Here's a look at that from the business end.
Source: https://youtu.be/zmWLT3m7Gv8
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Twins with Twins, Anyone?
- Thread starter kidturbo
- Start date
Rooster tail got cut off with the drive swap. But once I remove the drive spacers, it might grow back.
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Slip # dropped from 24% to 16. And they hook up hard on a roll out, aerate, shift at 20mph and stab it... I don't have the lower sections of air tube mounted up yet. So guessing some big pitch 5 blades will be interesting to test.
Today, another player goes down swinging..
Bullseye shaft failure getting on plane, free revving somewhere around 5300Rs and 12lbs of boost .
I actually said, it backfired.. Then scratched my head when it wouldn't make boost again.
Idled in on that engine for an hour afterwords. Cause other engine had sea pump issues. Bitch still runs like a charm, even after eating a batmo wheel..
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Bullseye shaft failure getting on plane, free revving somewhere around 5300Rs and 12lbs of boost .
I actually said, it backfired.. Then scratched my head when it wouldn't make boost again.
Idled in on that engine for an hour afterwords. Cause other engine had sea pump issues. Bitch still runs like a charm, even after eating a batmo wheel..
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When the boost gauge dropped to zero, but rpm stayed above 4k,, my backfire throughs faded pretty quickly too. Plus, that small fact that diesel don't backfire.. lol
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With all the problems you seem to have with reliability, it makes a person wonder if a Duramax boat is even worth the trouble. 
I see it more as issues with the after market hardware, used in 800hp and above builds.With all the problems you seem to have with reliability, it makes a person wonder if a Duramax boat is even worth the trouble.
Besides the unknown cylnder pressure leak on starboard when boost exceeds 50lbs, these long blocks are proving to be solid as ya get. And that issue only exists on 1 engine, so we can deduct that's either a cracked block, or bad deck work. Should have started with virgin blocks and o-ringed em, then I'd say these are about as bullet proof as ya can get..
But what can do about aftermarket stuff? All R&D for others who haven't played in these environment before...
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As of today, the engineering still standing board is down to a few well known names.
Banks Intake - feed it 85gpm of water as he states, knocks down IAT from 600F to 100F as stated.
Callies Ultra Billet Neutral Balance Cranks - They are first batch, still spinning, holding good oil pressure, and not spewing oil out the back yet..
Fluidampr Neutral Balance - First batch units, little tight on the hub, but feels smooth as ya can get in the 5k plus range. Had to beat up the engineers to build me some.. Welcome eveyone..
Howard's Pressurized Wrist Pin Ibeam Rods - Developed for a marine duramax application 20yrs back, but now lost to history. Feel lucky to own a couple sets.
Fingers Oval bowl Pistons - What is there to say.. Good engineers who share love in your hobby are hard to find.
Wagler AF camshafts - Ain't wiped a lobe or popped the keepers out yet at 6k, so profile and harness must be good.
That's the survivors list. Not counting GM hardware, blocks, heads, valves, and LML oil pumps.
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Banks Intake - feed it 85gpm of water as he states, knocks down IAT from 600F to 100F as stated.
Callies Ultra Billet Neutral Balance Cranks - They are first batch, still spinning, holding good oil pressure, and not spewing oil out the back yet..
Fluidampr Neutral Balance - First batch units, little tight on the hub, but feels smooth as ya can get in the 5k plus range. Had to beat up the engineers to build me some.. Welcome eveyone..
Howard's Pressurized Wrist Pin Ibeam Rods - Developed for a marine duramax application 20yrs back, but now lost to history. Feel lucky to own a couple sets.
Fingers Oval bowl Pistons - What is there to say.. Good engineers who share love in your hobby are hard to find.
Wagler AF camshafts - Ain't wiped a lobe or popped the keepers out yet at 6k, so profile and harness must be good.
That's the survivors list. Not counting GM hardware, blocks, heads, valves, and LML oil pumps.
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It really makes me sad my set of Howard’s will never see 4 digits but they are one hell of a good rod.
Does bullseye offer a cover with a speed sensor port?
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Yes it is.
And will let ya know tomorrow..
I doubt it was a single spike that caused it. But when one prop breaks loose, sometimes gotta wait a few seconds for the other engine to break loose before shifting. So if an overspeed failure, then be hard to prevent.
One of my diesel buddies did report them surging in the 2500rpm range at cruise. I can't hear at the wheel, but from back seat he reported hearing them in a pressure surge for a bit at cruise and sub 25psi boost range. That we can measure with an exhaust psi gauge.
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One more to add to the aftermarket fail list for the week.
Since the early days of my first PPE boat I've been a fan of the SX / Edelbrock EDL-1792 160gph fuel pumps. Primary reason is it's internal bypass regulator that doesn't require an additional return line. Edelbrock has tagged them "Not For Use With Diesel Fuel" for a several years now. I've personally never seen any issues running diesel fuel. They are a very simple vane pump design, with simple screwdriver adjustable spring bypass valve.
Last year I had one motor fail due to water intrusion. Purchased a new one, and just swapped motors leaving the fuel side plumbing attached. Well they obviously have an issue with their upper motor housing or wiring seals. As I went out for a test drive last week, lost fuel pressure on Stbd engine. While the true cause was an air leak on a old to me 10AN Earls swivel fitting, testing revealed that a bearing was going out in the motor. Soon as I cracked it open, found same issue as last year, water in the motor hosing... These things don't run in water, but do get washed off with a hose every couple weeks. Off to find a suitable no return line replacement.
Since the early days of my first PPE boat I've been a fan of the SX / Edelbrock EDL-1792 160gph fuel pumps. Primary reason is it's internal bypass regulator that doesn't require an additional return line. Edelbrock has tagged them "Not For Use With Diesel Fuel" for a several years now. I've personally never seen any issues running diesel fuel. They are a very simple vane pump design, with simple screwdriver adjustable spring bypass valve.
Last year I had one motor fail due to water intrusion. Purchased a new one, and just swapped motors leaving the fuel side plumbing attached. Well they obviously have an issue with their upper motor housing or wiring seals. As I went out for a test drive last week, lost fuel pressure on Stbd engine. While the true cause was an air leak on a old to me 10AN Earls swivel fitting, testing revealed that a bearing was going out in the motor. Soon as I cracked it open, found same issue as last year, water in the motor hosing... These things don't run in water, but do get washed off with a hose every couple weeks. Off to find a suitable no return line replacement.
Attachments
is there any difference between the Edelbrock vs the PPE branded one? I've have the PPE one mounted under my truck for over 10 years now exposed to water without any issues. looks identical to the Edelbrock one with the same simple internal bypass and screwdriver pressure adjustment
Exactly the same unit..
Is why I am so disappointed in these now. Bet the one I purchased back in 2010 is still good to go on the old boat.
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Actually the one I just replaced only needs a lower shaft bearing. Replace that and will now have a completely new/rebuilt spare. Still have the new in box lower half from last year.
And good thing because the one on port engine has required a "hammer assisted start" at least twice in past couple months. It's all original, from like 4yrs ago.
So plan is, put this last one back together and find the leaks before installing. Only 3 spots. Wires at bulkhead, bolt washers, or cap to body o-ring. Something leaking that bad should be easy to find.
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And good thing because the one on port engine has required a "hammer assisted start" at least twice in past couple months. It's all original, from like 4yrs ago.
So plan is, put this last one back together and find the leaks before installing. Only 3 spots. Wires at bulkhead, bolt washers, or cap to body o-ring. Something leaking that bad should be easy to find.
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