ShawnSmith

Happy me - not only did the stealth-stroker not raise any eyebrows at the local smog-and-lube station, but the sniff test says you could eat of the exhaust (at least once the motor is wamed up...)

I've also had it long enough to get an intial range on the fuel economy. Looks like around 12 mpg romping about in the city, and almost 20 mpg for mild flow-of-traffic highway duty.

I've probably put out more emissions in the form of fried rear tire particles than incompletely burnt petrol:

dr bob

I guess we'll need to add a new category PMt for particulate matter (tires). Keep it under 5 microns and never get near the regulatory radar, right? Overgeneration will hurt the wallet in different ways-- Pay your 'fines' at the tire store!

I'm almost convinced that one could install a twinscrew, and have a nice engine bay cover installed similar to what the AMG kompressor cars have, and cruise past the Cali smog inspection with no worries. Most mod'ed engines have big fancy brag labels on everything, red flags for inspectors. If it looks like a factory install, it will likely never get a second look.

FWIW, the inspector never bothers to look under my car for cats. He peeks at the vacuum hose diagram under the hood then gets glassy-eyed when he tries to locate the hoses. "Anything changed since last time?" is about as serious as it gets. More serious is the issue about them testing the fuel filler cap-- they can't, and the lack of a specific "Check Engine" light on the dash.


Nice job, Shawn and Greg!

GregBBRD

I suspect that it stalled and quit, without the guy knowing it!

So does this qualify as a green car? Car pool lane stickers on a 928?

Would not be possible without the work from John Speake! My hat is off, to you. That Sharktuner tuning tool that you made is just too nice.

Bill Ball

No NOX test?

With those 19lb injectors you are probably lean (look at those low HCs and CO!). That would have blown up the NOX, but they do not appear to test it in your area.

ShawnSmith

At idle and 2400 rpm with no load, I serious doubt the 19 pound injectors are a bottleneck

Calif smog emissions vary regionally - some counties require a test on a rolling dyno that is more strict. Thankfully, I don't live in one of those counties, although I believe the car would easily pass that test too.

nsantolick

Congrats on the passing scores. Well done...

I'm curious though; if you were to "start all over again", knowing what you know now, is there anything that you'd have done differently. If any, what areas of the whole process would you tweak (in the design stage)?










Nick - '89 S4 - Starting to read everything I can about stroker 928's...

"There is no substitute for cubic inches..." - Ferdinand Porsche

IcemanG17

Great results for a clean engine!!!

ShawnSmith

> I'm curious though; if you were to "start all over again", knowing what you know now, is there anything that you'd have done differently. If any, what areas of the whole process would you tweak (in the design stage)?

I'd short the stock market the minute I ordered the forged crank

I'm waaaay over budget, and a bit behind schedule, but I have what I wanted.

I could see possibly shopping for someone who already _had_ a car with many of these kinds of pieces in it, and getting a vastly better bargain starting with that, but darn it I liked the 928 I had.

I'll stand on this hand.

Bill Ball

Right, they certainly are not max'd out duty cycle wise, but the stock fuel maps could set you to the lean side with your larger capacity even with closed loop working its +/-20%. The upped fuel pressure offsets that, but the numbers you got look lean. Did you get new cats? Maybe that's it. A NOX would have been interesting. Heck, I understand you're happy to have passed! My 200K mile cats probably won't make it next time.

GregBBRD

Bill:

This thing has spent over 12 hours on the dyno, at my shop, being run in and tuned (we ran over 20 gallons of fuel through it.) It spent most of that time on the Sharktuner. It is not lean. It doesn't have all the timing that I'll put into it once it is broken in and it will need bigger injectors. I tune with two O2 sensors hooked up at the same time...to check on side to side variances. I've got the idle maps set a bit richer than stock, as a matter of fact. This is strickly a break-in mode. The rev limiter is set low, etc.

Try and keep in mind that it is running through a brand new set of cats...not a 20 year old set, when you look at the numbers.

nsantolick

Awesome! I'm really shocked by the results, and mileage, BTW. Anyway, congrats...






Nick - Hazleton, Pennsylvania

ShawnSmith

And now I'm free of the smog-police for 2 full years, mwahahahahaha!

IcemanG17

Bill
You can borrow sharkys......they "only" have 100k miles and sharky has never failed smog..