Enthusiastic Newb Needs Some Engine Build Advice: What Would You Do?

[ScottArizona]

So my '81 Euro SC came with an '84 3.2 motor installed. The PO pulled the original Euro 3.0 (930/10 version) after discovering a broken head stud, stripped it down to the longblock, and then abandoned the project after discovering he could "upgrade" the engine with a used 3.2 for about the cost of the repair work. That was in 2006-2007 ish, and the poor motor had been relegated to a dusty corner of the PO's garage for the next decade until I brought it home with me in December. Needless to say, I would like to restore some order in the Universe and reunite the motor with the car.

So, I bought the yoke, a stand, and a bunch of other special tools, and decided to start the tear down and clean up process myself, both to learn about the car and also to save some money. I have never torn down/built an engine before, but I feel like a can follow instructions, and with a little patience, common sense, and help from the forum (and Wayne's book), I figure I don't have much to lose by giving it a go. So far so good: rockers are all out, tensioners are out, remaining accessories are off, and one cam is out, but I'm waiting on the holder tool for the other side as its being stubborn (I thought I could get away with just a 17mm wrench and the 46mm crowsfoot, but that worked only for one side so I sprung for the holder socket and will give that a go). My plan is to break it down and clean up everything myself at my own pace, since there is no real urgency, and then give it to an expert for the "Reconstruction" (I'm way too OCD to trust myself with gauging wear, measuring tolerances, etc...I'd be a nervous wreck, so I will leave that to the pros). But, now I have some decisions to make before I start sending stuff out for machining, inspection, and re-conditioning. That is where you guys (and gals) come in!

This is what I know for sure:

1) I want more power. If I'm going to spend the dough, I want more than stock power levels (even Euro 3.0SC stock power levels). Nothing crazy, but an extra 50 ponies would be amazing. I'm not dead set on 50 hp, that's just the power level I imagine in my head would feel really "right" for my car.

2) I want it "somewhat" reliable. I don't mind fiddling, tinkering, or tweaking to keep things running well, in fact, I welcome it. But I don't want some ragged-edge, high strung, could-blow-up-at-any-time motor. I'd rather have a little piece of mind than that extra 15-30 high rpm ponies.

3) The CIS is gone. I know its reliable when set up and working properly, but I don't want the motor (or cam) potential to be limited by the CIS, and as we all know the parts are getting more expensive and hard to find, and frankly, my CIS has been sitting on a shelf for a decade and I don't want to have to trouble shoot every single seal, o-ring, or other plastic part that might be "dried up."

4) I'm 90% certain I want carbs. I know EFI is arguably "better," but I love the look, sound, relatively simplicity, "analog-ness," upgradability," and throttle response of carbs, and don't mind poor fuel economy or a bit of fiddling from time to time. At the end of the day, engine "character" and responsiveness is more important to me than outright power or 0-60 times. Its why I love my 996 gt3 more than my old stupid fast 996tt and old 997 gt3, and why I enjoyed driving my former e36 M3's and my old 2.5l boxster so much. Character Counts as they are fond of saying at my kids' elementary school.

5) I'm relatively certain the existing engine is in pretty good shape (but for the broken stud). I'm no expert, but so far I've seen nothing of concern in inspecting the rockers, the cams (no pitting, galling, etc...), sprockets, etc... Even the chain ramps look good. And, I believe the PO when he said that the engine showed no signs of any issues before he discovered the offending stud. This is what is complicating my decision so much...the 930/10 motor is such a sweet motor I hear! I almost wish the engine needed new P/C's because then it would make the upgrade decision so much easier.

6) Comfort is not a concern. Loud is fine, rough is fine, lopey idle is fine. When I want refined I'll drive my Cadillac Volt (i.e., ELR).

5) I don't want to go crazy and get divorced because of the motor build LOL! I realize what I want is not going to be cheap, but I also can't afford a Singer-esque, cost-no-object, titanium everything motor. I'm not opposed to spending, but the value proposition is really important to me. Looking for bang for the buck, with maybe a little bit of excess thrown in here and there for good measure!

