red beard

upon further thought... weight is not where the story ends or is even a true scale to guage flywheels. If I have slept on this correctly, a pound at just over 5" diameter can be .5"x.5" of metal,
now a pound of metal at near 14" diameter can be .5"x.18" all rough numbers just building a case in theroy here...
now if I remember correctly please do call me out if I am not looking at this propperly, as I dont have time to fact check all this stuff, and am just blabbering at this point, but I believe inertia involves fundamentally massXvelocityXvelocity. So... once again rough numbers here, that pound at 14" has 7.8 times as much inertia as the pound at 5"... same pound but a very different effect.once it gains velocity. Boil all the other numbers out of the mess and its simply (14 squared)/(5squared) to achieve the factor of effect.

Now we all know that it takes a somewhat universal amount of metal in a somewhat universal shape to build a functioning flywheel that will transmit mechanical force... but it would appear that the trimmings are much important here... I am going to hog out as much metal as I can out of the center of that flywheel, and make it as large and as thick as possible (within reason) out at the OD. It would not be incredibly hard to get a 40 lb unit to act like a 100 lb unit, just move 10 lbs 5 inches outward. really rough numbers.

so I figured I would check my memory, and here is the real deal, cut and paste below:

This equation is the rotational analog of Newton's second law (F=ma), where torque is analogous to force, angular acceleration is analogous to translational acceleration, and mr2 is analogous to mass (or inertia). The quantity mr2 is called the rotational inertia or moment of inertia of a point mass m a distance r from the center of rotation.

Different shapes of objects have different rotational inertia which depend on the distribution of their mass.



they are using R, I used D... ends up same factor of 7.84 between r of 2.5" and r of 7".

Penny for your thoughts.



Source: Boundless. “Rotational Inertia.” Boundless Physics Boundless, 26 May. 2016. Retrieved 25 Jan. 2017 from https://www.boundless.com/physics/te...rtia-325-6299/

kidturbo

Yes your on the right track as to how to place the weight and maximize inertia. Within two constraints on size, diameter an thickness.

Max diameter is set by what will clear the starter. And thickness is clearance on back side to bell housing. The face typically needs to be within set known value that provides proper coupler spline alignment with transmission shaft. In the last two pictures of damper above, I have it bolted up both ways to measure where these splines land.

We can't go much larger than stock on our diameter, and clearance to back side is also tight. I added some meat there on those flywheels above, then after test fitting,, cut .0120" of it back off them cause they hit. Here is the Solidworks design we started with.

[ATTACH=CONFIG]564125[/ATTACH] [ATTACH=CONFIG]564126[/ATTACH]

Those are very similar to the actual externally balanced flywheel we scanned. To gain extra weight, we added as much meat as possible to the center and picked up an extra 10lbs overall. If you want a lighter total, you would start removing meat from the center to have less impact on the final inertia value. So a 45lb unit would look similar to the example above. However, you would need to run a different damper with larger bolt patter now. I was shooting for the largest mass possible that fit the size constraints, and left clearance for springs on the damper. This is it...

[ATTACH=CONFIG]564127[/ATTACH]

One last factor to consider. These new Billet cranks with internal balancing weigh in about 25-30lbs heavier than a stock Dmax crank. Loaded up with Mallory. Over 200lbs of total spinning mass per engine on my builds.

[ATTACH=CONFIG]564129[/ATTACH] [ATTACH=CONFIG]564130[/ATTACH] [ATTACH=CONFIG]564131[/ATTACH]


So...

tommymonza

So what kind of horsepower and torque are you looking to reliably get out of this motor and how many hours do you think it will be good for?

kidturbo

The goal on these is 900/1800 reliably. Long as they operate happily up there, one would expect 800-1000hrs rebuilds. With adjustable tunes, they can be turned up or down on demand. Fueling is capable of 1200hp, turbos also.

All this bottom end hardware has been tested at 1500hp plus by plenty of truck guys on street and strip. Pistons remain the weakest link since they are cast alum. I know they will handle 700 all day long from my old boat. Mahle rates them at 900hp. We did an oval bowl mod and ceramic coated the tops for added protection. The rods are laser drilled for pressurized pin oiling, something else specifically done to increase service life. My friend ran those in a dragster making 1800hp at like 7000R's. So not much worried about spinning them 4500.

kidturbo

Back on Marinisation side, here is an offshore baffle setup I built. Below these are a 15qrt pan with 2 more slosh baffles and low oil level sensor. Based off a modified medium duty pan configuration, front sump from the factory. Recycling as many parts where we can..

[ATTACH=CONFIG]564135[/ATTACH] [ATTACH=CONFIG]564134[/ATTACH]

[ATTACH=CONFIG]564132[/ATTACH] [ATTACH=CONFIG]564133[/ATTACH]

red beard

I think once again you are doing the right thing (with those pans) for a smaller tougher boat that will have plenty of power to thoroughly thrash itself. my boat is a big heavy work boat, 22-23k lbs, blunt bow with no penetrating shape whatsoever, 15' wide, when its calm I can get on top and travel planing, when its rough, I just go slow, like 5-7 knots, otherwise everything gets tossed, tools, gear,dishes, bunks, food, crew. its just not worth hurting the boat or crew. I will go with a normal pan, never seen my oil pressure flicker in 20 years. I like your goals with that 800 to 1000 hours at your rating. I will set mine up to have 5 settings, 3400rpms will be the highest it will ever run for me, jet drive- so wind it up and let her pump when the boat stops going faster that's all ya get.
5- at 600hp or so,
4 at as high as i can get away with a safe EGT continuous WOT,
3 as high as i can get away with and keep the egt below 900F for continuous operation,
2 something lean and slow.... (safe for crew to operate), and
1 i would like to set up for a high idle, as this engine also drives hydraulic pumps, and refrigerant pumps. that is its sole purpose for most of the day. I figure I will spend 60% of my run time hours at idle or high idle just pumping fluids- like 50 hp load, then another 30% of the time on setting 2 or 3- (350 HP?), and another 10% of the time on setting 4.
I would like to get 10,000 hours out of this motor, that would be about 20 years... if I get 5000 I will be happy. I today have 5800 hours on each of the three gasoline MPFI- BBC's installed 14 years ago. they still run great with no problems.... today - but the end could be near, nothing lasts forever.
its kinda like no peek poker, my ante is on the table and i have my eye on the cards to ensure i get a clean shuffle, cut, and deal. Certainly got my fingers crossed for a great hand.

