Engine Mount Design Collaboration.

9517 Views 128 Replies 20 Participants Last post by MaxPF, 1 d ago

Dougal

Discussion Starter · May 13, 2021

Hi Guys

I know engine mounts are always a hot topic. Which ones work best, which ones fit best, which ones you can actually source.
I have reached out to Barry Controls: https://novibration.com/ and they're keen to design us a standard fitment to help out with vibration isolation and make all this easy.

But we need some info:
Weights. That should be easy.
Standard mounting configurations that work for most swaps. Particularly fore/aft location on the engine.
Space constraints inside frame rails etc.

I'm also going to forward some Isuzu 4BD1T info that can help too.

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Dougal

Discussion Starter · #81 · Jun 19, 2021 (Edited)

Looking at mount rubber hardness. McMaster Carr lists a whole heap with durometer of around 50-65: McMaster-Carr

They list 50 as medium hardness and 65 as medium-hard. Which helps narrow it down.

These ones at McMaster are very similar dimensions to the ones I've been using: McMaster-Carr
3" OD, 1.5" thickness.

They list max deflection at 0.15" compression and double that in shear. Durometer is 50A (similar to tyre rubber hardness).
Load capacity is good.

They also have 2 1/4" thick versions: McMaster-Carr
These can do 0.4" compression and 0.3" in shear.

It looks like I need to do some work on the geometry.

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Dougal

Discussion Starter · #82 · Jun 21, 2021

Okay, so I think that Cummins data is only applicable when you're bolting your engine to something like a war-ship. On a lighter vehicle it's not going to work.

I ran the calcs on my own setup. I called it a 520kg driveline (360kg engine, 80kg gearbox, 80kg transfer and brake).
Weight on the mounts comes out at 351kg front pair (about engine centre) and 169kg at the rear.

Cummins rates for 0.2" deflection (~5mm) come out at 70,200 kg/m front pair and 33,800 kg/m rear pair.
This is quite stiff.

I am running 3" round x 1.5" thick rubber isolators on a 40 deg angle and I want them softer.

McMaster Carr have data for a set of 3.125" round by 2.25" thick rubber isolators. Max deflection is 0.4"
They come out at ~32,000 kg/m spring-rate if mounted flat and ~8300 kg/m in pure shear: McMaster-Carr

So according to Cummins that would be as smooth as silk. Now it is while running. It's not while idling and shutdown isn't pretty.

The problem is we don't have an engine bolted to a warship where the rubber is forced to do the job. We have an engine bolted to a sprung chassis where the whole thing can vibrate on it's secondary springs.
So we need to go softer. But how much softer?
1/2? 1/3?

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Someoldguy

· #83 · Jun 21, 2021

Dougal said:
Okay, so I think that Cummins data is only applicable when you're bolting your engine to something like a war-ship. On a lighter vehicle it's not going to work.

I ran the calcs on my own setup. I called it a 520kg driveline (360kg engine, 80kg gearbox, 80kg transfer and brake).
Weight on the mounts comes out at 351kg front pair (about engine centre) and 169kg at the rear.

Cummins rates for 0.2" deflection (~5mm) come out at 70,200 kg/m front pair and 33,800 kg/m rear pair.
This is quite stiff.

I am running 3" round x 1.5" thick rubber isolators on a 40 deg angle and I want them softer.

McMaster Carr have data for a set of 3.125" round by 2.25" thick rubber isolators. Max deflection is 0.4"
They come out at ~32,000 kg/m spring-rate if mounted flat and ~8300 kg/m in pure shear: McMaster-Carr

So according to Cummins that would be as smooth as silk. Now it is while running. It's not while idling and shutdown isn't pretty.

The problem is we don't have an engine bolted to a warship where the rubber is forced to do the job. We have an engine bolted to a sprung chassis where the whole thing can vibrate on it's secondary springs.
So we need to go softer. But how much softer?
1/2? 1/3?

So in reading the manual the list only 2 directional forces" Vertical" and " rotational".. and I think were are mainly dealing with the tortional forces with our mounts making them level and making their axis vertical is helping some with the horizontal force rather than mounts at say a 45 degree angle in that would not help as much with the vertical force.. I think the vertical forces are the ones that are getting us.. I wonder if anyone has went to a off cant mount to the negative side where instead of the rubber face being either vertical or canted towards the engine at some degree if we mounted where the surface was canted towards the outside away from the motor... if that made any sense... ????

