Converting to dual exhaust

[SRISER]

I really like the looks of dual exhaust but have a couple questions for my esteem fellow Pelicans...

1. Does the rear valence come off and can you buy a replacement valence with dual exhaust cutouts?

2. Performance gains?

3. Covert from single in to dual out? Or keep single in?

4. 3" out or 4" out?

[dd74]

Originally posted by SRISER
I really like the looks of dual exhaust but have a couple questions for my esteem fellow Pelicans...

1. Does the rear valence come off and can you buy a replacement valence with dual exhaust cutouts?

2. Performance gains?

3. Covert from single in to dual out? Or keep single in?

4. 3" out or 4" out?

I've been down this road, so I'll give your question a shot:

The rear valence comes off and you can buy a replacement, but none comes equipped with dual cutouts. If one did, it was an afterthought by the P.O. In short, you have to cut out the right-side hole for the right-side pipe in a dual-out setup. None come set up this way as far as I know.

Performance gains are, like all things Porsche engines, up in the air. I've heard anywhere from 2 horsepower to 15. Sound quality and/or noise is also up for debate. Some say louder, while others don't notice a huge sound difference.

Converting to a dual-out system is where the most horsepower will be recognized. In most cases, the manifolds comprise equal-length headers. You can get this with SSIs, or the exhaust system from a '74 and earlier 911 engine, if you can find one.

3" or 4" outlets is a personal preference. You should test fit and eyeball both to see which one you like. I don't know if there is a perfomance gain or detriment one way or the other with different diameter outlets.

1. It comes off with about 7 screws. Make a template from factory cutout and use power tool.

2. Du know. Mine sounds better, but any minor perf gain is hard to tell from butt dyno.

3. Only you and your Doctor know for sure. Lots of people will tell you what to do. Others will tell you what they've done. You have to decide what's right for your car and your wallet.

4. 3" - marginally ricey. 4"- way over the top stupid ignorant ricey should only be on a honda with a 19 yo driving and several 13 yo's admiring. JMO but I am unaimous in it.

[RickM]

Best inexpensive modification I've done. Makes the car sound much better IMO. Do a search and you will see many threads with instruction on how to modify.

EDIT:
I was assuming you wanted to convert your existing muffler. But upon re reading that doesn't seem to tbe the case. Never mind

[JeremyD]

I just did this on my 1987 Cabriolet.

Valence comes off - screws under the bumper - have to take off the bumper pads too (big rubber pads) - Spray them penantrant first as they can be a b!tch to get off.

I cut my valence with a dremel - I had a scratch put on there by the previous owner - that was part of my justification process to go with a dual out and cut the valence.

Performance gains - I think minimal (I have heard 6-9 hp) I also did the premuffler which replaces the cat converter. No emission testing in florida!

Single in if you want to keep the factory heat exchangers/headers - If you go to headers then you can go to dual in.

What I have now is factory HE- dansk premuffler, and single in, dual out SS Dansk muffler with 84 mm pipes. It sounds very throaty - slight resonance around 1800-2100 rpms - I am very pleased with the sound and performance - waiting now for Steve W chip and I'll be good to go!

[SRISER]

Good info guys. Looks like I have a nice project for the spring! 3" dual out, dual in using SSI sounds like the way to go. Expensive, but the way to go.

[SRISER]

On second thought...perhaps single in...less work and expense.

[Superman]

The stock single-in system includes a catalytic converter. If emissions regulations in your area require it, you may need to keep that. Even so, you can switch for the test, and then switch back. The single-in system sucks in terms of performance. For performance, the most important thing is the equal-length header thing, which you get with SSI, or '74 and earlier stock systems, like Dave said. The equal length system, which is a dual-in system performs much better. Better lower end and better peak horsepower. Better better better.

