ptuomov

There chips are wear items, right? I think they have so many miles on them that we better replace them preemptively WYAT.

ptuomov

The Nikasil bores being broken in:


wrong video try this:


Breaking in Nikasil bores is interesting. As some motocross guys say, the Nikasil cylinder break in period is whatever it takes between warming up the engine on the trailer and riding it to the starting line. There’s a lot of truth to that. Nikasil doesn’t wear meaningfully and the new bore might go from RA 3 to RA 2 over the life. When used Nikasil bores are “honed” with aluminum oxide brushes, that mostly just deglazes the bore by removing combustion products that have been attached to the bore walls. The rings rotate in the piston, so those aren’t going to bed into the bore either.

The sum total is that with a Nikasil cylinder engine, you know right away whether you built a good engine or screwed up the bores. On the blow-by meter, the engine should seal well after three WOT sweeps thru the rpm range. If it doesn’t, one of the bore parameters got done wrong.

dr bob

I like tto add a little load so the gas pressure pushes the rings out some for break-in. Then change the oil to get break-in and build particles flushed out. Rings ar as seated as they will ever be. If there's leakage after 100 miles, there will always be leakage, so at that point I might as well start over with another set of rings.

Didn't this engine have dyno time on it? Rings definitely seat from that.

ptuomov

WOT = a lot of load. Good for break in!

The break-in is the three mile drive from John’s house to his shop with dyno.

This is a fresh new engine, with Nikasil bores, slipper (Forged Evotec style) pistons and skinny rings to do 8000 rpm. It hasn’t yet been run on the dyno.

ptuomov

Shakedown about to commence on John’s dyno. Ghetto?

Thom

Please add a few visible wires to please ghetto lovers

Have you already been thinking about how to implement a dry sump set up? It looks like there isn't much room for left for a separate oil tank. Here's hoping you won't need one but I'm not holding my breath on this...

ptuomov

Yes, have to keep it ghetto like the rest of the project.

I'm curious how far this engine can go in terms of rpms with the near-stock wet sump with some fairly subtle modifications. That's why these two engines are/will be wet sump engines.

If one were to turn it into a street dry sump system, the most natural oil reservoir location is where the stock wet sump pan is. All one would need to do is plate off the existing pan wet sump section and use that as the dry sump reservoir. Unless that section is completely sealed off and separately vented, pulling a vacuum to the crankcase with the scavenge pump wouldn't work, though. Other than that it would give you the standard benefits of the dry-sump system.

Fitting the scavenge pumps is a much more challenging problem.

Thom

It may be difficult to monitor how many more revs than stock it will handle without holding it constantly at peak rpm until it blows up, and that assumes that your improved breather can already handle the extra flow due to higher engine speeds.
Wouldn't a scavenge pump fit in place of the air pump, which I assume you got rid of a long time ago? Couldn't it be used not only for the dry sump, but also, if needed, to improve breather efficiency?

ptuomov

dude, that space and then some was taken up by two bigger air pumps.

Thom

Ok, get rid of A/C then. It doesn't look like this car was built for showing off on warm Summer days, was it?

ptuomov

can’t do without A/C in a street car

ptuomov

Has anyone made an adjustable throttle stop for 928 S4 that attaches to the throttle linkage on the driver side of the intake manifold and limits the maximum throttle opening by an adjustable amount?

dr bob

There's an adjustable cable end where the throttle cable connects to the bellcrank. Make the cable longer. Or, since you don't use the kick-down switch area with your manual gearbox conversion, consider a block there with adjustable-length bolt there to limit pedal travel. Trying to actually limit the throttle or even the bellcrank will result in stretched cable(s).

ptuomov

John is replacing some more wear items:




I think the “x2“ on this EZ-K must stand for double the trouble!

Speaking of trouble, I may need a second commuter boat. Two options are these, Buster Phantom Cabin and XO 270 Front Cabin:

ptuomov

Does this cleaned up wiring still retain the “ghetto” character of the project?




By the way, is it the case that there are two Bosch coil options available for 928?

“Bosch has new part numbers. #00060 for the old 0221 118 335; #00055 for the old 0221 118 322. But Robert Bosch's website lists #00055 as the proper coil (two required) for the 1989 S4 and 1990 GT.”

Some assertions, please comment:

The original uses are:
928 S4 86 - 89 M28.41, 42 8 5.0L 0 221 118 322
928 S4 89 - 91 M28.41, 42 8 5.0L 0 221 118 335
928 GT , GTS 89 - 91 M28.47, 49, 50 8 5.0, 5.4L 0 221 118 335

All the 944/951 versions seem to be using 0 221 118 322 / #00055. They have higher intended engine speeds from the factory than 928s.

In 928 32 valve engines, I believe the ignition control modules are the same regardless of the coil used.

Questions:

Is the dwell time controlled by EZ-K? I believe the ignition control module is dumb and doesn’t do that.

What is the difference between the coil options?

Do they require the same dwell time or different dwell times?

Do the EZ-K settings differ between 87-88 and 89-95 to reflect coil differences?

Which coil gives higher spark energy with the best settings?