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Discussion Starter #1
I have a 1985 spider graduate. I was told that a nice power addition to the car is putting on a 1-4, 2-3 two piece exhaust mainifold from an earlier year spider (was it 72-74?). Also was told that there is no emission gain.I live in california so emission checks are strict. has anyone done this and is there a noticeable difference.
 

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for about the same price you can get tube headers...i live in cali.( sacramento)..and every time i go in for a smog.. they say nice MG,Fiat, Triumph...they have no idea what they are working on..all they do is look.. and test...they don't know the diff.
 

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There’s a bit more to consider than just swapping out your existing manifold… First, about increasing power… Yes, your current manifold is purposely designed to slow down the flow of spent gases, and an earlier (’72 - ’74) set-up will restore the quicker gas flow. However, that’s only the first restriction. The second one is the catalytic converter. The OEM cat is small and also chokes the system. The third is the diameter of the pipe from the catalyst on back. If you don’t improve the flow through the catalytic converter, you won’t get the benefit of having installed the better manifold/headers. As far as the diameter of the pipe, it has a much smaller impact. Doing headers and a cat, without touching the cat-back system, will still yield a nice improvement over the current stock set-up.

With regard to emissions, note that the increase of gases flowing unrestricted through the headers also means that the level of pollutants will be higher. Thus, this is another reason why you should replace the catalytic converter with a modern one that is not just free-flowing for performance, but also much more effective and can better handle the increase of pollutants. This should allow the car to still remain compliant, with no net increase of pollutants coming out the tail pipe. (I must note that I don’t live in CA, but all ’85 Spiders are the same in the U.S.A., and NJ also has strict emissions regulations.)

As far as the fit, there are essentially a couple of choices. You can go with the earlier ’72 - ’74 headers, but this also means that you need to change to the earlier set of down pipes. These are the front down pipes that go into the catalytic converter. The earlier pipes were never attached to a catalytic converter, but they do feed into a resonator. You should be able to fit the cat in the same place where the front resonator is found. You will also have to drill an opening for the oxygen sensor, since the earlier set-up never used one. All of this is custom work, of course.

The other choice to replace the manifold is to use a set of aftermarket headers, such as the ones sold by Centerline. These replace not just the current manifold, but also the down pipes, so it is a 4-2-1 system. The included “Y” pipe connector has the bung for the oxygen sensor and so you have the complete system that is needed right up to the point that it mates with the catalytic converter. This off-the-shelf set-up still requires some custom work, to fit to the cat, and then to fit the cat to the rest of the stock system, but it is straightforward.

In the future, when you need to replace the cat back system, you could go with one that has a larger diameter pipe, to get a little more increase in performance.

Last, I should also note that you need to be aware that these modifications, while compliant with emission levels, are still illegal to use on street cars. Of course, a visual test is only as good as the knowledge of the inspector, and none of these set-ups look out of place. It is something to consider however, as none of the above is inexpensive. On the flip side, each small power increase is noticeable, and satisfying. Finally, as an added bonus, the increase in efficiency should yield an increase of about 2-3 mpg.

Best regards,
 

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Discussion Starter #5
Thanks for the reply Enrique, sounds like the centerline system with a larger cat converter is the way to go. The only other question is how much louder will it be?
 

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Since an engine is basically an air pump, wouldn't freeing up the floow through the exhaust make the air pump able to flow more air? Along with that air, it will flow more fuel, thus reducing fuel mileage. I know with my Harley, when I opened up the exhaust and the intake, I picked up more power but lost gas mileage.
 

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I KNOW NOTHING!!! But if there is an increase in MPG it may be
A-Better efficiency
B- more power equals less RPMS and maybe less gas used to achieve the same speeds

Correct me if I am wrong
 

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For me personally, more power generally means my foot seems to get heavier. If you know what I mean ;-)
 

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I ordered a new center muffler, and tail pipe minus the rear muffler from Centerline for my 87 Spider, and found out my exhaust system is from a series 4 Alfa which they said was also an improvement.
Bob Ferguson
 

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emmissions? out of the exhaust port they are the same no matter what header you use...once they hit my cat..they are cleaned up.. as for noise..not much diff... i do not understand how a header would change exaust emmission?? it's just pulseing down a tube.. cast iron or a steel tube..the cat. cleans it up..
 