Goat

· #84 · Jun 21, 2021

Dougal said:
Okay, so I think that Cummins data is only applicable when you're bolting your engine to something like a war-ship. On a lighter vehicle it's not going to work.

I ran the calcs on my own setup. I called it a 520kg driveline (360kg engine, 80kg gearbox, 80kg transfer and brake).
Weight on the mounts comes out at 351kg front pair (about engine centre) and 169kg at the rear.

Cummins rates for 0.2" deflection (~5mm) come out at 70,200 kg/m front pair and 33,800 kg/m rear pair.
This is quite stiff.

McMaster Carr have data for a set of 3.125" round by 2.25" thick rubber isolators. Max deflection is 0.4"
They come out at ~32,000 kg/m spring-rate if mounted flat and ~8300 kg/m in pure shear: McMaster-Carr

So according to Cummins that would be as smooth as silk. Now it is while running. It's not while idling and shutdown isn't pretty.

The problem is we don't have an engine bolted to a warship where the rubber is forced to do the job. We have an engine bolted to a sprung chassis where the whole thing can vibrate on it's secondary springs.
So we need to go softer. But how much softer?
1/2? 1/3?

35,100/16,640 kg/m front/rear respectively. If two mounts are used then ~17,550/8,320 per isolator.

Using McMaster isolator example: two isolators in the flat; ~64,300 kg/m. That's ~80% decoupling or lower end of "semi-soft".

Dougal

Discussion Starter · #85 · Jun 21, 2021

Goat said:
35,100/16,640 kg/m front/rear respectively. If two mounts are used then ~17,550/8,320 per isolator.

Using McMaster isolator example: two isolators in the flat; ~64,300 kg/m. That's ~80% decoupling or lower end of "semi-soft".

I was looking for load charts last night for this type of mount. I think in compression these mounts will be quite progressive but in shear they should be linear. At angles we should be able to just combine the compression and shear to get a a resulting load curve.
Because my thinking is the 0.2" normal running isn't necessarily our biggest concern. Shut-down shake etc is going to be quite reliant on how much total movement the mount has. It might be 0.2" sag plus/minus 0.1" when idling but might need +/- 0.3" for a smooth shutdown.

In which case a mount with a fatter slab of rubber is going to be better for shutdown shake even if the total sag holding up the motor is the same.

Dougal

Discussion Starter · #86 · Jun 21, 2021

I tried to run FEA (finite element analysis) on a rubber mount block at 45 deg yesterday. 175kg on a 3" square by 1.5" thick block at 45 degrees.
It gives me 2mm deflection. Which isn't that much.

I suspect that the smaller motor I've taken this mount dimension from doesn't need as much isolation so the mount is stiffer. Because the motor is lighter in comparison to the vehicle and the reciprocating parts are also a lot lighter and stroke smaller.

Goat

· #87 · Jun 21, 2021

This mount is 2.5" in length and the webs are 1.375" in thickness & 1.25" tall The center slot is 0.5"

It measures 1,240 lbs/in and is linear up to 400lbs, which is the limit of my force cell.

Have you considered lattice type blocks?

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Goat

· #88 · Jun 21, 2021

These are made by LORD Corp.

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Dougal

Discussion Starter · #89 · Jun 21, 2021

Goat said:
View attachment 131306

This mount is 2.5" in length and the webs are 1.375" in thickness & 1.25" tall The center slot is 0.5"

It measures 1,240 lbs/in and is linear up to 400lbs, which is the limit of my force cell.

Have you considered lattice type blocks?

I hadn't considered lattice type blocks. My general feeling was they are less robust. A solid block of softer rubber has less to go wrong than one with a lot of holes.

What's that mount above from? Is it about a 3" circle we're looking at? Installation for my application is more difficult with that type. I'd need to remove both chassis and engine side mounts to get the engine in. Currently I can drop the engine in, align it, get the bellhousing bolts in, lift it a little and then slot in the puck style mounts.

