Water/Meth with NOS Dyno

[Samurai 20V]

So STD ECU mapped for Jap fuel so could be anything from 99 to 101,

so you want to run 95, and you hope to compensate for the RON deficiency buy running water/meth injection yes?

 

Right first question, do you know for sure what boost the Mines ECU is mapped to?

 

Second question, if you do not monitor AFRs, how in hell are you going to know if your injecting enough meth to compensate for the lower RON fuel?

 

And finally IMO you don't stand a snowball's chance in hell of doing it by the means you describe, you will need a reliable wide-band lambda setup, and i certainly wouldn't do this without at least a piggyback ECU, as you have no other RELIABLE way of correcting the fueling or timing, adding water/meth injection and hoping that it will work is not the way to go.

 

I am not sure if you are pissed off in your reply, sorry if you are..

 

This is my first turbo car, and I am learning as I go along..As you can see, I dont have alot of vehicle tuning experience.

 

I was told that the Mines ECU has been checked till 1.3bar and deemed safe. (Previous owner).

 

I think what I am not understanding is the value that my AFR gauge reads and the effect that lower octane fuel will have.

 

You said that the AFR is a set value of the ECU and I have no control over it. I understand that part. It is the ratio of fuel to air by mass. So if the Mines ECU is mapped to 1.3bar, there is enough mass of fuel to match the mass of air that the 1.3bar brings..

 

However, if the timing is raised accordingly in tune with that 1.3bar, putting a lower octane fuel will result in uncontrollable combustion.

 

I hope I am correct so far.

 

What I need to ask is does the lower octane affect AFR as well?

[Tricky-Ricky]

No not pissed off fella:) i think i got the impression by some of your other posts that you had more knowledge than i thought thats all.

 

OK lets tackle this methodically, the Mines ECU that you have is mapped in japan for higher octane fuel.

 

Now you only have lower octane fuel available, and so are hoping to compensate with water/meth injection.

 

I will first explain how the ECU handles fuel and timing control,

leaving start up aside, once running at idle and low load/cruse, the ECU relies on lambda feedback from the std sensor, and this i know as "closed loop" this basically consists of the ECU receives the voltage from the sensor and tries to keep the fueling at stoic which 14.9 AFR, but because the ECU cannot hold the fueling precisely at stoic, as it a very fine adjustment for the injectors to hold, the ECU will first run more injector duty cycle and then less, in an effort to hold stoic, in response to the lambda sensors voltage, the result is a cycling of the AFRs during this action.

 

This closed loop response happens until certain predetermined conditions which are already programed into the ECU, and when these conditions are met, the ECU will go into what is know as "open loop" which basically means that once engine load is increased by either passing a certain RPM and/or RPM+boost, it no longer uses lambda feedback, and runs on a pre programed fueling and timing map.

 

Now that probably as simple as i can put it for now, and i suggest you do some reading into how a modern ECU controlled fuel injected engines.

 

You do obviously have some grasp on this, but i first have to ask just what AFR gauge you are using?

 

Next if you want to try and run your car with the current ECU at 1.2-1.3bar of boost on 95 RON you will as you say very lily run into detonation problems, now the easy way to try and compensate is to use the correct amount of octane booster added to the fuel you use,

 

The other way is what your suggesting buy using water/met injection, however this is perhaps more hit and miss than using an octane booster.

 

But IMO i would not try and do this unless you can carefully log and monitor weather your AFs are correct, and that your not getting any detonation, otherwise your risking your engine.

 

Sorry if this is a little complicated, come back to me if you need clarification, but its a big subject.

[Noz]

From what I understand. The percentage of meth to fuel would have to be in the tank, and rather large to take up the ratio of 95:99, meth is over 100 is it 114 I can't remember off the top of my head.

 

I don't think a water/meth injection system would be the best way to increase the octane, and purely only used as that.

