marcin944

i have a 83 944, and the exhaust system definitly needs to be changed. my friend told me to put in a straight pipe. however ive read that im goign to looes low end torque if i do that. i definitly need to change it so what is the best way i could increase my cars performace without buying a full system form comopanies like borla. i was thinking of taking the cat out, and istall a straight and then put a muffler at the end. what would be my best way to get performace and sound.

Renntag

On my 944 n/a I ran 2 1/2" mandrel bent pipe from the 'Y' back. I eliminated the cat as well. There are alot of mufflers to choose from. Thats my reccomendation.

Where are you in NJ?

Skip

I'm in the process of sourcing a custom exhaust, but still have not made a final decision. This is what's on my mind [ha,ha... very little, I know ]:

1. the na requires backpressure to develop good low-end torque (proven to me by viewing dyno sheets with no muffler or cat)
2. the na requires less backpressure than stock to produce more top-end HP (~5500RPM, ~10-15HP)
3. An aftermarket 4-1 header will significantly reduce back pressure and flow heat better than a 4-2-1.
4. An aftermarket 4-2-1 header will flow better than stock but retain some of the needed gas volume restriction, and retain a bit more heat (can be good if used properly).
5. Having the headers coated (Swain or the like) can significantly increase heat transfer, and protect the mild steel from rusting too quickly.
6. Most street cars must at least have the option of temporarily installing the dreaded emission device (CAT).

With all this and a bit more in mind, I'm looking for a 4-2-1 header, swain coated, test pipe with free-flow bullet muffler (with very slight baffling, possibly homebrew) installed in the same area as the OE Cat (provides a small amount of backpressure, and reduces the tinny sound reported by most test-pipe users), cat-back custom mandrel bent to hug the contours, but also be as straight as possible, then a secondary muffler.

So far, it looks like the Bursch fits my needs most closely, and is affordable (219 header, 199 test-pipe [+$165 for Swain coating). The primary muffler is a Dynamax (~50), the secondary a Flowmaster ($80). The custom pipe is ~$100 at the local "friendly" muffler shop.

As I said, I haven't decided for sure yet. FYI, Bursch, MSDS, Stahl, GHL, Huntley and others offer headers and test pipes. I know for sure the MSDS and Stahl are 4-1. The Stahl has good reviews (but only from two folks I've talked too who have them) but is ~$380. Some of the others require welding to install... which means I can't just pop my current Cat pipe on there... though it wouldn't be much trouble to modify mine to fit in there. It just gets to the point of diminishing returns if you try to hard too make something work.

Good Luck!

Skip

Renntag

Skip, that is very close to the same exhaust I have in mine. Very cool, indeed.

ThE sPaCeCoWbOy

i have msds headers, striaght pipe to a turbo muffler.....dont do it....its way too loud....and will give you a rice tone....

what i am going to do is take it from 2.5 to 3 install a cat and try to get a quite muffler....

no i have no idea what muffler to get....anyone have any ideas?

thanks,
space

marcin944

m in the union county area. ok so i should use a catalyc? i was thinking that just running a pipe with a muffler on the end would be the best bet. and yes i would also like to know if anybody has any ideas on the mufflers.

Roy LaZelle

Skip: Don't rule out the welded parts, since you could replace the welded joints with, 3 bolt flanges (welded on). It seems to me that you could tack one flange, fit the pipe and tack the other. If you want to do it yourself, I have a wire feed setup that works on that sort of thing. --Roy--

bs

skip:

i'm a bit confused about the relative merits of the "heat transfer" you mention. I'm not sure what you were considering beneficial.

here's the understanding that I had: hot combustion chamber==higher effeciency in transfering combustion engergy to physical force (less energy wasted as heat into the block/head). ceramic coatings: reflect radiated heat, but don't effect conduction, and are used for two reasons: in combustion chambers too keep the energy of burning fuel from going into the metal surrounding it so it will instead cause gasses to expand, and in exhaust headers/manifold to channel all that heat into the cat to decrease light-off time.

is my understanding correct? from that pov though, i cannot see why anyone who was thinking of putting in a test pipe would want to pay for ceramic coating on their exhaust manifold.

and just to put my 2 cents in on the cat issue: i am very anti-hippie and have been flamed here in the past for those veiws, but i think it is pretty damn stupid to run a street car with no cat. you are removing an extremely effecient device for reducing pollution for a very small gain... you get more "bragging rights" than actual power (yes, i personally have run a turbod miata engine on an engine dyno with and without the full exhaust plumbing and saw a less than 5 hp difference). that's like saying we should bring back leaded gas. driving to work in a car that you have added a 300% increase in harmful emmissions for a 2% increase in power (mostly at high rpm where you aren't anyway) is just plain dumb. and yes i did just pull that factor of 3 right out of my *** although i think it's the right ballpark.

and as a rejoinder to adrials response to the new guy with the cool tag and 4th grade english who started a topic on this: what "emmissions" test are you talking about that can be passed without a cat? i know that here in north cali where we have the "lax" versions of the so called smog laws, they don't even put the siffer in the tailpipe until they have verified the presence of all stock emmissions control devices, egr system, o2 sensors, evap system, and definately cat.

Skip

[quote]Originally posted by Roy LaZelle:
<strong>Skip: Don't rule out the welded parts, since you could replace the welded joints with, 3 bolt flanges (welded on). It seems to me that you could tack one flange, fit the pipe and tack the other. If you want to do it yourself, I have a wire feed setup that works on that sort of thing. --Roy--</strong><hr></blockquote>


Thanks, Roy... I'd probably end up welding myself to the car. To be honest, I've never touched one... but I'd love to learn on your car

Just ordered my exhaust (Bursch), so now I gotta figure out the muffler setup (with guidance from Huntley).

Skip

Skip

bs: Your explanation seems to be right along the lines of my understanding... so we are agreeing?

From my understanding, three things happens with ceramic coated headers (or heat wrap, to an extent)
1. protect header from the elements (prevents rust, much more so than wraps which can accelerate rust)
2. decreases exhaust heat loss within the tube, allowing scavenging of the gases for increases throughput... flows exhaust better/faster.
3. reduces under hood temps (where the standard of 1% HP increase for every 10 degrees drop in intake temp)

Are we close?

Skip