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Re: Nitrous 101

To: "Thomas E. Bryant" <saltracer@awwwsome.com>
Subject: Re: Nitrous 101
From: Jonathan Amo <webmaster@landracing.com>
Date: Wed, 27 Feb 2002 22:22:31 -0700
Tom,

Well thats funny on the NOS experts, we ran their tune-up and acquired 
several paper weights. We saved more parts running our own tune up 
instead of their recommended settings. But then again that was on a 
motorcycle and not a car. past years said by the engineers at NOS say 
our bike would not live with our setup.

on another note, could a bad tune-up actually save your engine on nitrous?

has bonneville proved engineers wrong what they say has not worked, and 
what they say won't work will?

Jonathan



Thomas E. Bryant wrote:

> Keith,
> 
> Lots of good info stated elegantly, as usual. One thing that I would 
> question though is the expansion benefits through out the stroke. As I 
> understand the combustion process, any expansion past roughly 23 degrees 
> past TDC is not very effective since the piston moving down the hole 
> expands the area in the cylinder faster that the gases expand.. As I 
> understand it, timing advance is desired to start the combustion process 
> at the proper time, dependent on the mixture quality, to reach peak 
> pressure about 20 degrees ATDC.
> 
> We have run nitrous with moderate success since 1989, when not many were 
> doing very well with it. We carried it on the car for a few years before 
> that, but had waited until we got things sorted out on the basic tune-up 
> to have the courage to use it. I can tell you this, if the basic tune-up 
> is not right, you will destroy parts when you hit the nitrous, guaranteed!!
> 
> Early on, I enjoyed a good relationship with Dale from NOS and gained 
> some excellent info from him. We have taken a bit of a vacation from 
> nitrous to pursue the gas class records, but we will be back on the 
> scene in the future. It is just too much fun to hit the nitrous!
> 
> Nitrous does speed up the combustion cycle and therefore needs to be 
> properly  retarded or detonation goes wild! I have seen the results too 
> often. Just the fact that the nitrous is being introduced, even if it 
> was the same oxygen content as the air we breath, still fills the 
> cylinder to a level above naturally aspirated engines which increases 
> heat and pressure requiring timing reduction.
> 
> We also retard 2 degrees for each 50 hp as suggested by the experts. We 
> us a MSD igniter with the retard function that has worked well for us.
> 
> Tom, Redding CA - #216 D/GCC
> 
> Keith Turk wrote:
> 
> 
>>What I was going to say about Cylinder pressure is this.... within a give
>>cycle an internal combustion engine operating at 100% volumetric efficiency
>>can produce X amount of HP.    We can aid the combustion process by several
>>artificial means.  lets take a sec and look at what is mechanically
>>happening to each of these and experiment with my understanding of
>>each..... as it relates to the cylinder pressure and the Manner in which
>>it's formed.
>>
>>I'm sure there is a fancier way of saying here's your choices... Naturally
>>aspirated....Turbo/Blower ... Fuel/Nitrous.... 
>>
>>In a naturally aspirated situation the fuel is ignited and the flame
>>propagation is directly proportional to the fuels octane... the amount put
>>in is virtually equal to the size of the bore and stroke of the
>>cylinder.... ( assuming your at 100% VE and not over or under it )....  As
>>the gases are ignited they start to expand and put a force on all
>>components off the combustion chamber... ( yep the head gets the same
>>force)  The Piston then is Forced to start it's travel down the cylinder
>>bore.... the gases continue to expand as the combustion process takes place
>>and force is produced throughout the stroke... ( for the most part )  we
>>fire that spark plug early to give this flame front time to advance to the
>>point it will excerpt Maximum force.
>>
>>In a Turbo or Blower application we increase the Pressure of the intake
>>charge and thereby allow us to install more air/fuel during each combustion
>>cycle..... so what happens is that the Volumetric efficiency is that it is
>>Radically increased in direct proportion to the amount of Boost and Fuel
>>added. ( up to a Point of diminishing returns )  Now when we fire this
>>fuel/air charge it's combustion process is greatly aided by the added fuel
>>and air... and it then increases not only the force down the stroke but
>>continues to expand for the FULL stroke of the motor....  somewhere in here
>>ya gotta know it's producing HUGE amounts of Pressure on the crank at 90
>>degrees or mid stroke and gob's of Torque are created as a result ... the
>>second key is the continued expansion to the bottom of the stroke.... so
>>it's making Mass hp.
>>
>>Okay now on to the only Fuel that I know about .... well I might expand on
>>my limited knowledge of Nitro but I would really rather someone with a clue
>>do that.
>>
>>Nitrous oxide is nothing more then a Oxygen rich air.... 33% oxygen by
>>content as opposed to around 23% in the ambient air...... N2O + two Parts
>>Nitrogen one part Oxygen........ hmmm this is making sense so far....
>>scary.... okay... what we are doing is introducing more Oxygen when the
>>Valve opens so the intake charge carries more capability to accept Fuel....
>>and it is the FUEL that makes the cylinder pressure.....   what does happen
>>thou is that this Oxygen rich mixture is that it burns FASTER so the actual
>>flame propagation within the cylinder is happening quicker and the
>>combustion process is almost taken to the point of being a Explosion
>>process..... what that means to us the casual observer is that the Flame
>>front travels much faster and the actual Fuel air charge is used up more
>>quickly..... so to is the power making capacity fuel/air charge..... think
>>of this as a tortise and the Hare..... story..... Nitrous charges hard up
>>front but by mid stroke it's about spent.....( that maybe exaggerated but
>>not much ).....
>>So anyway it's got great pressure making ability BUT it's also going to
>>impart high degrees of cylinder pressure in the early stages of combustion
>>through Mid Stroke.....  When you look at these high degrees of cylinder
>>pressure you have to understand that it's going to do some damage to any
>>component in the process that isn't up to the task....  It also makes sense
>>that you would want to start this process a bit later in the combustion
>>cycle hence the retarded timing...
>>
>>Whew.... Now I'm sitting back looking at all those sentences run together
>>thinking Dave Freiburger could edit this into usable information.... but so
>>could my second grade teacher.... only difference is He would have a clue
>>was I was trying to say. 
>>
>>Keith ( Okay Dahlgren.... did I listen or did I miss the class altogether?
>>)
>>----------

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