RPM

[Kenyon]

I wondered the sort of RPM other 356'ers run their cars at on a long motorway / dual carriageway run.

I appreciate how much stress you're prepared to put on the engine depends on loads of factors - including condition of engine, appetite for rebuild spend. As far as I am aware the engine in my B has never been rebuilt. At present it runs nicely, burns a bit of oil but seems smooth. Just did a near 1,000 mile trip and ran really well.

If I'm running for a long time on a motorway I tend to run at 3,100 revs which gives me a 100 kmh, obviously opening it up a bit for overtaking. Getting above that seems to make the engine sound a lot more stressed.

Anyone take their cars to higher RPM for extended periods of time?

Phil

[Lightweight_911]

When I had my 356C, if I was forced to using motorways I tended to run at 70-75mph which equated to ~3500rpm & it seemed perfectly happy.

When I took the car to Spa one year - in the company of several other DDK'ers in their 911's - I had to resort to driving at ~ 100mph on occasions in order to keep them in sight whilst travelling on the autoroutes.

I kept a close eye on oil temp & pressure but it seemed to cope with these speeds without any obvious problems.

[oldtimer]

Hi Phil , yesterday I drove my '55 Continental down to London W14 from Warrington Cheshire , 200 mile trip , mainly motorway M6 , M6 toll , M42 , M40 , to swap it over with a 356 I keep in London.

On the same day I drove my '64 C back up from London to Cheshire , doing same 200 mile route in reverse , so can give a fresh answer to your question !

The '55 car has a 912 engine fitted with full flow oil filter in addition to the usual bypass filter . Mileage over 90k , RHD so speedo in mph . I ran at 3500 revs on the 70 mph sections , occasional outside lane at 4500 for overtaking . Sounds a lot noisier at the extra 1000rpm , but oil temp stayed at 1/3 or less on the gauge. I think the engine would take 4500 for longer but as you are well over the speed limit if in top gear and the pre A gets a bit wild like a race car I don't do it.

The '64 car has standard engine rebuilt some 25k miles ago , also has a full flow oil filter fitted . Gearing similar , so motorway speed means 3500 revs . I find it easier to ease up to 4000 and keep up with traffic , enough torque to avoid changing down to accelerate . My independent specialist runs a 356SC and cruises at 4000rpm and uses more if required !

[Kenyon]

Thanks both. That's really helpful.

Andy, a similar scenario got me thinking. My mates tend to drive faster than me and I'm often playing catch up, usually at the Tolls on the autoroutes.

OT, that's a good amount of 356'ing for one day!

[40 scout]

4000 - with the alu cooler - 80-85 mph - all day no probs

Not quiet but temp ok - south of France - 10 hours

Steve

[Winston Teague]

Same, 4000 rpm, standard oil system. BUT i only do this beacuse it feels happy at this speed. For this kind of driving a Rolling Road session first is a must, if its running a bit lean, motorway driving can quickly kill an engine. I tend to like to work the throttle/revs a bit every few minuites, ease up, boot it a bit to overtake etc. If it feels 'stressed' don't go higher. Incorrect mixture settings and timing can make an engine feel rough or worse. W

[oldtimer]

OT, that's a good amount of 356'ing for one day!

Well , only a practice for taking the '55 to Gmund later this week for the 356 pre A International , over 3000 km round trip.
Was interested in Winston's comment about motorway driving killing the engine , I have to use motorways to get to where I'm going the same day !

[hot66]

think winston implied killing motors if not set up properly. I know 20 years ago I managed to kill the 1600 twin carb vw engine in my splitty on a motorway climb due to bad set up

[40 scout]

Fine on m ways - I went to Clm with 3 964 Rs’s so had to push on a bit !!

Just keep the oil topped up if it leaks a bit, like mine )

Oil not air cooled remember


Steve

[neilbardsley]

Same, 4000 rpm, standard oil system. BUT i only do this beacuse it feels happy at this speed. For this kind of driving a Rolling Road session first is a must, if its running a bit lean, motorway driving can quickly kill an engine. I tend to like to work the throttle/revs a bit every few minuites, ease up, boot it a bit to overtake etc. If it feels 'stressed' don't go higher. Incorrect mixture settings and timing can make an engine feel rough or worse. W

Why do you thinks this helps? I find that slowing and accelerating builds heat in the engine? I find that on my 356 the temp gauge raises quite quickly if I cruise at 4k in the summer but passes the test that Winston suggests. That is the engine is still willing to push on dispite what the temp gauge says. However, on my 912 I did long periods of 4k plus on the French motorways in hot conditions this summer with the temp gauge being much lower. I've just decided that the 6v gauges on my 356 are guessing

I would suggest that most wear is when the engine is cold, after start up, and that not many of these engines actually die from too much heat?

PS if you are worried about heat don't do what I did 6 years ago on the way to CLM. That is don't pull over and stop the engine! Much better to slow down for a bit or stop and let it idle but keep the oil moving.

[mycar]

Driving down to Silverstone Classic I moved into the outside lane to join a jolly Porsche procession speeding along without a care in the world.

A few fast miles later my co-driver commented that something smelled hot and didn't sound right.

We pulled over onto the hard shoulder.



Later.... much later the report came back.

'On close inspection it looks like the engine failure was caused by a big end bearing failure on cylinder number two. This has consequently over heated and damaged the con rod and the crankshaft journal. Two main bearing journals have also suffered severe wear and the bearing material has been pumped around the engine. When the rod bearing failed the piston came into contact with the cylinder head leaving small ‘witness’ marks on both the piston and the cylinder head.'

Fortunately the case remained intact but there was a shopping list.

'Main bearings
Rod bearings
Small end bushes
Piston and cylinder set
Cam shaft
Camshaft gear
Crankshaft gear
Gasket sets - top and bottom end
Fan shroud gasket
Con rod nut
Inlet valves
Exhaust valves
Valve springs
Flywheel nut
Spark plugs
Misc nuts bolts and washers
Cleaners, sealers and other consumables Engine oil

The standard crankshaft is not reusable as it has become too hot due to the friction caused buy the main bearing failure and lack of lubrication'

Used parts required :-

'Matched set of con rods or two replacements if we have suitable matches in our stock Good used cylinder head if the damaged head cannot be repaired'

And then...

'Re-size and line bore crankcase Repair flywheel bearing journal Flycut and spot face cylinder heads Replace valve guides
Recut valve seats - 3-angle
Repair damage in combustion chamber and match to other cylinder head or a good used replacement cylinder head from our stock.
Refurbish con rods - resize, fit new small ends and match weights.'

All in all the cost was... half a salary.

So enjoy your car but when in the outside lane, proceed with caution.

Especially if the engine is an unknown quantity.

[Kenyon]

Hmmm... that's a sad tale. Sorry to hear that. So proceed with caution then, keep the oil topped up and fresh and KBO.

Phil

[Gary71]

Sorry to hear that Mike. Gutted

[jeremyg]

OUCH Mike OOUUCCHH!!

My sympathies are with you and your wallet.

There but for the grace.....

[simon james]

Hmmm. Half a salary you say?
Not exactly a kings ransom in my case, but after reading this I’m going to mothball the 356 and concentrate on a lovely unrestored (but roadworthy) 100 plus year old car and it’s unnecessarily large low revving behemoth of an engine, whose designer insisted on four bolts for each big end!!!!