Goat

· #90 · Jun 21, 2021

Dougal said:
I hadn't considered lattice type blocks. My general feeling was they are less robust. A solid block of softer rubber has less to go wrong than one with a lot of holes.

What's that mount above from? Is it about a 3" circle we're looking at? Installation for my application is more difficult with that type. I'd need to remove both chassis and engine side mounts to get the engine in. Currently I can drop the engine in, align it, get the bellhousing bolts in, lift it a little and then slot in the puck style mounts.

The lattice isolator is rather robust. Here in the US it is the standard for equipment that requires seismic isolation.

3.5" diameter. It's the factory isolator for a 6bt.

Reactions: 1

Someoldguy

· #91 · Apr 28, 2022

Did we ever come to an optimal

Dougal said:
I hadn't considered lattice type blocks. My general feeling was they are less robust. A solid block of softer rubber has less to go wrong than one with a lot of holes.

What's that mount above from? Is it about a 3" circle we're looking at? Installation for my application is more difficult with that type. I'd need to remove both chassis and engine side mounts to get the engine in. Currently I can drop the engine in, align it, get the bellhousing bolts in, lift it a little and then slot in the puck style mounts.

did we ever come to an opitmal placement for mounts and type of mounts? thanks

W.R.Buchanan

· #92 · Apr 29, 2022 (Edited)

4

OK I'm a little late to this discussion, but I have some definite ideas about how to mount one of these engines.

First it kind of depends on how the vehicle will be used. If it is street only then mounts that support the engine and kind of limit its fore and aft and side to side movement, will probably work just fine.

However if the Vehicle is to be used off road in any challenging way then the mounts must not only support the weight of the engine but also positively capture its movement on all three axis'. Otherwise you will end up with holes in your radiator and general disappointment.

I learned a lot while building Early Rock Crawling Jeeps 95-03 ish. and they were evolving with every trip to a competition. The mounts on my Yellow Jeep broke on a mild trail in Moab and it took us 4 hours to recover it after only 5 minutes into the trail. About 200 yards!. That prompted me to design and build mounts using Poly Urethane Spring Bushings in the Tubular Mounts to positively locate the engine on all 3 axis'. No more problems with 12" holes in the radiator.

These mounts utilized the center mounting locations on the sides of he engine rather than the conventional mounts on the Front of Chevy 4's and 6's
These worked perfectly and there were no further failures. Even after rolling the Jeep 4 1/2 times the engine was still in place and running even though it was upside down. My right ear still rings constantly from that episode in 2003 !.

Coil Motor vehicle Steering wheel Automotive fuel system Automotive tire

Moving forward to the DeScrambler I wanted the same basic concept but bigger to deal with the 750 lb Weight of the Cummins 4 BT.

With the 4 BT as an off road power plant I decided it was best to mount the engine on the sides of the block so that the weight of the engine was supported entirely by the mounts independent of any "Cantilever" effects induced by mounting them on the front of the engine and relying on the Transmission mounts to support the rear and divide the entire weight of the power train (1150 lbs total) thus @280 lbs on each mount. This would put undue stress on the joints between the Engine/Transmission/ Overdrive/Transfer Case each of which would encourage oil leakage at some point.

The engine is supported near the #3 cylinder on the drivers side and #2 cylinder on the passenger side by Polyurethane Step Bushings that are 3" in diameter made of 60 Durometer Poly.. I made a mold to pour the Poly around a steel bushing in the center of the bushing.

The right side mount was a little complicated due to having to work around the Turbo Drain and pick up the front mounting holes in the block. The right side is much simpler.

White Motor vehicle Automotive tire Automotive design Gas

Tire Wheel Automotive design Automotive tire Tread

Wheel Tire Automotive tire Motor vehicle Tread

The rear of the Drive Train is supported by the Crossmember in between the Over Drive unit and the Transfer Case. So in the end the entire drive train is supported by 4 sets of the Poly Bushings, but the weight of the engine is mainly supported by the two engine mounts located on the sides of the engine and the Cross Member is taking the load of the trans and other piece parts. or about 400 lbs,.

Note: the Engine Mounts are bolted to the sides of the Frame Rails which incorporate bushings that go all the way thru the frame rail and are welded in place. In addition there is a "Shear Plate" on the top of the mounts that prevents the mounts from shearing off. So there is 4ea 1/2" G8 bolts holding the frame side of the mounts..

