Exhaust Options 1987 911 3.2

[TDW911]

1 hour ago, Peter M said:

I would expect the aftermarket headers to offer less attenuation based on the assumption that flow and noise are related proportionally.  However I have absolutely no idea and would be surprised if the increase in noise is any more than negligible

But as I'm realising with increasing frustration, no one seems know with any certainty (ie opinion based on real data) what are the best mufflers for these cars.  Surely we should know as a community which exhausts provide power gains and what the relativity is between them in terms of noise. There are pages and pages of posts regarding this subject on Pelican Forum and still no one really knows!   It appears most people are happy to spend their money based on trust and folk law.

If I ever buy another 3.2, it will be just like my first, standard headers and most likely a Monty 1 into 1.  "Just right!" to quote a bear.  

I’ve had a Monty on three 911s. Two with 1 in 1 out and the other with SSI 2 in one out. I agree, the Monty to my ear is perfect.

[Mike D'Silva]

1 hour ago, Peter M said:

 

But as I'm realising with increasing frustration, no one seems know with any certainty (ie opinion based on real data) what are the best mufflers for these cars.  Surely we should know as a community which exhausts provide power gains and what the relativity is between them in terms of noise. There are pages and pages of posts regarding this subject on Pelican Forum and still no one really knows!   It appears most people are happy to spend their money based on trust and folk law.

 

I went through this a few years ago. What I learned 1st hand, is that for a fairly stock motor, any off the shelf muffler will "work"... How do I define 'work' in this context? Easy: it will look better, and sound louder/sportier, maybe save some weight, and there is a chance it will elicit a few (handful) more hp.  Remember, we are only talking MUFFLER here (not headers/heat exchangers)

The M&K I purchased direct was quite stifling on my 3.0 (higher comp, bigger cams, itbs, efi etc) and droned like a wounded pig.

Bottom line was with baffled tips to try to kill the drone.

Middle line is with normal tips.

Top line is with open pipes. Bit of a difference huh.... All runs done on same dyno during the same session.

(As an aside, turns out I didnt have full throttle opening. I later altered the linkage to get 100%, and also switched muffler to a 997 GT3, using the smaller ports. It then produced 182 kw at the wheels but I dont have the chart). 

When I emailed Brian at M&K, he replied that his mufflers are not designed for modified engines.... that was the first time I had ever heard that... 

Also, messages from Steve Weiner suggested that I was not going to find what I wanted from either Monty or M&K and to have something made. When I messaged Monty and asked if he had any dyno charts for any of his mufflers he told me he didn't have, didn't need, his mufflers were in high demand, and he was thinking about closing anyway.. um... OK

So that's when I found out about using the GT3. It worked for me, on my particualr engine. Will it work for you? I dunno. But if you have a stock or fairly stock motor, and you just want a sporty exhaust note, buy a Monty or a Dansk and it will certainly sound like it picked up some HP.

 

 

 

[Coastr]

that midrange torque dropoff would be noticeable in the car - comparing green to pink line. 

 I have a monty 1 in 1 out and it gives plenty of butt dyno pickup but in reality the stock CIS motor is all out of ideas from about 5500rpm onward - just not enough airflow through intake and exhaust for the muffler to be the choke point.   I have trouble imagining a muffler can pick up any HP without headers and intake on stock car.  The 3.2 intake is undoubtedly way better than the CIS systems but the headers are still the same.  I've heard plenty of claims of 25 hp from SSI+muffler - sounds plausible I guess if you remove the cat as well.
Per mikes tale it's always a good idea to see if you're getting 100% throttle - linkages get old, cables stretch, things happen.

[Peter M]

2 hours ago, Coastr said:

The 3.2 intake is undoubtedly way better than the CIS systems but the headers are still the same.  I've heard plenty of claims of 25 hp from SSI+muffler - sounds plausible I guess if you remove the cat as well.

