bronto

Might be getting to be time to replace the resonator on my '79, seeing some rust there. I am looking in the 928 Intl. catalog and there are different part numbers for different early year resonators. Which will work on my model? '79 only?

GlenL

Don't know...but the PET is helpful. The pics are reasonably accurate.

Does your car have the battery box attached to the transmission? That'd change things. Otherwise look at the parts used in each year. Maybe the exhaust pipes are the same as a later year.

bronto

well I know that mine has a single exhaust and that the 928 was upgraded to dual at some point, but I'm not sure when. And I think the "pumpkin" was an original body thing, wasn't it? 928Intl. cart shows photos of more recent ones that have a more conventional muffler shape.

Don't know if my battery box is attached the to the trans. I don't have PET yet. Guess I should go get it.

BTW, 928Intl shows an item for a "center muffler" (no photo). Mine doesn't have that, in fact I had to add a cat back in to pass smog a couple of years ago, before that it was just a straight pipe to the pumpkin. If there is supposed to be a center muffler, I am surprised I didn't have to add that back in too(?).

James Bailey

You need to look under Y0UR car to see what is there ! It originaly had a cat and a resonator and the big rear muffler but what is there now ?????

bronto

Now there's a single pipe going to the after market cat, from there a single pipe goes to the pumpkin.

Landseer

It would be good to have a series of pictures showing stock exhaust throughout the series of model years.

84 had a single outlet cat, single in/out resonator, and a Y-split just prior to pumpkin. such that two pipes go into the pumpkin. It is heavy construction. Cat is connected to the rear pipes via 4 bolt flange.


85 and 86 had a dual outlet cat, dual-in /dual-out single resonator and dual pipes that lead into a dual inlet pumpkin. Heavy construction, with slip joints and clamps behind the cat. Bigger diam than above.

84 accepts 85/6 systems, direct fit.
The airpump feed pipe fits exactly in size and orientation.
The exhaust flanges match-up.
The pumpkin hanging tabs match the hanging points on the body.
* But the hole in the heat shield above the cat is in the wrong place (gotta switch shields, else use shears or a hole saw to remove the extra material). 84 o2 sensor is skewed toward passenger side, 85/6 is centered going up into heat shield.
* If you use the 85/6 exhaust headers also, though, you need to make a spacer near the pass header.

The reason I mention all this is maybe you can use 84 or 85/6 systems directly on your 4.5 liter car.

It works to go from early 32V back to 4.7.

Does 4.5 match 4.7? If so, like me, you can upgrade to bigger pipes using late stock parts. You just might want to replace the cat too, not limit it to the resonator.

This week's mission for me is taking my 84 USA 5 speed to the muffler welder guy. His mission is to build a Y. The car has 85 cat (dual pipe outlet), but my only candidate good cat back exhaust is the original 84 with a single flanged pipe. I need him to figure out a way using stainless 304 pipe to connect the systems. He will probably cut the flange off the 84 parts, along with 6 inches of pipe.

Despite being old, its heavy construction and seems to accept welding. The guy is welding mine while on the car so it fits. Computer plug disconnected for safety.

I'll ask him to let me take photos while its on the lift.

Again, not trying to hijack just trying to find some options for you.

Another is buying a magnaflow same side in / out offset short muffler in the approximate matching diameter and have it welded in as a resonator.
I've used a pair of these on a custom dual system on another 84 and they are great.

Darklands

@Landseer

What´s with your custom exhaust system on your 84 euro ?Is this a price sensitive way for a performance exhaust for OB cars?

Another solution is the cat back from 928 international.

Landseer

That's another story. It came on the car when Jim (Jadz928) bought it.
MSDS headers. (carbon steel / getting a little thin). Do the 4.5 and 4.7 have the same bolt pattern and pipe alignment configurations on the engine? I'm sure the archives answer that.
Early aftermarket exhaust dubbed "Afterburner 32" by DR, not sure if he built it or just gave it the name .
Later, Jim added a pair of bullet intermediates. They need to be replaced with sport cats.
I'm sure its as free flow as it can be, but it wasn't cheap.

Lots of options here for the 4.5, with a little bit of wire-welding.


Still we need somebody to pipe-up, so to speak, about compatibility with 4.7.

Sorry to take it off track.