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Hey all, my question for today is in regard to solid engine mounts.

Seeing as the gaping hole which is the engine bay is a weak part of the chassis I was thinking of mounting the engine via engine plates as this would tie everything together. I was thinking of using a thick aluminum plates as this would absorb some of the vibration but im also using a 4 cylinder which are not known for their smoothness compared to a straight 6.

Research on other pages and it seems to be quite car dependent for the outcome. Some car forums people say its barely an issue, mainly at a stop the you notice the chassis resonates with rpm. other car forums say that everything in the car buzzed and vibrated. So I guess it comes down to how the chassis/interior parts are constructed/connected.

So asking here. im hoping since our cars are quite bare bones and hopefully relatively stiff there shouldnt really be anything to annoyingly buzz and rattle? but maybe because they are quite stiff it will resonate though the whole chassis.

What have been peoples experiences? has anyone gone from rubber mounted to solid in the same vehicle? what was the difference?

Depends.

Do that on a V12 and it'll be fine. Will probably be fine on a straight six as well. As for V6s and V8s, it all depends how much vibration you can put up with. I tried it as an experiment exactly once on my old Datsun with its small inline 4. It shook the car so much that I thought I'd left a wrench on the front crank pulley. No thanks!

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That really depends on your engine of choice. I have solid mounts on my 7 and the vibration is not bad at all, but I have a horizontally opposed engine. On an other car I had stiffer poly mounts and had to remove them as the car vibrated so bad.

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Chris White
Locost 7 type 1 power and a rear transaxle
Lotus Elise Sold
ND Club Miata
Nissan Titan Sold
Rubi Wrangler
http://www.locostusa.com/forums/viewtopic.php?f=35&t=13200

My car has a 60 degree V6 and solid engine mounts, I don't notice any engine vibration at all. I did what I think you're talking about, a block plate that bolts to the front of the transmission tunnel and closes off that big hole.
Kristian

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V6 in a book frame build. Now registered.
viewtopic.php?f=35&t=7587
viewtopic.php?f=33&t=18172

Just had a look at your build and yep exactly like that. Do you also have a plate up the front though? I couldnt see one in the pics?

No, I have a more traditional engine mount on each side of the engine towards the front that go down to the lower frame rails. They are solid steel mounts though, as well as the transmission mount. The solid mounts haven't given me any trouble yet, and it's been running for quite a while like that.
Kristian

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V6 in a book frame build. Now registered.
viewtopic.php?f=35&t=7587
viewtopic.php?f=33&t=18172

I'm using Delrin pads for the engine (LS3) and transmission (TKO 600) mounts.
Not running yet, so nothing to report on the vibration front. Should be somewhere between poly pads and solid mounts. Probably closer to solid.

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Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."
Ultima Spyder, Northstar 4.0, Porsche G50/52

I started with the engine/transaxle combo mounted completely solid. I'm running a V8, and vibration has never been an issue. I have since switched the mount up a little bit. The engine mount has a bearing on the chassis side so the engine can tilt up and down when I'm installing or removing the transaxle. Again, vibration has never been an issue for me. What I would consider is how the chassis loads go into the engine when using solid mounts. You don't want to crack an engine block or distort the cylinders.

Ken

Yes I planning to use a solid plate that reaches from one side of the chassis across to the other and has holes to mount the motor in the middle of it...

Instead of 2 separate solid mounts with the engine in between.

My thinking with the one large plate the stresses will go though the plate rather then through the plate then the engine then the other plate.

Also by making the plate from aluminum it will hopefully absorb some of the vibrations.

Aluminum may not be the best choice for mounts; it has a finite fatigue life, meaning that it will fail eventually when put in application of forces such as bending or vibration.

http://mewelding.com/stainless-steel-vs-aluminum/

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Cheers,
Logan