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I have a 1985 spider graduate. I was told that a nice power addition to the car is putting on a 1-4, 2-3 two piece exhaust mainifold from an earlier year spider (was it 72-74?). Also was told that there is no emission gain.I live in california so emission checks are strict. has anyone done this and is there a noticeable difference.
Another way to go would be to purchase this:

http://www.alfabb.com/bb/forums/any...6-magnaflow-exhaust-systems-have-arrived.html

You would be supporting this site ( i think ) - and all you'd havta do is to place a cat just after the 2 into 1 connector, and drop a O2 sensor bung in just before the CAT...

Badda bing.

I'd lose the stinger on the end, but that's just me. You could also just take a screwdriver and hammer, and pound holes into the middle muffler, but that was just me when I was 16... :)

Vroom.
 

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Thanks for the reply Enrique, sounds like the centerline system with a larger cat converter is the way to go. The only other question is how much louder will it be?
Since you still have all the chambers that reduce the noise level, this won't be an issue. The headers would give a little deeper sound, more different than significantly louder. Do note that Spiders are loud. To test this, ask someone to drive your stock Spider around the block on an early morning, when no one is driving, and note how you will hear it coming from a distance. It's pretty cool actually, to hear someone going through the gears.

Since an engine is basically an air pump, wouldn't freeing up the floow through the exhaust make the air pump able to flow more air? Along with that air, it will flow more fuel, thus reducing fuel mileage. I know with my Harley, when I opened up the exhaust and the intake, I picked up more power but lost gas mileage.
At higher rpms, like when driving on an interstate, the engine is producing a lot of gases, and these spent gases can't get out very well, because of the restrictive design of the stock manifold. This lack of good gas flow chokes the engine, and makes it less efficient. A noticeable example of this occurs when going uphill in a Spider. The driver has to depress the accelerator more in order to maintain the speed. With a better flow on the exhaust side, and the same intake set-up (same camshaft lift, same cam duration, same overlap), the result at these higher (real world) speeds is that the improved scavenging of spent gases removes the "choking" effect. On the same uphill, the driver will notice that he/she doesn't have to depress the accelerator as much to maintain the speed. At higher speeds, where the restriction was most detrimental, the car will feel better overall, as if a little weight had been removed from it (even though it weighs the same). The improvement in that rpm range, which is where people drive at in the real world, is what yields the slightly better mpg. (If one were to drive around at 1500 rpms all the time, there wouldn't be any difference.)

Yes, there is an optimum point for efficiency with performance mods, and if you exceed that point, you can very well sacrifice gas mileage. A key factor here is that if you have the ability to greatly increase the amount of fuel that is delivered into the engine you can end up sending a lot of fuel that you won't necessarily be using. This is no different than if you drove around at high speeds around the side streets, only to slam on the brakes at every corner. In essence the fuel that you used to achieve the high speed should have carried the vehicle a lot further in distance, but by applying the brakes and bringing it to a stop, it is in effect being wasted.

Best regards,
 

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emmissions? out of the exhaust port they are the same no matter what header you use...once they hit my cat..they are cleaned up.. as for noise..not much diff... i do not understand how a header would change exaust emmission?? it's just pulseing down a tube.. cast iron or a steel tube..the cat. cleans it up..
aren't emissions tests/requirements typically applied to the composition of the exhaust gases, rather than the absolute magnitude of the constituent components? been awhile since i studied my emission report, but memory is that it lists, e.g., "percent carbon-dioxide" and "parts-per-million hydrocarbons" instead of "grams carbon-dioxide" or whatever. in this context, the increase in the volume of exhaust gases is not even detectable. just wondering.
Let me try to clarify and answer your questions by expanding on the explanation... A car produces a "pulse" of spent gases when each piston pushes up the residue of the burned mixture and it goes out the exhaust port into the header, when the exhaust valve opens. At low speeds, the amount of spent gases come no where near to filling up a set of short tubes. So at low rpms, the tubes don't restrict flow. At higher rpms however, these pulses are a lot more frequent. (In the same minute - rpm - a lot more spent gases are sent out into the tubes at 4500 rpm, than at 1500 rpm.) The spent gases can fill up the tubes to the point that at the juncture of two tubes, the amount of pulses of gases that meet cannot continue at the same travel rate, and the tube essentially slows down the flow of these gases. This is very much the case with tubes that meet up after a short distance. With longer tubes, these restrictions are removed, but by the same token, a larger volume of gases reaches the cat. Each pulse of spent gases that reaches the cat has the same percentage of pollutants, but with higher rpms there are many more pulses that the cat has to "clean-up". The cat is supposed to take each pulse and reduce its pollutants. The number of pulses that reach the cat do make a difference as to how the cat can reduces the pollutant level in each pulse by the time it exits the cat. This is where volume is a factor. That is also why emissions tests are conducted with the car on the dyno, with the probe at the tail pipe taking readings at different rpms. Otherwise, what would be the point of testing at different rpms? Of course, both the design and materials of a modern (albeit expensive) cat, are much better than one from 20 years ago, and one can be confident that they will do the job well.

