I had mine at 7000...

 

The 928 is know for higher rpm oiling issues with the crank at sustained running above 6000 rpm, especially the year models with a rev max of 5600. A cross drilled crank fixes their problem for the most part.

Besides the oil ban baffle, there is an issue with the way the oil galley that feeds the crank is fed on our cars. I don't remember all the specifics, but Lindsey Racing is working on an affordable solution.

 

Just recently, I have had my 951 over 160mph (GPS verified), with room to go. That was about 6000 RPMS and I really don't think it would take much longer to hit the rev limiter (6850 I believe), but there is just no need for it. Plus, after finding a broken inner valve spring on an 80k mile ALL STOCK engine I am kind of nervous about high revs.

Disclaimer: This was done in a controlled enviroment. (Not on a public road.) Please obey all local, state, and federal laws.

 

I was at a bit over 160mph when my headgasket went Didn't pull too much at those speeds with the tired old engine, k26/6 and dropping boost... hopefully next year she'll do better

 

Anyone done "highspeed" or "on the car" alignments/balance ?

As my car from the beginning has never really felt smooth or stable in the higher speeds; 100+

If I keep accel it feels smoother then when just cruising at high speeds. ????

 

I have checked my speedo numerous times with those "police flashing speed" displays. Seems about 5% off, minumum.

So, 175 indicated = about 166 actual.

Does bigger wheels make speedo show faster or slower then actual??

 

i had mine calibrated by a professional speedometer shop while fighting a ticket (i lost) once. on stock wheels at an indicated 100mph the actual speed was 95mph. they didn't go pass 100mph with the tests.

 

"wheels at an indicated 100mph the actual speed was 95mph"

5%

 

Easy way to do this, is to go out to the highway and drive for 10 miles per the milemarkers on the side of the road. Compare that to the accumulated distance on your odo, and then divide to get the factor. Porsches are notoriously optimistic, ie: they tend to read "high".

 

yeah, that doesn't hold up in court though... the speedo shop had some kind of dyno looking rig, but i'm not sure how they actually did because i had to leave the car with them.

 

My speedo read fast too, 100mph on the speedo showed 94.5 on GPS. When I swtiched to a larger diameter tire, it made my speedo very accurate. 150mph showed 150.3 on GPS .

 

using stock turbo S 245/45 R16 tires 6400 RPM in 5th = 168 mph.

 

According to the gear diagram in the 944 turbo booklet (1986) 6'500 revs = 278 km/h in 5th gear with standard wheels and tires. Porsche made a footmark: facts depend on tiretoleranz, wheel and tire dimensions. Wear and traction are not considered.

 

278km = 173 ????

 

170mph with 17" wheels was pretty spot on.
Don't try this at home kids !

It was a nice trip but I don't want to live there

'86 951