 

From comparing dyno runs using different octane fuel, for example 95 to 99, the power increase on high performance engines is usually noticable, from the dyno used on the first post on this thread the power increase with water/meth injection wasn't anywhere near as much as the improvement from a different fuel, so I wouldn't of thought the extra octane in the meth would be able to account for the loss of octane with the lower rating fuel.

 

Plus the fact, if it was a 50/50 mix, the amount of meth required to increase the octane rating to 99-101 would also include enough water to reduce power I would of thought?

[Tricky-Ricky]

From what I understand. The percentage of meth to fuel would have to be in the tank, and rather large to take up the ratio of 95:99, meth is over 100 is it 114 I can't remember off the top of my head.

 

I don't think a water/meth injection system would be the best way to increase the octane, and purely only used as that.

 

From comparing dyno runs using different octane fuel, for example 95 to 99, the power increase on high performance engines is usually noticable, from the dyno used on the first post on this thread the power increase with water/meth injection wasn't anywhere near as much as the improvement from a different fuel, so I wouldn't of thought the extra octane in the meth would be able to account for the loss of octane with the lower rating fuel.

 

Plus the fact, if it was a 50/50 mix, the amount of meth required to increase the octane rating to 99-101 would also include enough water to reduce power I would of thought?

 

Yes the injection method as i said in my other posts, would not be up to it, it could be done but would require to large an amount to be practical,

and would definitely require mapping for, so as i said the only option is to either use an additive,

or which i think may be the safest option use either a decent piggyback or stand alone ECU and map for the lower octane fuel, but I'm not sure he would be able to run 1.3bar even with WI.

 

Oh! forgot Methanol has an octane rating of 108.7.

[Samurai 20V]

No not pissed off fella:) i think i got the impression by some of your other posts that you had more knowledge than i thought thats all.

 

OK lets tackle this methodically, the Mines ECU that you have is mapped in japan for higher octane fuel.

 

Now you only have lower octane fuel available, and so are hoping to compensate with water/meth injection.

 

I will first explain how the ECU handles fuel and timing control,

leaving start up aside, once running at idle and low load/cruse, the ECU relies on lambda feedback from the std sensor, and this i know as "closed loop" this basically consists of the ECU receives the voltage from the sensor and tries to keep the fueling at stoic which 14.9 AFR, but because the ECU cannot hold the fueling precisely at stoic, as it a very fine adjustment for the injectors to hold, the ECU will first run more injector duty cycle and then less, in an effort to hold stoic, in response to the lambda sensors voltage, the result is a cycling of the AFRs during this action.

 

This closed loop response happens until certain predetermined conditions which are already programed into the ECU, and when these conditions are met, the ECU will go into what is know as "open loop" which basically means that once engine load is increased by either passing a certain RPM and/or RPM+boost, it no longer uses lambda feedback, and runs on a pre programed fueling and timing map.

 

Now that probably as simple as i can put it for now, and i suggest you do some reading into how a modern ECU controlled fuel injected engines.

 

You do obviously have some grasp on this, but i first have to ask just what AFR gauge you are using?

 

Next if you want to try and run your car with the current ECU at 1.2-1.3bar of boost on 95 RON you will as you say very lily run into detonation problems, now the easy way to try and compensate is to use the correct amount of octane booster added to the fuel you use,

 

The other way is what your suggesting buy using water/met injection, however this is perhaps more hit and miss than using an octane booster.

 

But IMO i would not try and do this unless you can carefully log and monitor weather your AFs are correct, and that your not getting any detonation, otherwise your risking your engine.

 

Sorry if this is a little complicated, come back to me if you need clarification, but its a big subject.

 

No problem mate..

 

I understand your explanation.. My understanding was along the same lines.

 

I have an AEM UEGO gauge but from your previous posts I understand you dont trust them to much..

 

Again, sorry for my inexperience here, the excess heat from burning 95 octane at 1.3 bar would show up in my EGTs correct? Would this also result in a leaner reading on the AFR gauge at said 1.3bar? The gauge will read a lambda value, which is the result of combustion correct?