red beard

from the face of the crank to the rear face of flywheel i need 1.643", and thats out to 13.875" diameter, from there the thickness will need to be at least .250" thicker to form a shoulder that will pilot my SAE 11 1/2 Centa drive plate, I could go a full 1.5" thicker there on that outer shoulder. from 13.875" out to 14.5" I have room to go out to 14.5 OD- provided I miss the starter nose.
a 14 inch disk. fully developed I think i could get mine to about 80lbs, but remember about 15 lbs of that is at the outer rim, and another 10lbs spread between 5" and 13" diameter, when compared to how its different from the 55 lb. one
real rough numbers here, mass centered at 5" diameter is 1/8 as effective as the same mass at 14" Dia., likewise mass centered at 10" diameter is 1/2 as effective as mass at 14" diameter.
A ten inch circle cuts the area of a 14 inch circle effectivly in half... ergo equal in and out of that 10" line means this is the balance point.
That extra 15 lbs that I can get is at 14" and is worth 30 llbs at 10", therefore is i make the remainder of the flywheel that is inside 14" worth about 25 lbs, then I have effectively made a balancer that has the inertial value of a 55 lb flywheel

we need to start talking about flywheels in different units than pounds, the whole thing gives me a headache. check out this link, its the best I could find without digging deep, about half way down the side bar, look for the six examples of solving for "I" the top two on the right pertain..."rod or disk about an axis"


https://www.khanacademy.org/science/...tional-inertia

I took some libertys and guessed on a few measures but this is in the ball park.
the 45 lb model you used would have an "I" total of 1110 lbs/in2
the ones you cut out would be about 1450 lbs/in2
space fully exploited I could make one 80 lbs that has an "I" of 2100 lbs/in2
or I could shed about 40 lbs and create a 40 lb flywheel that has an "I" value of about 1400lbs/in2 only because of the Sae 3 Housing which gives just a bit more room.

forget everything I said above the link - talking in units of "I" simplifies everything... apples to apples discussion.

kidturbo

Red you're thinking so hard that my head hurts...

But you are on the right track. My approach is to replace the rotating weight of the normal torque converter and flex plate that would be in a truck. With a unit that allows for multiple bolt patterns and fits all the possible dampers. While lighter obviously spins up faster, I'm mostly concerned about 50lbs of 18"+ diameter five or six blade wheels running fully surfaced. Leaving the water then hooking up again like ya just side stepped the clutch in a 2000hp drag car... Torque spikes that likely exceed that comparison. A nice heavy "symmetrical" flywheel is far less likely to grenade, promoting a warm and fuzzy felling for the builder.

In your case, a jet pump doesn't experience any such abuse unless you suck up a big rock... lol. So don't over think this to much, better to keep it simple.

kidturbo

Anyone have experience with this Johnson Pumps 10-13021-96 F8B-8 Heavy-Duty Impeller Pump with 1 1/2-Inch Ports ??

I was given some info on this pump a while back, specifically that it moves about 74gpm at 2000rpm through a 1.5" NPT inlet/outlet. Which is comparable to the 3 stage Hardin pumps that Hoodoo and I chose to go with on our builds. Price is reasonable for the flow rating, if they last. Doing a little reading I found a spec sheet for the F8B-3000 series of pump that seems to verify those numbers.

[ATTACH=CONFIG]564166[/ATTACH]
[ATTACH=CONFIG]564167[/ATTACH]

red beard

yeah, that was getting silly trying to quantitate those flywheels without thinking in terms of "I" (inertia).
something special happens when I run over small swell that is traveling the same direction I am... it tends to "blow out" engines will flare (jets completely cavitate briefly) right as i cross the small wave.
to combat this i only need to change my tack 10 to 15 degrees, and problem disappears. the 1999 MPFI BBC's computer was just fast enough to curb the flare and keep the engine within limits, 3500 to 5500 and back again inside a second, but it is annoying enough I usually just change course and tack to point b. how does the EFI live handle this?. I would hope faster and less pronounced with better tech.
What should I expect?

I would love to hard mount this engine, but the aluminum boat is a huge tuning fork and I will go with rubber isolators 236 M1 (six of them)


http://www.bushingsinc.com/index.php...ross-reference
http://www.bushingsinc.com/images/bu...-M1-SERIES.pdf

In designing these things these guys have taken into account amongst other things, two big factors, weight of combined unit, and shaft tourque. Most guys reading this will be 1-1 ratio, and this is what the hp specs on this sheet are set up for... beware if you have a reduction gear like I do consult with them directly, as the hp specs go out the window. Shaft tourque along with with unit weight is what matters.

4 of these mounts will cover my weight, but it will take six of them to get me close to the minimum to handle the torque. so with six it will be a more rigid (oversized) mountup than would be desired for vibration isolation (which is predicated by unit weight), but nearly undersized for torque. kind of the middle of a double edged sword.

I could have split that same difference with 1" studs in a four mount configuration, but i like having the engine support itself for gear (trans) removal, hence the six 3/4" stud choice.