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Carb to TBI

Discussion in 'Performance' started by AeaRy, Oct 30, 2021.

  1. AeaRy

    AeaRy New Member

    Hey Guys, I am new to Kei-trucks but have been a wrench turner most of my life. Gotta be honest though, my KS3 Sambar is the first carbureted motor that I have ever had to work on. Seems that upgrades would go much easier if there was a way to convert from carbed to TBI. Has anyone attempted or succeeded in this?
     
  2. fletcher0780

    fletcher0780 New Member

    I converted my Hijet to EFI, works pretty well.
     
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  3. AeaRy

    AeaRy New Member

    Yeah, I am thinking more TBI (Throttle Body Injection) which is a type of mechanical fuel injection vs a full re-wire + ECM/ECU addition to go full EFI. It's a nice middle ground that would allow for a turbocharger setup and intake modification.
     
  4. Limestone

    Limestone Well-Known Member

    fletch,
    Please Tell us more what you did, with pics and details!
    I don't remember past posts on this.
    Limestone
     
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  5. fletcher0780

    fletcher0780 New Member

    You're going to have a hell of a time with boost enrichment and boost timing retard if you're relying on a rudimentary control system. Don't be afraid of a few

    Here you go, it was actually quite simple. I have $855 into the conversion and have full spark and fuel control.

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    And all the crap left over:
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    My next step will be a little turbo with a goal of about 75hp, lets see where the weak link is in these engines. I know I can keep my timing and AFR safe, it's just a matter of what those little bitty rods can handle.
     
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  6. AeaRy

    AeaRy New Member

    Man...that does seem pretty easy. My normal subie tuner at MZM here in Austin was recommending a Garrett GT06 or RHB31 for a turbo setup. I guess worst case, if I screw it up I can re-use the Microsquirt on the EN07Y I'll end up replacing the carbed engine with and go SC/TC on it...lol
     
  7. bc_

    bc_ New Member

    @fletcher0780 How's your build doing? I was planning on doing a similar setup with a turbo. What's your duty cycle on the stock injector at the top end? It looks like that Honda throttle body only has a 240cc injector stock which I would think you'd be getting pretty close to the limits on, especially if you try and add a turbo. I see that you can get a 550cc aftermarket from DeatschWerks intended for the CRF450R that uses the same injector as the throttle body you have.

    Calculators say for 3 bar fuel, the 240cc is good for about 40hp and the 550cc would be ~75hp.
     
    Last edited: May 5, 2022
  8. AeaRy

    AeaRy New Member

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  9. AeaRy

    AeaRy New Member

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  10. bc_

    bc_ New Member

    That looks like it comes with a 100lb/hr (1050cc/min) injector, that should be plenty. That's not a bad setup either.
     
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  11. AeaRy

    AeaRy New Member

    Thanks
     
  12. bc_

    bc_ New Member

    That Holley is interesting, are you using it for ignition? You're 4 cyl, but it also only shows setting it up with 4, 6, or 8 cyl, with the Daihatsu 3 cyl we could probably set it up as a V6 and just treat 4,5,6 as wasted spark I would think. The throttle looks interesting on it as well, I see in your picture you have what looks like a bent aluminum bar for a cable mount and an opposing spring connected to something on the IM?

    Just thinking about options, still leaning microsquirt, but I like how it simplifies a lot of things. Significantly less wiring, includes wideband and display out of the box, no 4 wire iacv controller, etc. But I also don't quite understand how it would work with the factory position sensors/timing yet for ignition.
     
  13. AeaRy

    AeaRy New Member

    No, still using OEM coil/distributer for ignition. Spliced into OEM coil/tach signal for timing. Yes, return spring connected to static position on intake manifold just to ensure no stuck throttle. Unsure about a 3 cylinder utilization; would probably reach out to Holley for that particular question if you went that route.
     
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  14. Latka

    Latka Member

    Hey @fletcher0780, did you end up chucking a hair dryer on your setup? Would love to hear how that part went!
     
  15. fletcher0780

    fletcher0780 New Member

    The injector is 400cc, I haven't seen more than about 60% DC at 6500RPM and 100 kpa. I ended up buying an AMR300 supercharger that I have yet to install, but am going to aim for 10psi. The truck has been running solid on MS and the Honda TBI for over a year though, I don't miss the carb one bit.
     
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  16. bc_

    bc_ New Member

    That's excellent news, I've been collecting parts and slowly getting other projects done. I have the throttle body and a few related items, but lately been building bumpers, installing lift, and just driving it. My stock carb is still happy as can be, but it won't be with boost. A little boost would definitely wake this engine up I'd think. I don't need it to be a rocket ship, but some of the hills around here are painful.
     
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  17. AeaRy

    AeaRy New Member

    Boost definitely helps. In the interim I have gotten both a Supercharged KV3 and a Supercharged KV4 Maleza. Running meth/water injection on the stock AMR300 with a catch can/separator just to ensure no blow-by makes it back into the intake. Looking at the possibility of a SLIGHTLY smaller pulley on the 300 to get above the 8psi level it runs. I think an AMR500 might be a bit of overkill, but it with an oversized pulley might be in the future too!
     
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  18. Urbandefender

    Urbandefender New Member


    Do you have the File for the 3-D print? What filament did you use? Thanks
     
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  19. fletcher0780

    fletcher0780 New Member

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