944 Exhaust

[Stutzdriver]

OK I'll start out by saying i am cheap.....I want to upgrade the exhaust on my 1984 944 without buying any of the OVERPRICED aftermarket exhausts.

I have access to tube bending equipment, I weld and I want to upgrade for sound and performance. i also think I want to eliminate the cat which is not needed here in Ohio.

Any advice/suggestions?

[HondaDustR]

Depends on what kind of sound you like. I got a really awesome throaty sound by just clamping a 2 1/4" Thrush welded muffler onto the stock pipe in place of the stock muffler retaining the stock cat. It sounds amazing driving by a wall or guardrail and hearing the sound reflect off. I had initially tried the muffler with a gutted cat and then with a long glasspack resonator in place of the gutted cat and it went from kind of loud and ricey to really loud and horribly ricey. These motors make alot of noise and will exibit the classic 4 cyl rasp in a big way with the wrong system. I ended up deciding compromising a little flow performance for a huge jump in sound quality was worth it by just keeping the cat. A Flowmaster 60 may sound better with a test pipe or glasspack resonator, since it's basicly a quieter version of the Flowmaster 40/Thrush welded style of chambered muffler with an additional resonance cancelling chamber. Some people have had good results with a high flow cat mated to a small glasspack resonator to emulate the stock cat/resonator combo unit while gaining a little more flow.

The end result was pretty cheap, effective, and simple. $40 for the muffler at Advance Auto, a few clamps, a 2 1/4" straight section of pipe for the muffler exit, and a ~30 degree 2 1/4" turndown chopped into a 30 degree elbow and crammed onto the stock pipe. The stock metric size pipe is just barely small enough to enable 2 1/4" pipe to press fit around the outside of it, but you said you can weld something up, so that isn't of much importance.

What aftermarket muffler, or type of muffler makes these cars sound good?!?

Thrush exhaust project

[GAGES 944]

I have a thrush turbo exhaust that I'm working on putting on as of now and was going to put a glasspack in place of the cat but now I guess I wont and now I'm going to buy a highflow cat.

[Porsche-O-Phile]

You get what you pay for.

What part of "Porsche" do you think is the part that lends itself to being cheap? I haven't found it in almost 10 years of ownership.

While you can certainly go out and spend $2k on an exhaust, you don't need to. If you have a pipe bender and are a good welder, why not make one? Who knows, you might even end up with a marketable product too...

There aren't too many exhaust options for the n/a cars (nor are they particularly needed). There are many more for the 951 which has different requirements due to higher volumes of gas flow. The "cheapest" are probably the plain vanilla Lindsey Racing setups but those can also run well north of $1500 when you factor in options like coating, mufflers, cats, etc.

[ScoobySteve]

I would really avoid going the "down-and-dirty" route. While you can go really expensive, I'd find the middle ground. There are guys selling pre-bent stainless on Ebay. You can measure, get the parts you need, and have any decent welder mock it up.

I would go with an off-the-shelf muffler and then use bolt-in flanges and make several different resonator options so you can experiment to find the one that doesn't drone too badly. You'll end up with something that looks great, is durable, and sounds to your liking.

A friend of mine fabricates high-end catback systems for a couple of cars. It's not that complicated. Though, he is a bit obsessive and manufacturers his own mufflers (machined endcaps that come off to replace the packing, if needed).

[HondaDustR]

Originally Posted by GAGES 944

I have a thrush turbo exhaust that I'm working on putting on as of now and was going to put a glasspack in place of the cat but now I guess I wont and now I'm going to buy a highflow cat.

Well, I developed a theory on the effectiveness of glasspack resonators. The Thrush part that I tried had a smooth inner tube. I chose it over the Cherry Bomb part because of this because it looked like it would flow smoother. The Cherry Bomb inner tubes have lots of cutouts bent into the path of the exhaust flow that look just like giant cheese grater cutters rather than just smooth drilled holes. That seems to be the only thing these Sweet Thunder mufflers rely on, and the guy that posted them in my other thread said they do a very good job of eliminating rasp.
Corvette Exhaust System, Sidepipes, Mufflers - Sweet-Thunder.com - Chambered General - Main page

So I conclude, and my experience with the Thrush part supports it, that the Thrush does very poorly in reducing raspy high frequency sounds due to the lack of the cutouts in the tube and the Cherry Bomb may be a much better choice. The other downside to the Thrush is that the inner tube diameter for the 2 1/4" sized part is only 2", which besides a flow compromise on an essentially 2 1/4" stock pipe size, may further reduce its resonating capabilities. The Sweet Thunder part may be even better. The only thing is, the stock resonator in the cat has a smooth drilled tube, but it's also got three 2" thick bricks of ceramic catalyst to block out sound as well, and the holes in the catalyst are very small ~1mm.

