vanster

We drove about 5700 miles round trip in blistering heat. Out Hwy 50 and back on 80 speeds up to 125mph in spots and back. Total oil consumption was a quarter of a quart. Fuel mileage was around 19.1 mpg average.
Hard to find gas without ethanol at times. You take what you can get.
Not bad!

GregBBRD

How can this be?
California smog legal, with 400 horsepower and huge amounts of torque (low end, midrange, and at higher rpms), virtually no oil consumption, super smooth running, with great fuel economy.

Worth noting for those who do not know the history of 928's:
Porsche was not able to do this, with entire rooms full of engine engineers, working on two different versions of the 32 valve engine, over the period of 15+ years of development.
Hell, the Porsche factory was thrilled when a '95 GTS engine only used a quart of oil every 600 miles!

The Forgotten On

Porsche was also running out of money

GregBBRD

There's always some excuse, for virtually anything/everything that goes wrong:
Consider that Porsche could have left the oiling and breather system completely unchanged for the GTS models.
Sure, all of the 1987 to 1991 engines had problems with oil control.
But they were much better than any of the GTS models.
And leaving the engine alone (aside from the displacement increase) would have cost NO money. Zero Marks.
No engineering to pay for. No testing to pay for. No new parts which needed to be made to pay for..
However, Porsche engineers changed several aspects of the GTS engines which make those engines use more oil, because they were running out of money?

Sorry, I can't remotely follow that logic....

Think about it:
Porsche had been building 928 engines since 1977.
S4 style engines since 1986.
And I'm absolutely certain that they tested and took apart more of those engines than I've ever seen.
Rooms full of engineers and techs. Dedicated areas to test and run these engines, under all different conditions.
And test cars made and available to virtually anyone who worked at the factory to test drive and report back.
And the best they can do is deliver a GTS engine, some of which used a quart of oil every 300 miles (and some of which had the engines replaced by Porsche.)
And we're to believe that Porsche didn't take the time to disassemble those engines and see what went wrong?

And all it takes a simple mechanic, in California, to solve what they could not....for 15+ years?
More horsepower and torque than Porsche ever imagined....with virtually no oil consumption.

Porsche should be embarrassed!

IcemanG17

Not bad MPG at all considering the "fun" factor and heavy foot!

RennHarry

I know I'm an interloper, as a non-owner, but I agree with you Greg. I know these cars are not Honda Accords, but I find it amusing that "expensive" and "German engineering" sometimes mean "unreliable, expensive, and zero apologies from the manufacturer".
My wife had a 2002 Passat Wagon. What a fun car! Drove like a rocket ship. Nicely appointed. Really terrific interior. Biggest piece of crap and money sinkhole I've ever experienced. It was a sunny day when we got rid of the "German engineering"...
Greg, I know that you sell yourself short in your statement above, but it's quite possible that you care more, and are more interested in these cars than the staffers who worked on their designs over the years. They may have cared more about their pensions than the success of their design.
Cheers

Darklands

1996 was the Boxster on the market and I think from 1990 on everyone who can spell the word Engine was doing water Boxer engineering.

GregBBRD

And look at what a resounding success that engine was.
A true engineering marvel, right there!

Perhaps they had the night janitor making the significant design changes to the GTS engines?

Nah, he would have done better....

if you take a stock GTS piston to any piston manufacturer, on the planet, 30 seconds after they see itt for the first time, you will hear:
"That won't work."

When the oil control rings scrape the oil off of the cylinder walls, there has to be a path for that oil to be taken away. Otherwise, that oil, plus the oil from the next stroke, ad infinitum, just stays there, trapped, until it makes it's way to the combustion chamber or past the piston skirt.

Sorry Porsche, but that.was a really a dumb idea! (Along with putting a "sealed" steel ball bearing inside an engine.)

GT6ixer

Impressive Van. On my way to PVGP I drove 3900 miles and consumed 1 qt of oil. Had the same gas mileage (19.0) but have only 4.7L and 234 HP. Kudos to GB and the folks at PM.

Darklands

It's a shame so much late 928 engine died because of this.
Why went Porsche the way over displacement? With another top end the 5 l engine should do easily 50 hp more.
I think the 2 valve 928 engines are very nice constructions, simple and powerful with a little bit too simple engine Management.

Would be nice to evolve such an engine.

A 928 GT would also a good car for my garage .

I think late summer/ fall I'm ready for an bigger order from you.
​​​I would like to make my S bullet proof before I went to the other two cars.
Business is good at the moment, time for my Hobby.
My sail boat is sitting in the barn, not the right hobby for a busy farmer.
Cars can be driven every day.

The Forgotten On

^^ I plan on installing the LH2.3 that the S4 used (also what is in Van's car) on my 16V engine.

The tuning capabilities for it is solid and it is well documented. Plus it just works, especially for NA street engines like ours.

So the 16V engines can definitely be brought a bit more up to date!

GregBBRD

I've done this a couple of times on "big" 2 valve engines.
The knock sensor upgrade is worth the cost of doing this, alone. Add in the simple tuning (courtesy of John Speake and Jim Corenman) and, on initial inspection, this conversion appears to be a no brainer.
The only downside is that the wiring is a bit complex, adding in the additional injection pieces requires some thought, getting the proper counter ring on the flywheel requires effort, and one needs to add the ignition amplifiers, another coil, and the wiring for these pieces. This all requires a good chunk of.time and skills/machining capability that not everyone has.

GregBBRD

There's no doubt that the two valve engines had way less oil consumption issues than any of the 4 valve engines.
Aside from the cast piston issues (and lack of power) these were fantastic engines!
And building a 400 horsepower version, with diesel type torque, really makes a light early car something incredible!

vanster

Regarding fuel consumption...going over my records for the trip I realized that when I had to use fuel with ethanol ( 10%) my mileage dropped a bit. Not sure if Nate or Jim experienced the same thing. I didn't want to use fuel with ethanol but sometimes when it's all you can get ...
It's ****ty gas and it pollutes more than the dino fuel. BTW I don't drive thinking of what my mileage will be. On my way home I was driving as hard as I could from station to station. This is big freakin' country.

Speedtoys

Yes, ANY ethanol will lower MPG, you need more fuel will less energy capabilities to make the same 100Hp to cruise the highway at the same speed...