Steering, Suspension, & Brakes

tips, technology, tools and techniques related to non-driveline mechanical components

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In


Migge
Michael B.

(151 posts)

Registered:
11/18/2008 02:31PM

Main British Car:


Engine damper
Posted by: Migge
Date: December 08, 2011 06:52AM

Hello,

has anybody mounted an engine damper? Saw a simple made one at a race 2009. I know there are better ones available. Worth or not?
PICT5929.JPG


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5803 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Engine damper
Posted by: BlownMGB-V8
Date: December 08, 2011 08:12AM

You know, the motor mounts are supposed to do that, and if they don't then they really aren't right. I like the type of mounts that bolt to the front of the heads and go straight down to the frame rails. Very effective in controlling engine torque.

JB


roverman
Art Gertz
Winchester, CA.
(2979 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Engine damper, look for cracking.
Posted by: roverman
Date: December 08, 2011 11:02AM

Migge and clan, I have oem one ,on my Jensen Healey. It works so good, it's cracking the firewall ! Obviously this will be gone, with the hemi. Removing will allow the engine to be 2" to rear. Plan is to use urethane shock bushings,(4 minimum),through tubing linked to cage, into bh/block. Cheers, roverman.


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: Engine damper
Posted by: Moderator
Date: December 08, 2011 12:21PM

I know that car! It's a REAL factory-built MGB GT V8. I believe it still has its original MG-provided mounts on its frame. Exceptionally quick driver, tremendously clever builder and all around great guy... I'll get both of his racecars added to BritishRacecar.com sooner or later, but the photos I have at this time don't do his cars justice.

Quote:
You know, the motor mounts are supposed to do that, and if they don't then they really aren't right.

+1, with reservations. When OEM's use similar-looking supplemental devices, one hopes it's because they planned to from the beginning. When they're installed as an afterthought, it's an admission of failure. Probably they made the main motor mounts very soft to reduce noise and vibration in the cabin, then decided the main motor mounts inadequately secure the drivetrain in one particular axis.


Migge
Michael B.

(151 posts)

Registered:
11/18/2008 02:31PM

Main British Car:


Re: Engine damper
Posted by: Migge
Date: December 10, 2011 12:25PM

Found some other pics
Engine damper MGB.jpg
Engine damper MGB2.jpg
Engine damper MGB3.jpg


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1074 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Engine damper
Posted by: ex-tyke
Date: December 10, 2011 02:42PM

RE: That last photo........
There's something about engine mount designs attached to cylinder heads that doesn't seem right and prone to early failures


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5803 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Engine damper
Posted by: BlownMGB-V8
Date: December 10, 2011 10:55PM

Why would you say that Graham? Do you have a solid engineering basis? Because I don't see one. Compared to block mounts for instance, they are much more effective at controlling torque due to the wider spacing, just as effective in handling vertical loads, just as effective in handling side loads and longitudinal loads, and with 3 widely spaced 3/8" bolts attaching each to the engine just as solidly mounted. The load is transferred directly to the reinforced frame rail which is capped back to the front crossmember attachment bolt and has a through tube welded in. Compared to a front saddle mount which is near identical except for the attachment location and fewer fasteners, they transfer the load straight down rather than relying on a beam and require less space. Compared to "dogbones" or a central mount they need no supplemental torque control. I know you better than to think you would make that statement based only on hunch or impression so you've got me curious because I can't for the life of me figure out where you think there is a flaw. Please enlighten me if you would.

JB



ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1074 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Engine damper
Posted by: ex-tyke
Date: December 11, 2011 10:02AM

Jim - I have no definitive proof of any failure mechanism, but I see the possibility of head gasket failure with the constant loading/unloading of that joint.
Most of my argument probably comes from studying typical OEM engine mount designs over thr years - non that I know are mounted on heads.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5803 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Engine damper
Posted by: BlownMGB-V8
Date: December 11, 2011 11:32AM

OK, That seems a reasonable cautionary note, and if the head bolts or studs on an engine are in any way marginal I could see it contributing to failure. So this might not be an ideal system for a Buick or Olds 215 since they are known to be weak in the area of head bolt retention. But let's consider typical head bolts a moment. I guess we're looking at tensile strengths on the order of 80-120 thousand psi, right? So without running the numbers I'd guess that one head bolt is going to hold somewhere between 20-30 thousand pounds. Could be less or more, but that is on such a scale that the loading of the mounts is pretty insignificant. We could do an elaborate analysis but just taking a third of the engine & transmission weight, adding a fudge factor, say we're putting 200 lbs on each mount and triple that for dynamic loading so 600 lbs. then take the front four head bolts and divide the load between them, in the worst case we are putting a maximum of 150 lbs of load on the bolt, compared to the tensioned (stretched) load of 20,000-30,000 lbs each. This load is at a 45 degree angle as well so half of it is transformed into a lateral load. Does it really make sense to you to think the load of the mounts will effect cylinder head gasket sealing? With an iron block engine I just can't see it being a factor unless you're at the hairy edge of gasket performance. Aluminum may not be quite as clear cut but then the aluminum engine is also lighter and won't apply as much load either.

Agreed, it does not seem to be common practice, but I've not seen where anyone has gone to the trouble to research it either. I know head mounts are used on motorcycle engines though, and possibly on aircraft as well. So I think the concern is a fairly minor one. Basically if the engine is not known for head gasket failures these mounts aren't likely to cause problems. If it is, ... well that's a whole nother question isn't it?

JB


rficalora
Rob Ficalora
Willis, TX
(2621 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Engine damper
Posted by: rficalora
Date: December 11, 2011 08:45PM

Wouldn't another reason be so you can more easily pull the heads w/o having to prop up the motor?

