Fiats original exhaust system comperd to Vendors (Fiat 124)

[Thunberg]

Hi
I wonder if anyone has a dyno results (or links) between Fiats original 4-2-1 exhaust system (or some other Fiat system) and “Vendors” systems?

I cannot find any at all on the net. I have seen some vendors says it will give like 10% increase compared to “the original”, but the vendors often don’t say exactly what “the original” is and they also lack the dyno paper that shows the hole range in rpm which would prove their statement. I don’t want to spend money on a system that isn’t any good for my purpose compared to my Fiat 4-2-1 system. Perhaps I ‘have missed the vendors’ info?

[narfire]

From what I understand headers are nice and evidently Marks "snake-head" headers do make a difference. The 4-2-1 works well. I have Ansa headers but where the 2 goes into 1, I have cut there and installed a short 2" section and then continued with 2" to the muffler. (2" inner diameter) No cat or resonator, just muffler

[Thunberg]

From what I understand headers are nice and evidently Marks "snake-head" headers do make a difference. The 4-2-1 works well. I have Ansa headers but where the 2 goes into 1, I have cut there and installed a short 2" section and then continued with 2" to the muffler. (2" inner diameter) No cat or resonator, just muffler

I don´t doubt that Marks are "nice" or "make a difference" but i still lack graphs with a comparisment with a original Fiat system for showing how nice or how much difference they will make. I can´t find a single graph with comparisment from any vendors homepages actually. The only thing I have seen from different vendors are stuff like this:

"Dyno-tested to work"
"rise in power"
"10-horsepower increase over the original manifold system" (but were at 7500rpm or what)

Please show graphs Vendors

[Divers]

I would imagine showing graphs will be difficult unless you were to define the exact engine specs. Do you mean if you take a STOCK 2L engine with 4-2-1 down pipes, cat convertor, muffler with all the bends and compare that to a vendor system with no cat, 2" or better pipes and a free flowing muffler?

So many of us have tweaked our engines, that just going with a more free flowing exhaust was a no brainer....even without dyno graphs.

Just my $0.02

Robert

[Thunberg]

I would imagine showing graphs will be difficult unless you were to define the exact engine specs. Do you mean if you take a STOCK 2L engine with 4-2-1 down pipes, cat convertor, muffler with all the bends and compare that to a vendor system with no cat, 2" or better pipes and a free flowing muffler?

So many of us have tweaked our engines, that just going with a more free flowing exhaust was a no brainer....even without dyno graphs.

Just my $0.02

Robert

Of course the exact engine specs must be defined from the original and what the vendors have done to the upgraded engine as well. If the vendor change to much from the original set up it is worthless to say that only their header will have "10-horsepower increase" .

You say that "free flowing exhaust was a no brainer" but for me it is. Have read and heard that for example if using a 4-1 header system you can often lose power in the low and mid range but gain at the top, so if it aint a racecar the original 4-2-1 system could actully be "better" .

[TX82FIAT]

IMHO it would be difficult to compare any graph today with an original car graph for performance upgrades. All cars lose some horsepower and fuel efficiency as they age. You would need to show the exact same car with no other mods other than the change in Exhaust with a before and after comparison. Even then, you will not get a true number for all cars. Let me give you an example. How many cars with a 30 year old CAT still hooked up will see some sort of partial blockage from the old CAt and could see a 10% increase in power from that. A poorly running spider could see an off the chart increase in HP with a new exaust system from the header back. You would still not know how much of that increase id due to the header or how much is related to removed backpressure. A properly designed system should have enough backpressure to preserve almost all low end power.

[So Cal Mark]

I've posted dyno sheets from cars with my headers and I've challenged every other Fiat vendor to do the same. So far, none have posted any results.

[Thunberg]

IMHO it would be difficult to compare any graph today with an original car graph for performance upgrades. All cars lose some horsepower and fuel efficiency as they age. You would need to show the exact same car with no other mods other than the change in Exhaust with a before and after comparison. Even then, you will not get a true number for all cars. Let me give you an example. How many cars with a 30 year old CAT still hooked up will see some sort of partial blockage from the old CAt and could see a 10% increase in power from that. A poorly running spider could see an off the chart increase in HP with a new exaust system from the header back. You would still not know how much of that increase id due to the header or how much is related to removed backpressure. A properly designed system should have enough backpressure to preserve almost all low end power.

Of course I meant that the vendor dynotest the exact same engine before changing.

[Thunberg]

I've posted dyno sheets from cars with my headers and I've challenged every other Fiat vendor to do the same. So far, none have posted any results.

Thats sounds fine and did you dyno test the engine before changing to "your headers"?

But I´m sorry I cant find your dyno sheets at your homepage , do you have them published somewhere else? If so please link them

[Exit98]

Hi Thunberg,

Hey, looks like you just popped in out of the blue. Welcome.

So what brings you here? What's your Spider experience? Got any pictures?

[Europa]

Hi Thunberg,

Hey, looks like you just popped in out of the blue. Welcome.

So what brings you here? What's your Spider experience? Got any pictures?

I second that!

[Thunberg]

Hi Thunberg,

Hey, looks like you just popped in out of the blue. Welcome.

So what brings you here? What's your Spider experience? Got any pictures?

Thanks , sorry no experience of a spider but I´m thinking of upgrading my exhaustsystem to my SC if I find anything worth it.

Pictures of my car "the white one" (this is the last page of 20 pages)
http://sfk.ibk.se/forum/showthread.php? ... enumber=20

[Exit98]

Nice Coupe. Is that a special front bumper? I don't recognize it.

For what its worth, I think the stock 4-2-1 exhaust is hard to improve on. Money might be better spent on carburetion and cam work first.

[kmead]

That bumper was on the Series 3 coupes. In the US it was only on the late 73, and 74 models. The 75s had a big straight energy absorbing bumper.

[Thunberg]

Nice Coupe. Is that a special front bumper? I don't recognize it.

For what its worth, I think the stock 4-2-1 exhaust is hard to improve on. Money might be better spent on carburetion and cam work first.

Thanks and yes it is the original bumper from -73. When it comes to carburetion I have right now weber 40 idf, but sure weber 44 idf would be better I guess when it comes to a 1995 which i have in my car. But 44 idf:s are hard to get a grib on and they cost quite a lot more than I´m willing to spend.

For cams I guess the original is quite ok. I will not buy regrinds anyway, a lot of info on the "net" points to the direction that it is often a lot of trouble to get regrinds working good and sometimes people even have lost power in low and mid range. On top of that I´m not a beliver in Fiats "magic cams" either so the only cams "for me" are way out of my budget.

So the only upgrading I´m willing to do is some headers if any vendors can show me what they are good for and they need to be "much better" than the Fiats own 4-2-1 system because I like the design of the original stuff