equal length mani for D17
Joined: Sep 2005
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Re: equal length mani for D17 (iROCKtheSOHC)
still looking around to see what manifolds do 
all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though 
all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though
Junior Member
Joined: Jan 2005
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From: Boise, Idaho, usa
Re: equal length mani for D17 (vangdvd)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vangdvd »</TD></TR><TR><TD CLASS="quote">still looking around to see what manifolds do all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though </TD></TR></TABLE>ehhhh? 
all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though </TD></TR></TABLE>ehhhh?
Unceasing Measure
Joined: Feb 2002
Posts: 13,088
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From: Columbus Ohio
Re: equal length mani for D17 (vangdvd)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vangdvd »</TD></TR><TR><TD CLASS="quote">still looking around to see what manifolds do all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though </TD></TR></TABLE>
Manifolds are the paths that air takes both going into and coming out of your engine. As each cylinder has one segregated port through which air travels (intake manifold runner and exhaust manifold - header - primary), the non-interference length, internal diameter, surface texture, material and plenum/collector shape and volume are all important factors in creating a competant powerband.
Generally, you can assume a couple things from a physical standpoint that work for most applications: shortening the intake runners gains top end while shortening the non-interference (i.e. length of the primary before joining with any other scavenging path and/or collector) length of the primaries gains you low end. Vice versa, lengthening the intake runners will usually net you more low end and midrange power whereas lengthening primaries in the header caters to a high-revving powerband.
A good example of this is the ITR intake manifold. With a large plenum and short runners, the intake manifold of the ITR works in conjunction with the camshafts to create a powerband that feels solid and torquey all the way to 8500 rpm or so. If you've ever seen the intake manifold on a 2.4L Dodge Stratus motor, as an example of the opposite, the intake runners are incredibly long, granting the engine a more driveable, low and mid-range powerband that's suitable for daily driving.
As far as headers go, primary length shortening increases immediacy of throttle response and torque onset. Lengthening primaries - and keeping them segregated - will shift the powerband (read: peak torque) further up the rev scale and, generally, make the vehicle feel like its pulling harder up top. This works in turbocharger manifolds as well, with a "shorty" or "log" style manifold granting a quick spool, more midrange torque and a generally limited top-end based on the short runners' inability to scavenge efficiently at higher RPM. A "ramhorn" or "Medusa" manifold, on the other hand, increases the lag time down low with the benefit of having a much higher ceiling for maximum power production. Since drag cars generally only have to use the bottom 2/3ds of the powerband at launch, a header or turbo manifold with huge primaries or a tuned length is usually included in the build in order to allow them to be making peak power in the part of the powerband that they spend the most time in.
Any more questions?
all i could find from howstuffworks.com: "As a piston moves down in the intake stroke, air resistance can rob power from the engine. Air resistance can be lessened dramatically by putting two intake valves in each cylinder. Some newer cars are also using polished intake manifolds to eliminate air resistance there. Bigger air filters can also improve air flow." more stuff to do with D17 sounds good to me though </TD></TR></TABLE>Manifolds are the paths that air takes both going into and coming out of your engine. As each cylinder has one segregated port through which air travels (intake manifold runner and exhaust manifold - header - primary), the non-interference length, internal diameter, surface texture, material and plenum/collector shape and volume are all important factors in creating a competant powerband.
Generally, you can assume a couple things from a physical standpoint that work for most applications: shortening the intake runners gains top end while shortening the non-interference (i.e. length of the primary before joining with any other scavenging path and/or collector) length of the primaries gains you low end. Vice versa, lengthening the intake runners will usually net you more low end and midrange power whereas lengthening primaries in the header caters to a high-revving powerband.
A good example of this is the ITR intake manifold. With a large plenum and short runners, the intake manifold of the ITR works in conjunction with the camshafts to create a powerband that feels solid and torquey all the way to 8500 rpm or so. If you've ever seen the intake manifold on a 2.4L Dodge Stratus motor, as an example of the opposite, the intake runners are incredibly long, granting the engine a more driveable, low and mid-range powerband that's suitable for daily driving.
As far as headers go, primary length shortening increases immediacy of throttle response and torque onset. Lengthening primaries - and keeping them segregated - will shift the powerband (read: peak torque) further up the rev scale and, generally, make the vehicle feel like its pulling harder up top. This works in turbocharger manifolds as well, with a "shorty" or "log" style manifold granting a quick spool, more midrange torque and a generally limited top-end based on the short runners' inability to scavenge efficiently at higher RPM. A "ramhorn" or "Medusa" manifold, on the other hand, increases the lag time down low with the benefit of having a much higher ceiling for maximum power production. Since drag cars generally only have to use the bottom 2/3ds of the powerband at launch, a header or turbo manifold with huge primaries or a tuned length is usually included in the build in order to allow them to be making peak power in the part of the powerband that they spend the most time in.
Any more questions?
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