Hmm I see. I was thinking of using mine just as an overall safety net and to help with keeping carbon deposit build up down. Reliability and long lasting take a front seat over power for me.

 

Yeah... I'm not sure that's very sound advice... Intake temps are relatively arbitrary in regards to the overall goal of water/meth injection (WMI) of preventing pre-detonation and removing latent heat following a combustion cycle. If low intake temps were all it took to safeguard an engine then cold winter nights would be the safest time to romp the car


Most of the older/simpler Water Injection systems trigger off a set boost level, I know my first Aquamist was a simple on/off switch activated by an owner determined boost level. More advanced systems (that I'm aware of) are able to be scaled to match fuel delivery (think Aquamist Summer Unit) or based of gear/rpm range and boost levels if you're controlling the WMI flow with the ECU itself.

Further, running WMI OUTSIDE of the required/recommended range isn't likely to result in catastrophic drops in power, certainly not to the extent that it would override the benefit of the knock suppression properties. "Losses" from overdoing WMI are somewhere around 5hp right? The difference between 460whp and 460whp is relatively negligible and could be experienced in real world driving from day to day based on ambient temp fluxuations anyway



Not to come in guns blazing... It just seems like that's not exactly the best advise to be presenting as an undisputed fact.

Could you please go into detail as to why you feel like intake temp is the better variable to trigger WMI off of than boost?

 

I think it'd be a good idea to agree on three things:

1. the goal of water injection is to increase the effective octane of the intake charge. It doesn't matter if you're injecting pre turbo or post, pre intercooler or post. Thats its job.

2. Pre-ignition in a properly fueled street car is almost always caused by the VERY high intake temperatures.

3. There is a very specific air to fuel ratio (doesn't matter the fuel) that under ideal conditions will always provide maximum BTUs/power.

To say that intake temps are arbitrary to the overall goal of WMI is, in my opinion, a fallacy. Intake charge cooling is the sole reason for increasingly rich/saturated forced induction tuning.

With regards to the cold night:
A. I think you know that comment really serves no purpose other than to poison the well. B. You're confusing a cool intake charge to a dense intake charge.


Yes, old tech is crude and WMI is in constant evolution for the better. Thats the reason why Aqumist uses both boost and an IDC scheme on their HFS3 and HFS4, or even better a separate PWM signal.

We used to use carbs but now we dont because we're able to fine tune fuel delivery at an order of magnitude higher resolution. Same principals apply.

I think the 5 horsepower number is purely anectdotal.

If you're drowning your intake charge with something incombustable (water vapor) or an overly rich fuel (meth) you're reducing your potential to generate power. Also comparing your full throttle peak power losses to partial throttle/transient low power losses don't really work in this case. At an injection set point of 2 psi you may not be able to feel a power difference at full flog however low power and partial throttle you will be.

Word. Discussion is good. If these cars were all identical and we were doing comparisons in a normalized environment then sure, find whichever set boost point is nearing danger zone and throw water at it to increase effective octane.

These cars are NOT all identical and everyone is running them in different conditions so rather than throw out a magic number of a variable (boost) that only tells half the story.

What I'm getting at is one mans configuration may cause pre-ignition at 10 PSI where another may cause pre-ignition at 15 (numbers pulled out of my ***).

Take my statement and its tone as more of an effort to dispel the cookie cutter 'At 10 PSI you must do X'. Throwing out a boost number without knowing more about what the engine is doing is kind of like the old 'three mod' rule that was held on to a decade plus ago. Sorry to derail the thread from clearances.

 

Blah blah

Boost IS intake charge heat.

You aren't going to get away from physics just because your AIT sensor has a lag time...

 

The point of water injection is to prevent pre-ignition no matter how it occurs...... be it from a bad tank of gas, too much boost for pump gas, or any other reason (to include high AITs).

Back in my 'learning period' of 2000-2001 I blew *ahem* quite a few engines, partially (primarily) due to the fragile Hurley apex seals being pushed on me. This was always caused by over boosting, poor tune/lean condition, or a bad tank of gas.

The AEM water injection system that's pretty common/popular is boost actuated. Recommend starting to inject at 10ish psi, and set your max injection for your target boost. This is using windshield wiper fluid, which is primarily water. There is some small amount of alcohol which will lower AITs, but that's not the reason the setup is so valuable on a turbo rotary--- it's valuable because it covers you against Murphy's Law

 

That's a shitty way to respond.

Heat is a byproduct of compression/boost, higher efficiency compressors will have a lesser impact on said byproduct. You know this.

And how is focusing on the killer (heat) trying to get away from physics, obviously its important to account for hysteresis.


I agree, I just think that using boost as a one size fits all trigger point is NOT the proper way to go about things (it'll give you a good baseline) since there are so many other factors involved in heat rejection and isolation.

 

Increased intake temperature is a direct result of compressing the intake air charge.

Automotive MAP sensor responds much faster than automotive IAT sensor.

Engine is run off MAP input to measure engine load and the IAT is just a correction factor (for air density calculation leaning your engine IAT is higher and enriching when IAT is lower) to the overall injection and ignition maps.

It is fine and desirable that IAT sensor is slow reacting because you want more fuel with sudden MAP increase not less.

You want to inject water as engine load increases.

You don't want your water injection on when you are sitting in traffic idling and IAT are very high.

Its like you have never looked at a data log.

You can read this on the new BMW stock water injection system. Notice how they keep talking about full engine load...