And might there be shearing forces from engine torque and vibrations that could contribute to head gasket failure with rigid mounts to the heads?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5803 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Engine damper
Posted by: BlownMGB-V8
Date: December 12, 2011 12:04AM

Well first off the mounts aren't rigid since they use cushion mounts which are the same thing Pete uses in his crossmember 302 mounts, although I prefer the softer ones, so any forces whatsoever would be absorbed in the cushions long before they could affect the head gasket. And don't forget the head is located on dowel pins so it can't move anyway. Plus you also have the intake manifold bolted solidly to both heads giving additional reinforcement. I can't see that mass going anywhere. Do you think a multiplier larger than 3X is needed to account for dynamic loading? I mean we're talking about better than 3 G's of acceleration there, on a pretty heavy mass, and even then we're only MAYBE in the worst case scenario adding a 75 lb load (140 lbs at a 45 degree angle to the bolt) to a bolt that is already holding over 20,000 lbs. Doesn't seem to me it should make a difference even in a marginal case.

If you think you might be pulling the heads while leaving the block in the car then yes I could see that being an issue where you'd want to block up under the engine or let it rest on the crossmember, but I've done that sort of thing before and honestly it's a lot easier on the back if you just pull the motor and put it on a stand.

JB


roverman
Art Gertz
Winchester, CA.
(2979 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Engine damper/ stand back, it's a firewall !
Posted by: roverman
Date: December 12, 2011 12:07PM

" From somewhere outside the forrest", which area is more likely to take torsional loads better, the firewall or 2 feet in front of it ? I think we know the answer ? Theres a reason why "mid mount" motor plates are so popular-they work ! I'm not saying all cars should use them, but perhaps "borrow" on the designs. Picking up the torque off the bh. bolt pattern, should distort the chassis and engine block less, under high loads. Especially aluminum oem blocks, in a high torque/hp build. Yes Jim, your super-mondo cast iron blocks may not benefit. Cheers, roverman.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5803 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Engine damper
Posted by: BlownMGB-V8
Date: December 12, 2011 12:35PM

With a bellhousing mount (mid mount) you still need a front support. IH used those on their light-line trucks. The problem with an MGB or similar car is, where do you attach the mounts? It's a deal killer. And the main concern for torque control is distance from the engine centerline to the mount cushion. The head mount has that one hands down, and is also far and away the most convenient and easy to work with. And if the mighty 455 Buick in the Roadmaster isn't going to twist the body (even with fiberglass fenders) what is there to worry about? Twisting the block? You would WISH you had that much power!

JB


Migge
Michael B.

(151 posts)

Registered:
11/18/2008 02:31PM

Main British Car:


Re: Engine damper
Posted by: Migge
Date: December 13, 2011 03:20AM

I think, the problem with a mid mounted damper is the very short movement you have in the centre. If the engine is going to move a bit, it's easier to recognize that at the longest lever, the heads. may ist best to mount a plate that connects both heads and to use 2 dampers?


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: Engine damper
Posted by: Bill Young
Date: December 13, 2011 08:12AM

My tuppence worth, I think it really depends on the type of mounts you use. If you're using some stock type rubber mounts that are very compliant then a damper or bar would be a good idea, but if you're using something like polyurethane mounts, especially the type where you have a tube with poly bushings inside it then no damper would be needed as those mounts are very resistant to movement while doing a nice job of isolating vibrations. The higher the mount is in relation to the crank centerline the more it will resist torque as well, higher or wider, the effect is the same, more leverage from the point of rotation.



roverman
Art Gertz
Winchester, CA.
(2979 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Engine damper, chassis as a torsion bar
Posted by: roverman
Date: December 13, 2011 11:55AM

In longitudally mounted mounted engines,(front mounted/rear diff), the frame/unit body absorbs torque like a torsion bar. the "longer" you make this theoretical torsion bar, the easier to twist(chassis). By shortening the distance, and/or mechaniiclly linking (torque tube,etc.), to the diff., you reduce the weird door gaps. Transverse mounted engines have fewer torque resultant problems,(beam strength required). Cheers, roverman.



Edited 1 time(s). Last edit at 12/15/2011 12:31PM by roverman.


Migge
Michael B.

(151 posts)

Registered:
11/18/2008 02:31PM

Main British Car:


Re: Engine damper
Posted by: Migge
Date: December 27, 2011 08:49AM

Found 2 other pics
PICT7129.JPG
PICT7128.JPG


roverman
Art Gertz
Winchester, CA.
(2979 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Engine damper/ weight transfer
Posted by: roverman
Date: January 05, 2012 11:38AM

What if, engine/transmission weight was supported adequately by the bell housing bolts,(isolated for street use). Wouldn't this reduce front end weight since the pickup point has been moved rearward approx. 2 feet ? Regarding torque control, the torque lever length AND number of recievers(isolaters), in the mix,and durometer hardness, should determine the effectivenass. Science, roverman.



Edited 1 time(s). Last edit at 01/05/2012 11:47AM by roverman.


DiDueColpi
Fred Key
West coast - Canada
(1259 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

authors avatar
Re: Engine damper
Posted by: DiDueColpi
Date: January 05, 2012 05:14PM

Hey Art,
In this instance, the mass of the engine nor it's placement have changed.
So the weight distribution will not change.
What will change is the load on the motor mounts.
As they move rearward in the vehicle towards the trans mount they take more of the total drive train load.
Once they pass the center of gravity for the drive train mass the trans mount will become unloaded and have a negative pressure on it.
Because of this leverage action the mass becomes more and more difficult to support and vibration transmission increases dramatically.
Cheers
Fred


Sorry, only registered users may post in this forum.