Burn Wagner

Hello all,

I'm currently negotiating a very special 964RS.

The car has a special 3.8RSR engine with a 4.0L conversion, mahle pistons, carrillo rods, 6 individual throttles, and a rolling-road verified 385BHP.

The engine upgrades show invoices for 20.000 euros (£13.000)

Other track-biased mods include 3.8 RSR chassis and 3.8 RSR brakes.

Total invoices for upgrades go to 50.000 euros (£35.000), including 20.000 for engine.

The engine rebuild / upgrade was done 20.000Km ago. Use was mixed road and trackdays.

I'm looking for a 964RS for trackdays only but that can drive to and from tracks.

I would do 4 track days per year, around 1.5 hrs of driving each time.
Also, about 3000 miles of road driving per year.

Before going ahead, I need to check on potential servicing costs due to the competition-nature of the engine / mechanicals.

In what way would servicing an RSR race engine differ from a mildly tuned 964RS? Intervals? Costs each time?

At 20.000Km of mixed road / track work, a mildly tuned 3.6 RS would be as-new. But what about a race RSR engine? As-new also, or about due for a rebuild??

With a mildly tuned 3.6 (300BHP) I would anticipate about £3000 - £3500 of servicing costs per year. Would a RSR engine make a huge difference??

Thanks for your advice, as I'm lost on the potential servicing issues.

Cheers,

Burn

Geoffrey

Do you know the exact configuration of the engine. For instance, how did the engine configuraiton become 4.0l? What is the valve size? If the heads are the RSR Sprint heads, they have 54mm intake valves and the heads tend to crack between the intake and exhaust valves around 30 hours. A basica RSR engine in endurance trim is really what I think you are looking for, it will run on 98 octane street fuel and run 80 hours.

At 20k miles, the mildly tuned 3.6 would beginning to show exhaust valve guide wear to the point where the valve will be starting to wear one side of the valve seat.

Burn Wagner

I'm not sure what the detail spec of the internals is.

I do know that this RSR engine has 20.000Km of road use and is sold as being in perfect condition visually and mechanically by a highly reputed Porsche specialist.

Assuming an average of 50Km/h (it's actually hard to average more than that, given varying traffic and circumstances), this equates to 400 hours of road driving... so the engine should be on its last legs??

I guess the question is: if an engine that lasts 100 hours of intensive track use, how many 1000's of Km of road use will it last? ('cos if I need a rebuild every 5000Km, then clearly I should NOT buy this car...)

Cheers,

B.

Geoffrey

Race hours differ greatly from road hours. If you were to say that this was a factory RSR 3.8l endurance engine, I'd say go for it. However, being that it has been turned into a 4l engine, it bears more inspection to understand exactly what was done. For instance, the 102mm 3.8 cylinders are thin to begin with, what did they do to get 4.0l. If they stroked the crank, how did they do it, a custom crank or offset grind the stock crank.

Further, the value of a 964RS will lie with its originality, so you may want to consider a stock one which keep its value better than a modified one.

Burn Wagner

Thanks.

I have new info:

The engine mod is actually brand new (just 3 - 4 hrs on the dyno + 100Km on road), and not 20.000Km old.

The basis for the 4.0L conversion was a 3.8 RSR in Le Mans endurance spec.

The work was done by APP racing in the Netherlands - they prepare racing Porsches for various championships, and so are qualified for this.

The 4.0L involves very special pistons and liners, as well as a reboring of the cylinder feeders in the crank block. I think crank is unchanged.

I have called on a well-known specialist who says that the 4.0L capacity should not be a problem, but that any 3.8 RSR needs opening every 50hrs of intensive track use (would you agree, I would have thought 80hrs). They say road use will not add to engine wear and is negligeable, but that I should certainly avoid cold starting and short 15 minute trips.

The engine has RSR solid rockers, and I am warned that these imply difficult and costly valve clearance adjustment. True?

You have a 3.8 RSR?

Would you mind me calling you for a quick chat about serving requirements?
If so, then please indicate your time zone, as I am in France.

Cheers,

Burn Wagner

Geoffrey

I am curious about the 4.0l engine spec since the 3.8l engine is really 3.746cc. If they went to 104mm which I think is the realistic maximum you can go to, it is only 3894cc. The factory 102mm cylinders are not without their issues of being able to maintain roundness. I have also not heard of many success stories with boring out the cylinders since they are thin to begin with. However, I have no experience with the engine combination you are talking with.

In pro racing conditions, the engine needs to be rebuilt in 50 hour range you are talking about. Club racing and DE driving will help with longevity. Cold starting is never good for an engine, that is where most of the wear occurs since the cylinders are dry. The engine should always be fully warmed up each time it is started.

