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Exhaust systems
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924er  



Joined: 10 Jan 2006
Posts: 339
Location: Los Angeles California

PostPosted: Thu Jan 12, 2006 4:00 pm    Post subject: Exhaust systems Reply with quote

In previous threads, I always hear about people uprgrading their exhaust. I would like to upgrade my exhaust myself. When I first bought my 80' 924 it had no muffler attached and the exhaust just came out the the cat. It was really loud. but when i installed a new stock muffler from a local muffler shop, it came out quiet. but I lost alot of HP. so i was wondering if i can install one of those performce mufflers that are usualy on imports. will it give me better airflow, and have a racing tone? becasue i have never seen this on any porsche or even on this forums.

thanks in advance
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Khal  



Joined: 26 Sep 2003
Posts: 4864
Location: Sunny and lovely interior BC, Canada

PostPosted: Thu Jan 12, 2006 5:26 pm    Post subject: Re: Exhaust systems Reply with quote

924er wrote:
...my 80' 924 it had no muffler attached and the exhaust just came out the the cat. It was really loud. but when i installed a new stock muffler from a local muffler shop, it came out quiet. but I lost alot of HP.


You sure it didn't just sound faster...

Sure, you can have a performance exhaust put on. I don't know which supplier would be best to go to in the 'States but I'm sure they're out there.

Obviously, you need one to suit the 924 because it'll have different twists'n turns in it i.e. you couldn't just buy one for, say, a Nissan 350Z and bolt that on!

Even if you can't find an off-the-shelf unit, I'm sure any reputable exhaust shop will be able to make one for you, to your specifications. It'll cost ya, though...
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gohim  



Joined: 02 Nov 2002
Posts: 4459
Location: Rialto, CA

PostPosted: Thu Jan 12, 2006 8:01 pm    Post subject: Reply with quote

So you want to "Rice" out your car?

Most of the "performance exhaust systems" that you see on CA Rice cars are what we refer to as "coffee can" mufflers. IMHO they look ridiculous, and if you walk on on most of those cars you would see that they are big tubes welded onto the stock 1.5" diameter exhaust pipes at the rear of the car.

About all this does is make more noise.

Porsche calls the exhaust parts out of the rear of the cat the "final muffler", and the parts are supplied as a single piece. The original final muffler is not that restrictive, but a properly sized complete aftermarket "final muffler" could pick up a little more hp. Not more than 2-5hp would be my guess.

Simple replacing the muffler or the resonator is not going to get you anything, except for more noise.

You wrote that your car had no muffler when you bought it, and you had a "stock" muffler attached. Was/is that a muffler by itself, or a complete "final muffler assembly". Your car original had a muffler behind the cat, and a resonator at the rear of the car just before the tailpipe.
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Lizard  



Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada

PostPosted: Fri Jan 13, 2006 12:27 pm    Post subject: Reply with quote

if you want more power from your car by exhaust work then you would want 2.25" mandrel bent exhaust no cat and a decent muffler, you do want some backpressure, so go with a dynomax turbo muffler. or a 2.5" non mandrel bent exhaust pipe with the same style muffler, dont do anything else.

and when you say that you lost HP I bet you probably didnt, infact you probably would loose more without having the exhaust at least in the bottom end that is, unless it is dyno proven lost HP but I doubt they would let you dyno it without an exhaust.
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924er  



Joined: 10 Jan 2006
Posts: 339
Location: Los Angeles California

PostPosted: Fri Jan 13, 2006 2:08 pm    Post subject: Reply with quote

thanks for the replies guys. alot of help. ill look into that dynomax muffler being sold here at the local muffler shop. bassically after the manifold, there is a pipe leading to the cat, then to the stock muffler i put in. i actually think there will be better airflow if i put that performace muffler. ever since i put in the stock muffler, i felt that something is clogged in the exhuast. also im trying to put in a peformance filter with the intake. i need ur guyz help though becasue im going to remove alot of hoses i even dont know what they are for. ill post some pictures thanks.
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gohim  



Joined: 02 Nov 2002
Posts: 4459
Location: Rialto, CA

PostPosted: Fri Jan 13, 2006 5:33 pm    Post subject: Reply with quote

This is a joke right?

Are you really going to go tearing out hoses when you don't know what they do?

I suggest that you locate an experience Porsche 924 mechanic before you tear into your car without knowing what you are doing, because you are going to need him to get your car running correctly when you are done.

