Exhaust and Emissions - 86 Carrera

triwave · 03-04-2004, 04:30 PM

I have an '86 Carrera that is mostly stock, but has a few tweaks. I am considering an exhaust upgrade for street performance and sound. Started looking at SSIs and a new muffler.

1) SSI's eliminate the Cat right. Do people only use this setup for track cars? If no, how do you pass smog tests? I had to put the Cat back in for the CA DMV test.

< In NC (future home of this car) the DMV says they do a visual for original equip so if no Cat is in place you can't even proceed do a smog test no matter how clean the car runs>

2) If I just change muffler and leave Cat in place I should stay smog legal, but is there really much power increase?

3) Every muffler makes great claims about the best power/sound. What have people out there used and liked/disliked (why?)

4) Dual vs. Single out? My car is set up for a single, what benefit does a dual give?

I'm looking for any advice on what a guy can do that keeps a car street legal, or at least easy to make street legal when the inspection is due.

Thanks!

Warren

Joe Bob · Joe Bob's Garage

Shops that do smog that don't see Porsches often think that SSIs ARE dual cats....

Dual outlets are louder and give marginally better flow and seat of the pants feeling of more power. On a dyno you will see a little more HP, but not much. Typically more revs and power is seen on the top scale with dual otlets with a loss of low end torque.

Depending....big word. there....you might get away with SSIs on visual but it's not a given.

greglepore · 03-04-2004, 06:25 PM

You can almost certainly get away with a Euro premuffler and sport muffler. No real way to tell it from a cat unless you're a Porsche mech. On a hp/dollar basis this is a more effective solution for a 3.2, IMHO.

triwave · 03-04-2004, 06:50 PM

Greg - you feel something like a Dansk Sport Muffer and Euro Pre-muffler is good band for the buck? I have a cat bypass pipe (straight w/opening for O2 sensor) so I guess I'd have to get a Euro pre-muffler - they are kind of fat and look like a cat right? Is this a specific porsche part# or an aftermarket part? BTW, I assume the euro pre-muffler still allows you to run the O2 sensor in roughly the same spot?

Thanks,

warren

Lorenfb · 03-05-2004, 08:15 AM

When you remove the CAT, you "roll the dice" when you go for an
emissions test, especially if you have a chip and are high on NOx
to begin with. Operating closed-loop with an O2 sensor only
"buys" you so much. You still need a CAT for NOx.

Good Luck
Loren
'88 3.2

greglepore · 03-05-2004, 08:51 AM

Warren, I'm running a Dansk Euro-Premuff and Flowmaster 1/1 on my car.
I don't have direct experience, but there are several threads here discussing the fact that the premuffler gives a few more hp than the bypass. The bigger advantage in your circumstance is that you'll get thru visual-it looks like a cat. I don't have the Dansk part # handy, but Wayne carries them-you may need to call. They're on the Dansk site as well. The factory and basic Dansk part (one and the same) are normal steel, there is a stainless version available for a slight upcharge. The O2 sensor location is in the factory position.

What Loren has to say is correct, although in many states you'll get thru with the stock chip, O2 sensor, and perhaps playing with the fuel quality switch. Not sure how strict NC is with regard to limits for older cars.

For my money, the cost of SSI's v the add'l couple of ponies wasn't worth it. For exhaust mods to be worth much, you need to get add'l air into the engine, and on 3.2's that's not easy. The other advantage to the Euro premuffler is that you can reinstall the cat "easily" whereas with the SSI's you can't.

As to the various muffler options, that's as much a matter of taste as anything else. The 1/1 Flowmaster I have is just on the edge of what I'd accept for a car that gets use under a wide range of conditions. I suspect that I'd find a 1/2 a little too loud. I don't think you're reallly talking a big power difference one way or the other, and as Mike pointed out, you could lose torque, not a tradeoff I want to make for the street. There was a good thread recently about gutting a factory muffler as well, which looks very appealing if you have a welder.

Joe Bob · Joe Bob's Garage

Not only that....oil lines most likely need to be changed out. The commomn feeling on SSIs is that they are REALLY worth it on 3.0s...no so much on 3.2s....

Jeff Alton · 03-05-2004, 09:05 AM

I have a pre-muff in place of the cat on my 84. Passed emissions with flying colours. Engine has 120000 miles on it.

Jeff

JeremyD · JeremyD's Garage

I'll ditto on what Mikez says - most of the research that I did on the 3.2 reflected that SSI's if you have money to burn - and want to move oil lines - premuff, sport muffler and chip will get you the biggest bump for the buck and easy to switch the cat back if you need to pass emissions. Just bolt up with good quality bolts and plenty of antiseize.

Now a few weeks ago a guy from Texas posted that he passed Texas emissions with a SteveW chip and no Cat. YMMV - and CA is not Texas.

Me - I have the dansk premuffler, dansk dual out SS and SteveW chip. The dansk dual has a very nice sound - throaty - deep - no resonance - and I have a cab - so didn't want too much!

Click below and let the page open to hear a sound file of the dual out starting (It's background noise)
Click Here

Lorenfb · 09:34 AM

The key to the ease with which a car passes an emissions test is
dependent on the type of test (as Mikez points out on another
thread).

Some areas just do a static test at idle and 2500 RPMs. With this
test most are "home free" even with a chip. The "real" test of
the emissions system occurs under load on a dyno as used in
the major metro areas. This is where NOx becomes a real
problem because of the increased combustion temps the result
of engine load and becomes even more problematic with a chip
in hot weather.

Everywhere, over time, the "screws" will get tighter, "forcing out"
the older cars.

J Smith · 03-05-2004, 10:54 AM

Jeremy - That is a beautiful car, and a beautiful sound!

Josh

JeremyD · JeremyD's Garage

Thanks!

Bill Verburg · Bill Verburg's Garage

The SSI's on a 3.2 are on the small side, that coupled w/ the minimal overlap provided by the smog cam means that there is little to be gained from the "upgrade". An additional issue, not adressed so far, is heat.

I would use a euro pre-muffler and single out Dansk, Monty et all muffler unless additional engine mods are also done.

Stay far away form B&B.

Stay far away from any non ss muffler they wll rot out in no time at all.

triwave · 03-05-2004, 12:38 PM

Jeremy - I like the picture/sound you posted - and it begs another question from me. How did you convert the section below the rear bumper to have a cut-out on the passenger side for the "extra" pipe? I was considering a dual out but noted the addition of the cutout would be an extra thing I have to do... How much did it cost to do the mod? Standard parts available to do it? Thanks

Joe Bob · Joe Bob's Garage

You cut the valance for the extra pipes....or remove it all together if you have a nice stainless muffler.

Bill Verburg · Bill Verburg's Garage

Quote:

How did you convert the section below the rear bumper to have a cut-out on the passenger side for the "extra" pipe?

This pic shows a stock valance and a modified stock valance just trim to suit

The spat on the passenger side won't exactly match the one on the passenger side but it's not really noticeable.

If you insist on symmetry then Ruf does sell a dual out valance and passenger side spat that matches the drivers side.