"Up-spicing" the 2.7, my engine need a rebuild.. what now?
 

My original 74 Carrera has the matching number 2.7 engine in it, as many 2.7's it has low oil pressure, it has approx 100.000 miles on it and is bone stock with mech tenisoners. I want to put some more punch in this car and was planning on modifying the engine.. lately i have seen these cars raise in price so I am thinking about preserving the orig 2.7 and do the oil bypass an perhaps new bottom end and store it. (i am serious DIY and would only need purchase machining services..)

Perhaps I should get a similar 2.7 engine and build a 2.7 RS style or 2.8 engine. My budget should be around $5-10k.

Where should I go now? Look for a complete 74-75 engine or start with a good block and buy the pieces, or even search for a built 2.7-2.8 engine with good specs?

If you're keeping the original 2.7, why not go for a 3.0? The 3.0 is a more "sturdy" engine, providing a better base for performance upgrades. Plus, a 3.0 will last longer. A 2.7 may be cheaper to purchase, but the expensive machine work required in a 2.7 rebuild will likely balance things out.

$5-10K might not get you to where you want to be with a hotrod 2.7 or 2.8. Carbs alone will eat half to a quarter of your budget.

Performance wise - a 3.0 will have little to no difference from a 2.7, and a 3.2 will require a lot of work to install properly.

What I would do instead is get a closer-ratio gearbox.

if you are a serious DIY, consider this option: pull your original 2.7 and store it for a rainy day. this allows you a little breathing room to think about what you want to do with the motor. Pick up a 3.2 w/ DME for around $5500 and plug it in over a weekend. New clutch, etc. will eat up another $700 or so, but you'll have excellent reliable power for years to come leaving more time to think about and then rebuild your 2.7.

Chances are when you put your 2.7 back in you will be able to sell the 3.2 for $5K.

I guess there are 2 ways to go. Remove and properly store the existing motor and replace it with anything of your choice. Or, build what you have. However, it you're thinking of future value, as you indicate, then you really should stay along the lines of stock for a Carrera.

Think of this: you're out looking at cars and a seller says he put bigger jugs on it and now it's a 3.0 (a popular upgrade). Are you impressed with that fact or would you rather he had said it was rebuilt exactly as the factory built it?

I just did this to my original '74 carrera, I wanted to keep the original block since it is all matching numbers...

I helped a friend build my motor, it was a great experience...

I had the 2.7 block strengtened = time cert / shuffle pinned
I went ahead and modified everything else internally...
Elgin MOD S cams
9:5 pistons
reworked heads = match ported / polished
cross drilled cranks / micro polished
PMO carbs / match ported manifolds
etc....

If you do not care about using the original matching motor, shelf it, place a 3.0 in it's place.



http://forums.pelicanparts.com/uploa...1190933210.jpg

Think $12-22k for an RS spec motor, depending on what you can do yourself and whether you already have mechanical injection or PMO's/Webers in hand. If that kind of budget bothers you, don't even think about it. 2.7's are wonderful, but expensive. And despite shuffle-pinning and blueprinting and line boring and time certs mine still leaks!

So far so good for my motor, 1500 miles later still no leaks :)

although I do have a small valve cover leak on one of the bolt....

we followed supertech way of sealing the motor, w/ the threebond stuff

Lots of good ideas here, but I really want to have a high rpm small displacement engine.

The stock engine will be stored, first opened and then i may have to redo it somewhat, oil bypass + bearings. Have to get a better oil pressure, you could call it a sign of age... thanks good it does not smoke.. but it leaks! :)

I actually have a 3.2 in my 76 targa and it put quite a punch compared to the stock 2.7. I could do that, but i dont want to make many mods to chassi or el-system.. I already have fuel system + ignition, we are not going to use $5k on carbs here.

My thought was that I basically need new engine internals (p/c + bearings + minor parts) + machine work to the engine/internal parts. rebuilding and porting the heads.

If you have the fuel system, you're ahead of the game. The p/cs, etc. are sometimes seen on Pelican classifieds. In fact, I thought I saw a set of RS p/cs Thursday. I bet you could find any other parts at a competent Porsche mechanics shop. In the meantime, put in a "wanted" add on Pelican classifieds for the parts you need.

A high-revving 2.7 will more than make up for many later/larger engines. It's lighter, revs much faster than a 3.0 or 3.2, and with a 7.31 r/p 915, can be very sporty in addition to being tractable around town. I gave up a 3.0 in my '74 for a mildly worked 2.7 and have never once regretted it.

I only suggested the shorter gears simply because it would be substantially less expensive than building an entirely new engine, which can easily surpass $10K.

here's a pic of my carrera, it is US #434, maybe someone know it? it came from southwest to NJ and now it is in Norway

http://forums.pelicanparts.com/uploa...1190963805.jpg

An oil pressure idea. On my 73, replacing the oil pressure sensor gave me another 10 lbs of pressure at 5k rpm! No magic here, the old sensor was simply reading wrong. So try this before you tear the motor apart, if pressure is your principle issue.

yes, i tested the used oil pressure switch from another 2.7 some year ago, no change, it was still "too low for comfort". But perhaps I should order a new one and have it verified.

The fact is that the engine runs like a champ, from 3500 to 6500 it is very strong, the main concern is the oil pressure and drips.

There is also an interesting 3 liter engine for sale at the parts classifieds.. 3.0/3.2 short stroke, but i have no idea if I have to work my garbox with 50% power gain. I am looking at getting maybe 220-230 HP instead of my 175

A 3.2 short stroke can be a very nice engine, and as it is based on a 3.0, you won't have to any more work installing it than with a typical 3.0. It should develop at least 220 hp. Are there any more details on this engine? Is it still CIS?

You should know a 2.7 can also develop 220 hp, even more, if built to that sort of specification. But it's a different kind of 220 hp than what a 3.2 short stroke develops. If torque is at all important to you, I'd go with the 3.2 short stroke engine. I'm not sure, however, how your gearbox will handle the short stroke's torque.

Remember, it isn't necessarily the hp that could potentially kill these gearboxes; it's the torque.

the 3.2 in the classifieds is without heads and induction.. it is actually this one:
http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/361924-fs-3-2ss-project-engine.html
.. it may be gone but it seems like an interesting startpoint.

Have a slightly used set of TWM 3003 at hand and I was going to use the new Tec3 from electromotive, the Tec3 I traded for database recovery for a local parts shop.. he have to order it though.. :D

I am not experienced in engine management systems, so this is new knowledge for me. Have been interested in setting up such an engine a long time, now is the time.