Skunk2 Fit Exhaust is out!
#2
10-02-2006, 01:32 PM
Knowing that we are starting off with this stock setup:
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
#3
10-02-2006, 01:33 PM
they will be releasing a 50mm sized setup in the future, the 60mm would be used
along with like a turbo setup or something
along with like a turbo setup or something
#4
10-02-2006, 01:35 PM
I am also planning on intake and header so according to the folks at skunk2 the 60mm would work.
I also spoke with them on the phone today and they stated that they ran several setups and the 60mm made the most power on a stock motor.
I also spoke with them on the phone today and they stated that they ran several setups and the 60mm made the most power on a stock motor.
#5
10-02-2006, 01:40 PM
After looking at some generic exhaust sizing charts, the 60mm (close to 2.25") is suggested for smaller engines making ~150 hp. So it shouldn't be too big, if used w/ other mods.
leonine, did skunk indicate the gains they saw?
leonine, did skunk indicate the gains they saw?
#6
10-02-2006, 01:46 PM
Originally Posted by sonorliteman
After looking at some generic exhaust sizing charts, the 60mm (close to 2.25") is suggested for smaller engines making ~150 hp. So it shouldn't be too big, if used w/ other mods.
leonine, did skunk indicate the gains they saw?
leonine, did skunk indicate the gains they saw?
#7
10-02-2006, 02:22 PM
Originally Posted by sonorliteman
Knowing that we are starting off with this stock setup:
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
Last edited by docjim2; 10-02-2006 at 02:25 PM.
#8
10-02-2006, 02:30 PM
Originally Posted by docjim2
wouln't be a bit cheaper to buy a "universal" muffler and have 60mm pipe bent and welded to it? Uh, that is if you want it JUST for looks and not street racing.
#10
10-02-2006, 04:23 PM
Originally Posted by leonine
Yeah it probably would be cheaper but i'll spend the dough for a simple bolt on that i can do myself and to have a quality product. Not to mention it is stainless. That would cost $$$ even if you were gonna have a custom fab one.
Last edited by docjim2; 10-02-2006 at 04:25 PM.
#12
10-04-2006, 10:01 PM
Originally Posted by sonorliteman
Knowing that we are starting off with this stock setup:
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
"So the rate of flow for the VTEC engine is now 55litres per second as compared to 50 litres per second for the i-DSI and this is achieved by increasing the diameter of the exhuast piping from 38.1mm to 42.7mm while the rear muffler volume is increased from 8 litres to 10 litres at the same time." (taken from http://asia.vtec.net/Series/FitJazz/lseries/index.html)
So a 12% increase gave 5 lps flow increase going from the 38.1 (~1.5" diam) to the 42.7 (~1.7" diam) piping....apply this percentage change ratio to a 40% increase (from 42.7 to the larger 60mm piping) it should gain ~16 liters/sec in flow, all else being equal. I'm sure there is a more accurate way to estimate this...the above is very rough. But a 40% diameter increase seems really nice, although the Fit's stock engine may not make much more power.
Unless combined w/ other bolt-ons, I don't think the power increase would be that great. I think it is a very expensive way to change the sound of your car!
It doesn't quite work like that. The cross-section of an exhaust pipe is a circle. We know the diameter of the circle is 42.7 mm for the OEM pipe and 60 mm for the new pipe. Area of a circle is pi * radius ^ 2. So... for the OEM pipe, the cross-sectional area is 1432 square millimeters. For the 60 mm pipe, it's 2827. That's a 97% increase in area (and volume as a result)!
The Temple of VTEC article you quoted isn't saying that the exhaust size increase resulted in the 5 liters per second flow increase. It's simply saying the 1.5 liter engine (probably the head, mainly) can flow 5 liters/second more, and the exhaust piping is larger to avoid being a restriction.
In general, increasing the size of an engine's exhaust piping won't increase the flow rate of the engine unless the exhaust is the restriction. I'm certain that the Fit's exhaust stops being the restriction way before it's 60 mm in diameter. It's really likely that the head is the restriction, and increasing exhaust size (especially that much) has very little, if any, effect.
#13
10-04-2006, 10:18 PM
Originally Posted by yobtah
It doesn't quite work like that. The cross-section of an exhaust pipe is a circle. We know the diameter of the circle is 42.7 mm for the OEM pipe and 60 mm for the new pipe. Area of a circle is pi * radius ^ 2. So... for the OEM pipe, the cross-sectional area is 1432 square millimeters. For the 60 mm pipe, it's 2827. That's a 97% increase in area (and volume as a result)!
The Temple of VTEC article you quoted isn't saying that the exhaust size increase resulted in the 5 liters per second flow increase. It's simply saying the 1.5 liter engine (probably the head, mainly) can flow 5 liters/second more, and the exhaust piping is larger to avoid being a restriction.
In general, increasing the size of an engine's exhaust piping won't increase the flow rate of the engine unless the exhaust is the restriction. I'm certain that the Fit's exhaust stops being the restriction way before it's 60 mm in diameter. It's really likely that the head is the restriction, and increasing exhaust size (especially that much) has very little, if any, effect.
The Temple of VTEC article you quoted isn't saying that the exhaust size increase resulted in the 5 liters per second flow increase. It's simply saying the 1.5 liter engine (probably the head, mainly) can flow 5 liters/second more, and the exhaust piping is larger to avoid being a restriction.
In general, increasing the size of an engine's exhaust piping won't increase the flow rate of the engine unless the exhaust is the restriction. I'm certain that the Fit's exhaust stops being the restriction way before it's 60 mm in diameter. It's really likely that the head is the restriction, and increasing exhaust size (especially that much) has very little, if any, effect.
But you're correct about the volume increase being significant. I just wonder what a 97% increase does to the exhaust gas velocity...and if this really matters once exhaust passes the cat.
#14
10-05-2006, 07:40 AM
Originally Posted by sonorliteman
But you're correct about the volume increase being significant. I just wonder what a 97% increase does to the exhaust gas velocity...and if this really matters once exhaust passes the cat.
I have a couple of guesses on why Skunk2 would use 60 mm piping:
Either way, I'm guessing they didn't do it purely for performance. Without some major head work or forced induction, the L15 isn't large enough and doesn't flow enough.
#15
10-05-2006, 08:26 AM
Originally Posted by yobtah
The bigger diameter exhaust piping will definitely slow exhaust flow... but I don't know how much.
I have a couple of guesses on why Skunk2 would use 60 mm piping:
I have a couple of guesses on why Skunk2 would use 60 mm piping:
- It's what they had on hand, and it would have been more difficult to get smaller piping.
- They're worried people who are accustomed to 2.25" or 2.5" piping on Civics and Integras would see smaller than 2" piping on a $500 aftermarket exhaust and think it's not worth the price.
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