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Jimmy111
Samba Member
Joined: October 05, 2006
Posts: 2643
Location: Wyoming
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 Posted: Wed Aug 26, 2009 1:17 pm Post subject: |
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Yes, you need to add more fuel when the spray starts. This is one case where high EGT comes in handy. The higher the EGT the more Dihydrogen Monoxide (sounds more technical and cool than water ) you can add. The more you add the less air you require and the more power that will be obtained.
When the fuel comes incontact with the water at high temp and pressure everything basicly comes apart at the molecular level. when the H2O splits it absorbs more heat hence the cooling effect. But then that free O2 molecule joins with a CO molecule because Carbon has more affinity to O2 than hydrogen does and releases more energy.
The process is called a Shift reaction. In this case CO shift. |
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The Noof
Samba Member
Joined: January 25, 2005
Posts: 4346
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| Posted: Wed Aug 26, 2009 3:51 pm Post subject: |
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| miniman82 wrote: |
| Jimmy111 wrote: |
| Being that you are running FI with a O2 sensor, you shouldnt need to make many modifications like increasing Jet size. |
My system is set up so it's running open loop during boost areas. I only use the O2 for feedback during cruise, because I don't trust any black box to make tuning decisions about my engine. That being the case, will I need to add fuel when the spray starts? I could always set up another fuel table, and switch to that on the fly whenever I need to.
| Quote: |
| How do you plan on installing the intercooler? |
It's a PWR barrel cooler, which will be under the same boxed off enclosure the turbo sits in right now. Then I'll have an aux water radiator next the the left frame horn, with a fan pulling air through it. |
You're trusting the megasquirt for EVERYTHING else, including timing functions, so why not trust it for the rest???If you can't trust it, it should NOT be on your car. |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Wed Aug 26, 2009 5:43 pm Post subject: |
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| The Noof wrote: |
| You're trusting the megasquirt for EVERYTHING else, including timing functions, so why not trust it for the rest???If you can't trust it, it should NOT be on your car. |
It's a little more complicated than that, unfortunately. It comes down to the control algorithms themselves, and how well they work. The base fuel code has been around for ages, and is very stable. So has the Extra firmware, which contains the code that controls the EDIS ignition system (what I have). Again, very stable and reliable. Then there's the Autotune feature, and map tweaker in Megatune. As far as I'm concerned they haven't been around long enough to get all the bugs worked out, so I'm not apt to trust them just yet. Same thing goes for the boost controller feature, which is still 'experimental'.
Till they get those things working very well, I'm not willing to risk an engine with them. So it's not so much the MS itself, but rather all the 'aftermarket' code written for it.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Jimmy111
Samba Member
Joined: October 05, 2006
Posts: 2643
Location: Wyoming
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| Posted: Wed Aug 26, 2009 7:40 pm Post subject: |
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| You really do learn a lot when you make your own fuel maps. |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Wed Aug 26, 2009 8:14 pm Post subject: |
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In all honesty (and I'm not bragging here), I had done so much research prior to attempting my project, I pretty much knew how it was going to pan out. I spent so much time reading, I knew by the time I started that timing would have to come down and fuel would have to go up under boost, knew that lean mixtures and advanced timing was beneficial for MPG, and knew that trusting a wideband oxygen meter for feedback would be instrumental in all of that. In other words I knew what needed to be done already, I just had to do it. 
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Jake Raby
Samba Member
Joined: August 23, 2003
Posts: 7433
Location: Aircooled Heaven USA
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| Posted: Wed Aug 26, 2009 8:34 pm Post subject: |
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| I knew by the time I started that timing would have to come down and fuel would have to go up under boost, knew that lean mixtures and advanced timing was beneficial for MPG, and knew that trusting a wideband oxygen meter for feedback would be instrumental in all of that. In other words I knew what needed to be done already, I just had to do it |
Damn, I thought that was all common sense.. You had to read about that?
LOL
Its always good to research, I wish I could have read before I built my first boosted engine... But the internet wasn't too big back in the late 80s 
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell" |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Wed Aug 26, 2009 9:09 pm Post subject: |
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Well, I had to simplify or that post could have gone on for literally weeks... Naturally, in reality every engine is different, and will require differing amounts of all those things- I simply didn't assign numbers to them because they don't mean anything to anyone except me. I also had to research the ideal gas law, and injector sizes based upon engine displacement, output, injector duty cycle, and so forth. It's a lot of math, thankfully I'm a nerd. 
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Beetspeed
Samba Member
Joined: July 30, 2004
Posts: 429
Location: The Netherlands
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| Posted: Sun Sep 27, 2009 7:20 am Post subject: |
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Well, I can relate to most of Mini's statements as they my experiences as well. For the sakes of info gathering regarding EGT on real world conditions: Mine (2.2 ltr EFI type 4 with a smallish subaru IHI turbo) ran over 1425F (775 C) without water injection. This was in 5th gear at over 120 mph (!!). Reading off the gauges at those speeds is scary... When I switched on the WI (50/50% meth/water), EGt dropped over 100F (50+C)!
It normally runs around 700Celcius on the highway and with WI runs up to 750C WOT for longer periods of time. I do drag also but mainly track days and Nurburgring laps, where boost is on most of the time when your not braking
I hope my new bigger turbo gives lower back pressure maybe lower EGT, but this combo works very well as is actually.
regards,
Walter
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'75 SB 1303 2,4ltr T4 turbo: 10.58 @ 129.9mph
'65 Ruska buggy 1192cc EFI 80hp N/A |
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