And here is where I'm confused. I need help deciding just how far I should go, given where I sit at present.

1) Should I increase displacement? I'm thinking at least 3.2 ss, but would that really be much better than a fresh, perfectly running 930/10 high compression motor with carbs and a 964-ish cam grind? What about a 3.3-3.4? What are the downsides to going with 3.3 or 3.4? Reliability, or just cost?

2) Should I increase compression/twin plug? I probably would not feel comfortable increasing compression without twin-plugging, given that we are pretty much limited to crappy 91 octane here in AZ. So, besides cost, what are the downsides to a high compression twin plug motor? Less reliable? other downsides I'm not aware of? Or is it just cost?

3) Should I split the case? I feel like I should, regardless of what mods I incorporate, but should I do so even if I stay with the stock p/c's? My only worry is the "what is in there" concern since the engine has been "open" for years, who knows if there is an errant nut or washer in there somewhere, and the engine down in there looks bone dry and dusty, with visible remnants of the dried out paper towels that were shoved into the intake ports so many years ago!

4) Are there any "no brainer" while you are in there mods? Seems that the verdict is out on the benefit of boat-tailing, but then again, its not super expensive. Same with knife-edging the crank...I love the idea of reducing rotating weight. Where are the other "bang for the buck upgrades while the engine is out? Ti springs? lighter valves, maching the flywheel or just by lightened?


I know I've thrown a lot out there. I would sure love some feedback, given my goals and preferences, as I would like to start compiling parts little by little so my wife doesn't notice any huge anomalous expenditures that will fuel her home remodel or new furniture requests!

[ScottArizona]

Damn forgot to subscribe!

[Trackrash]

1. Displacement is king. The more the better. However you will also need to up your carb and exhaust size to match.

2. Twin plugging is the way to go. It just costs more money, since you will need a new ignition system. On a large street motor, probably a debatable return on investment.

3. Definitely split the case. Unless you had the motor running beforehand and know it to be perfect.

4. The best bang for the buck would be light weight pistons like JE or CP. Money no object get light weight rods.

What ever you do, make sure all the components you choose are well suited to work in harmony. IOW your cam should match your intended use and work with your displacement, CR, carbs and exhaust.

Good luck.

BTW, starting a thread automatically subscribes you.

[tirwin]

Can you please clarify something? You said that the car came with the 3.2 motor and then you go on to say the 3.0 that was originally in the car came with it. Are you talking about rebuilding the 3.0? That's what it sounds like but I just wanted to clarify.

I would like to hear what others say but if I were in your shoes with a working 3.2 and a questionable 3.0 in hand and I wanted some extra oompfh, I would modify the 3.2 and go with ITBs + EFI and change the cams and exhaust. It would be the best of both worlds of character and drivability in my book. Clean engine bay. Sounds great. Looks old school. Fire it up and it goes. No fiddling with jets or chokes or seasonal change issues to deal with.

You could do a 3.2/3.3SS with the 3.0 but then you're talking about new P&C's, head work, twin plug, different cams, etc. Costs are going to go up fast. Are you doing the work or paying someone to do it? ITBs vs carb cost is probably going to be roughly a wash. Again, I'd go the ITB route but that's just me.

I think the cheapest path to more oompfh would be to use the 3.2 and do a Steve Wong chip and different exhaust for pretty darn cheap (in comparison to a rebuild). Maybe that doesn't have the character you're going for though.

If you did do something with the 3.0, I'd go far something that is sort of an 3.0RS-ish motor.

At the end of the day, I suspect that $/hp gain you're better off starting with the 3.2. To keep costs in line, maybe you could sell one motor or the other to defray costs.

Check out Fred Cook's 3.3SS build. That's a good read. (Edit: I'll look for it. I think it's actually in the Engine Building forum.)