BMW reveal car with innovating water injection system - F1technical.net

 

I enjoy being shitty occasionally.
Oh, I should thank you for presenting the opportunity.

This is me shitting on someone online. I am surprised they caught me in a moment I wasn't rubbing my nipples.

 

I guess I'll respond to both posts in reverse:

Way to be an internet ******. Kudos. (see, I can be retarded too)


Yup, this is fact.

Stock yes, automotive? Nah. Open tips will update essentially as fast as an ECU can sample.

Yes, speed density relies on pV=nRT. To say that IAT is 'just a correction' is asinine.

Fine? Sure on factory power numbers. Desirable? Don't be a dolt. I'd also take into consideration my sentence RE hysteresis.

When using water injection to increase your effective octane. You want to inject water as the potential for pre-ignition increases. If you've got a cold as **** intake charge under full load....you don't need the water.

Of course not. And/or functionality in your WI setup? Using boost as a trigger point after testing your system and seeing at what pressures your intake temps get into the danger zone? I feel as if I've made this clear.

K.

Neat article/post, but now I have to ask myself. Are you a ******* idiot? Can you read? I was going to copy pasta and bold a few of their references to intake temps but goddamn, there are so many. I'd re-read that whole thing were I you.

All in all I respect what you've done with your FC great build and very neat and innovative stuff with the hybrid turbo setup, I've followed it for quite a while. But you sir, are a complete and utter douchebag. If you want to talk ****, PM me. Don't **** this guys thread up any more than it is.

 

Mmm... I don't entirely agree, nor do I entirely disagree.

Octane is nothing more than a rating system purely associated with fuel (US primarily) that identifies the ambient temperature that the fuel will spontaneously combust at.

WMI serves dual purposes: 1) the Methanol atomizes prior to combustion, which helps lower intake temps (mimicking an increased octane). However, 2) the water does not atomize that quickly, instead it flashes inside the combustion chamber and assists in drawing out surrounding heat (while also cleaning off carbon deposits) which assists on having a lower internal engine temperature going into the NEXT combustion cycle.

So higher octane and WMI serve similar purposes, but the way you've presented it sounds like they are identical in how they achieve the goal, along with having identical side results. Not really the case.


If we're going for overly simplistic explanations, then sure... But the subject is lost if you try to oversimplify it too far. Drawing back to my example of popping engines on cold winter nights.

I'm fairly certain that it's been covered (extensively) in the past that it's perfectly fine to inject WMI for safety after a tuning session with minimal negative effects. And again, oversimplifying to suggest that ONLY correct AFRs will attain max power is rather misleading. There are many more factors involved than simply AFR.


As others have pointed out, it's no more (and probably less) of a fallacy than is trying to push the idea that anything BUT Intake Temps is arbitrary...

You're presenting your opinion in a manner that disguises it as fact.


A. No. It's a real-world situation that MANY in this community have experienced, which effectively disproves your theory. That's not "poisoning the well" that's providing real world situations which support my statement. I'm not trying to deal in "Trumpian Realities" here..

B. Please provide the scientific backing which indicates that temperature and density are mutually exclusive when it comes to air (when all other elements, like elevation, humidity, etc., are the same).


^ Subjective statements.

Yes, as technology advances our control over the controllers input/output will also advance. That does NOT mean that the less sophisticated inputs are no longer just as effective as they once were...

That's fine.

Who said anything about "drowning" an engine? You're creating a strawman situation here...

I agree that running WMI during a break-in period should not be necessary, as the engine really shouldn't be under enough load to where it will need any additional cooling.

However, you are taking the OPs statement WILDLY out of context. I'm not sure if you did it intentionally or not, but you did it all the same..

I concur, however the OP was initially asking for advise as it would pertain to HIS situation (breaking in a recently rebuilt engine, and whether he should run a low level trigger point for WMI incase he accidentally went into boost during this period). In response you gave your opinion as it would apply to YOUR situation (apparently chasing the razors edge of power potential). Where as, in truth, your two situations are vastly different, so the advise you gave really doesn't apply and the manner in which you delivered it suggests that he would need to conform to it (or suffer the consequences).


I'd suggest you go back and revisit the situation surrounding the initial question, in comparison to the advise you gave and justification behind it. I'm afraid you've violated your own suggestion... (which is probably why people are jumping down your throat)

 

First off, your reaction to being goaded does NOT make him look worse, it only lowers your own standing in the eyes of impartial observers...

Ignoring that, however, I'll highlight the specific portion of that (interesting) article which matters the most:

The high-tech solution is not a simple matter of using intake temp alone. Load, RPM, and Temps (not specifically intake) are what they have cited as being used to trigger varying amounts of injection for a MotoGP Safety Car... Kinda high end application there

It's pretty well established that pressure=heat inside an engine, and boost = pressure, so it really could be inferred that they are running their triggers based on variables taking into account engine load, rpm, and boost pressures.

 

I did not post the picture or my comments to flame or troll dguy, but to remind him we are on the internet.

He has an agenda to become butt hurt and that isn't going to work out well for him online.

I don't know him or care about him (I'm not actually masturbating while thinking of ways to make him emotional like I said in my post with picture) I didn't take extra time or words in my post to insult him, he took that on himself.

I posted
Blah blah was the lengthy explanation I could provide had I not been in a hurry.

I went straight to the punchline figuring readers could sort the rest out.

When I saw dguy didn't understand and I had time I replied with the lengthy post.