The RSR solid rockers have lash caps which are used to maintain adjustments. You'll need a source for the lash caps when servicing the engine. You can convert them to standard rockers or the later style adjustable RSR rockers.

I have a customer built 964 3.8l RSR and you can seen the car/engine build in the Dec-March 2006/2007 issues of Total 911 magazine out last week. It is also on Rennlist, you can find it by doing a search on the 964 Forum under "Racecar Project".

My contact information is on my website listed in my signature. I'm in the Eastern Time Zone of the USA.

NineMeister

Burn,
I got your PM but Geoffrey beat me to it regarding specification and longevity. In truth the guys who built the engine should be able to tell you all they know, but that said it is unlikely that they will tell you if the engine has a limited life.

As Geoffrey says, the 104 p&c sets have ovality problems so if they have gone bigger to get the capacity it may be an issue, this is why we make and fit a 80mm stroker crank and limit the bore size to 103mm when we build a 9m 4.0 litre race engine (which is a true 3999.5cc). The design life of the 9m race engine is 50 hours on track.

Burn Wagner

Thanks Colin. Martin Pearce (MCP Motorsport) and Paul McLean (GT Classics) both vouch for your

expertise.

I have done my homework and know a lot more now:

The car in question is visible here, around middle of page.
It's the Rubystone one.
http://www.gtclassics.co.uk/gtclassics2.htm

964RS basic, with:

Engine:
- RSR 3.9L engine (not 4.0L after all)
- 6 throttles
- stock 76.4mm crank
- 104mm forged pistons / cylinders from Perfect Bore in England
- carrillo rods
- Solid RSR rockers
- Le Mans endurance spec
- 11.3:1
- 8200 revs
- 385BHP at 7750rpm
- Engine is brand new (just 100Km to set it up) and garanteed 5000Km.
- Engine by APP Racing in Netherlands (they do Porsche race engines)

Chassis:
- RSR 3.8 dampers
- RSR 3.8 brakes
- Uniball suspension

Bills for 50.000 euros of upgrades
Car in A1 near-concours condition

Car costs 65.000 euros.

I've spoken with the following Porsche race-engine specialists:
- APP racing in Netherlands
- Mougins Autosport in France
- Almeras in France
- Atra in Switzerland
- Pierre Ofsky in Switzerland
- Geoffrey who races and runs a 964 RSR 3.8

Mostly, they agree that the 104 bores may be unstable in pro racing, but would be absolutely fine in club applications.

Common consensus is to open the engine at 50hrs pro racing, or 75hrs club track days if I stick to 7500rpm and never over-rev the engine. I'm also told that doing a few thousand Km of road driving per year will be negligeable in terms of wear, so that I need only count the circuit time. I should limit cold starts, short trips and especially traffic, however.

One big question remains for me:

- I had initially assumed that opening the engine after the prescribed 75hrs entailed a full rebuild including new con-rods (don't they stretch a little with time?), new pistons / cyls, new rockers, etc. for about 15.000 euros total.

- I now suspect that this operation is just a detailed visuel check of the bottom and top ends, replacing crank bearings, piston rings, valve guides, etc. for about 5000 euros total.

So which is it? (again, assuming 75 hrs club use + around 15.000 miles road driving)

And if it's just the 5000 euros rebuild, then when does the big 15.000 euros rebuild come up?

------------------

I'm also considering a 964RS with 9M Motec+1, also at GT Classics.

http://www.gtclassics.co.uk/gtclassics2.htm
It's the Sun Yellow car.

The Motec+1 conversion was done 15.000 miles ago, and the car now has 60.000 miles.

Dyno test gives 330BHP from the 3.6, with lots of torque too. :-)

I'm assuming the bottom end was not touched during the Motec+1 conversion.

As the car now has 60.000 miles, and it's an RS with a full Matter cage (so some serious track driving done), when would you think the bottom end might need doing?

A thousand thanks,

Burn Wagner

Geoffrey

Cars that are tracked with relatively stock engines (964RS, 964RSR endurance, 9M Motec +1) will require periodic inspection. The higher they rev, the shorter the window. The larger the bore, the shorter the window. 4 years seems to be a good number here in the States for the 964Cup cars used in club activities. You will usually find the thrust main bearing worn, rod bearings showing wear, piston skirts showing signs of scuffing, cylinders showing signs of wear and ovaling, cylinder head exhaust valve guides shot, intake valve guides worn and a valve job required. Usual service is bearings, complete head rebuild, maybe with new valves, maybe not. Replace springs, retainers, locks. Sometimes P&Cs, sometimes not. Con rods possibly rebushed, but generally Ok. RSR engines maybe 3 years.

If it were me, I would seriously consider the 9M version since it retains the longevity of the 964 engine and will be a potent package. The 104s in the other one just bother me.