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Discussion Starter · #1 ·
Hey guys, am starting a fresh build and have a few ideas that I wanted to bounce off the community.

The project is to build a 16ft aluminum jet boat powered by a k24z3 and turbo with a southern 8.25" . I will likely go with aem infinity and dyno tune on my local engine dyno. The goal is to build a solid and reliable 350-400 ft-lb power from 3000 to 6000 rpm. Tell me if I am off on my ideas??

Engine will be from local wrecker from a low mile 2009 TSX, I have read these have stronger rods and I like the common exhaust manifold. I will fabricate an adapter to mount the turbo as tight to the engine as possible. Lots of room for the turbo and piping.

Turbo, need to find an experiences turbo builder that can help me specify this to get the torq curve needed for the pump

ECU, I have been tuning my turbo mustang([email protected]) for years with AEM tuner, but the infinity is quite different. I have lots of questions relating to vvt and safe timing numbers.

So, my first question; Is the k24z3 the best choice for engine platform? Or should i consider something else?
 

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96 civic HX K24a
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Hey guys, am starting a fresh build and have a few ideas that I wanted to bounce off the community.

The project is to build a 16ft aluminum jet boat powered by a k24z3 and turbo with a southern 8.25" . I will likely go with aem infinity and dyno tune on my local engine dyno. The goal is to build a solid and reliable 350-400 ft-lb power from 3000 to 6000 rpm. Tell me if I am off on my ideas??

Engine will be from local wrecker from a low mile 2009 TSX, I have read these have stronger rods and I like the common exhaust manifold. I will fabricate an adapter to mount the turbo as tight to the engine as possible. Lots of room for the turbo and piping.

Turbo, need to find an experiences turbo builder that can help me specify this to get the torq curve needed for the pump

ECU, I have been tuning my turbo mustang([email protected]) for years with AEM tuner, but the infinity is quite different. I have lots of questions relating to vvt and safe timing numbers.

So, my first question; Is the k24z3 the best choice for engine platform? Or should i consider something else?
It sounds like you have chosen the correct engine. Easy turbo manifold fabrication, low-ish rpm/power goals. You don’t want to take those past 7400 rpm or so but with a turbo it should make peak torque pretty early in the powerband and a lot of it. And if you do pop it they are pretty common engines to replace as not many use them for swaps.
 

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Discussion Starter · #4 ·
It sounds like you have chosen the correct engine.
Thanks for jumping in. After posting in this sub-forum i was worried it wouldn't get noticed.

With the engine driving a pump, I doubt it can make enough power to spin the pump past 6500. (HP demand increases exponentially with a pump)

What are the limits on power downlow with this block? Most folks aren't trying to make tq at 3000 as they will be spinning tires or snapping trannies and shafts, so i dont see too many examples to look at. If it is able to make more on stock internals i will go for it.
 

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Thanks for jumping in. After posting in this sub-forum i was worried it wouldn't get noticed.

With the engine driving a pump, I doubt it can make enough power to spin the pump past 6500. (HP demand increases exponentially with a pump)

What are the limits on power downlow with this block? Most folks aren't trying to make tq at 3000 as they will be spinning tires or snapping trannies and shafts, so i dont see too many examples to look at. If it is able to make more on stock internals i will go for it.
I don’t know anything about the pump driven stuff 😅
Looks like with a 5858 tq is a bit later than you’re looking for but it looks like they respond to boost well. You can go to 500-600 or so on a factory k engine but it’s basically a time bomb on when it will go.maybe a year, maybe tomorrow lol
 

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Discussion Starter · #9 ·
Thanks for the video link. I like the looks of that manifold. I will need to build one a little more compact to reduce heat soak into the engine bay.
 

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Here are what the 3 major marine motors are putting down for torque and horsepower.

2.3L Eco Boost
105429



5.3L Kodiak Marine Engine
105430


6.2L Kodiak Marine Engine
105431
 

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Arouse the DAMPFHAMMER!
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Tell me if I am off on my ideas??
With an healthy stock engine and right turbo setup this is achievable.

