 motor in a car that I am building into a track only car. Should I even mess around with building the 2.7 for the track, or just sell it and get a 3.0 SC motor? I think it may be better in the long run to go with the 3.0, I can switch to the SC motor and stay in the same class.

[Rouxzy]

Hey guys, do what I did to my '77, 2.7 when it was time to rebuild. It now sits in the corner of my garage and a 3.6 sits in the back of my '77. The costs of a more reliable, newer technological and much more power is the same as it would cost to do a proper rebuild of the 2.7. But I wanted a big boost in power, hence one of the reasons for the swap. If anyone needs parts for your 2.7 my engine hasn't been touched, except for the exhaust, I'm willing to part out.
Tom

[Facey]

Hey
after all this has been said, we could still advise on how to get some actualy power out of his 2.7L.


aside from the reliability stuff (case savers, rod bolts, head studs. 11 blade fan etc) the formula would be something like this:

40mm webers
95mm P&C's, 9.5:1 cr
better oil pump (gt3 (r?)or turbo)
early s-cam
SSI's
sport muffler ( i would go M&K)

this would be a very fun engine, it would love to rev and make pretty noises. It would also cost ALOT less then a 3.6 swap, though it also wouldn't make 3.6 power, however if you want to save some money, don't go to 95mm P&C's, just get new JE pistons, or fly cut the heads, or stretch the rods. and you'll have a high compression rs style engine when combined with 40mm webers (34mm venturi's) and an early s-cam.


just my 10 cents, i'm not an expert, but i have used the engine listed above and it was tons of fun, a great intro to the porsche world and it will outpace the stock 3L cars... and sounds nicer

[ventana]

Or- your could go with the 2.9 Mahle kit with 9 or 9.5:1 pistons a more aggressive cam and completely dump the CIS and replace it with a CIS to EFI conversion from Bitz Racing (about $1600)(http://www.bitzracing.com/products/Complete_kit/index.html) which would be my pick over the 40mm Webers. However, all of this would be dependent on you bullet-proofing the magnesium cases which as others have said, "It ain't cheap".

[azasadny]

Just be sure to put Webers on it!!

[Landrite]

Hey guys! I know this is an old thread, but I was curious to know if anyone knew what kind of hp and torque figures they got out of their modified 2.7l or 2.8l (92mm pistons) motor. Appreciate the help!!

[Jack Stands]

I had Supertec rebuild my 2.7 with RS pistons/cylinders, S cams, Weber 40 IDA carbs, case savers, Supertec head studs, and running through 914-6 heat exchangers. It made 199.6 rear wheel horsepower when we were done on the dyno, and it pulls great at all revs.

Not cheap, but none of these engines are to rebuild correctly.

[Landrite]

Originally Posted by Jack Stands

I had Supertec rebuild my 2.7 with RS pistons/cylinders, S cams, Weber 40 IDA carbs, case savers, Supertec head studs, and running through 914-6 heat exchangers. It made 199.6 rear wheel horsepower when we were done on the dyno, and it pulls great at all revs.

Not cheap, but none of these engines are to rebuild correctly.

That sounds pretty good! I was thinking about doing the 914-6 conversion. Any recommendations? Would you have gone with the 2.7l? It sounds like the right size for the 914, minus all the work. I was going to do most of the machining myself so no big deal there.
Thanks

[unclebilly]

If you have not split the case, and have no reason to do so, you can do the following:

1. Get JE 9.5:1 pistons and use your original cylinders. These can be shimmed to 9.8:1. These will allow you to run more cam. I am running Mod40s cams in mine. These won't work with CIS so you can go to webers or Zeniths. This setup with 34mm chokes in your carbs will give you about 230HP.

2. Get some 2.7RS pistons and cylinders. These are only 8.5:1 but will let you run more cam than the CIS pistons. The S cams will give you a 2.7RS build but these are a little peaky for the street. Run carbs with this setup or build an EFI setup.

3. You could do the 964 cams with the CIS pistons and keep the CIS injection. I think this build has mostly been speculated and I'm not sure if anybody has actually built this.

[Landrite]

Thanks for the advice. My plans have been to run the webers but I have recently considered building an EFI system for it. More than likely I will stay carbed since I like the look if that makes any sense.

That being said it is obviously not going to be a daily driver I like the idea of post 200's HP. Hence why I was considering the EFI. Instead I wanted to run higher compression in it to achieve that.

If I decided to run 9.8:1 pistons would it be advantageous to convert my heads for twin spark? I was considering JE pistons and they look fairly radically domed.

One last thing I am curious about is displacement. From my research so far I am getting pretty convinced that I can up it to a 2.8l with 92mm pistons and with the case-savers be ok. I'd like to think that if I up the compression as it will hold up as long as it doesn't get too hot. The case savers grip around 40% more surface area by my quick estimate.

Any thoughts?