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ok, so i know people have done exhaust cam retard, but has anyone done advanced ???
advanced cam retard
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31,144 Posts
If your not willing to put your Focus on a dyno and adjust the cam gear ( gears ) then dont mess with them
Tom
Tom
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x's 1000%
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theres a shop that said they will dial it in on dyno for me, would i see better low end pull?
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Like many "performance" options & adjustments, this is another case where results come primarily from a change in compromises - gains in one area result in losses elsewhere.
SVT/ST170 was tuned for added power at high rpm, but it also added tech. to improve power across the operating range. Cam timing is a compromise to not favor one end over the other excessively.
Changing timing to favor 'low end pull" is going to reduce power higher in the rev range where more power is produced overall. It's more common to adjust to favor the high rpm end to gain in maximum power available at the cost of some low rpm grunt. (race vs. street)
For your acceleration interests, you'd gain off the line and loose once you get into the high rpm band - the spot you'd be keeping it with each shift once you'd reached it. Short shifting to use low rpm torque isn't generally best for small 4 cyl. engines that could make more power at higher rpm when tuned for that.
You'd probably gain the most by tuning for top end power, just remember that it'll make getting off the line harder than it is now.
SVT/ST170 was tuned for added power at high rpm, but it also added tech. to improve power across the operating range. Cam timing is a compromise to not favor one end over the other excessively.
Changing timing to favor 'low end pull" is going to reduce power higher in the rev range where more power is produced overall. It's more common to adjust to favor the high rpm end to gain in maximum power available at the cost of some low rpm grunt. (race vs. street)
For your acceleration interests, you'd gain off the line and loose once you get into the high rpm band - the spot you'd be keeping it with each shift once you'd reached it. Short shifting to use low rpm torque isn't generally best for small 4 cyl. engines that could make more power at higher rpm when tuned for that.
You'd probably gain the most by tuning for top end power, just remember that it'll make getting off the line harder than it is now.
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Very overly simplistic explanation,
Advance, cam begins to open sooner and closes sooner also
Retard, cam begins to open later and closes later.
Overlap, this is the period when both valves are open slightly. Exhaust retard will increase overlap while advance will lower overlap.
In a low RPM situation, overlap can rob power by pulling good air/fuel out the exhaust.
In a high RPM situation, it can help make power by starting the intake pull sooner/faster.
So as Sailor touched on, many will retard the exhaust because you'll see more peak power from doing so (correctly); not necessarily a nicer curve though.
Advance, cam begins to open sooner and closes sooner also
Retard, cam begins to open later and closes later.
Overlap, this is the period when both valves are open slightly. Exhaust retard will increase overlap while advance will lower overlap.
In a low RPM situation, overlap can rob power by pulling good air/fuel out the exhaust.
In a high RPM situation, it can help make power by starting the intake pull sooner/faster.
So as Sailor touched on, many will retard the exhaust because you'll see more peak power from doing so (correctly); not necessarily a nicer curve though.
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