De-bunk the Myths!
#81
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man the stuff people will try and sell in the name of making power. you know there is no way to get a cheap bolt-on miracle piece of equipment to make your car better. I am old school and firmly believe cubic inches+cold air is the best way to go. supercharging and turbo are ok too as long as its done right.
#82
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Originally Posted by projectheavytouring
as for getting rid of myths.... this isn't a manufacturer specific thing... but this whole "you need backpressure to run an N/A engine" thing has got to be stopped. backpressure is BAD for an engine... what alot of ppl think of needing backpressure is actually exhuast velocity ... while backpressure may remain in an exhaust tuned for exhaust velocity, the idea is to get rid of as much backpressure as possible, while getting maximum exhaust velocity. just think about it for a second or two ... back pressure... this is exhaust getting forced BACK into the combustion chambers... not a good thing
http://www.hotrod.com/techarticles/a.../photo_01.html
#83
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Check this link out. It gives a very good explanation of "backpressure".
http://www.uucmotorwerks.com/html_pr...torquemyth.htm
At the same time, the reverse pulses that allow more air to be sucked into the combustion chamber, thus causing the PCM to change the fuel curve, does provide more torque. The more you open the exhaust, the reverse pulses diminish. That'* why most go with and "H" pipe when going with dual exhaust.
Saying that backpressure is exhaust fumes reversing into the chamber is not actually true. It'* "pressure", not back flow. Very different things here. You can have pressure without flow. That being said, you can have flow one direction, and still have opposing pressure.
Use this to determine exhause flow:
Exhaust flow rate =
D (in3) x full load rpm x E x (7* x 460*)
C x 941,760
D = displacement in in3
E = 0.85 efficiency for naturally
aspirated engines
= 1.2 for engines with scavenging blower (supercharger)
= 1.4 for turbo-charged engines
T = exhaust temperature; if unknown,
use 900°F for diesel and 1,200°F for
gas engines
C = 1.0 (two-cycle engine)
or 2.0 (four-cycle engine)
Once you have that info, use this to determine backpressure:
The silencer is, of course, the muffler, and/or any resonators. By using these formulas, you'll see that on any given stock or lightly modded engine, the backflow rarely exceeds 1" Hg. So, there'* no problem.
The problem arises when you modify the exhaust without changing other functions, such as intake, valve duration, fuel/air ratio, etc.
That'* not what we do here, nor do we condone changing only one thing. We warn plenty of individuals not to open the exhaust, or produce more boost, without also changing the breathability of the engine in its entirety.
Just do a search, you'll see.
http://www.uucmotorwerks.com/html_pr...torquemyth.htm
At the same time, the reverse pulses that allow more air to be sucked into the combustion chamber, thus causing the PCM to change the fuel curve, does provide more torque. The more you open the exhaust, the reverse pulses diminish. That'* why most go with and "H" pipe when going with dual exhaust.
Saying that backpressure is exhaust fumes reversing into the chamber is not actually true. It'* "pressure", not back flow. Very different things here. You can have pressure without flow. That being said, you can have flow one direction, and still have opposing pressure.
Use this to determine exhause flow:
Exhaust flow rate =
D (in3) x full load rpm x E x (7* x 460*)
C x 941,760
D = displacement in in3
E = 0.85 efficiency for naturally
aspirated engines
= 1.2 for engines with scavenging blower (supercharger)
= 1.4 for turbo-charged engines
T = exhaust temperature; if unknown,
use 900°F for diesel and 1,200°F for
gas engines
C = 1.0 (two-cycle engine)
or 2.0 (four-cycle engine)
Once you have that info, use this to determine backpressure:
The silencer is, of course, the muffler, and/or any resonators. By using these formulas, you'll see that on any given stock or lightly modded engine, the backflow rarely exceeds 1" Hg. So, there'* no problem.
The problem arises when you modify the exhaust without changing other functions, such as intake, valve duration, fuel/air ratio, etc.
That'* not what we do here, nor do we condone changing only one thing. We warn plenty of individuals not to open the exhaust, or produce more boost, without also changing the breathability of the engine in its entirety.
Just do a search, you'll see.
#84
#86
Ah... Here'* another one. The guys on spike TV (not sure of which show) claim that it works. Seems to me like another fake fuel saver to me.
http://www.fitchfuelcatalyst.com/pro...uto/index.html
http://www.fitchfuelcatalyst.com/pro...uto/index.html
#87
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Hmm, interesting product. Their review pages has a pretty good list of seemingly credible sources that used their product with positive results (few emissions, better mileage, some small power gains) http://www.fitchfuelcatalyst.com/products/reviews.cfm
I wonder what they are using as a catalyst, assuming the reviews I've read are true.
I wonder what they are using as a catalyst, assuming the reviews I've read are true.
#88
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Posted: Mon Jun 25, 2007 7:19 pm Post subject:
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Ah... Here'* another one. The guys on spike TV (not sure of which show) claim that it works. Seems to me like another fake fuel saver to me.
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Ah... Here'* another one. The guys on spike TV (not sure of which show) claim that it works. Seems to me like another fake fuel saver to me.
yeah i did see that show was wondering if its true and if they are going to test it
#90
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Originally Posted by pitts64
HEI distributers on older pre 72 engines.
The points work just as good on the old engines.
HEI was need when they leaned out engines for emissions.
The points work just as good on the old engines.
HEI was need when they leaned out engines for emissions.