Maximum safe constant rpm for track car

[mickster8888]

Just wondering what you guys would think a safe constant rpm would be for a stock 930?

[mickster8888]

Highest safe constant rpm

[voitureltd]

Originally Posted by mickster8888

Highest safe constant rpm

Just passing along info from another's opinion. quote "75% of redline".

[356911930]

Mick,

According to the WorkShop Manual, for my 1976 930:

Max. permissible speed 6700 rpm
Max. constant speed 6000 rpm
Governor cut-off speed 7000 +-200

Rahl

[mickster8888]

Thanks guys. I did a search and couldn’t find any info on the subject anywhere.

[voitureltd]

[QUOTE=356911930;12009130]Mick,

According to the WorkShop Manual, for my 1976 930:

Max. permissible speed 6700 rpm
Max. constant speed 6000 rpm
Governor cut-off speed 7000 +-200


giddy up those horses. I like the info for 90% of redline better than the 75% info for a stock 930.

[RarlyL8]

Decades ago I read a technical article about 930 drive train endurance testing done in the 70's. The stock cars were driven by a team of drivers on a large oval track at 6k RPM for thousands of miles, with the only stops being for fuel and to change the oil.

[Ollies930]

Brian,
do you remember if that was flat out in 4th (which would exceed the top speed given for those cars by 6-8mph) or in 3rd gear. That would be some very different thermal loads for the engine.

[RarlyL8]

4th gear, top end. I had a really hard time believing they actually did this type of testing. The purpose was for endurance racing.

[safe]

A German car that couldn't go flat out in top gear for hours would be an embarrassment and not released for sale.
Saab (not German I know) ran stock 9000s at Talladega at full throttle for 20 days covering 100.000 km, only stopping for fuel and services.

[RarlyL8]

This was the same, they ran the cars wide open for a month, non stop. Over 100,000 miles. Hard to wrap my mind around that!

[mickster8888]

Sounds like 5500rpms for short intervals on track for 20min sessions should be no problem.

[Alan L]

Originally Posted by mickster8888

Sounds like 5500rpms for short intervals on track for 20min sessions should be no problem.

I have driven mine harder than that for 20 yrs, no mechanical issues.
I first had an EGT gauge for safety. It had a red light (as well as the temp gauge) that kept flashing after about 3 laps. I disconnected it. It was around 900 Deg C from memory.
Your oil temp is the critical indicator - along with AFR.
I recently fitted an additional cooler - knocked the temps down about 20 deg C - in to the comfortable Hwy cruising zone. Happy with that. I try to keep the AFRs between 12- 12.5. They have gone as high as 13 - but I am unhappy about that and will rectify. That would only be short term - few seconds between gear shifts. But it doesn't take long for detonation.
Alan

[safe]

Originally Posted by mickster8888

Sounds like 5500rpms for short intervals on track for 20min sessions should be no problem.

Shifting slightly (100 rpm) before the revlimiter every shift for hours is not a problem. It's put there by Porsche to be a safe and useful limit. The engine internals is probably safe for more.

[flat6pilot]

Keep it below 6k and you should be fine.

[timc]

Originally Posted by RarlyL8

This was the same, they ran the cars wide open for a month, non stop. Over 100,000 miles. Hard to wrap my mind around that!

Interesting. Wide Open or 6K? Wouldn’t wide open be just under rev limiter?

[Midlife930]

My 930 is a 100% track driven car and spends most of its time at full throttle in all gears other than first. I shift between 6700 and 7000 with the occasional rev limiter bounce and the engine seems really healthy at about 64 hours now. The engine is running 964 cams and a ball bearing turbo sitting on Brian's headers, makes 460 at the wheels.
All good