Mr Helmholz - simple model

[Todd....!!]

FYI - In addition to the top fuel dragsters' engine being held at 7,000
rpm by the clutches engaging without spinning the tires(which is the
goal, there's a VERY fine line in tuning them clutch packs as you
probably know)...

His rear gears were only like 3.73's or so! So they stated.... EVEN with
those HUGE REAR SLICKS!  Wierd, ey?

LATER!

Todd....!!

William T Wilson wrote:
> 
> On Thu, 20 May 1999, Gary Derian wrote:
> 
> > If one has a sliding clutch, it should be set to hold the engine at max
> > torque rpm, not max power rpm.
> 
> I disagree, because of the effects of gearing.
> 
> A hypothetical engine makes 300 ft.lbs at its torque peak of 4000 RPM.
> At that RPM it makes 228.5 HP.
> 
> Let's say it makes 201.3 ft.lbs at its HP peak of 6000 RPM.  At that RPM
> it makes 230 HP.  This is an engine that could probably use a new cam. :}
> 
> Even so, once gearing is taken into consideration, it is better to use the
> HP peak.  You can have a 33% lower gear ratio at the higher RPM, which -
> more or less by definition - outweighs the decrease in torque at the HP
> peak.  Once we gear this engine down by 1/3 it makes the same 300 ft.lbs
> of torque that it did at its torque peak.
> 
> But let's say we have an engine that doesn't have its torque fall off so
> badly.  Let's say, instead, the engine makes 220 ft.lbs at 6000 RPM,
> instead, for an HP rating of 251.3.  This engine, when gearing is taken
> into consideration, can generate an effective 328 ft.lbs of torque - a
> noticeable improvement.
> 
> This is why engines are rated mostly in HP.  Torque is of course the most
> important component in acceleration, but what RPM the torque is generated
> at is just as important.  HP is a better measurement of torque at RPM,
> although of course a full printout of the torque curve is the best :}