sgraber
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| posted on 7/11/07 at 09:47 PM |
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exhaust fumes in the cockpit
exhaust fumes in the cockpit.
I replaced the windshield on La Bala this week and now I am getting a big smell of exhaust fumes when decellerating or just going slow. like air is
being sucked back into the low pressure area behind the windshield instead of continuing behind the car.
Any suggestions for where to start solving this problem?
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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DarrenW
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| posted on 7/11/07 at 09:57 PM |
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Sorry Steve - cant resist.... just take the wind shield back off
Was it like this with windscreen on before? If not have you changed the exhaust routing?
The solution will probs be in the routing of the exhaust (or direction ot tailpipe) or maybe in modding the design of the screen (angle, length etc).
I think id experiment with different tail pipes first.
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sgraber
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| posted on 7/11/07 at 10:13 PM |
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quote:
Originally posted by DarrenW
Sorry Steve - cant resist.... just take the wind shield back off
Was it like this with windscreen on before? If not have you changed the exhaust routing?
The solution will probs be in the routing of the exhaust (or direction ot tailpipe) or maybe in modding the design of the screen (angle, length etc).
I think id experiment with different tail pipes first.
HA! very funny DW...
Never could get the aeroscreen to look right, so back to the windshield. It does look a sight bit better IMHO.
I only drove the car on-track previously with a bunch of other racecars and so thought the smell was just everywhere. Now that I've had a chance
to put 100's of miles on the car it's become obvious the smell is coming from the car and not the environment.
I get the feeling that an undertray diffuser could help, possibly aiming the exhaust tip down, and worse case a winglet across the back... I guess I
am guessing right now.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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RazMan
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| posted on 7/11/07 at 11:17 PM |
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Still got the Supertrapp zorst on Steve? Perhaps a more directional tail pipe / silencer would help
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Doug68
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| posted on 7/11/07 at 11:48 PM |
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Steve,
Looking at the pictures of the car i think that the tail pipe is too close and under the rear bodywork.
So if you've got any sort of reduced pressure under the body then it'll suck the gas's back in there.
I suspect the radial exit supertrapp won't be helping with that either.
Doug. 1TG
Sports Car Builders WA
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sgraber
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| posted on 8/11/07 at 12:05 AM |
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Moved the exhaust down and more central, removed the supertrapp diffuser discs (whoa what a power increase! more on that later) and added some vents
to the decklid. Also put a screen up inside the roll-bar.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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sgraber
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| posted on 8/11/07 at 12:12 AM |
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What about a flat undertray for the engine and a diffuser?
Ok, off topic but I removed the supertrapp discs and the engine simply came to life. And I thought the car was quick before! Must have added literally
30hp to the top end! I can light the tires up through first and second gear with no problem now. 100mph comes up very quickly too.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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kb58
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| posted on 8/11/07 at 12:13 AM |
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quote:
Originally posted by sgraber
Moved the exhaust down and more central, removed the supertrapp diffuser discs (whoa what a power increase!
Yeah, I'll never again use a SuperTrapp. They seem to have attained the impossible. Come up with a muffler that's both really restrictive,
AND loud. Mine fell aparts, screws seized, stuffing coming out. A very sad conclusion to what, on paper, was a good idea. A large Dynomax has much
less restriction AND is much quieter - too bad it's so large.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Doug68
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| posted on 8/11/07 at 01:51 AM |
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So is the fume issue still there after these mods?
Doug. 1TG
Sports Car Builders WA
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sgraber
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| posted on 8/11/07 at 02:41 AM |
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quote:
Originally posted by Doug68
So is the fume issue still there after these mods?
Yes it is.
Kurt, do you like the way your exhaust came out the side of your bodywork in front of the right side rear wheel? I have to wonder if moving the outlet
to the side of the car would work to reduce the smell.
I also speculate that a wing or a gurney flap could make a difference.
I sure do wish I knew someone that could do a flow simulation on it.
[Edited on 11/8/07 by sgraber]
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Doug68
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| posted on 8/11/07 at 02:50 AM |
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You don't need to simulate as you have a real one!
Tape on a bunch of cotton wool tell-tales and take it for a drive, preferably with someone in another cat photographing the results.
Anyone got a good picture of this sort of thing to show what i mean?
Doug. 1TG
Sports Car Builders WA
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sgraber
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| posted on 8/11/07 at 02:57 AM |
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I know exactly what you mean and I was just arranging with a buddy of mine to do some of that on Saturday. I'll certainly post up the results
and maybe we can figure this thing out.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Doug68
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| posted on 8/11/07 at 03:09 AM |
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You might want one of these...
An exhaust and diffuser in one...
Big pimpin Tijuana style 
Doug. 1TG
Sports Car Builders WA
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Howlor
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| posted on 8/11/07 at 01:41 PM |
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If you parked that over here you'd have an array of beverage cans bunging each one!
Steve
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Spyderman
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| posted on 12/11/07 at 12:47 PM |
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Steve, are you sure the fumes are coming from the end of the exhaust and not from the engine bay?
Sticking or broken rings could be causing exhaust gas to be venting through crankcase breather.
You may have a slight leak from the exhaust system. Check if it is possible for fumes to enter the cabin from the engine bay.
Did you change exhaust and add engine bay vents at same time?
Terry
Spyderman
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sgraber
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| posted on 12/11/07 at 02:55 PM |
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Spidey,
I did in fact resolve the exhaust issue. This past Saturday I re-routed the exhaust out the side of the car in front of the right wheel. Identical to
what Kurt did on Kimini. I had a bit of an issue getting the exhaust piping to turn that way, as the downpipe on the turbo was pointing to the left
and I had to curl around almost 180 degrees, but it came out fine.
So now the engine has about 1 meter of exhaust tubing from the downpipe with a very short glass-pack on the end. It is loud, it is mean, it is deep
and it has extra horsepower. Best of all it blows up a big cloud of dust by the side of the road whenever you floor it! 
No exhaust smell in the cabin either.
Problem solved.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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iank
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| posted on 12/11/07 at 03:13 PM |
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quote:
Originally posted by Doug68
You don't need to simulate as you have a real one!
Tape on a bunch of cotton wool tell-tales and take it for a drive, preferably with someone in another cat photographing the results.
Anyone got a good picture of this sort of thing to show what i mean?
For those that haven't seen wool being used for aero
http://autospeed.com/A_108674/cms/article.html
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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