Is there anybody that doesn’t like a triple butterfly thing?
Not that I'm aware of!
Might be a dumb question, but what's holding you up with going EFI?
I was thinking the same thing. Mechanical injection works decent in certian applications but the tunability of an EFI system is pretty hard to beat.
While I've been extremely happy with how the Holley system works on the buggy, & I really like the tunability, along with datalog capabilities associated with EFI, there are some drawbacks when you're trying to keep a system as simple as possible, (multiple large fuel rails, filters, possibly pumps, an ECU of some sort, complicated wiring harnesses, etc) I realize that EFI can too be simplified quite a bit, but, at that point what are you really gaining,
No matter your fuel management of choice, a certain amount of fuel is required through the blower to cool it, that is usually better than 50% of the fuel going into the engine, & every EFI system I've seen in that application is a half dozen or so large injectors dumping fuel into the blower inlet, no different than MFI, a lot of EFI systems will have another injector in each manifold runner to fine tune each cylinder, (also done with MFI port nozzles) after all that how are you going to log & tune each cylinder? probably the same way as MFI.
Overall I do feel mechanical fuel injection is more robust, & more reliable.
Here's the link to the latest YT vid, it might be worth watching before reading this post, or maybe even re-read the post after watching the video,
It's kinda long, but I was trying to make sure I covered the basic stuff well.
I did get to mess with the truck thursday & part of Friday before going to the MT show,
After talking to a couple folks about tuning I decided to try going with a non staggered set of nozzle in the hat, (rather than .058-.056-.056-,050 front to rear, I installed .054-.054-.054,,,, eliminating the rear nozzle all together, this was just a test to see if I could get less fuel to the rear cylinders,
I didn't get any video, but I did end up bench testing the whole system, just so I could see with my own eyes what was going on,
I was surprised to see how much fuel can get through a little slot in the barrel valve spool & flow through all of the nozzles, even at a meager 5 PSI.
After again resetting the barrel valve I reassembled everything, & fired up the truck, then began leaning the the barrel valve out until the rear cyclinders started making heat,,,,,& still the front cylinders were at 900* on the pyrometer,
After shutting the truck down I checked the leak dwon on the BV & found it was back to where I had started, exactly,,,,Which I wasn't terribly surprised, the only way to control the amount of fuel getting to the engine is the idle poppet, & the barel valve setting, since I didn't change the poppet pressure setting much, I wouldn't need to change the BV much either, the actual nozzle difference wouldn't make any difference until more flow was allowed through the BV at a higher throttle input,
I was a bit surprised that eliminating the rear nozzles completely made little to no difference, this is kind of telling me that the blower is simply directing the majority of the fuel to the back of the manifold, at least at idle,
I did have a conversation with a fellow that tunes a top alcohol funny car, he says that he fights with this scenario quite a bit, & he suggested I go back to using the port nozzles (for tunning later) & then add "dribblers" to the system, a dribbler is simply a second nozzle added to the ports of the hot cylinders, those nozzles are also fed from the hat distribution block so they are functioning at idle, The cold cylinders can be leaned out, then find the correct nozzle size to bring the hot cylinders, or cylinders down to match, once the correct nozzle size is found that jet area is figured into the overall tuneup, (Most of the above would be simple to do with EFI, but it is certainly not hard to do with MFI,
So, since we were going to be driving right by Summit racing, I stopped by & grabbed a couple fittings to build 4 dribblers for my front 4 cylinders.
The easiest, cleanest way I could see completing this setup (without removing the manifold & drilling/tapping more holes) was to tee into the current port nozzles,
I started with a #3 AN female to #3AN male fitting with an 1/8 NPT port in the side, then adapted the port down to 5/16 fine thread, this is the thread an Enderle nozzle fits,
In the above pick you can see the change in threads towards the bottom of the threaded port,
Basically the female swivel threads will fit the current port nozzles in the manifold, & the feed line for that nozzle will attach to the male AN threads, then another, smaller nozzle will thread into the new adapted thread, the feed line to that nozzle will come from the hat, allowing a small amount of fuel to "dribble" into it's associated port.
I'm going to go into more detail on all of the port nozzles & dribblers when I do the MFI part 2 video,
Currently I am waiting for the small nozzles, & parts to build the feed hoses, all of that should be here this week & I can get back to tuning this weekend,
As far as monster trucks went,,,, the truck I was supposed to drive was taken off the schedule, Since we were already there Jerrod was pretty adamant that I drove his truck, I told him I would for the first show, & we'd see for the second, unfortunately his truck was having an electrical issue, that was causing the truck to cut out, almost like shutting the ignition off, then turning it back on again before the engine dies, It's seemed as though the the problem got worse through the day,
Still, I went a few rounds in racing, & had a good time in freestyle, until Jerrod shut me down due to smoke from oil getting on the header, I was done anyway since I could tell the front axle was no longer pulling, that turned out to be the drop box yoke on the front output had a bolt come out, letting the yoke slip off the shaft, a relatively easy fix, for the second show the electrical problem was getting worse, even still I was putting a good run on one of the big trucks in the first round of racing, right up until I clipped a course tire, tipping the truck up on two wheels, I had to abandon going for the win & do my best to drive out of a roll, fortunately no fiberglas was damaged this time,
I pulled off the track & handed the truck back over to the owner for freestyle, unfortunately the electrical gremlin was done playing, so the truck was too, I feel pretty bad that Jerrod didn't even get to drive his own truck this weekend, but, like he said, "I get paid the same either way"
I believe I mentioned earlier that Jerrods truck is a two seater, probably the best part of the weekend was the fact that every time I was strapped in the truck, Allison was strapped in the back seat, freestyle & all, She absolutely had the time of her life too, It was a great weekend.
I'll try to post up a couple clips from the day on here.
monstertruck.fandom.com
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