3.4 or 3.6 upgrade punchlist needed

[krd]

My 1988 911 has 172,000 mi. I am rebuilding (top and bottom end) this winter and was wondering what is required for a 3.4 or 3.6 upgrade. I'm looking for a punchlist or maybe some good resources.

[Quicksilver]

The 3.4l cans just go in. 3.5l cans require machining the case bore but that is fairly inexpensive. There are larger but you are running out of cooling room between the cylinders. I talked to one of the engineers at Ruf about it and they felt that it wasn't possible to solve the cooling issues with reliability in mind for bores larger then 100mm with the 3.2 bore spacing.

The best cooling you are going to get is the LN cylinders and their price is in line with the others that are available and they have great metallurgy and more fins per inch. For me the question is which pistons to use. Mahle is hands down the best for quiet running and long life but you would have to get them separately and match them with the LNs. The JE pistons will make more noise on startup but once they are warmed up they are great. So can you keep your foot out of it until the temp rises?

Any one I have talked to with a clue agrees you need dual plugs which isn't that expensive... until you get to the ignition. You can go with a few different replacement electronic ignition systems($$$) or a dual plug distributor with a signal splitter. The 964 distributor is the cheap choice, but you want to make sure the distributor has the ventilating hose upgrade. (apparently it keeps ionization from chewing up the cogged belt).

Upgraded power means upgraded cooling. I have never heard a definitive source say if the 3.2 has the cooling reserve for this kind of power increase.

In the rotating assembly there are only a couple things: Oil and rods/rodbolts.
The oiling is ok on the 3.2 but it is a bit on the edge. The 964/993 oilpump is a great upgrade for any 3.2 rebuild that is going to be used hard.

The rodbolts in the 3.2 are "stretch to torque" disposable items that can't take an overrev. ARP or Raceware bolts are a minimum. You can move the redline up a bit with those. If you are looking to really raise the redline you will need a better rod like Pauter or Carrillo.

If you are moving the power band up you will want a little more cam. Lots of choices but the 964 cam is a good non radical choice that will probably pass emissions. You will want an upgraded valve spring. Nothing too special, just a bit more seat pressure.

If you are going to this length you will want a much better exhaust. The exhaust is the one real bottleneck in the 3.2. The SSI is way to small for a larger motor (but it is still better then stock). B&B is a better size for the stock 3.2 and larger but there are a bunch of stupid engineering choices in it. (I have the B&B on my car and the only reason I like it was I got it CHEAP and I modified some things) 993 heat exchangers with the flanges flipped would be a good economical choice.

My list would be:
- Normal rebuild kit
- LN 3.5 cylinders
- JE pistons
- Pauter rods
- ARP head studs
- 993 oilpump
- 964 distributor
- Andial ignition splitter
- 964 cams
- Jerry Woods valve springs
- Steve Wong chip to pull it together
- Dow Corning 730 sealant to put it together.

[krd]

Wow, thanks Wayne, very informative. I may be sending you a PM once I get started for some more insight. thanks again.

[911st]

You can have the 3.2 crank offset ground with smaller rod journals and build up to a 3.75 but have to replace the rods to do this.

Or, could use a 3.6 crank.

[DW SD]

You could also use a crankfire ignition and individual coil packs for twin plug spark.

I'd plan to add either a front cooler or second carrera cooler in the driver's front fender for additional cooling.

Another option would be to swap in a used 3.6 (964 or 993) and not do the rebuild. Make sure you can have a knowledgeable tech evaluate the engine before purchase. Conversion parts will add up, too.

I'd guess you are looking at +$15k going down either path. Very ballpark.

Doug

[JeremyD]

Lots of ways to skin the cat. I wanted to keep the motronic

mine has:
3.4 mahle 9.8 to one jugs
~ 1MM taken out of pistons for valve pockets
Single plug
Magnecor Wires
extrude hone intake
993ss cams (Dougherty Racing Cams)
arp rod bolts
Supertech Head Studs
enlarged throttle body
competition springs and retainers (EBS)
993 Flipped Flange Heat Exchangers
MK 993 Bischof flange muffler
Steve Wong custom chip to pull it all together

Check out the flat torque curve of the 993 SS cams (what matters)


For comparison, here's my 3.4, in blue, compared to Ralph's 3.5, in red, compared to a bone stock 88 3.2 with a euro premuffler and stock chip, in green.