Sound reduction isn't free from the flow/performance aspect. The Thrush resonator, if purchased in a larger size that would have a larger inner tube, would offer nearly the flow characteristics of a test pipe while eliminating some of the low frequency rumble at low speeds (it did improve that noticably). Then it could be paired with a less agressive muffler like a Flowmaster 60, but given the fact the rasp from the Thrush I ran made it through the stock muffler pretty well, it probably still won't sound that good, assuming you hate raspy 4 cyl sound. Probably either a Sweet Thunder, hushpower, or Cherry Bomb either as a larger model by itself or a shorter model paired with a high flow cat would probably be the best solution. Some mentioned a true dual exit muffler helps alot in smoothing out the sound, as do resonator exhaust tips. I cut my experimental budget short for the time being by just running the stock cat.

Keep in mind, if you want to run different headers like the Bursh (4-2-1) or MSDS (4-1), that will most likely change the game a bit from a sound characteristic standpoint.

[GAGES 944]

Well what I'm doing is putting a thrush muffler on, a high flow flowmaster cat, and a header and taking it to an exhaust shop and have it all done right.

[HondaDustR]

Originally Posted by GAGES 944

Well what I'm doing is putting a thrush muffler on, a high flow flowmaster cat, and a header and taking it to an exhaust shop and have it all done right.

What model and size Thrush muffler and cat and what header, just out of curiosity.

[Catamax944]

This may sound stupid .....i also want to experiment a bit with the exhaust on the cheap side so i was thinking to try on a early 928 right side header(4-1) .Looks a bit restrictive but if it fits i would like to try it anyway just to see how the car reacts. What do you think?

Edit:This is what i'm talking about ,euro 928S header.Who knows maybe it will sound like a v8

[Stutzdriver]

I should clarify the "cheap" comment. I'm not exactly cheap but I do hate buying something I can make myself! I enjoy the challenge and much of what I make is better than what I buy.

[HondaDustR]

It will probably work, but probably won't work very well. The length of the primary and secondary (if it's a 4-2-1 system like the stock 944) runners on a 4 cyl exhaust are balanced and tuned to work with the exhaust timing of an inline four, and the length, primary and secondary diameters, relative lengths of the primary and secondary to each other and to the length of the system from the valve to the first outlet (usually the cat), etc. are taylored to the cylinder size, port length, cam profile, and what rpm you want it optimised for. A 4-1 system for a inline 4 is usually built with primaries as equal length as possible. A V8 has a different exhaust sequence for the banks of 4 cylinders and hence different header requirements.

Yeah I always enjoy experimenting, designing, building, potentially failing, trying again, and learning something in the process. I'll either eventually end up with exactly what I want, or a better idea of what to get from somewhere else.

[GAGES 944]

Im using the thrush turbo muffler, the cat I bought is a high flow bullet flowmaster as they said in the ad, (I can get a pic of it) and the header is off of lindseyracing.com.

[GAGES 944]

http://www.bestmufflers.com/bshop/images/CAT10-76.jpg

[Stutzdriver]

Looking at the Flowmaster catalog, what's the consensus on a 3" pipe from the factory header to the 40 or 50 series Flowmaster, no cat?

I think this can be fabricated pretty easy and I can include the "factory" exhaust hangers. Then finish with a 3" outlet into an oval polished tailpipe. i'll try and post some links/pictures.

Any comment?

[HondaDustR]

I think 3" is way too big for a NA. I wouldn't go more than 2 1/2". Bigger isn't necessarily better for NA motors in general. The exhaust gases will slow down too much. The stock size is just under 2 1/4" and is pretty sufficient for a stock motor.

The muffler I'm running is essentially a Flowmaster 40 knockoff and I love it.

[Stutzdriver]

2-1/2" it is, time to start working on this!

[moorepower]

I put a 951 cat-back on my 924S. It's 2-1/2" and the muffler flows a little better than an NA setup. Just cut off the 3-hole flange from the rear of your cat pipe, and using a 2-1/2" to 2-1/4" reducer, weld on a 4-hole flange from a 951 cat (or a 931 cat, which I had lying around). It's a direct bolt-in from there.

I can't tell any difference in power, but it sounds really good to me. A little more growl than an NA muffler, and no raspy sound like most of the aftermarket mufflers have. It's also a cheap solution. 951 guys will just about give them away when they upgrade.

[HondaDustR]

That's interesting and a good idea. I wonder what the difference is internally between the NA and turbo mufflers. I saw a white turbo earlier today and it had a much stronger exhaust note when he opened it up than a stock NA and the muffler definitely looked stock.

[wild man]

If your REAL cheap, like I was with my 924S, but wish to retain the stainless OEM exhaust system on the car, just gut the cat, cut out the baffle on the inlet side of the muffler, and weld it back together. That will unleash some sounds, and performance, that it didn't have before, but will NOT make it too loud.

P.S. This will make the the muffler straight through, like the 951 mufflers are, only for zero cost, if you can cut and weld.

[chills2]

Guys i don't mean to sound like a tool here but going cheap is not the answer. I am restoring a 1991 S2 therefore i had time to look for the right exhaust I searched off an on for a year until I founf Speedforce Racing in California they offer a SS Magnaflow with 2-1/2'' mandrel bent SS tubing very high quality for $550 cat back. It looks great and sounds great good too don't go with 3'' it is too obnoxious you can hear it on You Tube.