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Discussion Starter #21
I just had another look at the Isuzu 4BG1T industrial engine.
This one has the SAE bellhousing and the section drawing shows a far heavier flywheel, maybe even 3 times the inertia of my one.

http://www.isuzu.co.jp/world/product/industrial/pdf/b_draw02.pdf

I can't use this one directly as I'd have to shift either the engine forwards (crossmember and axle in the way) or drivetrain rearward (big hassles), but it means I'm on the right track with a heavier flywheel.

This 4BG1T is sold as a marine engine (presuming the same flywheel and bellhousing) producing 200hp at 2800rpm which isn't too far away from where I estimate I am now (bigger exhaust and intercooler and I'll be there).
http://www.isuzu.co.jp/world/product/marine/4turbo.html
 

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measure the weight of the dodge 5 spd flywheel and then measure the nv5600 flywheel. the 5600 flywheel is larger i believe adds 7 lbs but thats just from memory which i doubt is correct. there is more material on the 6spd flywheel and it is larger in diameter. that might be enough to increase the enertia
 

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i want to say the dodge flywheel for the 6spd applications is 15.25"-15.5" in diameter where as the dodge 5 spd flywheel is something in the ball park of 14.25" same thickness. i'll measure and post:idea:

the 00-03 dodge nv5600 6 spd flywheel is 63 lbs the later 04-05 6spd nv5600 flywheel scales in at 57 lbs or so.

unfortunately a freind of mine needed my spare flywheel which weighed 64#'s and was already to go on the back of my 4bt and had to steal my heavy one and swapped out his lighter 6spd flywheel with me due to the two of us needing to do a clutch job on his truck on the side of the highway..... yes it can be done in an 05 dodge in about 3 hours trailer still hooked to the truck
 

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Discussion Starter #25
So almost 11 years later I have ordered the steel cut and machining for my flywheel inertia ring.

I'll be adding a ring 390mm OD, 345mm ID and 30mm thick to the outside of the 4BD1T flywheel. This will increase it's inertia by about 50%.
I had hoped to fit a 40mm thick ring on, but it's too tight against webbing in the gearbox bellhousing.

Combined with an engine rebuild and engine mount modifications, I'm hoping for big improvements in NVH.
 

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It will be interesting to to see how much differnce you feel, both vibration and loss of excelleration.

Awhile back I did some research on "one way" idlers. They are also suppose to smooth things out. I know lots of new cars and trucks have them. Not sure if they smooth felt vibration or just smooth the pulses to the alternator and waterpump. I wanted to find one to fit my 4BT, but never pursued it past research.

On your experiment, did you workout any "baseline" tests to compare before and after you get it installed? It would be great if the differnce was dramatic, but I suspect it will be hard to say for sure. Our minds play tricks on us sometimes.
 

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Discussion Starter #28
It will be interesting to to see how much differnce you feel, both vibration and loss of excelleration.

Awhile back I did some research on "one way" idlers. They are also suppose to smooth things out. I know lots of new cars and trucks have them. Not sure if they smooth felt vibration or just smooth the pulses to the alternator and waterpump. I wanted to find one to fit my 4BT, but never pursued it past research.

On your experiment, did you workout any "baseline" tests to compare before and after you get it installed? It would be great if the differnce was dramatic, but I suspect it will be hard to say for sure. Our minds play tricks on us sometimes.
My baseline is 1600rpm "rumble" point in 5th gear. This is about 80km/h and you need to be very careful with throttle application below that in high gears. Lower gears no issue.
But I've had piston/ring/liner issues which will have contributed to that. With expected different compressions on all 4 cylinders (I didn't measure them, but the damage is there).

My Isuzu ute (3 litre 4jj1) is dead smooth pulling down to about 1200rpm. I don't know if it has a dual-mass flywheel or just a single heavy. I could look that up on parts diagrams but haven't yet.
 

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Discussion Starter #30
Are you planning on qualitative testing only? I know you are itching to use some of those Arduino chops and with an accelerometer quantitative analysis is easily doable...
I'm struggling for enough productive time to get my engine back together. Arduino has been gathering dust for a long time now.
 

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Discussion Starter #31
Picture of the inertia ring sitting there looking shiny:


This is 30mm thick, weighs 6kg. The 40mm, 8kg, one would have required shaving lots of stuff.
 

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Should be just the flywheel. Clutch is balanced in the factory independently of the flywheel, so that you can replace the clutch down the road.
 

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Johnny, that was my thinking too. The idea of adding more mass to the flywheel works on the 4bt as well. The engine with a GM flywheel tends to be a bit smoother than the Ford. Moving up to the larger SAE 3 or 2 can help even more. Don't know if anyone ever tried doing an SAE 1. Think those came on the 6ct but may physically bolt to a B series as well.
 

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Discussion Starter #36
Do you balance with the clutch assembly in place of just the flywheel?
The crank, flywheel and clutch was balanced about 25 years ago. They drilled the flywheel to remove material for balance and they also buffed up sections of the clutch cover. So while the clutch cover was balanced at the factory, it may have been installed a little eccentric which creates some inbalance. Because no assembly is ever perfectly aligned.
With the position marked and it balanced in place it's good.

So if they do it right the assembly should be in balance with and without the inertia ring and clutch cover installed.

On the RHS of the above picture you can see a pair of punch marks at 3 o'clock. This is the alignment mark for the clutch cover on the flywheel. The inertia ring covered those so I marked the top the same. The inertia ring intentionally has an irregular pattern and tight bolt fit so it will only bolt on one orientation.
 

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Discussion Starter #37
Johnny, that was my thinking too. The idea of adding more mass to the flywheel works on the 4bt as well. The engine with a GM flywheel tends to be a bit smoother than the Ford. Moving up to the larger SAE 3 or 2 can help even more. Don't know if anyone ever tried doing an SAE 1. Think those came on the 6ct but may physically bolt to a B series as well.
The 4BD1T flywheel is super light compared to a 4BT. Factory they ran low boost and relatively high rpm (3000rpm at 100km/h I think) in the trucks. Where I'm running 2000rpm at 100km/h and about equal to factory boost at 1200rpm. So the low rpm pulsing is a problem.

My rumble point is about 1600rpm currently in 4th and 5th gears. I'm hoping this drops it to more like 1200rpm.
 

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Sounds like that had exactly the desired effect. Curious if there is any kind of front balancer that could be added to the front of the crank as well? On the Cummins 4bt, the addition of the marine fluid dampener has a similar effect. Those units weigh around 10kg.
 

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Discussion Starter #40
Sounds like that had exactly the desired effect. Curious if there is any kind of front balancer that could be added to the front of the crank as well? On the Cummins 4bt, the addition of the marine fluid dampener has a similar effect. Those units weigh around 10kg.
I'm tight for room on the front of the crank. Factory they have a two piece rubber bonded pulley for accessories drive. I had another short drive today and honestly more weight would be even better. But to get much more would need a whole face-plate bolted to the flywheel and a spacer ring added to the bell-housing to push the gearbox back.

Huge job. But I'm very happy with this improvement.
 
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