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[KTL]

I agree the distributorless ignition is a smart choice if going twin plug. This eliminates the hassle of dealing with the twin distributor and the signal splitter. The Electromotive HPV-1 seems like a solid choice.

If going 3.4, I think you'd be nuts not to get a more agressive cam to take advantage of the increased displacement. The stock cams are sort of mild and you can make a lot more power with a suitable cam, as evidenced by Jeremy's 993SS cams.

If you plan to track the car, added oil cooling is definitely wise. I personally do not think there's any reserve in a 3.2. It needs more cooling IMO. I track my 3.2 all the time and on a hot humid day, i'll get very near the dreaded 250F mark on the temp gauge. I was hitting the same temps with a failed thermostat, that made my front fender cooler inoperative.



JD,

What kind of temps do you see with your 3.4 at the track?

I've watched alot of these displacement upgrades and seen some 3.6 conversions come together. I personally participated in the 3.6 conversion into an '88 Carrera and put the 3.2 from the Carrera into a '78 SC (this is where the 3.6 came from- already operating in the car). I like the 3.4 because it works with all of your existing components. The 3.4 is still "native" to your car and therefore you avoid the need for the 3.6 engine mounting console, rewiring, conversion flywheel, custom exhaust, etc. which is needed for a 3.6 swap. Plus with the 3.4 you end up with a fresh engine. Swapping in a 3.6 avoids the rebuild cost, but you of course lose the benefit of a rebuilt engine. If you can score a freshly rebuilt 3.6, well then that's huge. But you still have to deal with the conversion intricacies.

[Buckterrier]

+1 on the cooling. Had to add a front mounted cooler. So far temps at 185F and are maintained.

[JeremyD]

Even on the hottest day at sebring - last one



I see about 220 maybe 240 at the very very top - I have added the cooler scoop and opened my fog lights.

Most of the time I am in the 220-230 range.

I've seen a few guys get low mileage 3.6 engines and still need a rebuild. I like the fact that I have a clean slate.

[Quicksilver]

Originally Posted by JeremyD

Lots of ways to skin the cat. I wanted to keep the motronic

mine has:
3.4 mahle 9.8 to one jugs
~ 1MM taken out of pistons for valve pockets
Single plug
Magnecor Wires
extrude hone intake
993ss cams (Dougherty Racing Cams)
arp rod bolts
Supertech Head Studs
enlarged throttle body
competition springs and retainers (EBS)
993 Flipped Flange Heat Exchangers
MK 993 Bischof flange muffler
Steve Wong custom chip to pull it all together

. . .

You didn't happen to run it through an emissions test did you?
Very interested in if this could give numbers to pass a CA smog test.

[JeremyD]

I very much doubt you could get past CA emissions with the 993SS cams. I'd ask Steve Wong - but pretty sure you'd need the 20/21 cam like Ralph has (Ed Hughes might be using that one too)

[911st]

Some great iron here.

Wish the 3.2 had been optimized with a SW chip. Dynos differ but mine pulls 215+ rwhp.

I suspect that if it was chipped, the difference between the two big motors and the 3.2 would not be as dramatic and more correlate to a difference attributed to the displacement differences.

The upper end of a 3.2 with stock cams and ports seems to be about 270fwhp. That is what 3.2s with carbs or ITB's and optimized exhaust seem to achieve. I bet if we could get rid of the AFM and work the intake a bit we could get close.

Exhaust and cam timing can make a solid effect on where the TQ starts to fall off on a 3.2. It is surprising how well the stock cam can work on a 3.2 if allowed to.

Bigger motors do need bigger cams but the stock cam in a 3.2 is not a bad cam.

All good stuff.

Originally Posted by JeremyD

For comparison, here's my 3.4, in blue, compared to Ralph's 3.5, in red, compared to a bone stock 88 3.2 with a euro premuffler and stock chip, in green.

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