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Re: Performance Was Re: Priorities!

To: Todd Mullins <todd@nutria.nrlssc.navy.mil>
Subject: Re: Performance Was Re: Priorities!
From: Gary Burrell <garyb@pentek.com>
Date: Mon, 23 Jun 1997 11:31:56 -0400
Todd Mullins wrote:
> 
> Gary Burrell writes:
> 
> 
> Fact:  Higher speeds require the brakes to dissipate more energy than
>        lower speeds.
>
Agreed.
 
> Fiction:  More powerful engines force you to drive faster.
>
Agreed, however a more powerful engine has the ability to 
accellerate faster allowing you to get to a given speed 
quicker.  You don't have to use this but if you do you
are back to the "Fact" and may wish better brakes.  As I 
also said earlier, I run with stock brakes, and am perfectly
comfortable.  I belive you said earlier that braking 
requirements were a function of speed, and I agrre with this
the only point I was making was that the a higher performance 
car may allow you to reach a given speed quicker (also
a function of the driver) and thus get you into situations
where haveing better brakes may be desirable.

> Understand?
>
YES!

> > > All the electronic ignition really gives you is reliability and
> > > stability.  It doesn't actually make any more power.  The Sport Coil may
> > > allow you to open up your spark plug gap, which will make power, but not
> > > a whole lot (again - anybody have any hard data, so I can quit making
> > > such qualitative musings?).
> > >
> > Well no quanitiative data but qualitative data.  Sport coil allows
> > higher voltage at plugs.
> 
> Agreed.
> 
> > Electronic Iginition also supplies more
> > power to plugs than points,
> 
> Disagreed.  Electronic Ignition doesn't send a damned thing to the spark
> plugs.  Electronic Ignition ONLY tells the coil when to fire.
> 
> > Also at high RPM (5500) points suffer
> > from point bounce)
> 
> Right; forgot about that one.
> 

While the electronic igntion in and off itself doesn't supply any more 
power to the coil, however I believe from the some stuff I've seen in
the
past that switching of the elctroinc ingition has different 
characteristics than the switching of points allowing it to 
switch on/off quicker and leading to a quicker coil collapse,
thus more power.  The power comes still from the coil but is
helped by the characteristics of electronic ignition

> > A quote from  "Performance MGB" about the
> > Newtronic (Pirhana) Electronic Ignition: "We ran a rolling road
> > comparison test against conventional points.  The resultant power
> > curves prove the Newtronic Ingintion system offered greater power"
> > My results on my car (qualitative) support this.
> 
> There isn't enough information here to debate.  And I still contend that
> any increases in power due to "hotter spark" come directly from the
> coil.
>

That may well be true!  However I still mine works great.  And while
they don't give much data, and it may all be due to the coil or points
bounce, the results above while sketchy support this.
 
> > > > After you've done this you probably want to change the carb
> > > > needles on your SU's to something slightly richer
> > >
> > > I've never quite understood this thinking.  If you need a richer
> > > mixture, why not simply turn the jet screw a few flats?
> >
> > This only serves to richen the mixture at Idle not accross the
> > entire power band.
> 
> I'm sorry, but this is blatantly incorrect.  Do you know how SUs work?
>
Yes, I do and  rewording the above I can say this serves to richen
the mixture at idle and may not provive "sufficient" richening across
the power band.  The SU needle is tapered and different tapers
allow for different air/fuel ratios at a given lifting of the 
piston.  You have some control over the starting point of this
taper by adjusting the jets up/down, but the taper is a function
of the needle.

Case in point with my car after I had done everything
to it I took it to my friend the mechanic who tuned it using an
Exhaust gas analizer and found the even with richening it at idle
my current needle where too lean at higher RPM,  we tried a few
different needles and he picked the one which had the best 
characteristics.  As I said He did this using an exhaust gas 
analizer, and someone with more knowledge than I would have to
tell you what to look for when using one of these.  I also can't tell
you which of my modifications required these changes as I had done 
alot to this car.   
 
> And can anybody else tell me why engine modifications require a
> different needle?
> 
> > O.K. Now for Some real # from  MOSS UK "Performance MGB"
> >
> > Stage 1: K&N Filters, LCB Manifold
> >
> > And now the numbers measured on a dyno
> >
> > Stock:  74.1 bhp  105 ft/lbs
> > Stage 1:  80.7 bhp 110 ft/lbs
> >
> > My obsevations 9% more power just by adding K&N and LCB header
> 
> Yes, but how much does the LCB header alone net you?  K&Ns are routinely
> claimed to yield 3 to 5 horsepower; how much does that leave for the LCB
> header?
Well assuming K&N numbers are right from 1.6 to 3.6 H.P.  Not a lot but
easy to get.  As I mentioned earlier it's easy to get the first 10% it's 
costly to get the last 10%.  Also a 9% gain in horsepower while not 
large is not insignificant.  I bought my LCB because I needed a new
exhaust and my mechanic friend was able to get me a good deal on a
complete system including the header in stainless.  The power 
considerations were secondary.  However I can say that I am quite
pleased 
with the increase in performance and drivability with the mods I 
have made over the years.  Of course your choices and YMMV.

Have a good one 


Gary
-- 
Gary Burrell 
Design Engineer
Pentek Inc. One Park Way, Upper Saddle River NJ 07458
Phone: (201)818-5900  Fax: (201)818-5941 Email:garyb@pentek.com

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