So, my first question; Is the k24z3 the best choice for engine platform? Or should i consider something else?
My counter-question would be why a 99 mm stroke engine, when the 86 stroke engine is more reliable on boost and enough for this task?

I have lots of questions relating to vvt and safe timing numbers.
I have tuned engines on 15+ different ECU's, the Infinity is a princess, but when you know to handle it, it is one of the most flexible ECU's on the market, in it's price class it is not beatable regarding flexibility. How do you guarantee the ECU can stand the water? The Infinity has no IP certification, nothing I would test also. How do you get the harness waterproof? Housing which is waterproof?

Turbo, need to find an experiences turbo builder that can help me specify this to get the torq curve needed for the pump
Not really a need if you go through all relevant threads here. But anyway I could help you, as I am a race engine designer, builder and tuner.
 

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Arouse the DAMPFHAMMER!
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Which engine is 86mm?
K20A, K20A2, K20Z1, K20Z3, K20Z4. All these have one in common, all have the iVTEC for performance. All should have oil squirters, performance heads, 11.0:1 CR (except K20A), forged crankshafts, best cams for turbo applications and we all have seen 350-400 ftlb's on turbo applications with stock longblocks, stock IM and E85, a few do this also with gasoline.

My favorite example: (1) Another 600whp stock block K20 | Honda / Acura K20a K24a Engine Forum
 

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Discussion Starter · #16 ·
Not really a need if you go through all relevant threads here. But anyway I could help you, as I am a race engine designer, builder and tuner.
excellent! You sound like a good friend to have.

Do you think we can build more power that the marine examples above?
 

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Arouse the DAMPFHAMMER!
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Do you think we can build more power that the marine examples above?
A friend and I am building a 1200 hp 2-Liter VAG engine for a drag application. If VAG is able to do that, Honda K-series can double this ;). Serious, the stock parts has limits regarding forces, like forged aftermarket stuff has it, the later has just a higher limit.

From one of my jobs, the one at MTU (oldest series production engine company of the world), where we built also engines for boats, yachts, vessels, ..., I know those engines are not allowed to fail to pull that boat safely home. Therefore I wouldn't test limits on a boat application with an K-series. If you budget includes implementing forged and proper designed rods and pistons I would assume 1000 hp is not a problem as long as sea water cooling is allowed for intercooling. The challenges are knock, vibrations and shocks when the boat jumps on higher velocity and maybe fuel tank volume :D. Ethanol or EXX fuel helps massive on the knock side when mpg should in a serious area. Vibrations and shocks are a design question to challenge. There are a lot of more questions to solve, but these are the ones I would row first for now.

How does the drivetrain looks like?
 

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Discussion Starter · #18 ·
How does the drivetrain looks like?
that is the beauty of jet boat. No clutch or weak transmissions to worry about. Once I have the engine dyno’d I send the dyno graph off and they will spec the pump to handle it.

I will take a closer look at the k20 engines. I figured the newer motors with more displacement is better.🤷 but that is why I am here. Lots of info on this forum!
 

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Arouse the DAMPFHAMMER!
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The issues with the 99 mm stroke engine are: higher side forces at the piston due to the low rod-stroke-ratio, the long rod, which can more easily bend and the higher vibration level which makes external weight's like the turbo more risky for leakage and so on. I see the scene is diving into boosting stock 99 mm blocks with 700 to 800 whp. This is really dyno queen stuff and not reliable in a boat application as the load at higher speeds is much different. Torque demand oscillates in water, causing a lot of torsional vibration stuff, which is much more challenging for a long rod/long stroke setup as for a more compact crank assembly. This is no street use, where torque oscillates much less. Water can be a real bitch when the boat jumps over little waves at higher velocity and the torque at the drivetrain follows directly the friction losses over time at the boat: when in air and when in water. Also the diving depth of the propulsion component isn't constant, causing also differences in torque demand in oscillating manners.
 
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