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Looks Like I'ma gonna be a Caddy Guy - Now What? Stroker L92 LS3 Build

Slidin Gator

Well-known member
We'll sort of a Caddy guy :stirpot: got a worn out L92 with 234K miles out of an Escalade.


Talked to one salvage yard and they wanted a core charge, I said a 200K+ mile motor is a core, found one elsewhere with an honest price, no core. Gonna start with forged internals so I might as well put in a 4.00" stroke setup. Bore will be whatever it takes to clean up once I get in, but boring will be to the minimum. Ultimately I am looking to turn a 76" 3-4 wide blade with a 2.55 box on a 14'x7' Stossel hull. I plan to build the valve train to handle 7,000 RPM and configure to turn around 5,500. 450 Hp would be more than enough, I am aiming for 500 max at 5,500. I expect to normally operate between 3000-4000, so I am looking for torque to come in hard just below 3,000. I intend to run EFI and plan to throw away the worn out injectors, so upgraded injectors are planned. I'm still researching porting, valve and cam options, definitely interested in input, but I won't trade low end torque for top end power on this build.

I have just started researching ECU options and would appreciate input, Holley has a new ECU and harness assembly that seems to check all of the boxes :scratch:

Starting at the bottom, both of these threads and posts call for 0.0025" bearing clearance


unforgiven11B said:
Welcome- here is my recommendation some will say differently but my research is from Proven combinations and proven engine builders
Not that it matters to this point but are you going carb or stand alone efi? On LS the difference can be a few grand. On to the assembly. Unless you are using the long block as Is, Get a good balanced rotating assembly I would suggest (lunati), Callie’s, stay away from eagle. If you are rebuilding throw your head, main, and rod bolts out they are Tq to yeald and should not be reused. If you upgrade to main studs make sure you have your machine shops line hone and bore using the new STUDS or you will be furious when it won’t rotate by hand or burn up some bearings
The build specs below are for a 500 hp 408 LS based off a L92.
Mains- .0024-.0026 in 50ft/lbs-out 60ft/lbs (ARP studs)
Rods- .0024- .0026 45 ft/lbs
Rod bolt stretch- .0055- .0060 “am for .0055” (ARP bolts)
Piston to wall - .0035
Bore finish-280
Crank end play- .004
Ring gap- use manufacturer recommendation for 150 hp shot of N02 mine is Top ring Bore x .0060, 2nd ring bore x .0070, oil ring min .0015 suggested use is .0035
That should get you started. Take it slow lay everything out and if something doesn’t feel right stop and recheck. Good luck and let us know how it turns out


CarMotorBarge said:
Been busy lately with work. Getting back to this thread. So I don't plan to spin 8000 RPMs. The max will be 7000 RPMs. Hopefully I will get a little more longevity out of this motor. :shock:

The interesting thing is the LS7 comes from the factory with a 7000 RPM rev limit. The LS2 from the factory has a 6800 rev limit. The LS3 from the factory has a 6600 rev limit. Hopefully if I put some aftermarket valve springs and lifters, I will be OK spinning 7000 RPMs. 8)

Here is the latest on the build. I have the main bearings in. Check the clearances. Here is the data:

Main Bearing 1: 0.0026"
Main Bearing 2: 0.0023"
Main Bearing 3: 0.0025"
Main Bearing 4: 0.0033"
Main Bearing 5: 0.0035"

The perfect clearance is 0.0025". Bearings 4 and 5 are a little higher than I would like. Think I am going to pull the main caps and swap a few bearings around to get all of the clearances closer to 0.0025".
Does this not make you an LS guy?? :stirpot: Excellent platform to build your power plant out of. The specs are directly from Dave at water thunder for a L92 418ci. so I trust them to be tried and true. The Holley systems are pretty nice and not too complicated as far as set up and initial start up,fitech is more of a headache for initially. My only suggestion would be a balanced rotating assembly. You should have no problem achieving your goals.
unforgiven11B said:
Does this not make you an LS guy?? :stirpot:

I reckon it does, Caddy Lite? :dontknow:

Thanks for the build info you posted, I'm sure I will have more questions for sure going forward.
kwanjangnihm said:
yep new handle "slidin radiator" :stirpot: :lol:

That the best you can come up with after 2 days of thinkin? I expect more out of you Kwan :banghead:

That said, I do have plans for a different radiator setup.