[Bill Verburg]

W/ a n/a engine the best paths to power are displacement and revs, both will require additional peripheral changes to the engine

+50 is a lot for a 3L that's ~255, a stock 964 3.6 is rated for 250

adding displacement means increasing the bore and or stroke, given the stud spacing on a 3.0 bores or 98mm or 100mm are possible, but not bigger

stroker cranks to 76.4mm can be used, 100mm bore x 76.4mm crank is 3600cc, this may sound good but a stock 964/993 is that 11.3 cr and has 250hp and great reliability

revs will require conrods and crank + cams, more power this way means a narrower less street friendly rev range, also has revss go up MTBR goes down the relationship is exponential

Hp is expensive, how much do you really want?

[ScottArizona]

Thanks All.

Trackrash, for some reasons my settings default to "no subscription." Haven't been able to change the default for some reason!

Tirwin, sorry for the confusion. Yes, car came with a 3.2 installed (along with headers, wong chip, intake, bursch exhaust...so most "normal" bolt on 3.2 mods are done). The matching 930/10 3.0 with the broken head stud came as part of the deal (on a furniture dolly lol!). My thought is to put the matching engine back in, and hot-rod it just a bit. If the euro high compression p/c's check out, I'm wondering if I should just do carbs, cams, and overall refresh, and call it a day. My goal is to use the 3.2 in a long-hood project some day (and will probably do a slick ITB updgrade at that time). Lots to think about! I really need to get some seat time in various configurations...still only have been a passenger in two air-cooled cars ever!

[mikedsilva]

I kinda think you are going to be disappointed with your 3.0 after running a good 3.2.
The numbers will be matching, but will that be enough to make you still feel good driving it?

[ScottArizona]

Originally Posted by mikedsilva

I kinda think you are going to be disappointed with your 3.0 after running a good 3.2.
The numbers will be matching, but will that be enough to make you still feel good driving it?

That is exactly the reason for this thread. Want to see how to get a bit more oomph out of the 3.0 if I'm going to go through the expense of fixing it. And, I want to use one of my motors for a hot rod/track car build using a long-hood roller at some point, and it just seem wrong to use the 3.0 for that purpose since it matches my current car.

Thinking maybe just carbs, cams, and general re-fresh might get me to a point where I don't feel much of a drop off from my current set up.

[msmall215]

As others have said, I think you'll get more straight up umphh from a 3.2. Horsepower gets expensive with these motors and you may soon find the cost for chasing HP in a 3.0 will begin to approach that of a 3.6 swap...then the slope gets really slippery. I have a Euro SC with its original 930/10 that I just converted to ITBs with Rasant/AEM, SSIs, and an M&K 2/2 GT3 muffler. I left the internals completely stock as I didn't want to go down the road of P&Cs and cams since 964 is as hot as it gets with CIS pistons and I wanted more of an emphasis on low and mid range power It's at the tuner as we speak and I'll let you know the results this way you have some kind of baseline to go from. My hopes are somewhere around 200 at the wheels, so 240 at the crank.

[Bill Douglas]

The 3.0 being the superior engine...

[Bob Kontak]

Originally Posted by Bill Douglas

The 3.0 being the superior engine...

Name more than five reasons. I dare you.

Honestly, keep the 3.0 in the corner.

[Bill Douglas]

I'm a Kiwi, we can only count to four.

[3rd_gear_Ted]

Sell the 3.0 and find a used 3.6, you'll be close to the same $$ at end of build and have 100 HP more

[Rich76_911s]

Honestly I don’t think you’d be disappointed going from a 3.2 to a euro compression 3.0 with carbs and cams to match. The throttle response will make up for the lost horsepower. (Assuming this is a street engine). I had a 3.0l single plug car and I really enjoyed that setup.

If I lived in Arizona I’d definitely go efi thoigh only because of the huge altitude variation you can get on a road trip out there. You can go from Scottsdale to flagstaff in 2.5 hours and once you get to flag at 7000ft you’ll be pig rich. Adjusting carbs and doing it well on a 6 cylinder isn’t easy. Choose Efi and you can do twin plugs with coil on plugs. If you do go that way have your head machined to accept 993 knock sensor bars.

