3.2 Engine rebuild: Keep 3.2 or covert to 3.4L?
 

Hi all,

I'm having my engine rebuild on my 1987 911 Targa, as after 106k miles I had excessive oil consumption. It was supposed to be a top-end rebuild, but now that we have dropped the engine, it's evolving into a full rebuild due to leaking main 8# bearing, worn valves, worn cylinder heads, and worn Alusil cylinders + pistons.

I want to keep the car reasonably stock since it's a Targa and a daily driver, but if I anyway will be I'll be in the market for a new cylinder+piston set, I'm currently trying to decide whether I should keep the engine stock 3.2 with a set of Nickies, or I should bite the bullet and go the 3.4L conversion with the Mahle kit?

The car will be fitted with a 997 GT3 muffler + rarelyl8 long tubed heat exchangers, so there should be plenty of air.

My options:

Option 1: Keep motronic + single plug + Steve Wong chip + 964 cams + ARP hardware + AASCO springs + 95mm Nickies with EU/ROW compression

Option 2: Keep motronic + single plug + Steve Wong chip + 964 cams + ARP hardware + AASCO springs + 98mm Mahle kit 3.4L conversion

What would you do and why?

I appreciate your input!

/k

If your cylinders are done, an option is to see if EBS is still working with Millennium and producing replated cylinders. They used to offer bored out and replated with Nikasil, but I think you could also just have them replated at stock size. I'm running a set of 98mm cylinders from them and I'm quite happy with how they turned out. Although last I talked to Millennium a few years ago it sounds like the price has gone up considerably.

I'm running a setup similar to option 2 and am very pleased with it. Similar in that the cylinders were done by EBS and I'm running Carrillo pistons. As per the suggestion, check with EBS about getting your cylinders reworked. And the stock valve springs are good quality plus have reasonable seat pressures, no need to replace them unless the measure out of spec.

I had my Nikasil cylinders bored to 98mm and re-plated via EBS Millennium 5 years ago, and have been very pleased. I used Mahle pistons (Max Moritz wedge dome). I think as long as you are dealing with new pistons, and re-done cylinders, it costs next to nothing to upgrade to more displacement. You will be happy with the move. Talk to EBS about it.

Agree with Lyle. If you're already into P&C, I can't see any reason not to go for the additional displacement. I had my cylinders bored/plated to 98mm and used JE pistons. No complaints.

I also dropped in a 76.4mm cup crank to bump to 3.5... not exactly cheap, but low end torque is great!

Get your Alusil cylinders replated. Go to 98mm bore if you wish
Buy the pistons you want
You only need std valve springs
Fit ARP rod bolts when the conrods are resized
Replace all head studs with new steel
Keep the standard 3.2 headers as they are better than most realise
Fit an M&K muffler of your preference.
Wong chip

Keep it simple and enjoy.

The next step up is a huge step in budget and you have to ask "Is it worth it?" The next step is twin plugs and modern EFI.

3.4
 

Go to 3.4 and use Sal Scarceiiars package which will give you 260 RWH on single plug.His parts work and not expensive.Fred

@auchenberg

Where are you located? If SoCal, you can checkout my '87 3.4 with 964 cams and Sal Carceller MAF. Currently has stock heat exchangers with M&K active pre muffler and 1 in / out muffler. I'm amassing parts for M&K long tube headers and 997 GT3 RS muffler.

Definitely go with the 98mm bore.

following with interest. I'm in the same boat, bought a 3.2 that was torn down for rebuild and never finished. parts are good, and the previous owner purchased 98mm cylinders, so I'm part way to a 3.4 already, just haven't selected pistons because I keep going back and forth on what CR to run, haven't decided if I want to go to the expense of twin plugging the heads.