In the mean time, my response :D :D

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Knowing Chuck I can envision a radiator capable of holding 5,000psi up on the grass rake built to bust brush as well as cool the engine.

Like something out of Terminator
I cant wait to see you bring that old Lyocming to the scrap yard :D. Serious question, which one you think will burn less fuel running a boat like you do the 0540 or the CM? Yes I know thats not the only thing to consider :thumbleft:
Shit that L92 tuned right will burn far less than the 0540 if you stay outta the pedal. And done right you shouldn’t need to get in it. This all of course takes into consideration all other things are correct, such as prop,reduction, crank angle, etc.
I think Chuck runs a lot of gound.....I was wondering if it would be more efficient breaking trail and in the water.... or one or the other but not both??? I was thinking across the board that CM would burn less.
I do run a lot of ground and expect that I will not be staying out of the pedal, hopefully I just have more pedal. I have run with LS powered Palm Beach boats and the fuel burn is similar. I expect to get a little better fuel burn, but not a huge change on ground. It should improve on skinny, but in deep water I turn similar RPMs as I do on ground.

Ultimately it takes XX amount fuel to make XX Hp. All of the efficiency gains in truck engines gave them better fuel mileage overall, but hook up my old 25 foot offshore boat to my new truck, and it would still be 10 MPG just like the 90's trucks. Aviation motors run rich under load, so there is a bit to be gained. Improved prop efficiency is the other area for gain. We shall see. :dontknow:

Ultimately, I am not so much looking to gain range with a lower fuel rate. I am looking to gain range by hauling more fuel :thumbleft:
Great to see your starting the project Chuck !!!!!

It's started, but the new septic drainfield last month and new sod next month have put a crimp in the parts budget for a bit.


First things first, ripped these hunks of iron off and put them by the road, saw a scrapper grab em that afternoon.


When I opened up the oil pan I thought this is way too clean for a 234K mile engine. Something's up, everything is too clean.


Dig a little deeper and I was thinking GM wouldn't mark the cylinder numbers on the rods.


Once I figured out that this engine is a rather low mileage rebuild, I started to wonder if there was a chance that it had a stroker crank :cheers:

Alas no, I came up with 3.622 for the stroke, it's a standard reman replacement, no expensive forged parts. If I was planning on putting the engine in a truck, I would have stopped before pulling the heads and stuck her in for sure. As it stands I measure a bit of wear on the cylinders and they look clean. I will be taking the block and heads to the machine shop next month to find out exactly where I stand on measurements. Knowing it's a reman means we have to double check to see what they might have screwed up. :violent1:

I sure do see a lot of design improvements vs. the old small blocks I'm used to, I particularly like the skirted block and 6 bolt main bearing block system. So now I have a block, heads and maybe a partial induction and injection system.

Siamese cylinder walls, not a lot of thickness. I want to minimize boring.

823 casting number heads.


I also note that the spark plugs stick out right in the path of the intake valve, interesting.

Seems from your posts you have plenty of engine knowledge.

If you are do some upgrades.
A few things to check out
Molnar Cranks and Rods
Brian Tooley New Shaft Rockers with Trunion setup inexpensive for a shaft style system
That intake makes more power up to 5300 than any after market intakes matched with the correct injectors
GM makes an 8 qt pan the has a side drain instead of a rear drain www.Airboatstuff.com
They also have the low drives side alternator mount kit.

Good luck and enjoy
You will be amazed at the power
Plenty of power can be made with that. Mr. Gerald (new old glory) his water thunder is L92 based. I believe if not mistaken it’s the 418ci 550hp package. You are definitely right path. You are petty knowledgeable on here so look up the references to Dave’s build he did for Airboting Magazine I have all the articles but for the life of me can’t locate them to reference the months and year of the 4 articles. He builds a carbed 418 from ground up gives tq specs and clearances for his builds a lot of great information. I have ported WT intake and matched carb, WT wiring harness and WT ecm.
Slowly putting the 408ci L92 engine together.
Based off cam specs you might not have enough prop to tame the beast 76” might come in a tad short?
One Eyed Gator said:
Seems from your posts you have plenty of engine knowledge.

