I lurk here most of the time, but after reading your replies about catectomy and related topics I just had say: Well done. I am in Walnut Creek. I drive a White 89 S4. I bought the car with an RMB and enjoy the exhaust note, but would never remove the cat.

So my question is: Where does that place MY logic center?

 

Hi Wayne:

Nice to hear from a fellow sharkster in the area! It sounds like you have a beautiful one, too!

Don't worry about your logic center! It is where it belongs... :-)

Yes, that is/was an interesting discussion. Initially I just wanted to tease John a little, but it turned really serious. In the end it felt a little like talking to the Taliban about converting to Christianity. And John just did not want to sped $1k on a replacement cat - which he can get for a lot less...

They threw in all kind of distractions, like defective cats, rising fuel regulators (which have same effect on cat equipped cars), socialist governments, and lot's of "I want" type statements.

But as I am writing this, none of them was really able to prove that a 928 burns as clean without a cat, as it does with. Maybe we'll see some smog test results of an S4 without cat soon. I doubt it, though, as these would most certainly help MY case...

Europe was a little late with adapting this technology. I worked in an Autohaus during that time, and was in the middle of all the discussion. American consumers had for years gotten inferior technology, and that's what many people in Europe had heard of.

Once the catalytic converter cars were available and the German government gave buyers breaks in the vehicle registration tax, people kept coming and buying them. They quickly realized that these cars were more reliable, needed less maintenance, and were just as fuel efficient as the older cars, or even better.

Why that? Because they were all fuel injected, had electronic engine and iginition management, etc. Many had larger engines with more torque, allowing for a more relaxed driving style and saving more of the expensive fuel.

I haven't heard anyone in Europe questioning the cat technology in a long time (they do question the high gas prices, though, and I would, too!). Today, a car without cat is virtually "un-sellable" in Germany.

The latest thing over there are turbo diesels with cat, some even equipped with particle filters. These vehicles are a lot of fun to drive, beause of the immense torque. They run circles around most comparable gasoline engine cars. Yet, they use only about half as much fuel. With the new diesel injection technologies you can't even tell it's a diesel - sounds almost exactly like a gasoline engine.

If you ever have a chance to drive a New Beatle or a new Mercedes with diesel engine, go for it and feel free to be amazed!

And if you ever drive on a German Autobahn, don't be surprised, if at 140mph someone passes you with a "diesel" badge on the trunk lid... ;-)

Are you on Bill Ball's mailing list for local shark owners? Hope we can put together an event in early 2002.

Happy Holidays!

 

928 exhaust

My S4 currently has surgically altered converters; I can say that after I altered them (2), the S4 did seam to be a tad more responsive. I can’t say I could feel like I added more seat of the paints HP/TQ, just a quicker throttle response and the tone changed a little Deeper throughout the RPM ranges. When my new exhaust is complete it will be as follows.

DEVEK header into a 3 x 3 Dr. gas x-over(with the O2 sensor threaded bung welded in at a 1-1:30 position) and then into a pair of 3 x 3 High flow converters like the Dynomax™ Super Converters or the MagnaFlow Performance Exhaust High-Flow Catalytic Converters with a 2 ¼ reducer on the outlet side. The type of mufflers has not yet been decided.

I am hopping to get good Dyno numbers and a super great sound from this set-up and still be earth friendly. No I’m not a tree hugging, endangered flower-planting liberal, I just think it’s the right thing to do!

Merry Christmas to all

Max


DEVEK headersDr. Gas XovernullDynomax Super ConvertersMagnaFlow Super Cats

 

Thank you, Max!!!

Merry Christmas to you, too!

 

Nicole,

I must say I do enjoy the eloquence of your answers!

Now for some additional teaser bits:

1. Just installed hollowed out cats on my car ('89 GT). Additional growl factor is NOT the purpose in this case (I am perfectly content with the sport exhaust the GT has). I have been experiencing a bit of pinging (even with octane boost) when rolling on the throttle from ~2500 rpm. Previously had retarded the timing a skosh, but decided that reduced the power production too much (so timing was returned to original specs). One train of thought was that the cats were just restrictive enough to elevate the combustion chamber temp to contribute to this pinging. With the hollowed cats, the pinging is now not as evident. A byproduct of this is that the car now has a throatier, raspier sound; is a bit louder (similar to installing a RMB); and, in my opinion quite reasonable/livable/not too obtrusive. I'm pro-quiet (stealth is cool ).

2. Someone on another thread asked what a car with cats emits. Here are the results for my car:

2500 rpm cycle
--------------
Max Allowed Average Mine
HC(ppm) 140 20 6
CO (%) 1.00 0.10 0.01


Idle cycle
----------
HC(ppm) 120 29 4
CO (%) 1.00 0.10 0.02

3. Plan to do emissions retest after the holidays.

4. Plan to dyno the car again to measure hp/tq. (Butt dyno says it is stronger.)

5. Engine does breathe easier and respond faster.

We'll see what the numbers say.

Happy Holidays and a Prosperous 2002 to all

 

Nicole, you are, indeed, eloquent. Your commentary is refreshing.

My plans are to build a 6 or 6.5 liter stroker motor. I have purchased a "new" S4 crate motor and will be selling my existing engine. I just haven't decided on timing for that. I am not on Bill's mailing list but would like to be: sirwayne_66@hotmail.com

 

Build a 6.5 - guarantee you'll absolutely love it!