 

How would a tuner check for detonation in such a situation?

 

Thanks for taking the time to reply in such detail..

[Tricky-Ricky]

No problem mate..

 

I understand your explanation.. My understanding was along the same lines.

 

I have an AEM UEGO gauge but from your previous posts I understand you dont trust them to much..

 

Again, sorry for my inexperience here, the excess heat from burning 95 octane at 1.3 bar would show up in my EGTs correct? Would this also result in a leaner reading on the AFR gauge at said 1.3bar? The gauge will read a lambda value, which is the result of combustion correct?

 

How would a tuner check for detonation in such a situation?

 

Thanks for taking the time to reply in such detail..

 

No problem! basically because the ECU is mapped to provide the correct AFRs at any given load/RPM using 99/100RON fuel all the way to 1.3bar, so what happens when you use only 95 RON is that you will encounter detonation and higher EGTs much earlier in the loadings,

 

 

 

The ECU will still inject the correct amount of fuel for the air mass/pressure that the MAP sensor has measured, to give the correct AFRs, but because the the fuel has less knock resistance,

the result will be much reduced power partly due to less efficient combustion, and mostly because the ECU will retard ignition timing and run a default fuel map because of the detonation it has sensed via the knock sensors.

 

As for whether lower RON will effect the overall AFRs i would say yes it will, the AEM is OK but just not up to the quality of some others on the market, most good tuners will use det cans to detect detonation, which can be easily made from a pair of ear defenders, some tube and a flattened piece of metal tube which is then bolted to a suitable place on the engine block/head.

 

There are electronic det sensors which are fine to but need to be properly calibrated to be reliable.

 

As i said in my previous posts, i think you best/easiest option would be to use an octane booster to get the fuel to 99RON, but it may work out expensive in the long run, otherwise i think the piggyback or stand alone ECU option would also be an option.

 

I will say if you could obtain a std ECU it is possible to run 95 RON , but i still doubt you could run 1.3 bar.

[Samurai 20V]

Thanks alot man.

 

I understand now..

 

If I go with this ECU, EGT and detonation is going to be the key factors to check for.

 

I do have the stock ECU, but the car runs so much nicer with the Mines, I want to use it.

 

There are race fuels available in SA, but at high cost. I can use Toluene which is freely available but not convenient.

 

I have heard rumours of Shell releasing 99 octane fuel on the pumps, that will be like heaven if they do.

 

I will do some more reasearch in the meantime, when the car does get to SA I will run the stock ECU with stock boost.

 

Thanks again for all your help.

[Samurai 20V]

There are electronic det sensors which are fine to but need to be properly calibrated to be reliable.

 

I was looking at the HKS knock amp, seems like a decent bit of kit. Any experience with it?

 

I don't have much faith in the local tuners in my home town so a bit of kit like this might help me in keeping my car safe by myself.

[Tricky-Ricky]

I was looking at the HKS knock amp, seems like a decent bit of kit. Any experience with it?

 

I don't have much faith in the local tuners in my home town so a bit of kit like this might help me in keeping my car safe by myself.

 

I personally use one of these, http://www.phormula.co.uk/

They are pretty good and much cheaper that the HKS stuff, i did the initial testing of the KS-3 on the Supra, and have used it ever since, once set up right i find it pretty reliable, it also has a data out for logging, but i would still advise that any initial set up/testing be done with det cans.

[Samurai 20V]

I personally use one of these, http://www.phormula.co.uk/

They are pretty good and much cheaper that the HKS stuff, i did the initial testing of the KS-3 on the Supra, and have used it ever since, once set up right i find it pretty reliable, it also has a data out for logging, but i would still advise that any initial set up/testing be done with det cans.

 

Thanks mate.. You have been a great help..

 

I just checked the price of the HKS, very expensive...