LS Swap Seafari 25

[FishStretcher]

I can only offer you a modest amount of guidance based on experience with other engines.



I did a fair amount of cooling work on Rotax 912 IS sport 100hp 4 cylinder aircraft engines. These were liquid cooled heads, but air cooled cylinders. And an oil cooler.



Crucially, they can operate for a long time at or near full power, like a marine engine.


For a 100HP engine (metric HP, but close enough for what we are discussing here) they were rated at 73.5kW for 5 minutes or 72kW continuous


Go to flyrotax.com and look for the installation manual for details: d06847.pdf


They required 30kW of liquid cooling, 6kW of air cooling and 10kW of oil cooling for takeoff. Takeoff is the worst condition, especially for oil cooling because of this highest engine speed.


In my experience, this air cooling was largely unneccesary except at above 80% power.

So, if we think the GM 5.3 is more efficient than a Rotax 912 iS Sport, and it probably is, then an estimate would be 30kW of water cooling 6kW of air cooling and 10kW of oil cooling for every 100HP at the crank.


So for the estimate: for every 100 metric HP you make 73.5kW shaft power and need 46kW of cooling.

Again, the 5.3 may make less heat, it's a modern engine.



You say you cam make 400HP. That's at WOT, at maximum engine speed. Power requirements are very approximately related to the cube of speed. So at 80% speed, you will need very approximately 51.2% power. (and heat rejection). Or 200HP.


So at 80% speed at 200HP, you need 2x(30+6+10)kW cooling. Call that 92kW heat rejection.


You have 350,000BTU/h heat rejection. My online calculator and a couple of references make me think this is 102.5kW.



So. For a first guess- I think you might overheat running at full throttle at full engine speed. But you are probably fine for almost all operation.


This is just a guess- a slightly scientific guess with a reference, but just a guess. You could be OK at all speeds. I don't think this is a terrible place to start for cooling. But it doesn't seem overcooled.


Remember, this is just an opinion that you got on the internet, using a different engine as a benchmark.

[Xcomunic8d]

EDIT: a plate to plate will not work. Much, much more cooling required. Do NOT attempt


It has occurred to me that I made an error in telling you it will only be 350k btu’s. That’s the main heat exchanger however there will be additional 50k (25k for power steering and oil each). So I’ll try to figure out what that looks like.

Heat soak is also a concern. I plan to have a bilge vent blower on the bilge exhaust side keyed to ignition so it pulls hot air out of the compartment and should draw cooler air in naturally. This blower is not to be confused with another blower I will install for venting gas fumes.

Thanks for doing all this math. There really is only one way to find out for sure. It will have a ps cooler and an oil cooler.

If needed a bigger exchanger is not the end of the world. But we will see. I’ll get up on plane and get going fast on rare occasions but majority is high speed trolling. 13mph. Give or take conditions.

[Xcomunic8d]

So it’s been a lot of hurry up and wait here. Not sure I posted this but all 3 of my kids tested positive for COVID. And per Hawaii law, all of us (me, wife, and kids) were quarantined for over 20 days.

Wiring-

I did end up getting a LS1 stand-alone harness. I couldn’t find a gen 4 stand-alone. Turns out the 2008 was an oddball Ls due to connectors etc.

https://www.ebay.com/itm/313583141284

I did have to cut off and replace the ev1 to ev6 injector connectors. From old harness. This was free for me. I’ve read mixed reviews on adapters and this way it’s permanent.

The map sensor I had looks compatible but if you do this double check that
I did have to order some older style O2 sensors denso 234-4337
The coil brackets, coil harnesses, and coil harness extenders have finally come in this week. Took about 3 weeks to get those. And the flexible oil dipstick says oct-nov to arrive.

My harness came with compatible parts id’s. I ordered a maf sensor. Will probably need an ait sensor as well.

My pcm came in from lt1swap.com Brendon was great and super fast to work with. very close to being ready to start this.