Actually Bruce the 3.2 headers have larger tubes than the early ones - 1 5/8' vs 1 1/2'.  SSI's were also only available in 1 1/2" tube size until recently which made them of limited value to the larger engines.  However SSI have recently added 1 5/8' headers to their inventory as the result of years of requests and Eisenmann starting offer a SSI copy in the two sizes.

I agree, we hear plenty of claims but don't see much data to support the claims. Even if we got in the habit of dynoing our engines before we do any modifications so at least we can see the effect of the change relative to standard. That would at least give us half of hope to identify value for money modifications.

[Peter M]

2 hours ago, Mike D'Silva said:

So that's when I found out about using the GT3. It worked for me, on my particular engine. Will it work for you? I dunno. But if you have a stock or fairly stock motor, and you just want a sporty exhaust note, buy a Monty or a Dansk and it will certainly sound like it picked up some HP.

Mike,

So the GT3 is your "go to" solution for performance street cars?  But isn't it way too loud?

I was hoping your thread in Pelican would uncover some gems but I'm probably more confused than ever!

Which Muffler? Dynomax, Magnaflow, M&K - Dyno Charts - Pelican Parts Forums

It would be interesting to hear what the big name engine builders and tuners Steve, Steve, Henry, Mike and William are actually putting on their customer cars.

Like many things I should quit complaining and actually starting doing some experimenting myself.  Maybe we could loan or borrow exhaust parts with other PFA'ers so we can get some real data ourselves and start to build a power/noise ranking.

 

[Mike D'Silva]

I figured you can only learn so much by reading what other people do.. and it turns out that what sounds crap to one person might sound fantastic to another. 

The GT3 muff works well. But if you can find one, they are not cheap. Plus you need to have some sort of tubing made up to fit a set of headers. 

Another way to go is to have something like this made. You still need headers, and then have them merge in the middle. This setup works well too. Pipe diameter appears to be very critical as it affects gas speed, and torque down low. Too large, and you will have a SLUG. Too small, and it will take off like a turbo but run out of lung capacity around 5k. Something in the middle is needed, and depends on engine specs.  There is no such thing as one size fits all. 

[Coastr]

6 hours ago, Peter M said:

Actually Bruce the 3.2 headers have larger tubes than the early ones - 1 5/8' vs 1 1/2'.  SSI's were also only available in 1 1/2" tube size until recently which made them of limited value to the larger engines.  However SSI have recently added 1 5/8' headers to their inventory as the result of years of requests and Eisenmann starting offer a SSI copy in the two sizes.

I guessed someone would call me out on port sizes!  The point is the 3.2 exhaust is the same basic shape even if it is a bit bigger.  It’s a compromised design to funnel exhaust into a single cat and 1-in, 1-out muffler.   The gains are found going to a header style and 2-in mufflers.  The point stands that SSI being undersized for 3.2 would limit performance. 
 

some idle days I dream about starting a performance exhaust company even though I have zero industry experience.  But designing and testing exhausts to increase performance and noise sounds like fun.  Ferraris with new exhausts sound amazing, as does just about any performance engine. 

[OZ930]

Phil Irving wrote a book called “Tuning for Speed”.  He goes through exhaust design and tuning among other things.  

[sydr]

This is a slippery slope. For my 1984  3.2 Carrera I had purpose made performance oriented headers and two zorst outlets.  No heat exchangers.  No heater!!  Exhaust noise was wonderful.

BUT - It droned so much at around 3,000 rpm (cruising speed) that it did my head in.  Awful.  And in winter, I froze (which might have something to do with the fact that I always drive my 911 with windows and sunroof open.) 

It took a lot of experimenting (read time + dollars) before I ended up with heat exchangers that don't do terribly much, a single zorst outlet, a resonance tube and markedly less drone - quite acceptable, thank you - and a bit less performance.  Still sounds great, lovely crackle on overrun too.  At least it no longer does my head in and the car still goes like a scalded cat. It should do, with a GT3 crank and rods, 3.8L , twin spark, hi comp pistons, direct to head throttle bodies, GT3 inlet plenum, Motec and, and, and.  But I still hanker for twin zorst outlets, heat exchangers that are more effective and of course, no drone.

