craig1410
|
| posted on 2/9/06 at 11:25 AM |
|
|
SU Carbs Exposed - Would they pass?
Hi,
As many of you are aware, I'm building a Locost with a Rover V8 engine. This is fitted with twin SU carbs and ITG foam filters and I am
currently trying to build a bonnet bulge to cover them up for SVA...
However, I am very worried that my current (HUGE) bonnet bulge will not pass SVA due to line of sight issues. The requirement is that you need to be
able to see an unobstructed view of the road at 4 degrees below horizontal from an artificial "drivers eye" point of view.
"Simon" on the forum had problems at SVA with his line of sight and had to do some extra work on the car to get it past the test - I think
my bonnet bulge may be even bigger than his which is why I'm worried.
Anyway, lateral thinking kicked in and I am now considering building the bonnet bulge to cover only the inlet manifold and carb bodies (and linkages
etc.), leaving the carb dashpots and air filters exposed. I'm pretty confident that I can make the ITG filter SVA compliant and thought I could
make a little rubber cap for the SU dashpot to cover the plastic cap which may have some non-compliant radii.
Has anyone tried this for SVA?
There are some pictures in my photo archive in the "Bonnet Bulge" folder showing my provisional bonnet bulge cut out of PU foam.
Opinions welcome as always...
Thanks,
Craig.
|
|
|
|
|
RichardK
|
| posted on 2/9/06 at 12:49 PM |
|
|
Wonder if it's acceptable to temporily raise the height of the seats
Just a thought.
Regards
Rich
|
|
|
UncleFista
|
| posted on 2/9/06 at 01:15 PM |
|
|
quote:
Originally posted by RichardK
Wonder if it's acceptable to temporily raise the height of the seats
Just a thought.
Regards
Rich
Then you'd need to worry about the seatbelt anchorages being high enough above the seat etc. 
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
|
|
|
craig1410
|
| posted on 2/9/06 at 01:49 PM |
|
|
Hi,
My seats are Cobra Roadster 7's and they are on Cobra sliding rails so are already higher than "normal". Also, in addition to seat
belt anchorage heights I would need to worry a bit about smacking my head off the rollbar which is quite close to my head already. Beside the SVA
aspect, I just didn't like the bonnet bulge I ended up with, it was just a bit "in your face". Simon managed to get his looking a
lot better but I think that was partly because he didn't use proper air filters.
I have actually started working on my foam former to see what it looks like with what you could describe as nostrils at each side for the air filters
and the SU's sticking out. With nice polished dashpots and the already nice ITG filters I think it could look quite good and certainly a bit
less vulgar than my original bonnet bulge. It would also be beneficial for performance as the air filters would be breathing cool air and the
aerodynamics of the car should be substantially improved...
If the exposed SU thing doesn't work out I can re-assemble my original design as I am being careful to preserve the foam pieces as I cut them
away.
Cheers,
Craig.
|
|
|
rusty nuts
|
| posted on 2/9/06 at 04:31 PM |
|
|
Check out e bay for a Holley,Weber etc and manifold to fit?
|
|
|
craig1410
|
| posted on 2/9/06 at 05:49 PM |
|
|
Rusty,
I would love a Weber 500 and manifold but I can't afford it right now. My plan always was to use the engine completely as standard until I could
properly evaluate it to see what condition it is really in. Then I might start planning a rebuild which would culminate in a rolling road session.
Besides, I like SU carbs and have a good bit of experience tuning them. They are also perfectly good in performance terms and will not restrict the
engine until it is pushing out 250BHP+
The other good thing about them is that they are quite efficient so fuel economy should be reasonable.
Fair enough suggestion though but one I have ruled out for now at least.
Thanks,
Craig.
|
|
|
907
|
| posted on 2/9/06 at 06:08 PM |
|
|
Hi Craig,
Any chance of a pic of what your trying to cover with your bulge.
You might get a suggestion or two if those of us who wouldn't recognize a RV8
if we fell over it, could see what the problem is.
Paul G
|
|
|
craig1410
|
| posted on 2/9/06 at 07:58 PM |
|
|
Hi Paul,
I don't have any photo's of the carbs with air filters attached but here is a photo of the SU carbs to give you an idea.
I'm just in from the garage having spent the day working on the bonnet. I have just coated the PU foam in resin and will wait until tomorrow
before covering it in wax and release agent and laminating a couple of layers of CSM. I should then be able to dig the foam out from the inside and
put on another couple of layers from underneath. I know this is an ar$e over t1t method of fibre glassing but it should be okay. I'll maybe use
the bonnet as a buck and make a proper mold one day...
Cheers,
Craig.
 