Must have a ligenfelter trg-002. The Holley terminator x’s are still not in stock.
Need a 4pin to 2 pin alternator connector. I’ve thought about wiring it up myself but still reviewing harness diagrams. I do have a resistor here and maybe I can make that setup work. We’ll see. The ict billet 4pin to 2 pin waalt30-6 is only $30.

Will be ordering gauges soon. Think I’ll be going with Faria Chesapeake in black.

https://www.boatid.com/faria-beede-i...iABEgJ8SPD_BwE

And need fuel system. Mainly a pump. Anyone have suggestions for inline fuel pumps? I’m thinking about an inline pump from summit and keeping an evil energy from Amazon onboard as a backup.

It’d be pretty pricey to put in tank pumps in and really a pain if they failed.

[wattaway2]

Glad to here your out of quarantine and since you didn’t add anything I assume everyone is doing well!? God help anyone else that might try and work on it down the road😀but sure sounds like you’ve got it figured out! Hope the Lava isn’t a issue . My step daughter in Capt. Cook is ok

[Xcomunic8d]

I’m never parting with this boat. I hope I’m happy with performance. Family is all aok. The lava is all in the volcano park a good bit away. A few years back it was flowing and within 10 miles of me.

I live in HPP. You step daughter should know where that is diagonally NE from her to me roughly. Rainy season is starting here I got to get a cover up ASAP.

[Xcomunic8d]

I put another order in with summit

This ones for the fuel pump, ligenfelter converter trg-002, 4 pin to 2 pin alt harness, and msd custom plug wire kit.

That’s gonna get me really close to firing it up. I need to order some gauges, fuel hoses, regulator, and some other stuff but nothing too major left on the engine.

I can’t wait to fire it up, or at least try to. I’m sure I’ll have some issues to work out.

[wattaway2]

It’s a boat OF COURSE. There will be issues——-lol
Amazon must be a God send over ther, we wanted metal cooler cups for our vacation but didn’t want to drag them there in the baggage looked and had them ship a 4 pack there thru Amazon for like $26-28 then left the set for her there, no issues with what do you have in the bag?

[Xcomunic8d]

Yeah Amazon prime is a must here. Real nice of you to give to others. Yard sales and second hand everything is pretty normal here. Amazon’s shipping has gotten slower, sped up, and is slowing down again. But they did open a warehouse in Hawaii so that did help some during COVID but I think the supply chain is really messed up getting stuff to them.

Summit is still lightning fast with very reasonable 2 day air prices.

So far no issues (that I’m aware of) But I won’t really be able to fine tune until I get it firing. But as is all things engine. It’s one thing to bolt it together. It’s another to make it run and keep it running.

Fuel system and cooling system are next on the list.
Need: fuel water separators, fuel hose, -an fittings, c5 regulator, return hose setup.

Cooling: All my fittings and hoses for the cooling system. Power steering cooler, oil cooler.

[Xcomunic8d]

So yet another order for parts

Ict billet 5’ spark plug wires.

https://www.amazon.com/ICT-Billet-Un...omotive&sr=1-2

Faria Chesapeake black gauge set.

https://www.amazon.com/Faria-KTF003-...28983850&psc=1

Ls oil drain valve

https://www.amazon.com/EZ-Oil-Drain-...motive&sr=1-12

Fuel regulator /filter

https://www.amazon.com/EVIL-ENERGY-F...NsaWNrPXRydWU=

AIT sensor for LS1 harness

https://www.amazon.com/ACDelco-213-2...omotive&sr=1-3

Holley Term X is back in stock. So do I try to return ligenfelter trg (if can-it’s unused) and go Holley? or do I stay with what I have? Bear in mind that’s $800-1200.

[flyingfrizzle]

Holley all the way. Love my 12.3 display with the dominator ecu. The Term X is a much better value though. Lot of good support for the Holly stuff and you will be happier in the end...