Avice please, the physics and and exhaust system
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Anonymous
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Anonymous
Back pressure is a torque killer , why restrict the ex gases? , tis the scavenging that determines torque/power , the camshaft plays a critical role , tis all to do with VE , which boils down to intake valve closure , which again will make no noticable difference on a street motor , high rpm motor is a different ball game.
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Anonymous
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Anonymous
Hi Moparfolks,
A good friend of mine in the US has done all the research on street driven Mopars and their exhaust systems!
Who is he you may ask?
He is the Owner of Accurate Exhausts!!!
In my opinion , he knows it ALL!
A 2.5inch system into a 2.25 over axle pipes with one Hemi Muffler, is as good as anyone needs with a daily driver.
A 3.0inch from system into a 2.5 over axle pipes is as big as any street car will ever need, unless you have got a real big motor!!!
There is alot more to it than we can discuss, so keep it simple methinks
Happy New Year Bacca
A good friend of mine in the US has done all the research on street driven Mopars and their exhaust systems!
Who is he you may ask?
He is the Owner of Accurate Exhausts!!!
In my opinion , he knows it ALL!
A 2.5inch system into a 2.25 over axle pipes with one Hemi Muffler, is as good as anyone needs with a daily driver.
A 3.0inch from system into a 2.5 over axle pipes is as big as any street car will ever need, unless you have got a real big motor!!!
There is alot more to it than we can discuss, so keep it simple methinks
Happy New Year Bacca
take the mufflers out completely.... instead use standard 2.5 or 3 inch tube with a 1.5 inch tube drilled with 1/4 inch holes mounted inside for about a foot where the muffler used to be.
sounds like a cherry bomb with no glass fibre in it. NICE !
not a sensible modification.
you want a slight step out of the head into the header.
gasket sized to header so you don't burn the edges......that's my sensible suggestion. exhaust gas bounces back and forth like smoke rings from each junction this step will stop it going back too far and raising the pressure at the exashust port.
Dave
sounds like a cherry bomb with no glass fibre in it. NICE !
not a sensible modification.
you want a slight step out of the head into the header.
gasket sized to header so you don't burn the edges......that's my sensible suggestion. exhaust gas bounces back and forth like smoke rings from each junction this step will stop it going back too far and raising the pressure at the exashust port.
Dave
The Greater Knapweed near the Mugwort by the Buckthorn tree is dying
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Anonymous
Not a fan of that idea at all. That will choke the system even more.Dave999 wrote:you want a slight step out of the head into the header.
gasket sized to header so you don't burn the edges......that's my sensible suggestion. exhaust gas bounces back and forth like smoke rings from each junction this step will stop it going back too far and raising the pressure at the exashust port.Dave
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Dave-R
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From http://victorylibrary.com/mopar/mopar-tech.htm
If possible, slightly enlarge the inside of the flange opening in the header itself to produce a sharp step (be careful of grinding off the tube weld). Do not radius the edge. A 1/16” bevel is generally possible and will help. If there is not much room, don't grind all the way into the flange - a 45° angle is fine. This has a minor anti-reversion effect, helping to prevent back-flow at low engine speeds; helps clean up idle quality, etc.
If the primary pipe inside diameter is more than 1/8” larger than the actual port opening in the head, the header flange bolt pattern can be slotted slightly to raise the centerline of the primary pipe above the center of the port, until the bottom of the pipe just matches. This puts the pipe's effective center closer to the most active area of gas flow, and the mis-alignment at the roof allows the highest-pressure gas an easier path away from the port; also adds some degree of anti-reversion.
If controlling reversion is more important than maximum port flow (e.g. primary diameter is very large), Vizard suggests the mis-match should be at the bottom of the port where gas flow is slowest, and therefore most likely to reverse-flow at low engine speed.
An easy way to effect a small increase in exhaust efficiency, if space permits, is to move the header out away from the port by 1/2” or more (using an extra gasket and longer studs or bolts). This moves the restrictive angle farther away from the port - every little bit helps here. It also reduces local exhaust port temperature in the head slightly. An easy spacer is an extra header flange or 2, but be sure that the transition from the extra flange to the header is not restricted. The extra flange may be slightly larger than the port opening in the head, but must not step down entering the header. Do not taper, blend, or bevel the extra flange to act as a transition between the port and the header.
If possible, slightly enlarge the inside of the flange opening in the header itself to produce a sharp step (be careful of grinding off the tube weld). Do not radius the edge. A 1/16” bevel is generally possible and will help. If there is not much room, don't grind all the way into the flange - a 45° angle is fine. This has a minor anti-reversion effect, helping to prevent back-flow at low engine speeds; helps clean up idle quality, etc.
If the primary pipe inside diameter is more than 1/8” larger than the actual port opening in the head, the header flange bolt pattern can be slotted slightly to raise the centerline of the primary pipe above the center of the port, until the bottom of the pipe just matches. This puts the pipe's effective center closer to the most active area of gas flow, and the mis-alignment at the roof allows the highest-pressure gas an easier path away from the port; also adds some degree of anti-reversion.
If controlling reversion is more important than maximum port flow (e.g. primary diameter is very large), Vizard suggests the mis-match should be at the bottom of the port where gas flow is slowest, and therefore most likely to reverse-flow at low engine speed.
An easy way to effect a small increase in exhaust efficiency, if space permits, is to move the header out away from the port by 1/2” or more (using an extra gasket and longer studs or bolts). This moves the restrictive angle farther away from the port - every little bit helps here. It also reduces local exhaust port temperature in the head slightly. An easy spacer is an extra header flange or 2, but be sure that the transition from the extra flange to the header is not restricted. The extra flange may be slightly larger than the port opening in the head, but must not step down entering the header. Do not taper, blend, or bevel the extra flange to act as a transition between the port and the header.