[Diy_efi] traction control & nitrous (devlish combo?)

[Perry Harrington]

Ya know, I thought some more about this.

I think trying to do traction control while on nitrous is just plain
dumb.

No offense to Scott, I'm simply stating that Nitrous is a wildly
different beast.

Nitrous is not stable in the sense that it's inert, much like air.

Air is fairly inert in the sense that it doesn't require special handling,
and it is the standard by which IC engines work.

Put Nitrous in the mix and you have a gas which requires careful
handling.

Now Scott sort of answered my questions, but I don't think he got
what I was trying to get at.

If you are running TCS on a car with 1 axle power and that car can
break loose without Nitrous, then you are already at the deemed stage
of power which TCS is useful.

Nitrous is not intended as a long term power adder.  It's intended for
filling in the gaps of your VE curve, or as a WOT power adder.

Trying to use nitrous as a full time power adder seems like a cost
losing proposition.  For the volume of gas and the power gained, not
to mention the constant replacement cost, it's a waste.

It seems to me that TCS is really a 2 benefit system in standalone
fashion: Launch control, and crude yaw control.

I see a TCS addition as a faster way of getting off the line.  TCS at
speed is a tricky proposition because yaw plays a lot into that equation.
Without an active yaw control system (conventional systems would apply
front brakes to prevent over yaw), TCS merely limits power.  You would
need a very agressive TCS to prevent yaw, since it would need to prevent
the accumulation of traction breaking power, not just react.

Active yaw systems will cut engine power and use brakes to prevent pitching
the car.  These systems are tuned to the car at hand, since every car
is going to be different in how it yaws.  RWD cars will tend to yaw a lot
sooner.  AWD cars will yaw depending on power bias and surface.  FWD cars
will yaw mostly due to suspension tuning.  Thus all of these vehicles have
different needs.  TCS is a very small part of this equation.

On an FWD car, TCS basically reduces understeer at speed, while giving
traction.  On your application I would try and tune your car for a steady
state, N2O is not a steady state.

So, I would recommend that the Nitrous arming switch disable the TCS.  It
makes no sense to enable TCS and try to integrate Nitrous control into the
system if it wasn't designed with that in mind to begin with.

The TCS system Scott bought is the simplest strategy usable, and it's exclusive
of Nitrous.  *IF* Nitrous was absolutely neccessary, an ABS based TCS would then
be needed on top of power control, and then you still have the problem of N2O
not being a steady state to tune for.

These are just my thoughts.  It was an interesting conversation because it
gives me ideas for a DIY TCS that would be fairly easy to implement.  My
Mustang could due with a TCS system...

--Perry

On Thu, Feb 27, 2003 at 09:36:41AM +1100, Bill Washington wrote:
> Scott,
>     I think, as has been suggested by others, the risk would be too 
> great to contemplate trying your original proposal, however a couple of 
> general questions about your original proposal:
> 1.    With the main fuel (injector) turned off roughly how much nitrous 
> would be in the cylinder?
> 2. I ask the question because depending on the nitrous/air ratio it may 
> be damaging (lean), very dangerous (explosive mix), or safe (too lean to 
> support sustained combustion).
> 
> 3. the suggestion of cutting off the nitrous with or before cutting 
> injector(s) may still leave sufficient nitrous in the manifold to cause 
> the same potential problems.
> 
> Good luck
> Bill W
> 
> >>> Seems to me that you are going at a problem in a backwards
> >>> way. I would assume that the TCS is required even for
> >>> non-nitrous operation?
> >>    
> >>
> > No, this is merely an add on to a well-functioning car. There is 
> > plenty of power to turn the tires into smoke at launch, but judicious 
> > applications of the throttle minimizes that problem.
> >
> >>> If the engine has enough power to break the tires loose without
> >>> nitrous, then adding nitrous is a waste.
> >>    
> >>
> > Any respectable performance car should be able to break the tires 
> > loose at launch, methinks. :^) At this point, I have around 200hp all 
> > motor. With the nitrous, I'll add another 75 or so. That extra power 
> > will certainly overwhelm the tires at low speeds, so I won't even 
> > engage the nitrous until well into second or third gear. Additionally, 
> > I envision this traction control system to be more of an aid while 
> > cornering during backroad driving. To make it work with the nitrous 
> > (an apparent fantasy at this point) would really be an added bonus.
> >
> >>> Does the Racelogic system have a "staged" configuration option?
> >>    
> >>
> > The system is plenty capable of handling boost because the 
> > supplementary fueling is handled by the main injectors. The same would 
> > be the case for a dry nitrous system which uses the main injectors 
> > instead of independent foggers like mine. Therefore, there's no need 
> > for a staged set up when used in this manner. It just doesn't help me 
> > in this case.
> >
> >>> I would expect the unit to have an enable line that could be tied
> >>> to the nitrous arm.
> >>    
> >>
> > I'm not sure what you mean by an "enable line". Do you mean an 
> > auxillary output to control a secondary function (such as this)? Now 
> > that I've gotten some more advice and have thought about it a while, I 
> > think that controlling the nitrous/fuel solenoids directly will be 
> > problematic. Their cycle time is lots slower than the main fuel 
> > injectors. Thus, precise and smooth control of that system is likely 
> > to be impossible. I'm quite sure that at this point, I'll use the 
> > traction control for use without the nitrous. That seems 
> > counter-productive, but launch (with or without nitrous) is really the 
> > trickiest part of a dragrace. I can certainly handle the power 
> > modulation on my own when I'm down the track a bit.
> >
> >>> BTW, is the car you plan on using it on AWD?
> >>    
> >>
> > No, this is a FWD Volkswagen, actually. -a 1980 Scirocco to be exact. 
> > :^) Anyway, that you *very* much for the advice! -- Scott F. Williams 
> > NJ Scirocco nut '99 Subaru Impreza 2.5 RS Mazda 323 GTX turbo 
> > "assaulted" vehicle Golf GTI 16v "rollycar" ClubVAC: "Roads found. 
> > Drivers wanted."
> >
> >  
> >
> 
> 
> 
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://www.diy-efi.org/mailman/listinfo/diy_efi

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi