"Grindintosecond" (Grindintosecond)
08/30/2015 at 11:03 • Filed to: None
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"Grindintosecond" (Grindintosecond)
08/30/2015 at 11:03 • Filed to: None | 2
| 4 |
PS9
> Grindintosecond
08/30/2015 at 11:10 |
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Nice V12 bathtub you got there.
904 GTS
> Grindintosecond
08/30/2015 at 15:01 |
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Nicely laid out air box, with injectors out of site, clearly being hidden by those gorgeous looking throttle slides. Beautiful looking velocity stacks too...
Often wondered about the length of those velocity stocks, being different length. Some enormously short and some very tall, such as these. The reason for the tall ones became self-explanatory at a day of testing a 908 at a dusty race track. After pushing ever harder, finally it happened: even the very skilled driver, having driven the course over and over most of the day, finally spun the car out, resulting in a huge cloud of dust and stalled engine.
Having no air cleaner that would breed as freely as some do nowadays, the engine of course had none. Just a fiberglass covers atop, to prevent rocks and rubber ‘marbles’ to be ingested and large owal holes for air to enter freely.
Upon restarting the engine, the driver made a few more flat out laps before arriving to the pit lane. Noticing a large amount of dust absolutely everywhere, the engine man took off those fiberglass covers over those stacks and there was the evidence: as the pulsation in the intake happened by the valve opening and closing of the gasoline wetted already air charge, those stacks were perfectly clean about to just bellow the rim, with but still about 10% left dusty. So, clearly, if shorter let say by half, half of that charge would have spilled out if not as tall as they were.
TA4K
> 904 GTS
08/30/2015 at 18:32 |
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As I understand it, the length of the trumpets is actually an engine tuning thing, not a debris thing. Depending on the length of the intake runners as they are also called can change the torque curve slightly to tune the engine for different situations. That is why if you take apart a lot of performance airboxes, I.e BMW and Fiat etc, you will still see these trumpets, even though there is an airbox and filter further upstream. I have seen them on BMW V8’s and 6’s, and also on a Fiat 131 Abarth.
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904 GTS
> TA4K
08/30/2015 at 19:32 |
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CORRECT; absolutely nothing to do with debris.
An engine crankshaft stroke, size of valves, shape of the combustion chamber, spark plug(s) positioning, cam shaft opening duration, timing as well as fuel injector position has a lot to do with engine tuning.