Mechanical vs Vacume secondaries
5th Gear Member
Joined: Jan 2006
Posts: 3,926
From: Puerto Rico
Vacuum secondaries are great when you have an auto street setup and some are adjustable. When the balance tilts towards strip (and there are also ways to maintain streetability) a DP setup is adjustable for real fine tuning under either conditions.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
+1
Mechanicals are easier to get better throttle response out of also(that 2nd accel pump makes a huge difference). With a vacuum sometimes you have to open the secondaries slower than you would otherwise, to account for the lack of a 2nd accel. pump, so you get shorted for performance by feeding the engine air more slowly than it could tolerate if you're able to add the fuel needed when you WOT.
Vacuums are good for auto cars with real tight converters, like a factory converter.
I run a mechanical on my driver, and I can WOT in 5th(manual) at 1,500rpm or less with 0 issue. Obviously it doesn't pull hard, but no hesitations, no stumbling.
Mechanicals are easier to get better throttle response out of also(that 2nd accel pump makes a huge difference). With a vacuum sometimes you have to open the secondaries slower than you would otherwise, to account for the lack of a 2nd accel. pump, so you get shorted for performance by feeding the engine air more slowly than it could tolerate if you're able to add the fuel needed when you WOT.
Vacuums are good for auto cars with real tight converters, like a factory converter.
I run a mechanical on my driver, and I can WOT in 5th(manual) at 1,500rpm or less with 0 issue. Obviously it doesn't pull hard, but no hesitations, no stumbling.
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