Rescued attachment SUCarbs.jpg
|
|
|
craig1410
|
| posted on 2/9/06 at 08:06 PM |
|
|
...and here is a picture of the type of air filter I have. Mine isn't quite as deep as this one. In fact mine is 40mm internal height and 65mm
overall height.
|
|
|
907
|
| posted on 3/9/06 at 08:08 AM |
|
|
Instead of the filter being mounted upwards & outwards could it be mounted on a bend that faces down?
Paul G
p.s. sorry for the crap drawing
 
Rescued attachment air-filter-mount.jpg
|
|
|
craig1410
|
| posted on 3/9/06 at 12:56 PM |
|
|
Hi Paul,
Good suggestion but I don't think there would be enough room and this would place the filter directly above the exhaust manifold which would be
bad for performance and might even melt the filter...
The Rover SD1 has a couple of 180 degree bends which go round behind the engine (ie. above the gearbox but again I didn't have enough room with
the battery and pedal box etc.
Thanks again,
Craig.
|
|
|
NS Dev
|
| posted on 4/9/06 at 11:56 AM |
|
|
I see no reason why you cant stick the carbs out through the bonnet, I have seen nothing specific in the manual.
As you say, the SU tops are pretty good anyway, and you could probably smooth off the plastic caps enough to make the rad req.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
|
|
|
hearbear
|
| posted on 4/9/06 at 12:47 PM |
|
|
Try and get the manifold of the mgb gt v8 this turns the carbs 90' and moves them backand i think lowers them slightly
3.9Ltr SSC Stylus should be fun
|
|
|
craig1410
|
| posted on 4/9/06 at 05:33 PM |
|
|
Hi,
Yes I've been looking out for an MG manifold on ebay for a while now but they are pretty rare. They are also not as efficient as the SD1
equivalent as the air flow has to turn through 90 degrees.
I'll hopefully post some pics of my provisional solution later tonight or tomorrow.
Cheers,
Craig.
|
|
|
chrsgrain
|
| posted on 4/9/06 at 06:03 PM |
|
|
A Dax V8 has passed SVA with the carbs poking out of the bonnet, pretty much as you suggest... no pictures I'm afraid, but it can be done...
Chris
Spoing! - the sound of an irony meter breaking...
|
|
|
chrsgrain
|
| posted on 4/9/06 at 06:20 PM |
|
|
Found a picture on one of the Dax site.... second car from the bottom of the (long) page... wasn't the one I was thinking of, but done in a
similar way.....
dax pictures...
Chris
Spoing! - the sound of an irony meter breaking...
|
|
|
craig1410
|
| posted on 4/9/06 at 09:10 PM |
|
|
Chris,
thanks for those links, that is exactly what I was hoping someone would show me - quite reassuring!
Here are a few pics of the (very rough) solution which I've come up with. Not quite as elegant as the Dax for sure but once I've skimmed it
with filler it should look okay.
 
Rescued attachment P9040113.JPG
|
|
|
craig1410
|
| posted on 4/9/06 at 09:11 PM |
|
|
and another
 
Rescued attachment P9040114.JPG
|
|
|
craig1410
|
| posted on 4/9/06 at 09:13 PM |
|
|
and one more from the drivers eye.
I think this is much better than my previous "extra large" bonnet bulge solution but would appreciate any constructive criticism you may
have. I know I will need to watch not to leave too big a gap between air filter and body and will need to put a cap on the SU carbs and the little red
tab on top of the air filter. Apart from that I might need some radiused trim strip around the red band on the filters but that should just about do
it I think.
I am hoping that I will get just enough heat from the bottom half of the filter to prevent carb icing but have a nice clear stream of cool air for max
power. Not a major problem 'cause I can't see me driving it much in icy conditions...
Cheers,
Craig.
[Edited on 4/9/2006 by craig1410]
 
Rescued attachment P9040118.JPG
|
|
|
.jpg)
