DDK - Die Deutschen Klassiker

Hi all,

I am about to strip my 3.2 engine. The car has done 89k miles. When I bought it it had been sitting around for 5 years. I have rebuilt pretty much everything else and am now going to tackle the engine. On startup I get a lot of smoke and so I think at least the valve guides are very worn. Oil pressure doesnt get much beyond 3 bar which seems a bit low some might do the bottom end as weel whilst I have started!

The real question is whilst it is apart should I look at doing some sensible upgrades. It is a standard car and I want to keep it that way, but having said that I put SSis and heat exchanger backdate and Steve Wong chip. I have heard that 964 cams are a good upgrade but I assume I would need to do something with the ECU to get more from it. Does it have to be 964 cams or are there other makes of cam that are good for this engine.

Any thoughts / advice or experience?

Cheers

Roger

I asked the very same question on Impactbumpers site a few years ago.
To get a decent bhp/torque increase you need to spend hard.

964 cam change seemed to get mixed reviews if used with stock P&B.

In the end the general consensus was:

Capacity increase to 3.4 or 3.5 = £££££££££
High compression pistons with good deep valve pockets to suit..
GE cams, designed for the job
Total rebuild with better rod bolts, possibly better rods for much higher rpm
Twin plug if going for 3.5, but good for a 3.4 too. iirc you can use the 964 dual distributor, but not sure.
Carbs if mpg is not a concern, 46mm Webers or 50mm PMO for the 3.5 capacity.
Jenvy or PMO injection bodies and all the bits required if injection is your bag.
A well known ECU, I was going for Emerald or DTA

I think Nick moss on here built a potent '3.2' for his rally car.

I just found the costs ridiculous and didn't bother as it seemed only 300 bhp max would be the result.
I'm sure there will be a lot more opinions to come!

Thanks for the post, that is very interesting.

I definitely didnt want to change the induction system as I know it gets v expensive and would end up in the hot rod arena rather than standard car!.

Looks like standard will be the way to go but I will teardown and see what I have to replace anyway!. Previous experience of engine rebuilds is that the costs are always much higher than you can possibly estimate but we'll see!

Cheers

Roger

I have indeed built, or had built, several 3.2/3.4/3.5 motors.
I have converted 2 customer 3.2s to 3.4 (barrels and H/C pistons), 964 cams, SSIs with single outlet SS Dansk silencer, lightened flywheel but standard induction. These mods give you a much more responsive engine, a superb sound without the boominess of many aftermarket silencers.
My own 3.2 has a 3.5 Redtek motor, which requires the cases to be machined for larger spigots, RSR cams, headers and ITBs. 320 bhp and a £25K bill.

Hi Roger - excuse me for jumping in, hopefully it'll expand the discussion and yield more info

Nick - i'd be interested in your views on whether the 964 cams (ie with the existing 3.2 and also the option of 3.4 P&C's) work with the existing Motronic ECU, throttle body etc as standard, or does one get the ECU re-chipped? Are the 964 cams a straight swap physically or are there other considerations?

Further a hypothetical question based on a halfway house solution (ie cost effective) - would it be possible to change the cams to say S or RSR and have the ECU re-chipped to match whilst keeping the standard induction system, or are the limitations with the standard system such that one wouldn't get the benefits of such cams (or perhaps would have to go with an after market ECU)?

Many thanks

I am not sure RSR cams will work without extensive work to the rods and pistons.

The rods won't suffer the revs and without different pistons the valves will not have enough clearance.

The reason that most people limit themselves to the 964 cam is that the profile is safe in terms of valve to piston clearance.

It is possible that the 993SS cam may work and is a little more 'aggressive'.

We are just machining the first prototype cylinders with a 98mm bore and have matching 'slipper' style pistons due in 3-4 weeks.

I have 2 engines, both 3.2
First is in a road going 1973 911T, has SSI and Dansk 2 in, 1 out silencer. Rest is stock and 140k miles old, never been apart. Runs really well, strong, steam engine torque and easy to drive.
It will stay this way for as long as possible.
Second is a fresh DIY rebuild from the crank out with PMO carbs, 2.7 RS distributor with coil and points etc. Home made equal length custom exhaust, standard heads, P&B and cams, and a light flywheel from Fenn Lane Motorsport ( Fetuhoe above), aluminium clutch cover.
247 bhp and 210 lb.ft torque. It is a hill climb only engine.
Very quick throttle response and a smooth pulling engine.

The stock 3.2 IMHO is a boring sounding engine, but is a delight to drive on the road.

If this is the purpose of your car, then, again IMHO, build it stock and very fresh everywhere.

Just my 2 pence worth.

As ever Chris I'm staggered by what you're doing but don't understand why your great work is top-secret Of course I was being a dimwit asking about RSR cams as had totally forgotten about the valve/piston interface. I guess my question is, within limits of that (ie 964 or 993SS cams possibly), is it necessary or even possible to re-chip the Motronic - makes sense as the chip is replaceable and all sensors etc in place, connected, calibrated etc.

Generally it does seem that improvements to the 3.2, in addition to what my "hot" one below has had done below, are fairly limited unless budget is BIG...

Graham - strangely my Porsche engine ownership mirrors yours. I have a standard 3.2 in 1987 Carrera which is a great, mellow car. Then I have a hotted-up 3.2 in the RSL replica - engine is chipped, lightweight flywheel and pressure plate, headers and race exhaust so very responsive, yet still with masses of torque (especially felt in 950kgs) which is a delight - the exhaust is neighbour "compliant" up to 2750, then promptly turns hooligan.....lovely

Finally Roger - seems that given what you've already done, short of lighter flywheel and PP, you're on the cusp of having to spend significant money. The way I see it, it's a tricky interlinked dependency - change one thing for the better and you have to change a bunch of other things!!! Good luck!

The money scales can tip very quickly, look at nick's pro engine build cost.
I could not justify that for a hill climb car when I spend about 40 seconds on a run, sometimes 31!

There are times when a total engine swop is better, a high spec 964 engine, but finding one is very difficult and then there is a risk over the condition...

In my hillclimber, I am/had seriously thought about selling the current drive train and fitting a high output Boxster engine instead, but there are quite a few pitfalls.
I have lost interest in doing such surgery as the package works well, is 'charming' and reasonably competitive, and I'm too old now to make good use of another 100 bhp.

Any engine swop is tricky in places, the 3.2 into the early shell is prob the simplest.

The real question to ask is what use you will make of the car and use that rational to decide on the engine spec. imho.
I think deciding on a budget is the hardest part of all.

A wife knowing what you are up to helps sort that out.

Engine all stripped, better than expected. generally engine all ok, valve guides shot esp inlets (which was a surprise to me).

So heads off for work, will get the bottom end balanced with clutch whilst it is apart but from the sage advice I think I will keep standard/as is . I have a number of 'hotter' 911s, 993TT and GT3 clubsport and the 3.2 isnt ever going to keep up!. I think I will keep it easy and stick to standard. Have built hot engines before and I know that one thing leads to another and once you start changing things it always escalates!.

Thanks for all the great information.

Cheers

Roger

Wise move imho.