Mechanical vs Vacume secondaries
12-18-2009, 09:34 PM
#4
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
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.
01-02-2010, 04:00 PM
#5
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
+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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