which one, A 79 3.0 or a 81 3.0

ferrari2porsche · 07-03-2002, 07:39 PM

OK going from a 2.7 to a 3.0. Trying to decide between a 1979 3.0 or an 1981 3.0. which is better and easier to install???

Bill Douglas · 07-03-2002, 07:46 PM

Well, an 81 has got more HP. I'd probably use the one in the best condition. Bill '79SC

nostatic · nostatic's Garage

If it is a US spec engine, the '79 has an air pump, while the '81 has an O2 sensor. I believe the conventional wisdom is that the O2 sensor is preferable.

pbs911 · pbs911's Garage

81 3.0: 180bhp@550
244@4200 torque
9.3:1 C/R

79 3.0: 180bhp@5500
237@4200 torque
8.5:1 C/R

This is assuming both are US motors.

The 81 will have the O2 sensor, the 79 will not. The 79 will have the air pump, the 81 will not. Most eveyone removes the air pump and disconnects the O2 sensor so that is moot, IMHO.
I would chose the one with the most history and upgrades such as chain tensioners, turbo valve covers and pop off valve. All things equal the 81 has a little more torque but they are pretty even motor performance wise.

1980SC · 07-03-2002, 09:52 PM

As we said before, if the '81 is a USA engine, then it will require the extra crap needed because of the O2 sensor. A control box under the passenger seat along with it's relay and the associated wiring. The '79 will be easier.

Rob
1980SC euro

Early_S_Man · 07-03-2002, 11:39 PM

This is a completely redundant thread ... since the SAME QUESTION and multiple answers have previously been posted! Did you NOT even bother to read your previous thread?

Wayne 962 · Wayne 962's Garage

Calm down folks. The more important thing to ask here, is which motor is in better condition. A 3.0 purchase + rebuild will cost you twice as much as a 2.7 rebuild. Some engines are good, but a lot of 3.0 liter engines are upgraded because they are tired and old, and the owner wants a 3.2 or a 3.6. Most of these engines need rebuilding, or will in the very near future...

-Wayne

1980SC · 07-04-2002, 05:56 AM

I know it's a tough decision. Wayne makes a very good point. If I were selling my 3.0L on ebay, it may seem like a good engine. 116K miles, good compression numbers, no broken head studs, quiet valves, clean, all CIS components well sorted and adjusted, and updated with Carrera tensioners and a pop off valve.

Too bad it blows a big cloud of blue smoke every time I floor it.

Rob
1980SC

ferrari2porsche · 07-04-2002, 06:52 AM

Hey early_ asS_man, just trying to get as much info as possible before spending big bucks. If redundancy bothers you, turn the channel.

yelcab1 · 07-04-2002, 08:15 AM

Lighten up everyone. No need to go ballistic for such a small thing.

ferrari2porsche · 07-04-2002, 09:07 AM

You're right Yelcab1, I appologize. lets all kiss and make up.

dd74 · 07-04-2002, 09:52 AM

I was (and still am) all over the place with my various 911-related questions and I know I've been repetitive. Don't let it bother you. Keep asking. One of us is bound to answer you in a positive and helpful way. As for me, I never get tired of answering whatever question I can.

What the guys said in regard to your question is correct. Personally, I'm not sure there's that large a seat-of-the-pants difference in SC motors, and I'm not sure (as was outlined in one of my prior questions), that mixing and matching parts from one SC motor to the other is entirely that cost efficient and overall mechanically feasible, unless you're willing to do more work inside the motor. As for stock engines, I think any SC motor's a good choice.

One way or the other, it's a painless and simple swap. I've heard 3.2s are more complicated, and my mechanic sort of shuddered at the thought of a 3.6 swap. Rebuilding your 2.7 is another idea. Read the board members ideas about 2.7s, and you'll see some convincing arguments to work with your current engine.

Good luck, and keep asking those questions! An informed public is a free public.