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?
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.
fletch, Please Tell us more what you did, with pics and details! I don't remember past posts on this. Limestone
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. And all the crap left over: 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.
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
@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.
It's actually fully complete. I went a different direction and used a Holley Sniper EFI 550-552 setup. TB is good for up to 2BAR of pressure, so an AMR500 will be in its future as well. Working on a write up now, but here are a couple links for the build: https://www.facebook.com/customautoatx/posts/114147151229248 https://www.facebook.com/customautoatx/videos/543985620389341/ https://www.facebook.com/customautoatx/posts/109891818321448
That looks like it comes with a 100lb/hr (1050cc/min) injector, that should be plenty. That's not a bad setup either.
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.
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.
Hey @fletcher0780, did you end up chucking a hair dryer on your setup? Would love to hear how that part went!
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.
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.
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!
I used PLA, then painted with engine enamel, holding up so far. https://drive.google.com/file/d/1NMdsEXUOYZYFy466yQC3Ox5xsp0hwh5y/view?usp=sharing
Update: the 3d printed part finally succumbed to heat and fuel, I ended up having the part cnc'd online out of 2014 aluminum for $132. at the same time I upgraded to a 60lb/hr injector: https://siemensdeka.com/product/60l...ort-style-with-ev1-connector-fi114962-37-5mm/ to give me boost headroom. With the AMR300, I dyno'd at 70HP to the wheels. I gutted a 2nd throttle body, filled the injector and IAC ports and added it pre supercharger, then Y'd the throttle cable to both. I used a VW style recir valve after the throttle body vented to atmosphere to ven pressure when throttle is closed. Truck is far more driveable now.
Even though it's an older thread, it's good, fletch, that you came back and let everyone know what you're experience was with you're homemade part, and what happened and how you resurrected it. This thread can be very help full for others as it already has been. IMHO! Limestone
The 5th gen Supercharged Sambars come with an AMR300. The later 6th gen models used an AMR500 with a bigger pulley to slow it down and make essentially the same amount of boost. Subaru did have to come up with a different mounting/piping arrangement to allow for the physically larger supercharger though.
Did a little poking around. These aren't "gospel truth" measurements, but what I've found online. Would love to have one of each on my desk to measure! AMR300 17.5 cm wide 10.5 cm tall (6 ⅞" wide, 4 ⅛" tall) AMR500 23.5 cm wide 23c cm tall (9 ¼" wide, 9 1⁄16" tall) A ChatGPT inspired visualization of the size in centimeters: and in inches: I'm sure there are very valid reasons that Subaru went with the AMR500 and spun it slower. I'm looking for maximum angry bee noises!
I believe the reason was that Aisin stopped making the AMR300 in favor for the AMR500. The dimensions are not really the problem since there is plenty of space around the earlier models, but since the AMR500 moves more air per revolution, they had to slow it down to compensate.
Ok, I'm falling into a rabbit hole here. AMR300 Estimated Mechanical Efficiency: 40-60% (Middle would be 50%) Boost pressure: 5 - 10 psi (I used 10psi) AMR500 Estimated Mechanical Efficiency: 50-65% (Middle would be 57.5%) Boost pressure: 5 - 15 psi (I used 10psi) Then I did more snooping and found the compressor temperature rise equation (*More ChatGPT assisted tomfoolery!) Where: T2T_2T2 = Outlet temperature (in Kelvin) T1T_1T1 = Inlet temperature (in Kelvin) P2P_2P2 = Outlet pressure (absolute pressure in Pascals or bar) P1P_1P1 = Inlet pressure (absolute pressure in Pascals or bar) γ\gammaγ = Specific heat ratio (typically 1.4 for air) ηc\eta_cηc = Compressor (mechanical) efficiency as a decimal To start off, I chose 75 degrees Fahrenheit (23.9 C), 10 psi for both, and used the middle of their estimated efficiencies: AMR300: 259.6°F AMR500: 232.3°F I am currently running an EN07C. I am most likely going to change over to fuel injection with a Megasquirt. When my truck left the factory, at the crank it was rated at 38.8 hp. The estimated power increase at the engine (crankshaft?) (I guess in magic, magic land we can do this): AMR300 @ 10 psi: 65.2 hp AMR500 @ 15 psi: 78.4 hp Just for giggles, I redid the same calculation, but with the AMR500 pushing 15 psi of boost. AMR500: 298.7 °F ...and, good god I just spent the last 45 minutes trying to figure out how to ...figure out the size of intercooler needed. This rabbit hole is big. My guess is that I should probably aim for an easy starting point like 7 psi of boost: AMR300: 220.5°F AMR500: 201.5°F (Dang, those temps came down an appreciable amount.) Man, there is SO much to learn. This is gonna be fun though.
For what its worth, the stock Supercharged engine does not have an intercooler, it just dumps hot air right into the engine.. lol. Stock pressure is somewhere around 0.5 to 0.6 bar, so about 7 or 8 PSI.
Yes sir! At least...in our truck world I've got all sorts of dumb ideas to spend lots of money to find the weakest link in the engine / transmission. Honestly, this whole quest started because 38 hp does not get me up and over the hills here at a reasonable rate. Should I have bought a supercharged Sambar and a Classic front and called it a day? Probably.
You could live you're life, "Shoulda Coulda" , but instead you're trinig to improve you're unit as these little things, like you said @ 38 hp, Don't want to get with the program and hills! Limestone
The acceleration is totally acceptable on “my side of the island” but as soon as I chose any of the ways across the island (3 of 4 realistic ones) I run into the 4th gear, foot to the floor for like 5+ min, 40 mph @ 5,000 rpm+ world. Yuck.