With the dual-in system, you have some choices. Dansk is popular and is a good performer. I personally have the Triad final exhaust, as does Dave. I want to be respectful here since Wayne does not carry the Triad line of products, and because the Triad guy is a personal friend. But I have to say that the Triad final exhaust system is a dual-in, dual-out that does not require cutting any valence. It was designed to meet certain track competition classes that disallow body modifications. The other two things I will say about this system are that the Triad sounds better than any other performance exhaust, hands down, and it makes noticeably more power than the stock hotdog muffler I have to compare it with. Oh, one more thing. In all fairness, the Triad makes a resonance under 3000 rpm that annoys some people. But again, with the throttle open, through 3500-4000-5000-6000 rpm, this final exhaust system is the best, hands down, in my opinion. I'm not going to put a link here, but Triad has a website (still under construction but you can see a picture and dyno results).

Finally, I agree that 4" is just over the top. 3" is as far as I will go.

[SRISER]

Superman:

Thanks. I can always count on good advice from you.

[Superman]

STR, if you're going to rely on advice from me, you're in deep trouble. Once, in chatting with JW after I had recently posted my opinion that JW could nearly replace a fuel pump while holding his breath (I think fuel pumps are pretty easy to change), I commented on another topic that "i'd have to use my imagination." JW, a man of few words, just said "Well, you've got plenty of that." I let him get away with remarks like that because he's right, he's twice my size and I respect his opinion.

Anyway, all of you should be very careful about using advice you get from me.

[Wil Ferch]

Look at my previous threads on this:
-- single vs dual out...all by itself ...is no more than 0-3 more hp.
-- dual -in equates to use of SSI system, quoted around 13 hp benefit for 3.2's ...closer to 18 hp for 3.0's.
-- if you keep single-in, but use Euro Porsche pre-muffler to replace the cat ( not a simple test pipe), you get very close to SSI type performance, but a bit less mid range torque. High end hp is very close. Easy conversion back to emissions legal status, unlike SSI. For bolting, use 5/16" x 1.5" long stainless bolts ( 18 pitch) with matching silicon/bronze nuts. Very close to original metric size ( 8 x 40 mm carbon steel), and uses the nearly same 1/2" bolt head where the "tools" attach ( 8mm uses similar 12 0r 13 mm head).
-- right side cut out. You can go more elegant by cutting the valence with a right side opening ( on the right cut-out itself) to be "slanted" to mimic the left side "slant". Notice that the right rocker ends "square" and the left rocker ends "slanted".
-- further refinement is if you bend over a formed lip on your cutout, like a fender lip. Can be done with a padded vice grip, go slowly and repeat a number of times...don't do all at once. Looks more finished.

---Wil Ferch

[curlesw]

Mark, what type of exhaust do you have?

Wayne C.
82 SC

[JeremyD]

Dansk Dual out...

Originally posted by curlesw
Mark, what type of exhaust do you have?

Wayne C.
82 SC

Wayne,
Mine is a Flowmaster 1 in 2 out. Matter of fact, it has a history. It was installed on Jack Olsen's BB1 for a few months till he changed to a different setup.

[RoninLB]

on the single or dual out,

I think it's kinda subjective.. maybe if you have a big overlap cam it'll sound different than a low overlap cam in the same design muffler. maybe big dual out for big overlap. and hp being equal for both engines. I think I wrote this correctly...........Ron

[RoninLB]

Originally posted by Jeremy964


Dansk Dual out...

That is a very nice install.. perhaps a little fine tuning, but very nice .........Ron

[Doug Zielke]

Nothing to do with exhausts here, just want to welcome you to this forum, Ed!

[Steve W]

As Wil said, with the Dansk sport mufflers, there really is no difference in hp between dual or single out, just the sound. In fact, the single out may have a slight edge, about 1/10 of a hp. I expect to compile a collection of dyno sheets which Dansk is currently compiling for their performance exhaust systems and when I receive them, I will post them up on my site along with the correct reference part numbers of each of their systems for information is seemingly non existent right now. A collection of sound bites from each of the mufflers may also be uploaded, so I'll keep you guys posted.

[Randy Webb]

The sound change but no hp change is not just for the Dansk -- it's also true of the factory mufflers. I think the entire Dansk line is based on them.

That's actually a pretty decent deal since most aftermarket mufflers actually LOSE power. Someone posted that one - either a Monty or Fabspeed -- did gain hp on a dyno run tho. No details on the engine configuration.

[SRISER]

I think keeping the single in with dual out Dansk is what I am going to do. Great pics in the previous posts. Thanks Pelicans!!