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29 Apr 2007, 23:43 (Ref:1903077)
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#1 | ||
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Racer
Join Date: Dec 2005
Posts: 137
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Why the loss of speed?
I have a Old Mk2 cortina that I use for a bit of sprinting and drag racing, Powered by a 4ltr Rover on downdraft TBs, normally I run a closed airbox ducted to cold air from the front panel, as an experiment, at SantaPod last weekend I took the bonnet off and removed the airbox, so the TBs were open to atmosphere and about 6" below the bonnet line, the car ran without a problem but for one thing, over the 1/4 the car was 5-6 mph slower with the bonnet and airbox off than with it on, do you lot think its the aerodynamics of the bonnet being fitted or wind sheer/suction over the trumpets causing the engine to richen up as there is no lambda fitted to the ECU
Unfortunatly I dont have access at the moment to pics of my engine, so heres a link, its the 7th pic down, http://www.oldskoolford.co.uk/phpBB2...ic.php?t=42590 many thanks Ian |
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30 Apr 2007, 06:46 (Ref:1903142)
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#2 | ||
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Veteran
Join Date: Jan 2003
Posts: 2,071
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i would of thought your right on both counts ian, areodynamics would certainly of suffered and it is resonably well proven that filters and airboxes can allow the engine to breath better by reducing air turbulence across the intakes
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__________________
AKA Guru its not speed thats dangerous, just the sudden lack of it!
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30 Apr 2007, 20:13 (Ref:1903708)
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#3 | |
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Racer
Join Date: Apr 2006
Posts: 185
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I agree, you're intake trumpets are now probably kind of in the 'wake' of the front of your car and not getting decent onset flow.
A possible secondary effect would be the influence of the airbox on the tuning of those trumpets. It's not an area i know a fat lot about but i have designed some intake boxes for 2 strokes and the careful management of the rpessure waves in the intake tract is critical for optimum performance (though i'm led to believe that 2-strokes are even more sensitive to that than 4-strokes, because of the influence on charging & scavenging the cylinder). |
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1 May 2007, 08:21 (Ref:1903984)
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#4 | ||
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Veteran
Join Date: Aug 2004
Posts: 14,699
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Would you not get a ram effect as well with the air box in place.
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__________________
You can't polish a turd but you sure can sprinkle it with glitter!
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1 May 2007, 09:54 (Ref:1904030)
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#5 | |
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Racer
Join Date: Nov 2006
Posts: 262
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Ian did u put the car back together as it was and run it back to back. Anyway it's a no brainer. All the above guys are right..........trikes
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1 May 2007, 23:54 (Ref:1904632)
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#6 | ||
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Racer
Join Date: Dec 2002
Posts: 338
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If you look at photos from dragsters from the 60's most of them ran flat plate above the intakes of the carbies to stop fuel being sucked out of the carbies (I think that was the reason).
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__________________
Think drifting is tough. Try it on gravel, in the dark, amonst trees...............
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