Im thinking about going injected(hat style). I love the way these things look. What are the pro's and con's? What style fuel pump do you have to run? Can you run the clay smith pump?
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The plumbing for a hat on any cruising deal is the biggest problem in set up.
You need a T or Bullet tank fed by a standard block or electric pump and the mechanical pump for the hat. I set mine up with a bock pump to fill my bullet tank, the Enderle pump crank driven and a tiny electric pump that feeds a solenoid for a single start nozzle.
You will need bypass lines from your bullet or T tank to dump excess fuel back to your side tanks also.
How they run on gas on a lake boat ........from what I've seen, is nearly unusable. Bring along plenty of rope because you're going to be towed a lot.
That's why most guys run them on alcohol. The lack of tunability is not as noticable with a fuel that requires that much volume.
Good injection system for a trailer queen boat though.
Consider the tuning challenges.
To produce a proper 14.5:1 fuel mixture at idle with EFI on gas takes aproximately a .002 sec injector pulse on the intake stroke which is every other revolution. That's a fraction of a drop.
With a mechanical system, When all the injectors are flowing fuel 100% of the time, how could you ever get the injected fuel quantity down to match that ? It's impossible. They end up with a sloppy rich mixture that has actually subtracted HP rather than added it. I've seen it many, many, times.
Let the bashing begin !!!!!!!!!!!!!!!
Try changing the pill, I know it's a huge pain in the ass, takes at least thirty seconds. Then there's that damn barrel valve adjustment and idle speed, another 45 seconds or so.
Having Enderle set everthing initially is the trick or at least someone that understand injection.
I have four other friends runing injection, 3 hats 1 stack with zero issues.
The plumbing was a pain in the ass getting the returns and venting right since I'm feeding a bullet tank from two side tanks.
Tuning photo attached, not on the trailer.
Almost forgot, the throttle response is worth it alone and I have no issues having to peddle it with two springs on the linkage.
Last edited by 500BBC; 02-03-2009 at 12:01 PM.
There are companies that convert a mechanical FI to electronic FI... Fully programmable, just a thought
What you see are guys that throw the hat on there.....throw the pill and bypass that Enderle said to START WITH (which means fat....never burn your customer down) and expect it to be a turn key operation.
Don't put a MFI system on if you don't intend to tune it to get it right. When you understand it you find it is simple as hell.
This thread was specifically asking about MFI on gas and that would be way more of a tuning challenge considering the small volumes of fuel required to get a usable A/F ratio. I don't believe it's possible to get a consistently accurate A/F ratio over the whole rpm range that a lake boat gas engine runs in.
An accurate A/F ratio would be near stoich at idle and a light load cruise speed and richen up to 12:1 on hard accelleration. At best the MFI would be rich all the time as there is no means to sense load.
I would like to see a datalog of an O2 sensor on a MFI gas engine.
I want to say FAST makes an EFI hat. All the cool oldschool looks, w/ modern tunability.
With all due respect Mark. After switching all my stuff to injection I would never go back to carbs. I was told over & over & over it would never work on the GN. That was a few years back. My jet boat runs clean, starts right up (other than smoking a starter or 2, not the fault of the injection) As far as tuning they are a sweet heart to work with. 1 pill, a bypass spring & some shims for good transition, a tickle of the barrel valve & thats about it. It takes a little patience's & some help from a knowledgeable source & from there its happy sailing. Also I run mine on gasoline only.