The 80 924 has the late 924 revised emissions controls. You don't have the EGR pump, EGR filter, or complicated vaccum system of the 79 and earlier cars.

There isn't anything you can remove from the car, under the hood if you expect to pass the CA Emissions (Smog) Test.

Your car weighs over 2600 lbs, and it only had about 110hp when it left the factory over 25 years ago. You didn't buy a stoplight drag car, you bought an underpowered 25-year old touring car. If you haven't figured it out yet, many of the current econoboxes are going to blow your doors off from traffic light to traffic light. The 924's specialty is handling in the twisties, if you can't handle that, save yourself alot of grief and get rid of the car before you dump a fortune into it and buy an old 5.0L Rustang.

Now back to your exhaust. You didn't answer the questions that I posted after your first message. Porsche does not sell replacement muffler for the 924, only the complete final muffler (from cat to tailpipe as I explained to you before). So the muffler that you had installed, cannot be a "stock" muffler. What was installed on your car was probably a "generic" (one size fits all) muffler. There is no telling whether it was built to original Porshce specs, but I am guessing... NOT!

So the aftermarket muffler that you had installed could indeed be affecting the performance of the engine. BUT it isn't a "stock" muffler, unless it came from Porsche (and we have already established that it didn't). For your information the "stock" muffler that Porsche supplied is hard to improve if you are going to match all of the parameters ) except engine hp output) that Porsche set with the orignal equipment.

You can improve slightly on what was there originally, because the original exhaust system was designed in the early 70s, and exhaust technology has improved. But don't fool yourself into thinking that you can get more that 2-5hp without making major investments of $$$ and replacing everything from the collector flange to the tailpipe.
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924er  



Joined: 10 Jan 2006
Posts: 339
Location: Los Angeles California

PostPosted: Sat Jan 14, 2006 6:43 am    Post subject: Reply with quote

Quote:
Are you really going to go tearing out hoses when you don't know what they do?


No ofcoarse i wasnt!! im first going to know if i need them before i start removing . im not trying to race anyone, i just want some more power for myself, and show.

i need to know what these these lines that are connected to the intake manifold, beccasue they are in the way of the intake im ging to install. and what is the sensor plate for located batween the airbox and the fuel distributor? ive seen people without that, when they put in the performance air intake.








and about the muffler, now i know what you mean about "stock". the guy at the shop said it is an ordinary stock muffler. but i guess your right about that. its an all fit muffler. stupid me, i did have the original porsche muffler but it had leaks on it, and i just got rid of it : ( would should i do? keep it or get an aftermarket. i dont really need 2-5HP a nice tone would be nice.




thanks[/img]
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gohim  



Joined: 02 Nov 2002
Posts: 4459
Location: Rialto, CA

PostPosted: Sat Jan 14, 2006 7:25 am    Post subject: Reply with quote

924s have been around for 30 years with the same low hp. Numerous magazine project cars and articles have been written ablut attempts to increase hp with bolt-on parts.

For the most part, ALL WERE FAILURES. Doesn't matter what you waste your money on. Bolt-ons will make VERY LITTLE DIFFERENCE. Changing the intake manifold will gain almost nothing (1hp?). Not worth the time to install.

Cold Air Intake? A myth fostered on stupid people trying to get something for nothing. Most aftermarket intakes simply add a cone filter inplace of the stock air cleaner. The stock air cleaner works fairly well because it will flow more than the engine consumes. You can get the same thing as adding a Cold Air Intake by simnply drilling a few holes in the air cleaner cover (NOT THE AIR SENSOR HOUSING) with a 2 inch hole saw.

The sensor plate that you mention that you have seen removed from cars? That's the CIS Air Flow Sensor. Remove that, and you get no fuel to the fuel injectors. Put holes in the intake tract between the air flow sensor and the throttle valve, and you will have an engine that is running too lean, or not running at all.

The only way that you can eliminate the CIS air flow sensor is if you are moving to DFI or carbs. Carbs do not get you anything on a street car except for tuning problems, drivability problems, poor gas mileage numbers, and failed emissions tests.

Don't need the hp? Why are you planning on changing the intake and the air filter? You just want more noise, right? Every honest little improvement helps when you only have 110hp. and 2650lbs. 1 or 2hp, here and there, is all you are going to find without major surgery to the internals of the engine.