 

Wayne,

Hello, I am also in Walnut Creek and hopefully will be buying a 928 (either late "S" or early "S4) sometime after tax time next year. I was wondering if you had someone do a pre-purchase inspection on your car and if so would you recommend someone in the area ? I have received some tips from Nicole about a month or so back, but would welcome any more that you may have.

I kind of had a bad experience with the dealer near the BART tracks over here. They have an S4 on the lot but one of the salesmen told me that he didn't have time for me when I asked what year it was and if he could give me other information about the car.

Thanks and have a Merry Christmas to you and other Rennlist members !

 

928Modeler,

Does the S4 at the place near the Bart tracks (is it at Cole European) interest you? If you want an opinion, perhaps I can swing by there next week and have a look.

 

Yes, the 6.5 is a very nice motor indeed.

Rick isn't that what Marc built for you?

The Pinging is what drove me to alter my cats as well. It turned out to be bad knock sensors in my case (PITB). With all that was done to your motor, I would not suspect this to be the case.

I to am the stealthy type Thats why I haven't decided on my new mufflers yet.

Moving more exhaust/heat would be a logical next step. How warm is it running when you notice the most pinging? Do you think there is room to maybe run the water/anti-freez a bit cooler?

Have you guys thought about changing the heat range of your plugs?

I did noticed a slight differance in the amount of ping when I swaped out the stock coils for a pair of my very hot, very strong Jacobs Ultra coils.

O-Well

I'm sure you guy on the west-coast will get it all figured out soon.


HHD's

Max
Jacobs Ultra Coil

 

Rick,

Thanks for the offer. Let me wait a little while though. At this point, I really am just interested in seeing different machines before I narrow it down. I missed the Devek get together. I want to see what kind of cars are out there and what kind of condition they are in. Like I said before, I am interested in either a late "S" or early "S4".

I still have some questions though. How is the headroom like in the car ? Did any 928's ever (aside from the Club Sport, I think) not have the sunroof ? One last item, and this may seem weird. I like the front and rear of the "S4" models, but I would like to know if the rear spoiler could be taken off and made to look like it was never there. I think it detracts from the looks of the rear of the car. Thanks again.

 

928Modeler,

Tall genes didn't make it into my DNA, so headroom isn't an issue for me. Friend of mine is 6'3". We drove my previous 928 (an early '87S4/auto) non-stop from Portland and he said it was quite comfortable.

Recently saw an blue S4 that, as you're considering, did have the rear spoiler removed and the mounting holes filled in to look like it was never there. Although I like the look with the spoiler better, this was a very nicely done job.

Good luck in your search.....

 

Hi Max,

Typical operating temp is from one needle width to the right of the zero of "170" to one needle width to the left of the 2/3 line (hope that makes sense).

Definitely better with the hollowed cats, there's only a very slight and infrequent amount of pinging now - nothing to be concerned about and the knock sensors take care of it just fine. The brain can't keep up - this engine revs very quickly.

New knock sensors already installed.

Coolant ratio is already optimal.

Good suggestion to try cooler plugs (thanks).

Why do you suppose the Jacobs coils helped?

Thanks.....

 

Max, you're planning a similar set-up to what I installed on my GT. I'm currently running MSDS headers(plan on switching to the DEVEK level 2's this spring) into a Dr. Gas 3" X style crossover, then reduced to 2.5" pipe back to a pair of Spintech mufflers (installed where the intermediate mufflers normally reside)then more 2.5" pipe back to an RMB. Sound is probably more than what you're looking for, but I wanted low restiction and more power. Loudness was not a concern to me, as long as it was quality sound, and not just noise. And no, I did not install any cats, but I had already put a cat bypass in on my old system, so it really wasn't an issue. Got rid of my air pump and plumbing too. (sorry Nicole--not intended as a jab, it's just the facts of what I've personally done) She runs great and has more top end power, although I feel like the mid-range has suffered a little. I need to get back to a dyno to see where I am now. Baseline was 299.3 HP and 297 ft. lbs. of torque at the wheels. I'm estimating around 315 hp and 305 torque now. We'll see what the dyno says. Good luck with your new system.

 

Rick,

"Why do you suppose the Jacobs coils helped?"

Well there are a couple of reasons "I think".

1. The ultra coil (most High-Output aftermarket (AM) coils as well) are designed to operate 8 cylinders. The 928 uses one for each set of four cylinders (you already knew this). This allows most coils (AM) to run cooler, longer and voltage recovery time is cut in half at the least.

2. The hotter spark at most if not all the 928's RPM ranges will burn more fuel and produce a hair more punch.

Side note: more burnt fuel mean less? Yep you guessed it! Smog

Chris Lockhart,

What is your reasoning for switching from the MSD to DEVEK L-2 headers?

What did the Dr.Gas x-over do to the exhaust tone/pitch, higher, lower or the same?

Which Spin techs muffs do you have?

I have been looking close at the Sportsman Street XL and the Truck RV muffs. The truck RV muffs are the Quiet ones, so they say?


My intent is the same a yours high-flow, but with fewer db's and the Earth Freindly Cats (EFC's).

I have been researching muffs for quit some time (about a year now). I think I may end up adding some small dia./short race muffs (baby glass packs w/ 3"in/outs) just behind the Cats (EFC's) to cut the db's and still allow the pipes to flow(?).

The trick is to get just the right amount a flow and back presure and not have to use up all 45 watts of the car stereo at 70 MPH.

Merry Chistmas to all

Max

89s4 stock exhaust manifolds, altered cat, factory muff's and an RMB. :-) Whoya