If you are do some upgrades.
A few things to check out
Molnar Cranks and Rods
Brian Tooley New Shaft Rockers with Trunion setup inexpensive for a shaft style system
That intake makes more power up to 5300 than any after market intakes matched with the correct injectors
GM makes an 8 qt pan the has a side drain instead of a rear drain www.Airboatstuff.com
They also have the low drives side alternator mount kit.

Good luck and enjoy
You will be amazed at the power

Thanks 1 Eyed, I know enough to be dangerous, "Dangerous" might be a good name for this boat, particularly the first time I hammer down and muscle memory makes me pull back on the rudder stick in deep water. :violent1:

Thanks for the list, I will be looking into all of that. My plan is a cable throttle body for the existing intake, it's just so damn ugly. :shock:

unforgiven11B said:
Based off cam specs you might not have enough prop to tame the beast 76” might come in a tad short?

Too much power? That's a problem I am willing to deal with, but you are hitting on my key concern here, I do not want to overpower, that's just more torque roll to deal with all the time. When I started looking at options I started at a 5.3, they can be hopped up to meet my goals, or close enough. But the more I looked the L92 was the "why not" option, engine weight is pretty much the same as the 5.3. It's a whole lot easier to make my power goals with more motor. Adding the stroker crank is just another initial "why not" as long as I'm into the short block.

But the 2.55 is starting to look like too much gear, apparently there just isn't much of a market for props to push over powered narrow hulls :dontknow: I am still investigating props, but it looks like a narrow set of props options on this odd ball build, so that is going to drive the rest of the choices.

These motors make 400+ ft-lbs and 406 Hp with the factory setup on 87 octane, just stroking it is around 450 Hp/Tq and it's a short trip to 600/600. I would absolutely prefer to keep RPM down, both engine and prop, I don't want this boat sounding like a Nascar race.

At this point it's a good view looking at the build from the perspective of too much power vs. too little.
My hoist scale is not working, so I never got a complete engine weight. I weighed every part I took off, starting at 92 lbs for the bare block.


Here is the full tally for as delivered, without the 21 lbs of cast iron exhaust manifolds.


Here is my estimate of items left to add, less prop.


Add the two together and I get 550 lbs. That's 50 lbs over my goal. Still within my build margin, but equal to 8 gallons of fuel or one late season skinny hunt dog. That factory oil pan is looking heavy and I'm wondering just how much crank and dampener mass I really need:scratch:

Is a flex plate normally included as part of the gear box?
Water thunder posted a few post a while back with weights. I believe his weigh 430-460 dressed engine, and a touch over 500 with gearbox and headers. I don’t know how to copy a link or I would have attached them for reference.
I have not seen a flexpate/ fly wheel come with gearbox. But some dealers may include one as a convenience?
I have run a 268 and 2.55 on a 400-425hp iron 6.0 it is on a 14x7-6 alumitec SS rigging setup for fishing the gulf. Currently with the 2.55 I cruise at 3000, 3200 loaded for fishing in deep water. I wouldn't hesitate to 2.55 or 2.68 with the right size prop. Less gear is more stress than spinning the motor a little high in the RPM range to me. I also don't run a high lift cam like some do, just easier on the valve train. It make ok power .525.lift with GM ASA cam and a longer duration. This cam is an LS3 crate motor makes 525hp and has a very flat torque curve. You can run the ls6 valve springs with it.

BTW Tom Molnar was the lead guy at K1 for a number of years before he start his own company. His products are built to tight tolerances. I have a set of his rods on the way and saving for the crank. Just need a few parts to finish my 408 Iron block.

I lot of guys shave the intake ridges to smooth it out. Looks a little better but take a work.

I also run an ATI single belt balancer, which will shave a few more lbs off you total lol.
4 BLADE 76" MAXIMUS I would think could hold it back..... maybe a 3 blade. I only have about 7.5 degrees of pitch in mine.