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914World.com _ 914World Garage _ V-8 Engine mount / vibration isolation
Posted by: drive-ability Feb 21 2006, 07:02 PM
I know most of you guys have Porsche engines but most have a lot good ideas about most power plants. I have a V8 car and from the start my goal was to make it a reasonably comfortable driving car. One of the things I am looking at is adding more engine mounting points. I have a Renegade set-up and am thinking of installing a set of 911 engine mounts where the engine cross-member connects to the body. Thats as I understand the factory 4 cyl is done. Not using 911 mounts but similar. My question is about where the vibration comes from, at what point is it transfered the most. I wonder how much is transfered through the drive axles? You could have a great set of engine / transmission mounts and still get a lot of vibration via the axles. What do you guys think on the subject..? I know using the 911 mounts on the Renegade cross-member will introduce more forward / aft movement but the 911 mounts seem to have a firm hold on my transmission. 
Posted by: Dr. Roger Feb 21 2006, 07:13 PM
you mean like this and this?
Posted by: marks914 Feb 21 2006, 07:24 PM
Hey
I use solid mounts to connect the V8 mount bar to the 914 body. (911 solid mounts) and 911 sport mounts for the trans mounts. The rubber chevy mounts between the block and the engine mount bar will isolate any vibration.
Mark
I typed the word mount alot in that post.
Posted by: rick 918-S Feb 21 2006, 07:32 PM
Mine is mounted solid. I don't notice any more vibration than my car had stock on the rubber mounts.
Posted by: drive-ability Feb 21 2006, 08:21 PM
| QUOTE (rogergrubb @ Feb 21 2006, 05:13 PM) |
| you mean like this and this? |
That in the second picture is what I am talking about. I would however was thinking about removing some of the cross-member to keep the engine at the same height. Have you driven the car with that set-up ?? If so, does the engine / trans move, hit the firewall during hard braking?? or ??
Posted by: marks914 Feb 21 2006, 08:32 PM
This is what I did. If you use the solid 911 mount, you do not have to modify anything. It bolts right in at the same height. No problems hitting the firewall beacuse there is less movement.
Mark
Attached image(s)
Posted by: drive-ability Feb 21 2006, 09:49 PM
| QUOTE (marks914 @ Feb 21 2006, 06:32 PM) |
| This is what I did. If you use the solid 911 mount, you do not have to modify anything. It bolts right in at the same height. No problems hitting the firewall beacuse there is less movement. Mark |
The reason I am asking is because I wish to use the non-solid mounts. I don't think the skimpy block mounts isolate much vibration. They work great but there is still a lot of vibration running down the long cross-member.
Posted by: marks914 Feb 22 2006, 04:00 AM
The chevy motor mounts are rubber, there is no need to use 2 sets of rubber mounts on the same thing (engine). Everything is still isolated by rubber.
Are you talking about the motor munts or the trans mounts?
Mark
Posted by: neo914-6 Feb 22 2006, 09:13 AM
Have you driven your car without the body/xmember mount and it's vibrates too much for you?
The properly tuned V8 revs smoothly.
I originally had more "isolation" in the trans mount and Brad changed them to solid. It helped solid shifting.
I was told by the conversion designer (Jaide) to mount the bar solid to the body for correct engine placement. You would drop the body if "stock" isolation was added.
The engine bar to engine mount is sufficient for isolation. I switched to Polyurethane but I haven't got the car running yet.
If you're after more vibration isolation go for it. It will just add some more R&D. 
Posted by: Dr. Roger Feb 22 2006, 09:30 AM
| QUOTE (drive-ability @ Feb 21 2006, 08:49 PM) | ||
The reason I am asking is because I wish to use the non-solid mounts. I don't think the skimpy block mounts isolate much vibration. They work great but there is still a lot of vibration running down the long cross-member. |
Truth be told, I originally set my V8 up like this. After ONE drive the rubber mounts came off as it threw shifting, engine movement, and ride height off. (Hey, a brother's got to try. Right? LOL...)
I would not suggest going this route.
Heck, even with my radical cam I'm mor ethan satisfied with the vibration dampening of the motor mounts as they are.
If your V8 is not idling smoothly and your not running a radical cam, then you've got other problems. Really.
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