Drax240z Posted December 16, 2002 Share Posted December 16, 2002 What type of radius on the donut? 1"? And what flavour of jelly in the middle? Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted December 16, 2002 Share Posted December 16, 2002 Picture the classic donut with no center and then cut it in half. The hole of the donut would be the same size as the carb airway entrance. The radius would be considered 180 I guess, but then again I'm not that good at math! lol later,norm Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 16, 2002 Share Posted December 16, 2002 I'm not forgetting, I don't know squat about fuel metering! Just so it is clear, all my comments were based on testing of SU carbs, modified and stock,(flat shaft modified), on a Supeflow airflow bench. No fuel, not motor, just air. -Bob Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted December 16, 2002 Share Posted December 16, 2002 Obviously better fuel metering is good. But the reason for a radiused air horn is to allow flow to develop in the inlet tract with minimal pressure loss and turbulence. Making the air take a hard 90 degree bend is something like having a reduced diameter restriction in the carb mouth. Now how to make Bob's and Norm's results make sense relative to each other, as they're both well known to be reliable sources? I believe Bob when he says aftermarket air horns don't flow any more than the stock ones, and the flow sucked with no air horns. And of course I believe Norm's trap speed actually went up .5mph (insignificant for 99% of us, significant for Norm) with the removal of the stock horns. I'd guess that Norm got more high-end power by reducing the inlet tract length (shorter length => tuned rpm goes up) than he lost by not having a radiused inlet. Of course he's on the right track with the stubbies. It'd be nice to see some dyno results to see what the torque curve is doing. I'd bet peak torque went down with the removal of the stock air horns, but peak torque rpm went up, giving greater peak power. Then I bet the original peak torque was regained with the stubbies, at higher rpm, giving even greater peak power. That's my guess. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted December 16, 2002 Share Posted December 16, 2002 Just to clarify Dan, I started averaging around .5 mph faster after the installation of the homemade stub stacks over no airhorn at all.That is in the 1/8 mile so it stands to reason in the 1/4 mile it may pick up .8 mph. I don't remember the mph gain I got years ago going from stock airhorns to no airhorns, but I do remember my ET times were anywhere from .05-.10 quicker without any airhorns. later,norm Quote Link to comment Share on other sites More sharing options...
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