High performance 3.0 - - - thoughts?
 

After plenty of discussions with my mechanic, he has finally convinced me that the following set up is what I want:

Based on a 79 Euro SC 3.0:

Used, in spec 3.2 95mm Mahle Cylinders
New JE 10.5:1 95mm pistons
New Raceware Rod Bolts
Steel head studs
Reconditioned Rods
"special grind" Webcam cams, between early S and 906 (my
mechanic's favorite cams)
Ported and Twin Plugged heads
Crankfire Twin Plug Ignition
Rebuilt 40IDA Weber carbs with large venturis

Your input is greatly appreciated.

Thanks.

sounds good!

are 40IDA webers big enough...how about 46 PMOs?

just had an engine built for my 76...83 SC 3.0. close to standard specs. just cleaned up the heads a bit, lightened rods, better head studs & rod bolts.

+1, gonna need 46mm Webers.

The nuances involved in picking an engine spec are generally determined by intended use, but there are other considerations.
All engine configurations (even F1) have compromises built in.
The question is or should be "where do I want to compromise?"
To respond intelligently to your question, there would need to be a plethora of questions asked and answered.
If you're asking "will this engine configuration work?" the answer is "yes".
If you're asking "is this the best engine for your needs?'' the answer is "who knows?".

A quick story:
I recently had a customer bring in a one owner 83 911 SC with 250K miles on it. He wanted an overhaul. We sat and talked and as is my usual MO I suggested some cool performance modifications. You know , the usual litany of higher compression, better cams, bigger ports....yada yada yada.
He thought it all sounded good. So I wrote it up.
He didn't have a ride home so I rode with him to his house and so I could drop him off and bring the car back. On the way home I noticed that he shifted his Porsche at about 3800rpm. I asked if he always drove like this? His response was " always". At that point, I decided that performance mods were not in his best interest. With his constant input, we ended up lowering his compression and advancing his cam timing. We also built a special distributor to take advantage of the lower compression. Now he can run regular gas and enjoy an engine that offers better performance at the range he has chosen to drive his car.
Is that engine choice correct for most Porsche enthusiasts? Of course not, but it is correct for him.

Budget, smog laws, collectibility, intended use and reliability are all necessary considerations when choosing the correct spec for your engine. Just like hot rodding old American classics, there is no "right way". Build your engine (car for that matter) to suit your needs, not some spec chosen for you by someone with an agenda or what you read in some book.
Cheers

Very well said, Henry.

So JL... The question is how will you use the engine. Those cams and build spec will create a high HP, High-revving engine. Sounds fun if the car is a canyon carver or track beast. I don't know how much fun it will be around town or on those long straight roads in West TX.

Your anecdote is right on, Henry.

I will be using this engine on a lightweight 73 911T with a decent amount of suspension upgrades that I intend to use primarily on the track (DEs and Autocrosses). I would also like to take the occasional Texas hill country scenic drive and try and keep up with folks like you, Jamie.

I have participated in a total of 4 DEs using my basically stock 81 SC and do want to become a regular at these events. I have had the pleasure of driving an early car with a nicely set up 3.0, very similar to the one I'm building that's a blast to drive, and I guess it's been my inspiration.

I am definitely on a budget. I have paid for everything but the ignition and build so far. I just want a decent enough engine that won't leave me saying I left a good amount of HP on the table had I just checked with the right people before all was said and done; therefore this thread.

Who will be doing your build?

Sounds like a good choice for your intended application. I have plans for something similar and the parts are on the shelf. I just haven't found the time.

Let me know next time you are over in Austin-area. I will be happy to show some of my favorite roads.

Eric Davis with Eric Motorsports in Corpus Christi, TX is doing the build. He is a very reputable guy in our area. He takes forever, but does a great job. His rates are also very reasonable.

I will most definitely let you know when I'm in the Austin area. I'd love to see those roads.

We had an engine done with very similar specs to yours, a bit different on the cam, but otherwise just as you intend (Kevin Farrell - Injection Labs). We have 40 PMO's on it.

This is a great engine. A little cranking for a cold start, give it a couple of minutes to warm up. After that it is smooth and tractable across the entire RPM range. No tempermental issues whatsover. I've driven it every where, some 9,000 miles on a car that has no top (roadster like). Broad power band that builds alot of enthusiasm above 5K. With the twin-plug, I've been able to run confidently on pump gas.

The 40 PMO's on our car and the 40 webers on yours. Hmmm... I think for street driving they are great, but if you really want to pour the coals to it, better go with 46's in my humble opinion.

That said, we would commision another build EXACTLY like this one in a heartbeat for a street driven car.

angela