On Fri, 20 Jun 1997 23:44:32 -0500 (CDT) email@example.com
(Todd Mullins) writes:
>Rick Morrison writes:
>> [ I wrote: ]
>> >Fact: Higher speeds require the brakes to dissipate more energy
>> > lower speeds.
>> >Fiction: More powerful engines force you to drive faster.
>> Fiction- more powerful engines make cars faster
>> Fact - more powerful engines accerate cars quicker
>It's bordering on pedantic perhaps, but DRIVERS accelerate cars
>The motor just gives you the means. It's akin to the oft-abused
>"Guns don't kill people; people kill people".
It's not bordering on pendantic, It's well south of the border.
>> difference being that speed, while dependent on availible power, is
>> a function of gearing. Example (non LBC) My works Moto-crosser was
>> extremely modified for power. In fact the versions we rode put out
>> twice the power of the un-modified version. BUT the top speed was
>> 20 mph SLOWER. Because the purpose was to get there quick, not
>I fail to see how your example clarifies anything.
Point being that high performance engines DO NOT equal high Speed.
Gearing plays a major part in top speed.
>It doesn't matter if you take 2 seconds or 2 minutes to get to 60 mph;
>the exact same amount of energy must be dissipated by the brakes.
Granted the energy dissipated is exactly equal, but the time for
dissipation will vary with the state of the brake system. Air drag and
rolling resistance will stop the car from 60MPH, and dissipate the exact
same amount of energy, but I doubt you want to rely on that in your next
encounter with the little ol' lady who pulls out in front of you.
>> As to the need for better brakes with a modified engine, one must
>> consider the entire car when making modifications. The thing is a
>No, it's not. The brakes have NO functional or causal relationship
>with the engine.
If that is the case, then why did they stop making cable operated
brakes, or replace the drums on the front with disc (or all four corners
for that matter). I agree that brakes are not directly related to the
engine. But then again, neither is the driver!
>> To look at it another way, suppose you modified and improved your
>> system. Does that then mean you then must drive at a higher rate
>> because of better brakes? Of course not. Then just because you
>> more powerful engine, you are not forced to drive fast.
>Right. I thought I said that already.
You implication, I thought, was that by improving the performance of the
engine, the owner/driver would operate it at a higher rate of speed. If
you meant the opposite I'll admit to being wrong.
>> But the purpose
>> of power is to utilize the quickness, thus under those conditions
>> it is appropiate to take that advantage, then it behooves you to
>> ability to DE-celerate in a similar manner.
>Are you confusing acceleration with speed?
NO, they are seperate functions and the distinction must be kept in mind.
The whole point about brakes is whether or not you have a modified power
plant, the brakes, being a safety device, should be capable of operating
at the most effecient level possible, within the realms of availible
technology. Presently it is quite possible and in some cases probable
that many of of have tires on our cars that exceed the capacity of the
brake system. Well, why not take advantage of the enhanced abilities of
the tires and upgrade the brakeing system. It makes for a safer car.
However, one caveat here, All the discussion about improved braking
systems assumes the driver is capable of utilizing the enhanced ability
of the improved brakes. If that driver is a member of that vast majority
of drivers who haven't ever heard the term "threshold braking", much less
know what it means, then any brake improvement is totally lost on them.
>> But electronic ignition are capable of firing a much more powerful
>> than is a point style system, especially at higher RPM's
>Okay. But it's still the coil that makes the spark. Electronic
>ignition with a stock coil and plug gap shouldn't make any more
Electronic ignition with a stock coil and plug gap is about as logical as
a horse drawn MGB. Todd, this is not a good argument. The whole purpose
of electronic ignition systems is to enable you to utilize the higher
output coils and consequently the greater plug gap. Which you will never
be able to do with a point type ignition. The second big plus of
electronic ignitions is the more precise timing, again which a point type
system cannot hope to obtain.
>> >And can anybody else tell me why engine modifications require a
>> >different needle?
>> The airflow rates into and/or out of the engine have changed, and
>> necessarily in a linear manner.
>Is this solely due to the cam? Something tells me the answer is
>probably "no", but it might be nice to find out that at least a few
>things in life are simple and predictable...
Sorry, life just aint that simple. There are just too many variables to
engine design and modification to have pat answers. Cam selection and
specs are part, as is port design, intake design, exhaust design, valve
design, etc, etc, etc.
It's not an exercise in mathematics, where everything works to a set
formula. There is as much art involved as physics. If there were simple
answers, I would have a Midget putting out as much HP as a F1 Williams.
>> Just to keep the pot boiling, I submit my tuppence wortth
>Boil, baby, boil!
>Todd.Mullins@nrlssc.navy.mil On the lovely Mississippi (USA)
>'74 MGB Tourer with an analytical bent
>Atheist #685 "Whatever, baby."