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PostPosted: Mon Sep 05, 2005 10:09 pm 
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Thanks for the feedback guys. A few comments:

Diceman wrote:
Turbo cars are far more predictable once they come onto boost it is all about cylinder pressures and the rate of burn with a turbo car. Hence my reasoning that the dreaded WI actually slows the burn and loses torque/power. You need cooling that is predictable and you can map to or dont bother IMHO (especially on a custom built engine for your desired boost/rpm).


Hmm...'predictable cooling' :roll: wouldn't we all like that :wink: I don't know about the Apexi PFC but the MoTeC has temperature correction mapping capability built in so it should be possible to react to changing conditions. Mark reckoned when my engine temps went critical following my rad problems at Silverstone the MoTeC would have immediately cut the boost and retarded the ignition. As you know it is possible to hook the ERL WI into the MoTeC OR 'map' it separately if you go for the System 2s. I don't think any loss of power/torque is significant although if you have any evidence to the contrary I'd be all ears.

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The only time that WI is usefull is as a band aid for running high boost on a stock engine without other intercooling efficiency increases. (Jp waits for flaming )


Ouch!... a bit harsh, if the WRC teams deem it necessary to run WI then it must be benefiting them somewhere. They also run FMIC's but clearly don't feel this is the total answer.

BTW what's a Cadbury Caramel how to :?: ... :?

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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PostPosted: Mon Sep 05, 2005 11:20 pm 
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WRC cars are working within constraints of teh rules. hence with teh rstrictor they make shedloads of boost in the mid-range (just where the engine is at peak VE and hence peak torque and peak cylinder pressures. Thye just cant get bhp out of them without cheating so they have to run a high boost application.

The Motec does have inlet air temp correction and water temp correction as does the PFC. Inlet air temp doesnt start to knock off timing until 60 degs on both and circa 110 degs on water. If I were to run WI it would have to be in line with fuelling (constant ratio) and I would probs adjust the inlet air temp correction to a lower temp so that you retard timing when the WI fails and inlet temps go up. I dont have proof of torque loss but I have read numerous occasions of losing 5-10 % of torque from others when it is just strapped on like a band aid.

As you know I have a Aquamist 2D kit which runs inline with the injector duty cycle once a set boost level is reached. I havent fitted it yet though :-)

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PostPosted: Mon Sep 05, 2005 11:23 pm 
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Cadbury make chocolate :arrow: :lol: :mrgreen:

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PostPosted: Tue Sep 06, 2005 1:12 am 
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JP, I guess from your comments you are in the camp of those who believe WI is not a good thing because if it stops working you risk detting your engine? I don't subscribe to this at all. Its like those with massive FMIC's who think they can run without WI or others who turn it off during winter ...... totally crazy. They all seem to miss the point which is to use WI to minimise the risk of transient detonation. Running a FMIC is going to do nothing to control temperatures in this situation. Perhaps the turbo spec will have a bearing on post compressor, pre-intercooler temps but until someone monitors them we wont know for sure*

If you are running with a map so close to the edge that WI failure risks your engine I'd suggest the map is too aggressive. Like you say, most mapping is set to lower boost/retard ignition at temps over 60-70 deg C. Whenever I've lost my WI I've generally stopped boosting over 1bar within 30 seconds. My plenum temps will rise from about 45-50 to 70+ deg C within about 15 seconds. Maybe I've been lucky but I think its also a function of a conservative setup with the mapping.

Kerplink :!:

*As an aside I hope to have my MXL loom and sensors installed by the end of the month so we can start building up some factual data :D .....am I right in saying you can't log the Apexi PFC data ?

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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PostPosted: Tue Sep 06, 2005 8:11 am 
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Don,
If teh water injection is mappable and small quantities (and the correct ones!) are used then it can be used as a safety device without losing too much power. I understand fensport use the smallest jet and minimal injector duty cycle for teh water on the corolla. If you had the car also setup with the inlet air temp correction starting at 45-50 degrees retarding timing on higher temps I see no reason why this is classed as running on teh edge. All you are doing is applying teh correction maps to suit the engine better?

Yes I agree that mapping on the edge so that when the WI fails you are at the onset of det is a stupid idea. I also think that the typical "lets strap on non-mappable water injection so I can run higher boost" is a fools game. This seems to be the typical route for most gt4 owners. I appreciate you are not typical :-)

If it does doen correctly then it has a place in teh safety boat.

