Using the block as a stressed member

Tim Taylor Wrote:
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> I can't seem to find any pictures if it online but
> while it is common practice to use a stressed
> block in formula cars they do it to blocks that
> were designed to handle the loads. I can also
> think of two examples where they went to great
> pains not to feed loads onto a stock engine block.
> Gigantic billet machined valve covers were
> created to send the chassis stresses through
> instead.
>
> It would be very application specific to determine
> if you were going to put bad enough loading on the
> engine block to distort it and cause damage in
> operation. So, not that anyone here is going to
> try it but your best bet is to do a giant billet
> valve cover that can handle being attached to your
> chassis as a structural member.
>
> A 7 post rig is also unnecessary for finding the
> torsional rigidity of your chassis. Just bolt the
> back suspension pickups to the floor sitting on
> some rigid mounting, support one front suspension
> point on a jackstand, apply a big lever to twist.
> The twist can be measures and converted into a
> lb/degree or other applicable measurement. Nobody
> is going to do that either so it doesn't really
> matter. Like Grant said fix all the other stuff
> first.

Tim, I agree and I wouldn't do it (*stress a block*). I was talking about the mounts being useful to strengthen the strut towers. The bit about the bushings was to acrane about how all bushings give, which as you know is bullshit.

Also, I was pretty sure we were well into pure wankerdome for the sake of it.. maybe I was being too subtle? "Something you need to do, definitely not. "

Edit for clarity

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Andrew M
Onterrible
30ish



Edited 1 time(s). Last edit at 03/21/2008 12:45AM by hudson.

hudson Wrote:
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> >
> > Too bad Toyota didn't have such well
> reasoned
> > arguments cause it looks like they fell for
> the
> > same mistaken logic that I did on their only
> > serious RWD car they did:
> >
> >
> > See piccies no 4-5-6 and 23
> > Some of you 'pooter whizie boys could you put
> one
> > of those photos here?
>
> John, you're coming off as if that was an attack
> man. I know you don't mean to come off that way
> because I'm pretty sure I said it was a good idea
> and you did a good job on Kevin's car at least 4
> times.

No I don't take it as an attack. I just find it a bit odd how an idea which actually is rather common (small diameter solid hard rubber bush, mounted horizontally) on numerous cars, and so many guys are deciding that they don't need anything like it.

>
> Lee/Vorpal was talking about using the engine as a
> stressed member. I was just pointing out that
> mounting the engine that way doesn't in and of it
> self particularly achieve that. The cross member
> should be doing most/all the work anyways. However
> the mounts could be used to strengthen the strut
> towers.

Yeah I was kinda wrinkling my nose at the stressed member idea, its one of those hard to put any real figure on what it would accomplish.

But the "getting the lump of iron off the crossmember" would have made a pan swap i did on a guys car you scraped thru his pan being silly 20 times easier.
And the reliability, PROVEN reliability of the simple bush is sorta a plus.
I lurv simple proven in hard competition designs.
>
> He's talking about making the car stiffer and I'm
> wasting time talking about how he could go about
> it.
>
>
> Andrew McNally
> Hamilton ON
> 28

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
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john vanlandingham Wrote:
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> No I don't take it as an attack. I just find it a
> bit odd how an idea which actually is rather
> common (small diameter solid hard rubber bush,
> mounted horizontally) on numerous cars, and so
> many guys are deciding that they don't need
> anything like it.

It's definitely better. No doubt in my mind. As you say, taking the load of the engine off the cross member is WAY better. Worth the work? That's for the builder to decide. And as you say, the type of bushing being used in the horizontal mounting is for sure more robust.

> Yeah I was kinda wrinkling my nose at the stressed
> member idea, its one of those hard to put any
> real figure on what it would accomplish.

Well, as Tim points out if you actually stressed the block in any meaningful way you'd more than likely break your engine.

Edit: And yes as you've pointed out several times, the serviceability is improved. I like the idea that you could have a complete front end (steering, suspension etc) ready to rock and bolt it in with less than 10 bolts regardless of design without having to worry about the engine.

---

Andrew M
Onterrible
30ish



Edited 1 time(s). Last edit at 03/21/2008 01:18AM by hudson.