Bridge port EFI and mpg
#1
Bridge port EFI and mpg
What kind of mpg can a 13b bridge port get with ITB and fuel injection ? I know that I shouldn't think of fuel consumption with a Bridge port but we are considering fuel injection over a weber carb for a friends rx7 1st gen as he drives it more than once a week.
Thanks
Thanks
#2
Sharp Claws
iTrader: (30)
it really depends on the ECU and how well you can refine the tune, i've seen some claim over 20mpg still with a bridge but most usually get in the 16-18mpg range on the highway, in town forget about it.
the issue is mainly with the MAP sensor signals being extremely spikey and AFRs all over the place. a carb can do the just as well if you can tune it, i've thrown together a few n/a bridges with holley carbs that ran further on the highway than some of the turbo FI cars.
the issue is mainly with the MAP sensor signals being extremely spikey and AFRs all over the place. a carb can do the just as well if you can tune it, i've thrown together a few n/a bridges with holley carbs that ran further on the highway than some of the turbo FI cars.
Last edited by RotaryEvolution; 04-12-14 at 08:32 PM.
#3
Old [Sch|F]ool
Depending on the weather, 18-29mpg highway. Weather is a very large factor, the hotter it is the better the fuel economy is. I can generally expect 25mpg under normal conditions.
That is highway driving. In city driving, I get maybe 2-5mpg. I do very little city driving so this does not concern me. Cold start and idle are economy killers.
I drive the car maybe 600 miles per week plus regular 500-700 mile weekends, averaging about 20k per year. Fuel economy IS a major concern for me, since the less fuel it uses, the more I get to enjoy the car.
I have a slightly larger than "homologation" bridge port on the secondaries (appears to be the same port window as Racing Beat sells... heck they probably developed it for Mazda ) and due to the tiny primary ports I have to run, the primaries are slightly smaller but the eyebrows are still the full height of the port runner.
My throttle body is an old Holley 750cfm vac-sec carb (the ubiquitous 3310) that I milled the choke horn off of and modified for 1:1 mechanical secondaries. Bodged a TPS from a 2-valve Ford 4.6 on the side where the choke linkage would go. Vacuum signal for the EFI (I run speed-density, not alpha-N) comes from the port under the primary fuel bowl, and the signal is cleaned up with a restrictor orifice I made by gluing a piece of carb cleaner straw into a vacuum connector. It's still a little bouncy but nothing severe. The engine's bouncy anyway
That is highway driving. In city driving, I get maybe 2-5mpg. I do very little city driving so this does not concern me. Cold start and idle are economy killers.
I drive the car maybe 600 miles per week plus regular 500-700 mile weekends, averaging about 20k per year. Fuel economy IS a major concern for me, since the less fuel it uses, the more I get to enjoy the car.
I have a slightly larger than "homologation" bridge port on the secondaries (appears to be the same port window as Racing Beat sells... heck they probably developed it for Mazda ) and due to the tiny primary ports I have to run, the primaries are slightly smaller but the eyebrows are still the full height of the port runner.
My throttle body is an old Holley 750cfm vac-sec carb (the ubiquitous 3310) that I milled the choke horn off of and modified for 1:1 mechanical secondaries. Bodged a TPS from a 2-valve Ford 4.6 on the side where the choke linkage would go. Vacuum signal for the EFI (I run speed-density, not alpha-N) comes from the port under the primary fuel bowl, and the signal is cleaned up with a restrictor orifice I made by gluing a piece of carb cleaner straw into a vacuum connector. It's still a little bouncy but nothing severe. The engine's bouncy anyway
#4
Senior Member
iTrader: (1)
A guy on the dodge neon forum had great success using this to get a good vac signal.
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www.neons.org • View topic - ITB's rule the world
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