Whilst we all seem to think of inlet air temps of circa 70 degs as frighteneing they are not that high in the grand scheme of things. Many turbo cars ruyn higher temps from the factory. The ST205 is blessed witha good intercooling setup. However lower inlet temps do reduce the overall thermal gain that the engine is trying to remove via water cooling - allow more/denser air in and reduce the risk of det. It is a good goal.

The whole water injection debate is a bit of a uinknown IMHO. How many of us "the supposed techy nerds" run mapped water injection? How many have monitored the effect of adding water injection to power/torque and det limitation effectiveness? I also have another concern that the addition of water vapour on the air inlet temp sensor is is moving teh measurement from a dryish bulb temp to a wetish bulb temp. This will be different for the same actual temp, just read differently by teh sensor.

If you are running high boost in a car not designed for and not effectively intercooler then yes WI has a place. Map it or dont bother and run lower boost IMHO.

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PostPosted: Tue Sep 06, 2005 11:02 am 
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Well,

I have no impirical evidance to back this up but

My butt dyno tells me that WI has added grunt to my car. With it the pull at 4k revs certainly feels noticeably better. However, the only evidance I have is a somewhat suspect (due to lack of operator understanding LOL) torque curve from the i-Color showing over 400 Nm of torque (equates to 307 Lb/f). Not exactly scientific but given that I (possibly LOL) have the unit set up with accurate weight info this could actually be quite close to the mark
If true this would be a prodigous amount of torque for a lowly 1.14bar boost

The other (slightly more technical) way of looking at this is knock supression

Around the point of peak VE (and peak torque) the engine is severely knock limited. Timing must be pulled out (compared to optimum) to keep the engine in one piece
Water injection will help this in two ways. Yes, lower charge temps are critical but there is also some retardation of flame fronts and det reduction even with standard water. If you add meth into the equation then it gets even more complicated as the flame front speed is further reduced and additionally the meth adds slightly more heat dispersal to the picture

It's a very complex subject and one I've barely scratched the surface of yet. I'll see if I can dig out some of the links I have......
BTW, I completely agree that mappable is the way forward for true WI control and effectiveness


One other thing to bear in mind re Fensport :-

They are not pushing the engine that hard IMHO. Sure, they have tuned the nuts off it for straight line work. However, the occasional straight line blast is not ever going to thermally load it like track work. Witness their absolute refusal to admit the need for an oil cooer despite the hard evidance that both Mike and myself have for overheating oil when pushed.


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PostPosted: Tue Sep 06, 2005 4:56 pm 
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Steve, maybe the stock ECU has not needed to knock back the timing with your water injection fitted?? Hence you are actually getting more torque.

I woudl actually like the water injection to be triggered by inlet temps rather than boost AND mapped. That way it would help off teh lights away from traffic to bring the temps back down quyickly. It should also come in when high boost is used.

Indeed water once added with meths is a more complex issue. What about Toluene injection?? Surely this would be better with a High calorific value and MOn/Ron rating.

Re Fensport - yes point taken. However heat soak is surely an issue when awaiting the staging lights?

You all know my feelings on water injection and have donw for a long time. Good discussions. Unfortunately I dont have experience enough to give you the tachnical answers from my reasearch :-) However I have never read or heard a good word from serious tuners about water injection. The only two people I have heard advocate it are Datajon and Fensport. I think for this purpose WRC cars shoudl be ruled out of the equation as they have different rules to abide to. Formula 1 turbo engines were run on race fuel (toluene mainly) So where do we look for turbo cars running pump fuel without rules?

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 Post subject:
PostPosted: Tue Sep 06, 2005 5:30 pm 
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GOLDMINE HERE
(Not just W/I although there are many papers on thar alone :) )

To view this site you will need
Adobe Reader
1 pocket protector
Plastic Mak
1 pair extra thick glasses
One of those hats with the little windmill thingy on top
Several gallons of coffee
Patience
Dimmed lighting
"Physics for dummies"
At least 3 variations on the word Glaven
A quick read up on Professor Frink if the above meant nothing to you

But if you read through it there's some very useful stuff there. The paper on the effect of water vapour on flamefront propagation is highly interesting!

It seems the other links are probably all on my home PC


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