Dick Axtell
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 posted on 24/10/03 at 05:29 PM |
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Brace Bar 'R'
Hi All (especially Xflow users),
The fuel pump on my 1600 Xflow is uncomfortably close to that engine bay brace member, 'R'.
Anyone else have this problem? If so, how did they solve it?
TIA
Dick
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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Jon Ison
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| posted on 24/10/03 at 06:36 PM |
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is bar "R" the one that goes at an angle from scuttle to side at top rail height ? or is it one of the lower 2 ? either way move it to
suit clearance, the books a guide NOT gospel.
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Mk-Ninja
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| posted on 24/10/03 at 06:44 PM |
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Its the top rail
I'm sure I've got one, just don't know where I've put it
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craig1410
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| posted on 24/10/03 at 08:52 PM |
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I'm using a Rover V8 and thus I can't really use an "R" rail at all but it is an important structural member so try to keep it
as long as possible within the limits of clearance allowed by your fuel pump. You may have the option of using an electric pump and just fit a
blanking cover over the space left by the mechanical one.
In place of an "R" tube I have had to add several extra tubes to replace the lost stiffness.
HTH,
Craig.
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Dick Axtell
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| posted on 26/10/03 at 08:03 PM |
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Brace Bar 'R'
Seems that the most straightforward solution appears in the Engine + Transmission section.
(Change the fuel pump).
Thanks anyway for the feedback.
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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Chris Leonard
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| posted on 27/10/03 at 12:15 PM |
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I came across the same problem. However the engine should sit slightly to the left, (19mm I think looking from the back of the car forwards). This
gives enough clearance for the fuel pump and also offsets the Prop UJ's - which apparantly is a good thing
Cheers Chris
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TheGecko
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| posted on 27/10/03 at 12:57 PM |
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Dick,
The other option is to split the brace into a Y shape. The attached photo shows such a brace in an Aussie built car.
Hope this is helpful,
Dominic
 
Engine bay of Mike Laws Locost showing modified 'R' tube
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craig1410
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| posted on 27/10/03 at 07:19 PM |
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Yes the Y brace is a good alternative albeit not as strong as the "R" tube it replaces. Cymtriks did FE analysis on the various options a
while back.
My choice would be to ditch the mechanical fuel pump and mount an electric pump at the back as low as possible and as close to the fuel tank as
possible, ideally in it. On cars which accelerate rapidly like the Locost you can get significant loss of fuel pressure when trying to
"pull" fuel along the entire length of the car while it is accelerating hard. Better to "push" it using a good electric
submersible pump as this experiences much less loss of pressure and give you the fuel when you need it most.
Anyone out there experienced this first hand? I've only read about the effect to be perfectly honest.
Cheers,
Craig.
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cymtriks
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| posted on 27/10/03 at 11:17 PM |
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tube R
The following are results of my analysis of engine bay mods (tube R variations)
Here are the results for chassis stiffness in ftlbs.
The book chassis:- 1155
My modified chassis design as described in earlier posts:- 2505
Both the above have standard tube R layout.
The book chassis with two shorter R tubes, one on each side of the engine, to allow wide engines to be fitted:- 907
My mods but with two short R tubes as above:- 1898
The conclusion is that fitting two short R tubes instead of one long one as in the book reduces the stiffness by about 25%
The book chassis but with two Y braces, one on each side of the engine, from where the H tubes meet tube Q to the tops of FU1/2:- 1215
My high stiffness design but with two Y braces as above has over 2700. A picture of this is in the photos section. That's not far of an Ultima
chassis stiffness and is more than double the book chassis stiffness.
Kitcar spaceframes range from 400 (hopeless) through 1000-2000 (most kitcar chassis) to over 3000. Of course you can make any stiffness you want but
there comes a point where the chassis is simply easier to make as a monocoque.
Ladder frames are much better than people think and are a lot better than the worst spaceframes. Ladder frames usually fall in the range 800 to 5000
though the stiffer chassis tend to weigh a lot more than they need to. Weight for weight for a complete car they are about 5% worse than an equally
well designed spaceframe but are a lot easier to get right in the first place. They are also hard to seriously mess up which is why the worst ladder
frames tend to be much better than the worst spaceframes.
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craig1410
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| posted on 27/10/03 at 11:30 PM |
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Cymtriks,
Thanks for putting into numbers what I more or less tried to put in words 
Did you ever simulate a single Y brace on the offside as per the standard book "R" tube?
Cheers,
Craig.
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David Jenkins
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| posted on 28/10/03 at 08:25 AM |
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I'm surprised that the fuel pump causes a problem - or have I mounted my X-flow lower than everyone else! (I did have to chop the sump,
though...)
My pump is slightly lower than the R tube.
David
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