The only negative to this set up is that it does transmit vibration of the Engine to the frame very efficiently. Maybe some day I will go back and remake the step bushings from softer material. BUt for now looking at ways to lessen the vibration that the engine makes in the first place.
However the drive train is located very solidly in all 3 axis'. Period!

OK,,, that is what I did to mount my Engine /Drive Train. YMMV

Randy

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Reactions: 4

Someoldguy

· #93 · Apr 29, 2022

W.R.Buchanan said:
OK I'm a little late to this discussion, but I have some definite ideas about how to mount one of these engines.

First it kind of depends on how the vehicle will be used. If it is street only then mounts that support the engine and kind of limit its fore and aft and side to side movement, will probably work just fine.

However if the Vehicle is to be used off road in any challenging way then the mounts must not only support the weight of the engine but also positively capture its movement on all three axis'. Otherwise you will end up with holes in your radiator and general disappointment.

I learned a lot while building Early Rock Crawling Jeeps 95-03 ish. and they were evolving with every trip to a competition. The mounts on my Yellow Jeep broke on a mild trail in Moab and it took us 4 hours to recover it after only 5 minutes into the trail. About 200 yards!. That prompted me to design and build mounts using Poly Urethane Spring Bushings in the Tubular Mounts to positively locate the engine on all 3 axis'. No more problems with 12" holes in the radiator.

These mounts utilized the center mounting locations on the sides of he engine rather than the conventional mounts on the Front of Chevy 4's and 6's
These worked perfectly and there were no further failures. Even after rolling the Jeep 4 1/2 times the engine was still in place and running even though it was upside down. My right ear still rings constantly from that episode in 2003 !.
View attachment 133483

Moving forward to the DeScrambler I wanted the same basic concept but bigger to deal with the 750 lb Weight of the Cummins 4 BT.

With the 4 BT as an off road power plant I decided it was best to mount the engine on the sides of the block so that the weight of the engine was supported entirely by the mounts independent of any "Cantilever" effects induced by mounting them on the front of the engine and relying on the Transmission mounts to support the rear and divide the entire weight of the power train (1150 lbs total) thus @280 lbs on each mount. This would put undue stress on the joints between the Engine/Transmission/ Overdrive/Transfer Case each of which would encourage oil leakage at some point.

The engine is supported near the #3 cylinder on the drivers side and #2 cylinder on the passenger side by Polyurethane Step Bushings that are 3" in diameter made of 60 Durometer Poly.. I made a mold to pour the Poly around a steel bushing in the center of the bushing.

The right side mount was a little complicated due to having to work around the Turbo Drain and pick up the front mounting holes in the block. The right side is much simpler.

View attachment 133484 View attachment 133485 View attachment 133486

The rear of the Drive Train is supported by the Crossmember in between the Over Drive unit and the Transfer Case. So in the end the entire drive train is supported by 4 sets of the Poly Bushings, but the weight of the engine is mainly supported by the two engine mounts located on the sides of the engine and the Cross Member is taking the load of the trans and other piece parts. or about 400 lbs,.

Note: the Engine Mounts are bolted to the sides of the Frame Rails which incorporate bushings that go all the way thru the frame rail and are welded in place. In addition there is a "Shear Plate" on the top of the mounts that prevents the mounts from shearing off. So there is 4ea 1/2" G8 bolts holding the frame side of the mounts..

The only negative to this set up is that it does transmit vibration of the Engine to the frame very efficiently. Maybe some day I will go back and remake the step bushings from softer material. BUt for now looking at ways to lessen the vibration that the engine makes in the first place.
However the drive train is located very solidly in all 3 axis'. Period!

OK,,, that is what I did to mount my Engine /Drive Train. YMMV

Randy

Your Timing is PERFECT... i was just going to start a new thread... My 4bt into a ram 1500.. looking for moun Ideas... Had read about front mounts.. ( easy.. ) but they scare me.. as all the=at weight and forces between the engine and the end of an aluminum case on a 47ry ( A618) seems to be a problem waiting too happen.. have been looking at a side mount but not a lot of room between the Vacuum pump/power steering pump and starter.. if you had any ideas to share I'd be eternally grateful... besides.. i'm not sure this thread reached its objective.. OPTIMAL MOUNT Points... thanks very much for your write up..