Something else that is probably important to note about volume and exhaust systems. It is not good when the tubes don't get filled up with enough spent gases, because not enough back pressure is created. It is also not good when the exhaust tubes get filled with too many spent gases, and the gases trying to exit the combustion chamber and enter the header cannot get out. One could surmise from this that there is an issue at low rpms, and at high rpms. And this is the case. In the absence of an exhaust system that can dynamically change its tube diameter, the best that can be done is to select a constant size, which is in effect a compromise. Thus, every exhaust system is a compromise, and it will not be ideal throughout the rpm range. Hopefully, it is best suited for the rpm range at which the car is driven most. Hence there are larger diameter exhaust systems designed for race engines that are usually run at high rpms, and these wouldn't really work well in street engines that normally run at considerable lower rpms.

why illegal? if an aftermarket exhaust system were to produce lower emissions (and here let me include noise, just for the sake of argument), why should that be illegal? again, i'm just curious here.

by the way, i've been through intake inspections ("are those the stock air filters?"), and cat inspections (the mirror on a stick trick), but not specifically header or cat-back inspections.

-jason
WA, USA
They are illegal because they have not be certified by any government agency. This has nothing to do with how well an aftermarket product works, or not. All car components of every manufacturer are certified for use, but aftermarket components don't necessarily go through the process. Note that the Alfa aftermarket suppliers have disclaimers and warnings in their sales literature which state that a particular component is only for off-road use. If an aftermarket fabricator where to invest the time and money to certify its product, then the product would be legal. (There are manufacturers of of aftermarket products for other much more popular marques than our Alfas, which actually do this.)

Obviously visual inspections vary, but a system that passes emission tests with flying colors will always attract less attention and be subject to less scrutiny than one that produces high levels of contaminants, as if to advertise that it has been tampered with. I have never had any issues with my headers or cat-back systems, but I know that if the car were to fail a test, the inspector could start questioning any component.

Best regards,
 

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I'm posting years later on this, but I have an 1985 with an aftermarket header (1/4, 2/3 from Shenkle, installed in 1990). Flunked the visual. If you're going down this road, be wary.

1985 Graduate
 

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Yep, skip the centerline headers, as stated there is a chance you will fail visual inspection and I believe they generate more heat in the engine bay.

If you change your manifold your current down-pipe and cat will have to change also and possibly the mid-muffler as they are different configurations through the years.

Unless you want to be doing a lot of custom work I'd suggest 2 options:

1 Used 70's 2-piece manifold + Magnaflow system (with cat welded in)
2 Used S4 2-piece manifold + S4 downpipe + S4 mid-muffler.

I am planning the second route, have the parts, just need the time.... :D
 

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"I'd lose the stinger on the end, but that's just me. You could also just take a screwdriver and hammer, and pound holes into the middle muffler, but that was just me when I was 16... :)"

Yep, nothing like a big exhaust leak right under your butt to make your day.
 

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I echo the above comment: you do have to change a bit, as I remember it (it has been 20+ years, and I was younger then), but the Shankle, which looks like the IAP aftermarket header, is a 2 piece, and drops to the bottom of the engine bay, and heads back a bit and then is joined. I had to weld to get it to mate up, just above the cat. It seemed simple at the time, but in retrospect, it was a pretty significant change, as the original header stops about 4 inches below the exhaust ports in the block, and the new ones covered more ground.

As an update, the inspection is supposed to find a code stamped on the header to pass, but I talked to IAP who has factory supplied headers, and they don't believe there is a DOT or EPA code stamped on them. They tell me I can return them unused if I want to inspect or see how much work needs to be done to re-install. I feel like I'm heading for Kafka novel....
 

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Discussion Starter #18
I had my muffler guy install the headers and new cat on my 85 from centerline, took him a while to get things lined up properly. Haven't had any problems since, I little louder, a little more power though. Just had a CA smog check and the car passed emissions but failed the visual. Lucky for me the smog guy said that he didn't see the header pipes.
 
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