Without a doubt open the case up. Make sure you get good crank and rod bearings. There has been some talk about Glyco bearings not being good quality. At least there was in the past. TurboKraft helped me locate good bearings for my engine build. We used porsche Motorsport bearings.

[tirwin]

Originally Posted by ScottArizona

Tirwin, sorry for the confusion. Yes, car came with a 3.2 installed (along with headers, wong chip, intake, bursch exhaust...so most "normal" bolt on 3.2 mods are done). The matching 930/10 3.0 with the broken head stud came as part of the deal (on a furniture dolly lol!). My thought is to put the matching engine back in, and hot-rod it just a bit. If the euro high compression p/c's check out, I'm wondering if I should just do carbs, cams, and overall refresh, and call it a day. My goal is to use the 3.2 in a long-hood project some day (and will probably do a slick ITB updgrade at that time). Lots to think about! I really need to get some seat time in various configurations...still only have been a passenger in two air-cooled cars ever!

No problem, just wanted to make sure I understood you correctly.

The question to me is when you say “hot rod it just a bit” will you be happy with the $ spent versus the result? I tend to think not. Let’s say you split the case and do minimal rebuild work. Change head studs and a few little things and put it back together. None of that stuff is going to impact torque or hp much. As Bill V said, it’s displacement and revs.

Back a few months ago I was laid up in bed for a few days after having foot surgery. Long story short, I did a lot of reading and spent a lot of time in Excel. What I started working on was a theoretical engine model calculator and cost estimator.

It was a very interesting exercise for me and I learned a lot. I didn't discover anything new, but I did understand a great deal more about engine theory and I have a better understanding of why many of the engine builders here say what they say.

Let's take a situation with 100mm bore and 70.4mm stroke. That works out to be a 3.3L. The estimated range of max torque is between 204 & 242 ft-lbs. The financial cost between what has to be done to get from the bottom of the range to the top of the range is huge. Just look at the cost of increasing displacement from 3.0 to 3.3L. That alone is substantial. But the devil is going to be in the details to get to anywhere close to max torque. There is a financial cost to eeking out the maximum efficiency of an engine. That means all factors have to be optimal - piston shape, compression, fuel burn, mixture, timing, cam profile, head flow. That is where it gets expensive. My guess is you probably can't get there with carbs because you're only going to be optimal in a narrow band of overall driving conditions (compared to something like EFI).

This is something I've thought about many, many times. I think, as others have said, that you would quickly get to the point where the cost of modifying a 3.0 hits a point of diminishing return.

3.6 motors are becoming rarer and recent prices are reflecting that. But for the amount of money to achieve what you want with a 3.0, I think it would ultimately be cheaper (and easier) to buy a used 3.6. But one thing is for sure... it will never be cheaper than it is today.

Hope this helps.

[porschetub]

Originally Posted by Bill Douglas

I'm a Kiwi, we can only count to four.

Oh dear ,I have a 914/6 so I can count to 6 or more,go to Wellington a fair amount,great place.
Both my kids live there around evans bay.

[tdw28210]

I would let the 3.0 continue to sit and maximize HP with the 3.2 (twin plug, Rasant, etc.) ESPECIALLY if the car itself is at or near stock condition. A stock, numbers matching '81 Euro will only be worth more going forward. If you feel the need to use those tools you purchased, use them to rebuild the 3.0 stock specs.

[GaryR]

The fact that you have the 3.0 longblock and no matching CIS system I think your idea to hotrod it a bit has merit. Fresh rebuild, new PMO carbs, twin plug, more aggressive cam, proper headers, light FW and up the CR slightly is a quick and easy way to get a nice responsive motor without getting crazy. You won't get 50HP but I think you will see/feel a good difference between that and a stock 3.2. Of course you could always drop the CR, up the displacement, cram a turbo on there and easily get your 50 too!

[BURN-BROS]

3.0 liter base
98mm bore
mod S cams
Twinplug
10.5/1 comp
SSI exhaust
PMO 46
M&K R muffler

This combo should get you around 280hp, strong midrange and a redline of 7500 rpm

This

[ADDvanced]

So.... whatcha doing with the 3.2?