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The mkiv Supra Owners Club

NOS and RLTC


Gareth Davies

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I was just wondering if there would be an interaction between the RLTC and an active NOS system. Since the RLTC controls the injectors would this mean that on a missed cycle the NOS would still fire and cause all kinds of problems on the next detonation?

 

I don't really understand both technologies clearly enough to see if they can simply be made to complement one another. I'm sure i'm not the only one considering both.

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if you were running a wet system the NOS and addition fuel would still be injected into the cylinders, with the "normal" air being pumped into the cylinders too the mixture would go lean, if you were using a dry system that used the standard injectors to add fuel (I think it does this by increasing the fuel rail pressure by making the pressure relief valve not allow fuel back to the tank until a higher pressure) then you would just be pumping NOS down the drain. Tricky one.

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I too have given this some considertaion as ill be running

both on my supra. I think Ash and I decided that when NOS

is activated wed have to have some sort of system to disable

the traction control. Which is a pity, because when NOS

is activated in a car knocking out 600bhp+ through the rear

wheels, traction control would have been quite handy..... :biggrin:

 

Oh well.

 

 

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I may be wrong on this, but isn't the NOS injected just before the throttle butterfly, therefore is fully mixed with the total air supply.  When the RLTC starts cutting, it misses a sequence of sparks, if you were to kill the NOS then that would be an instant 50-100 (or whatever) instant power loss and then instant gain when 'released' followed by instant wheelspin!!!  Probably don't have fine enough control over the injection.

 

Guess the big question is does air+NOS+spark ignite and therefore run lean, or does it just blow the unburnt mixture through - in which case does that cause extra heat in the turbo??

 

 

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Quote: from Ring Master on 8:55 pm on Dec. 12, 2001[br]

I too have given this some considertaion as ill be running

both on my supra. I think Ash and I decided that when NOS

is activated wed have to have some sort of system to disable

the traction control. Which is a pity, because when NOS

is activated in a car knocking out 600bhp+ through the rear

wheels, traction control would have been quite handy..... :biggrin:

 

Oh well.

 

 

 

If I remember rightly the AEM ECU is supposed to be able to control NOS as well, if this was done by adding extra fuel through the "standard" injectors then piggy backing the RLTC would give you full shuttoff off of fuel per cylinder so you would just have air, nitrous and spark on that stroke therefore no bang (bit of nitrous wasted mind).

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Guest Martin F
Quote: from Steve Cargill on 11:26 pm on Dec. 12, 2001[br]

 

 When the RLTC starts cutting, it misses a sequence of sparks, if you were to kill the NOS then that would be an instant 50-100

 

 

Nope the RLTC cuts the injector pulse not the spark, hence the concern about running lean.

 

 

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Couldn't you get tricksy with the pulse tables in the RLTC, convince it that you had seven injectors, and then use the seventh injector output to trigger the NOS on and off?  There must be some "remote output" (like a stereo head unit uses to switch on an amp) which can be activated when slip is detected.

 

Or, use two synchronised RLTC units maybe?

 

I don't really know enough about the system to suggest how to do it, but what would be really clever is if you had the system set up so that you could have 10% slip dialled in, but at 5% slip the RLTC cuts the NOS, and then begins cutting fuel if slip continues to increase to 10%.

 

Perhaps Pete Betts could furnish us with a box of tricks?

 

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Guest Martin F

 

That sounds like a possibility.

 

I'm sure somebody could connect an OR gate to all the RLTC outputs and then link this to the NOS relay.

 

They are not strictly outputs if i remember rightly as the RLTC sits on the ground side of the injectors and normally the ECU just grounds the injectors sequentially as each cylinder fires. The RLTC interrupts this path to ground if slip is detected hence disabling the injector.

 

This is all from memory so i could be out here.

 

If this is the case you'd probably want to use a NOR gate.

 

 

 

 

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The next question is - how is the NOS injected into the engine.  If the fuel injector cut is near instantaneous, the NOS needs to be to  . . .

Not exactly, N2O is does not burn by itself, if there is only NO2 and air in the chamber the spark will not ignite it, just as if it was just air.

 

One other option is to get the add on kit that allows the RLTC to use spark cut instead of fuel cut, then you just have fun when it ignites in the exhaust :biggrin:

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Quote: from Martin F on 11:34 pm on Dec. 12, 2001[br]

Nope the RLTC cuts the injector pulse not the spark, hence the concern about running lean.

Sorry Martin, a typo - see my last paragraph about if the air+NOS+spark could ignite, or about the oxygen rich mixture being blown onto a glowing turbo.  Think what happens when you blow on something glowing red hot - more oxygen = more heat.  Just a thought!

 

(Edited by Steve Cargill at 8:18 am on Dec. 13, 2001)

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I remember ChrisW telling me that proper aftermarket ECU's, such as the MOTEC, have a traction control facility.  I didn't ask whether you could control NOS, be dead handy if you could though...

 

Of course that brings the question is the ECU TRAC as good as the RLTC system....

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Quote: from Steve Cargill on 7:31 am on Dec. 13, 2001[br]
Quote: from Martin F on 11:34 pm on Dec. 12, 2001[br]

Nope the RLTC cuts the injector pulse not the spark, hence the concern about running lean.

Sorry Martin, a typo - see my last paragraph about if the air+NOS+spark could ignite, or about the oxygen rich mixture being blown onto a glowing turbo.  Think what happens when you blow on something glowing red hot - more oxygen = more heat.  Just a thought!

 

(Edited by Steve Cargill at 8:18 am on Dec. 13, 2001)

 

Oxygen is not flammable, it is a necessary part  of the  combustion process, neither  is  NO2,  both are gases that  enable  other  fuels to burn.

 

So unless you have leaky injectors, when a particular injector is cut  all you should have in the  cylinder when the  plug sparks  is oxygen plus other  atmospheric gasses and  Nitrous oxide if you are  running a NO2 kit.  Providing  you achieve complete combustion in all other  cylinders there should be no unburnt  fuel for the  oxygen and  NO2 to assist to ignition around  the  turbos or other  hot spots in the  exhaust system.

 

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1 part nitrogen bonded with only 1 part oxygen is not what you would call a stable mix. Unlike 1 part carbon with 2 parts oxygen, for example. The electron bond is *very* easily separated.

 

All it takes is a spark, or a bit of heat, and the oxygen will say bye-bye nitrogen and bond with other oxygen.

 

While I agree that oxygen, in itself, is not flammable... it is THE ULTIMATE oxidiser.

 

Yours,

J

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