Dougal

Discussion Starter · #94 · Apr 30, 2022

Someoldguy said:
Did we ever come to an optimal

did we ever come to an opitmal placement for mounts and type of mounts? thanks

No progress but it's a good place to share ideas. I agree with Randy that mounts should be central on these engines. As well as supporting the engine best it puts the engine loads into the stronger part of the chassis (front suspension) instead of overhanging out the front.

I want more vibration isolation than the solid mount type. I agree there has to be a limit on how far things can move which needs to be considered with the maximum displacement you'll get with flexible mounts and chassis flex. It's important that the natural flexing of the chassis doesn't tear your mounts apart either at the flexy bits or the welds!

Landrover used sandwich mounts with steel brackets intended to contact on over load in any direction. Seems to be a good compromise.

Reactions: 2

W.R.Buchanan

· #95 · Apr 30, 2022

Vacuum Pump/PS pump is one the Drivers Side, Starter on Passenger Side.? Some room there for your unit but it may be tight.

IMHO the side mounts are the Optimal Mount Points for the engine, that's kind of why I used them.:>)

Randy

Someoldguy

· #96 · Apr 30, 2022

W.R.Buchanan said:
Vacuum Pump/PS pump is one the Drivers Side, Starter on Passenger Side.? Some room there for your unit but it may be tight.

IMHO the side mounts are the Optimal Mount Points for the engine, that's kind of why I used them.:>)

Randy

starter and vaccum pump on drivers side.. which is why I am looking to eliminate the vacuum pump.. but its proving a tough find to find a conversion kit or the proper PS pump with gear from trucks... looked at literally 100's today.. all have `1 problem the gear to mesh with their splinted shafts.. the pumps are plentful if I want to wait 2 more weeks to get one.. then you have to reduce pressure and flow on most of them.. 100 KPA or 1,500 psi and 2-3gpm flow rated and need a big reserve tank...

W.R.Buchanan

· #97 · Apr 30, 2022

Find a PS Pump off a Bread Truck Motor. Mine came off a Doritos Van, same thing. Also the Bread Truck Pump will have returns for both the Power Steering and the Hydro Boost Brake Booster. That way you can eliminate the Vacuum Pump all together, however then none of your vacuum operated things like Cruise Control or any of your HVAC duct valves will work. So keeping the Vac Pump might be a good idea.

Randy

Someoldguy

· #98 · Apr 30, 2022

W.R.Buchanan said:
Find a PS Pump off a Bread Truck Motor. Mine came off a Doritos Van, same thing. Also the Bread Truck Pump will have returns for both the Power Steering and the Hydro Boost Brake Booster. That way you can eliminate the Vacuum Pump all together, however then none of your vacuum operated things like Cruise Control or any of your HVAC duct valves will work. So keeping the Vac Pump might be a good idea.

Randy

I have looked and looked and looked.. no success.. unless you have a source?

Reactions: 1

MaxPF

· #99 · May 1, 2022

4

W.R.Buchanan said:
OK I'm a little late to this discussion, but I have some definite ideas about how to mount one of these engines.

First it kind of depends on how the vehicle will be used. If it is street only then mounts that support the engine and kind of limit its fore and aft and side to side movement, will probably work just fine.

However if the Vehicle is to be used off road in any challenging way then the mounts must not only support the weight of the engine but also positively capture its movement on all three axis'. Otherwise you will end up with holes in your radiator and general disappointment.

I learned a lot while building Early Rock Crawling Jeeps 95-03 ish. and they were evolving with every trip to a competition. The mounts on my Yellow Jeep broke on a mild trail in Moab and it took us 4 hours to recover it after only 5 minutes into the trail. About 200 yards!. That prompted me to design and build mounts using Poly Urethane Spring Bushings in the Tubular Mounts to positively locate the engine on all 3 axis'. No more problems with 12" holes in the radiator.

These mounts utilized the center mounting locations on the sides of he engine rather than the conventional mounts on the Front of Chevy 4's and 6's
These worked perfectly and there were no further failures. Even after rolling the Jeep 4 1/2 times the engine was still in place and running even though it was upside down. My right ear still rings constantly from that episode in 2003 !.
View attachment 133483

Moving forward to the DeScrambler I wanted the same basic concept but bigger to deal with the 750 lb Weight of the Cummins 4 BT.

With the 4 BT as an off road power plant I decided it was best to mount the engine on the sides of the block so that the weight of the engine was supported entirely by the mounts independent of any "Cantilever" effects induced by mounting them on the front of the engine and relying on the Transmission mounts to support the rear and divide the entire weight of the power train (1150 lbs total) thus @280 lbs on each mount. This would put undue stress on the joints between the Engine/Transmission/ Overdrive/Transfer Case each of which would encourage oil leakage at some point.

The engine is supported near the #3 cylinder on the drivers side and #2 cylinder on the passenger side by Polyurethane Step Bushings that are 3" in diameter made of 60 Durometer Poly.. I made a mold to pour the Poly around a steel bushing in the center of the bushing.

The right side mount was a little complicated due to having to work around the Turbo Drain and pick up the front mounting holes in the block. The right side is much simpler.

View attachment 133484 View attachment 133485 View attachment 133486

The rear of the Drive Train is supported by the Crossmember in between the Over Drive unit and the Transfer Case. So in the end the entire drive train is supported by 4 sets of the Poly Bushings, but the weight of the engine is mainly supported by the two engine mounts located on the sides of the engine and the Cross Member is taking the load of the trans and other piece parts. or about 400 lbs,.

Note: the Engine Mounts are bolted to the sides of the Frame Rails which incorporate bushings that go all the way thru the frame rail and are welded in place. In addition there is a "Shear Plate" on the top of the mounts that prevents the mounts from shearing off. So there is 4ea 1/2" G8 bolts holding the frame side of the mounts..

The only negative to this set up is that it does transmit vibration of the Engine to the frame very efficiently. Maybe some day I will go back and remake the step bushings from softer material. BUt for now looking at ways to lessen the vibration that the engine makes in the first place.
However the drive train is located very solidly in all 3 axis'. Period!

OK,,, that is what I did to mount my Engine /Drive Train. YMMV

Randy

Mine is very similar. I used off-the-shelf urethane leaf spring bushings. As I mentioned in the "Show Off Ur Motor Mounts" thread, these work well and provide adequate vibration absorption for a 6, but they would be far from optimal for a 4. A similar mount using the second gen Dodge mount inserts, as shown above in post #87 of this thread, would be much better. Even then, vibration absorption is likely to be marginal for a 4BT, unless you happen to have one with a balance shaft.

These are actually my second iteration of the leaf spring bushing mounts. The first version didn't allow as much slope on the turbo drain. With this version, the slope is still totally inadequate, which is forcing me to put a drain bung in the pan right below the pan rail. Eventually, I will swap to coil front suspension, and when I do so the stock Chevy frame-side motor mount brackets will go away. This will necessitate fabricating yet another set of motor mounts. When I do so, I will likely end up running aftermarket urethane bushings for the Dodge second gen motor mounts. I will still use tubing though!

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Someoldguy

· #100 · May 1, 2022

MaxPF said:
Mine is very similar. I used off-the-shelf urethane leaf spring bushings. As I mentioned in the "Show Off Ur Motor Mounts" thread, these work well and provide adequate vibration absorption for a 6, but they would be far from optimal for a 4. A similar mount using the second gen Dodge mount inserts, as shown above in post #87 of this thread, would be much better. Even then, vibration absorption is likely to be marginal for a 4BT, unless you happen to have one with a balance shaft.

These are actually my second iteration of the leaf spring bushing mounts. The first version didn't allow as much slope on the turbo drain. With this version, the slope is still totally inadequate, which is forcing me to put a drain bung in the pan right below the pan rail. Eventually, I will swap to coil front suspension, and when I do so the stock Chevy frame-side motor mount brackets will go away. This will necessitate fabricating yet another set of motor mounts. When I do so, I will likely end up running aftermarket urethane bushings for the Dodge second gen motor mounts. I will still use tubing though!

what Is that [power steering Pump> Number type if you can tell please?... thanks

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