The motor question took me longer than almost anything else on the build sheet, and what ended up on the contract is a Honda 350 outboard, a Honda BF350AUDA with the 30 inch shaft, hanging off the back of a Raider Coastal 230. I've been reading about this engine pretty much nonstop since February, and I got a short animated explainer made that shows how the thing is put together, so I figured I'd put the video and everything I've picked up in one place for anybody else looking at the same motor.
Why one Honda 350 and not twins
Twins were on the table for a while, I'm not gonna lie, cause there's something about two big outboards on the back of a boat that just looks right. Kylo Matlock at Selkirk Marine talked me through it though, and his take was that a 230 doesn't get the same benefit from twin outboards that a longer 250 does, so go with one big Honda 350. That's not what a guy trying to upsell you says.
So I went with the single and let the Kraken trolling motor and the second station handle the slow stuff a kicker would have done, which is all on the Decisions page if you want the longer version. Part of it goes back to the Sea-Doo too. After that whole stump and airboat situation, which I wrote up in Who I Am and Why I'm Doing This, I wanted something tough and simple more than I wanted something flashy. I'm sure people will argue single versus twins at every ramp on the Cumberland forever and that's fine, I just know who I asked and what he told me.
What the Honda BF350 is
Honda calls the BF350 its flagship outboard, and it's built around a 5 liter V8 that Honda designed just for it. Per Honda Global it's the first time Honda has put a V8 in an outboard. Displacement is 4,952 cc, which is 302 cubic inches, and it's rated at 350 horsepower at 5,500 rpm with a full throttle range of 5,000 to 6,000 rpm, per Honda's technical specifications.
It's a four-stroke SOHC 60 degree V8 with 32 valves, an 89 mm bore and a 99.5 mm stroke, a 10:1 compression ratio according to the BF350 brochure, and a 1.79:1 gear ratio. The Honda Marine product page lists VTEC, lean burn with oxygen sensor feedback, and 86 octane fuel, so regular gas, which I'll admit made me happier than it probably should have.
The video
This runs 2:38 and goes through the size, how the V8 fits in the cowl, the power, how it comes apart and how it turns the prop. Click any chapter under the player and it'll jump right there.
Original 3D animation with an AI-generated voiceover. Internal proportions are approximate and every spec comes from Honda.
How it's built, the parts I thought were cool
The bank angle is the one that got me. Most car V8s run their cylinders at 90 degrees, but Honda went with 60 degrees on the BF350 to keep the motor narrow enough that people can hang more than one on a transom. The catch is that with a 60 degree bank the usual crank layout would need a balancer to cancel out the vibration, so Honda used a 60 degree crank pin offset that cancels it without one. That gives you uneven firing intervals, and Honda says it actually spreads the engine noise out and makes it quieter, and since every cylinder breathes a little different they gave each of the eight cylinders its own fuel injection map. The crankshaft is made from the same high-strength material as the second generation NSX crank and gets twisted after forging, before it cools, which is a sentence I never thought I'd get to write on a boat blog.
There's a bunch of practical stuff too. The oxygen sensor sits at the top of the cylinder head, and Honda kept the exhaust and the cooling water in separate channels down to the top of the gearcase so the sensor doesn't get soaked. It has four water intakes instead of two, so one clogged port isn't the end of your day. It runs two throttle bodies side by side, and Honda says it can keep making power on one if the other acts up. The gearcase is about the same size as the one on the BF250 even with the extra horsepower, and the alternator is rated at 93 amps total with 70 amps for battery charging, which matters with all the electronics on my build list. All of that is on the Honda Global tech page and the V8 design page if you want to go deeper than I did.
Size and weight on a Coastal 230
The overall width is 650 mm, or 25.6 inches. Honda's Japan marine catalog lists the overall height at 2,272 mm for the 30 inch U shaft and 2,145 mm for the 25 inch X shaft, with a length of 1,120 mm. Dry weight without the prop is 776 pounds for the 30 inch U and 765 pounds for the 25 inch X, and the recommended transom heights are 25 and 30 inches, all from the brochure. Mine is the 30 inch, so that 776 number is the one I care about, and it's a lot of motor to hang off the back of any boat, which is part of why I wanted a welded aluminum hull built for it. I went into that more in aluminum vs fiberglass and the Raider Boats review.
What Honda doesn't publish
I went looking for a torque number and a firing order and couldn't find either one from Honda. The only thing Honda says about firing is that the 60 degree pin offset gives irregular interval combustion, so I'm not going to guess at the rest. You'll also see dual stage induction show up on some spec lists, but Honda only lists that feature for the BF135 through BF225, so I left it out.
About the animation
The video is an original 3D animation made for this site, and the voiceover is AI-generated. The model is a stylized illustration, so the internal parts are close but not exact, and the overall dimensions and every spec on screen come from the Honda sources linked above. It isn't made by Honda or affiliated with Honda in any way, and Honda, BF350 and VTEC are Honda trademarks.
FAQ
How much does the Honda BF350 weigh?
Honda lists a dry weight of 776 pounds for the 30 inch U shaft and 765 pounds for the 25 inch X shaft, without the propeller, in the BF350 brochure.
How big is the engine in the Honda 350 outboard?
It's a 60 degree SOHC V8 with 32 valves and 4,952 cc of displacement, which is 302 cubic inches, rated at 350 horsepower at 5,500 rpm per Honda's specs.
What fuel does the Honda BF350 use?
Honda lists 86 octane on the BF350 product page, so regular unleaded.
Does Honda publish torque or a firing order for the BF350?
Not in any Honda source I found. Honda says the 60 degree crank pin offset gives irregular interval combustion and leaves it there.