Any suggestions will be gratefully received.

[Peter M]

11 hours ago, OZ930 said:

Phil Irving wrote a book called “Tuning for Speed”.  He goes through exhaust design and tuning among other things.  

Unfortunately Phil's calculations for megaphones probably aren't relevant (or legal!) to our street cars! 😁

I think we are pretty confident about the header design, it's the muffler design that we all seem to struggle with as there is a lack of reliable data on the pro's and con's of each option.  Of course the scavenging effects all but go out the window with adding mufflers. 

Steve Wong did produce a table of comparisons of the various bolt on modifications maybe 2 decades ago but later retracted it as being inaccurate.  I suspect he realised that it wasn't a apples with apples comparison due to different dynos and different ignition and fuel mapping.  

That's the frustrating part about all this is that you would think there would be a few well proven and importantly quantified exhaust options that we would simply select from knowing that option D typically allows for 10rwhp more than option C but is typically 4dB louder for example.  It is not as though there is much variation in engines and their likely increments of modifications. eg 3.2's seem to be typically completely standard or only lightly modified with the usual Wong chip and aftermarket muffler or 3.4's with standard intake manifold. 

 

[sus911]

7 minutes ago, sydr said:

This is a slippery slope. For my 1984  3.2 Carrera I had purpose made performance oriented headers and two zorst outlets.  No heat exchangers.  No heater!!  Exhaust noise was wonderful.

BUT - It droned so much at around 3,000 rpm (cruising speed) that it did my head in.  Awful.  And in winter, I froze (which might have something to do with the fact that I always drive my 911 with windows and sunroof open.) 

It took a lot of experimenting (read time + dollars) before I ended up with heat exchangers that don't do terribly much, a single zorst outlet, a resonance tube and markedly less drone - quite acceptable, thank you - and a bit less performance.  Still sounds great, lovely crackle on overrun too.  At least it no longer does my head in and the car still goes like a scalded cat. It should do, with a GT3 crank and rods, 3.8L , twin spark, hi comp pistons, direct to head throttle bodies, GT3 inlet plenum, Motec and, and, and.  But I still hanker for twin zorst outlets, heat exchangers that are more effective and of course, no drone.

Any suggestions will be gratefully received.

Go back to stock 3.2 and sleep at night....

By the way Syd I love your car, nearly as much as mine!

Edited 31May, 2022 by sus911
forgetfulness

[Peter M]

22 minutes ago, sydr said:

This is a slippery slope. For my 1984  3.2 Carrera I had purpose made performance oriented headers and two zorst outlets.  No heat exchangers.  No heater!!  Exhaust noise was wonderful.

BUT - It droned so much at around 3,000 rpm (cruising speed) that it did my head in.  Awful.  And in winter, I froze (which might have something to do with the fact that I always drive my 911 with windows and sunroof open.) 

It took a lot of experimenting (read time + dollars) before I ended up with heat exchangers that don't do terribly much, a single zorst outlet, a resonance tube and markedly less drone - quite acceptable, thank you - and a bit less performance.  Still sounds great, lovely crackle on overrun too.  At least it no longer does my head in and the car still goes like a scalded cat. It should do, with a GT3 crank and rods, 3.8L , twin spark, hi comp pistons, direct to head throttle bodies, GT3 inlet plenum, Motec and, and, and.  But I still hanker for twin zorst outlets, heat exchangers that are more effective and of course, no drone.

Any suggestions will be gratefully received.

I remember that exhaust!

911 Exhaust system, complete with extractors/headers plus mufflers - For Sale, Barter, Trade, or Swap - PFA (porscheforum.com.au)

 

[sus911]

Pete I think I may have filed away somewhere dyno charts for my car completely stock (with poorly adjusted throttle linkage) then with a Steve Wong 911 chip installed.
I also have a much more recent chart done when I fitted the 993 HE's & M&K 2/1 muffler. Let me know if this helps your curiosity & I'll try to dig them out.