Auchenberg -

Sounds like you and I are in very similar places. My 86 Targa with 130,000 miles had excessive oil consumption that I'd attributed to worn valve guides, but I was putting off doing anything until I had time and a couple other reasons to go through the trouble. Dropped the engine a few months ago to deal with a badly leaking oil pressure warning light sensor, and bore-scoped the cylinders after a leak-down showed nearly 60% on number 4. Found a patch of scoring from a broken ring. That finally started me down the top-end route, and I decided to go for the Mahle 3.4 conversion, single plug, SW chip, and 20/21 cams aiming for mid-range power. Also deleting the after-market cat someone put on there a while back since I don't have to smog. Still up in the air on the muffler choice at this point. Bit the bullet and split the case to deal with a leaking #8 bearing as long as I had everything apart anyway.

I'm hoping to have it all back together in the next 3-4 weeks, work and other random events permitting.

- Chris

Why go 3.4 when you can go 3.5...? :D

Fantastic, I've decided to go with almost the same build! Mahle 3.4L conversion, single plug, 964 cams, full renovation of the bottom case, ARP bolts, Enlarged Throttle body, and custom chip from Steve Wong to match Rarelyl8 headers with a GT3 muffler.

I'd love hear how things are going! My mechanic ordered the parts this week.

I'd love to experience your engine, but currently on the east coast :/

I'm going for the 997 Muffler + headers too! My post here: http://forums.pelicanparts.com/porsche-911-technical-forum/1076156-project-997-991-gt3-exhaust-911-3-2-a.html

How's the MAS working for you? Did you feel a big difference?

Cool. Love that GT3 muffler thread. It inspired me to pull the trigger.

Sal's MAF kit is pretty sweet, especially as it's all new parts (with refurbished ECU). It's less about outright power gains tho. I went with it because you can run it on a 3.2, but it's also adaptable to larger displacements, 3.4, 3.5, etc.

Reach out to Sal, he's very helpful and super knowledgeable.

The issue w/ larger cylinders is reduced support in the block deck and secondarily stud spacing

3.0 thru 3.3 stock have 86mm stud spacing, 3.6 90mm

all have the same 118mm bore spacing and 59mm stagger

I'm not familiar w/ the cylinder base dimensions of the 3.0 thru 3.3 but on the 3.6s the larger 102mm bore cylinders come w/ 2 different base specs 107mm and 109mm the 107s are light duty street use only due to the lack of support around the base, the 109s are also provided w/ a far more robust base seal scheme

Unfortunately, I'm still waiting on the heads to come back from the machine shop. Should be this week, though, and I'm eager to get it all put back together. I'm wondering a bit about keeping the stock exhaust headers (at least until I get the engine back in and running). I figure I can decide to mess with them after the fact, and I've never been one to change too many things all at once anyway.

- Chris

Because of the added expense to split the case and for the 76.4mm crank. I bet this woulda added another 30% to the cost of my build. I woulda done it had Jae Lee thought it was necessary, but we opted not to split the case.

I'd likely do a 3.6 (or 3.8 build) swap before building a 3.5.

Auchenberg,

Hopefully your work is coming along - mine is finally back together (minus the chip, which I just ordered), and outside of tracking down a bad brand-new CHT sensor (replaced it because the old/original one looked horrible) causing rough cold start issues, it's definitely a noticeable improvement over the stock (and tired) 3.2. Did some break-in work over the weekend, and need to dump the oil again, but so far it's gone fairly smoothly. No dyno yet, but the seat-of-the-pants feel is telling me there is something additional. That being said, I'm sure just stock-new performance on a 3.2 would be an improvement at this point, so we'll see.

- Chris

OK...just noticed Fred's comment "Go to 3.4 and use Sal Scarceiiars package which will give you 260 RWH on single plug.His parts work and not expensive.Fred". This sounds like a no brainer...what percentage of the HP increase due to Sal's parts or the displacement? I rebuilt my 3.2 several years ago but have always wished I'd done some more "while your'e in there" things. Sal's upgrade, AFAIK, wasn't available back then.

Anyone have an opinion on the RPM limit of a 3.2 crank and rods (with ARP bolts of course) swinging 98mm JE or CP pistons? Can it support 7300RPM with a bit of extra cushion? Lets assume the valvetrain is built to withstand it.

Thinking of a 3.4 build on my "Rot Rod" using ITB's and a nice big cam and headers.