Chassis stiffness...

[Ricardo Montalvo]

This is an interesting comment from the Ultima Factory in response to questions from potential customers:

"Surely solid mounting the engine with a mounting plate would significantly strengthen the engine bay?--

Yes it would but this simply doesn’t suit a road going car and would make the car too harsh. What we have done is to replace this structure with careful triangulation placed in the engine bay area to transmit the suspension loads across the chassis. This solution is the best of both worlds."


I was worried about this previously too, but it's a myth. At least in the SLC it is. It's not just "acceptable", it's a non-issue in my experience. There is no comfort issue or compromise with the solid engine mounts in the SLC.

I was ready to cut out the solid mounts and install the optional poly-mount setup until I actually experienced driving an SLC with solid engine mounts on the street. I'm happy I didn't go through the effort before knowing for sure.

 

[Luke S]

I've never had an issue with solid mounts in "street" cars be it front or rear engine. Once you get radical with .800" cams and 8000 rpm fasteners become an issue, but not really a comfort issue. Yes a little harmonics, but not a concern with any type of aftermarket exhaust notes (ie it will excede the engine harmonics).

I don't really get the comment from Ultima, as stiff is stiff. Why add more weight/bars to compensate for not using the engine as a somewhat partially stressed component. Lotus was using engine/transaxles as stressed components forty years ago (not that Chapman endorsed comfort over function).

Anytime the payload of a vehicle takes on this much of the overall mass, there has to be compromises. Look at sportbikes that need full suspension tweaks to perform two up. If a vehicle gets down to 2k lbs and has a variable of +/- 200lbs your not going to ride like a Cadillac anylonger

 

[Dave]

Looks like the Ultima GTR finally stepped up their game a little bit on their chassis. http://www.pistonheads.com/Gassing/topic.asp?h=0&f=20&t=1272251&mid=0&nmt=New+Uprated+Ultima+Chassis

Now if they'd just update that front end and windscreen to look more modern....oh wait, Fran did that already

 

[James]

I've never had an issue with solid mounts in "street" cars be it front or rear engine. Once you get radical with .800" cams and 8000 rpm fasteners become an issue, but not really a comfort issue. Yes a little harmonics, but not a concern with any type of aftermarket exhaust notes (ie it will excede the engine harmonics).

I think that also has to do with the fact that the LS3,, or for the most part all cross-plane crank V8's are pretty smooth because of the crank weights counter balancing the vibration.

From what I heard of the F50 (engine bolted to body) was once described by Mr. Clarkson as "the engine didn't feel bolted the back,, it felt bolted to your back". That's a V12, which I thought was a relatively smooth engine, but I guess not that smooth. I'll definitely have to ride in an SLC with solid mounts to see how it feels before I decide on which ones to go with on mine.

 

[Mike]

My LS376 (480hp-hotcam) solid mounted motor only vibrates the car for about 2 minutes when started cold & before motor warmup. After warmup and when driven on the street any vibration is not that noticeable. Perfectly acceptable in my book.

 

[Mick Ridley]

Has anyone had experiance with mounting the Rover V8/ Buick 215, In a similar way

As it is a cross-plane crank V8, Would it be as smooth as a LS3 ?




.

 

[TSR]

Any one,
Have any idea where the new LM-P falls on the chassis stiffness scale?

 

[James]

This may fall into "Gee-wiz" but, what grade aluminum is the SLC Chassis. Yes, I could look at mine,, if I wasn't 8000 miles away in the middle east...lol.

 

[Mick Ridley]

Looks like its 6061 T6

 

[Luke S]

There goes concours! They welded the beam in upside down, how will the judges be able to look past such horror and lack of detail.

JK of course