[Peter M]

8 hours ago, sus911 said:

Pete I think I may have filed away somewhere dyno charts for my car completely stock (with poorly adjusted throttle linkage) then with a Steve Wong 911 chip installed.
I also have a much more recent chart done when I fitted the 993 HE's & M&K 2/1 muffler. Let me know if this helps your curiosity & I'll try to dig them out.

Yes please Phil, I like a bit of comparative data!  Not interested in the absolutes as dynos vary but the extent of change is useful.

Do you still have your original 1in 1out muffler? 

[sus911]

53 minutes ago, Peter M said:

Yes please Phil, I like a bit of comparative data!  Not interested in the absolutes as dynos vary but the extent of change is useful.

Do you still have your original 1in 1out muffler? 

I just noticed something looks not quite right between these charts. The max HP rpm??

Yes Pete still have my full old exhaust system.

[rminc]

Big price difference between M&K and Monty for the same 1 in 1 out system. Think it worked out to about $800 cheaper for the M&K shipped from Europe with taxes as opposed to the Monty. Couldn't justify it. Just waiting for M&K to replenish stock. 

Alternatively if anyone has a 1 in 1 out. I'm interested in purchasing. 

[sydr]

On 01/06/2022 at 18:18, sus911 said:

I just noticed something looks not quite right between these charts. The max HP rpm??

Yes Pete still have my full old exhaust system.

What am I missing here?  1984 Carrera should produce around 235 hp unless it was for the USA where it was emasculated somewhat

[Yeatesy]

27 minutes ago, sydr said:

What am I missing here?  1984 Carrera should produce around 235 hp unless it was for the USA where it was emasculated somewhat

You aren’t missing anything, actually that’s a 4hp gain as ROW cars had 231bhp whilst US cars had 207bhp from 84 - 86 and 217bhp from 87 - 89. 

[Mike D'Silva]

33 minutes ago, sydr said:

What am I missing here?  1984 Carrera should produce around 235 hp unless it was for the USA where it was emasculated somewhat

I guess, add 15% for drivetrain loss? = approx 203... ?

[Peter M]

9 hours ago, sydr said:

What am I missing here?  1984 Carrera should produce around 235 hp unless it was for the USA where it was emasculated somewhat

The 231hp is quoted from the flywheel while most dyno charts you see in Australia are rear wheel hp which is much less due to drivetrain and tyre contact losses.

Most Pelican and Rennlist numbers are like Mike says where they measure the rear wheel hp and add a notional 15% to cover the estimated drivetrain losses.  Sometimes some other very questionable "correction factors" are added to raw numbers as well.  On these forums its all about swinging dicks to the point the numbers don't mean anything.

Also be aware that the commonly used US dyno "Dynojet" reads about 18% higher than the most commonly used Australian dyno "Mainline".

My realisations from all this is to take all published dyno numbers with a grain of salt.  Dynos are only really useful as a tuning tool and for gathering comparative data. eg do a dyno run on the base set up first and then do one mechanical or tune change at a time and then run on the same dyno with ideally the same operator. Repeat until the money runs out!

Phil's 170 to 177ish rwhp for his lightly modified 3.2 aligns with the 130.8rwKw (or 175ish hp) I measured on my low compression '88 3.2 (nominal 217hp) with Wong chip, cat delete and M&K 1 in /1 out muffler on a Mainline dyno a few years back.

Don't get me started on how useless "butt dynos" are!

[sydr]

Thanks for explaining that so well 😊

[Mike D'Silva]

I'm waiting for the day, when a hub dyno setup, is affordable for the enthusiast to use in his garage...

[Peter M]

3 hours ago, Mike D'Silva said:

I'm waiting for the day, when a hub dyno setup, is affordable for the enthusiast to use in his garage...

Mike, if your neighbours don't love you enough with your engine test stand, can you image how emotional they will become if you get a hub dyno! 😁

[sus911]

My butt needs a dyno upgrade. I have no complaint about how the car pulls.