The biggest hp advances will be found by advancing the timing advance as far as you can without engine knock, while running a premium brand and grade of gas. If you have a timing light and the knowledge, this does not cost you anything and could be good for up to 5hp.

Exhaust? Go too big (larger than 2.5 inches) and you hurt hp, not help. CIS fuel injection requires some backpressure to scavenge the combustion chambers for good ignition and power.

The cheapest relatively inexpensive exhaust improvement is a switch to the 944 exhaust system. You should be able to find a good used collector/downpipe, and final muffler for less than $150. Install the 944 exhaust system with 931 or 944 hangers, and slash the 944 collector where is lines up with the collector output flange on the 924. Use the 924 flange on the 924 collector to make an exhaust system that you can unbolt, because you need to remove the xhaust to perform some 924 maintenance and repair (like the clutch, transmission, and rear suspension). This is a proven upgrade that should yield 8-10hp, and has on other dyno'ed cars.

Like I wrote before, you should read up on the car BEFORE you waste your money on things that will not get you anything.

The left upper arrow that you made points to the aux air regulator. No choke on the 924, with fuel injection. The injection system richens the mixture, and additional air is supplied by way of the aux air regulator. The aux air regulator has a thermal system and flap that opens to allow filtered air into the intake to speed up the engine idle for a few minutes until it closes, and the idle speed then drops.

The lower right arrow points to the CIS air flow sensor.
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Miker  



Joined: 25 Jan 2005
Posts: 47
Location: Cali

PostPosted: Sat Jan 14, 2006 8:33 am    Post subject: yes, no problem to upgrade Reply with quote

try looking at magnaflow or flowmaster, both are a straight through design that do not restrict air flow and give a nice mean throaty sound. I have a magnaflow on my jetta and my 911 and will also add to my 924T when ready. They usually cost about 50-75us dollars but it varies on style. Try ebay also, very good mufflers their from reputable suppliers.
Mike
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1987 911 Carrera 3.2
2000 Getta VR6
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924er  



Joined: 10 Jan 2006
Posts: 339
Location: Los Angeles California

PostPosted: Sat Jan 14, 2006 10:42 am    Post subject: Reply with quote

I see. So i guess ill just stick to what i had it before

i got to clean the engine at least make it look good.

About the 944 muffler, ill prolly go to a junk yard that specializes in german cars, and they might have the mufflers. if not that then maybe the magnaflow, or the dynomax. thanks for all that advice Gohim, and the rest.
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DS-777  



Joined: 16 Sep 2005
Posts: 134
Location: Michigan USA

PostPosted: Sat Jan 14, 2006 10:43 am    Post subject: Reply with quote

I checked the flowmaster and magnaflow websites, and they cost a lot more than that. The price was right up in range with that of Remus mufflers, and from what I've heard, Remus is the best. They tune the sound of their exhausts, just like BMW, Ferrari, et cetera.
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Vince Ponz  



Joined: 02 Nov 2002
Posts: 3581
Location: Florida

PostPosted: Sat Jan 14, 2006 10:57 am    Post subject: Reply with quote

Try using a 944 muffler.
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79 931 Euro stock
88 924S SE
87 911 Targa stock
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endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Sat Jan 14, 2006 3:36 pm    Post subject: Reply with quote

DS-777 wrote:
I checked the flowmaster and magnaflow websites, and they cost a lot more than that. The price was right up in range with that of Remus mufflers, and from what I've heard, Remus is the best. They tune the sound of their exhausts, just like BMW, Ferrari, et cetera.


Summit Racing has Magnaflows and Flowmasters for $65-$125. Some in polished stainless. I couldn't find Remus on the net for any less than $300. Do you know a better source?

Todd
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endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Sat Jan 14, 2006 3:48 pm    Post subject: Reply with quote

924er wrote:
I see. So i guess ill just stick to what i had it before
i got to clean the engine at least make it look good.



If you want to really clean things up you need to switch to EFI. This is an old picture but after building a custom coolant tank that mounted where the windshield washer bottle was it started looking downright civil under the hood



Ofcoarse I have since then mounted up a supercharger and turned the engine bay back into a plumbers nightmare

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....
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DS-777  



Joined: 16 Sep 2005
Posts: 134
Location: Michigan USA

PostPosted: Sat Jan 14, 2006 3:58 pm    Post subject: Reply with quote

I have seen slightly cheaper than $300, but not much. I'll have to take a look at summit racing if that what it costs, all I checked out was the official website of each.
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