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-   -   Mythbuster: continuing project thread of my 1303 '75 (https://www.germanlook.net/forums/showthread.php?t=9953)

effvee April 9th 2011 20:35

Doing great Walter
 
Ah, Hi Walter:o, at what point will you be happy? Now don't get mad Walter, I'm in your corner. Is this engine a test bed/mule engine that can or ment to be sacrificed? I'd really like to see you just loving what you have done, thus the name Mythbuster. Enjoy your ride, nice work.

Wally April 10th 2011 05:47

Quote:

Originally Posted by effvee (Post 80324)
Ah, Hi Walter:o, at what point will you be happy? Now don't get mad Walter, I'm in your corner. Is this engine a test bed/mule engine that can or ment to be sacrificed? I'd really like to see you just loving what you have done, thus the name Mythbuster. Enjoy your ride, nice work.

No worries Francelle, I hear you and your not the first one saying this ;)
There is no fixed limit to where I will be 'happy' as I really wouldn't know where the limit is at the moment. I also do not intentionally want to sacrifice the engine either mind you. If you were experiencing the things/data I do, you would also feel much more easy with the power levels surely. Its a step by step exploration of the possibilities so you will.

Case in point: At this moment we got 355 hp at just 1.0 bar boost and 418 with lambda approaching 1.0 (!), so lets round that off to 420 if fuel would have kept going. That's a 65 hp gain in just 0.3 bar. Therefore I see crazy power if I could have the fuel system handle 1.6 bar...:rolleyes: There doesn't seem to be any restriction to go there as the engine has run at 1.6 bar (and over) before.
All this with just 0.500" valvelift and moderate duration on a 2.2 engine with stock head castings, stock crank, rods and type 4 case.
When your this far involved as I am, you just constantly 'see' new areas that can be improved upon. To get there, you just not copy what you read on other vw aircooled related fora ;)
Tuning this far also brings out and enhences you own weaknesses and my weakness for now seems to be the wiring...:o

70Turbobug April 11th 2011 01:11

Considering that you do all the work yourself with little or no "professional" help the results and ghe evolution process of this engine earns the highest respect imho. Keep up the great work Wally! One way to find out if your wiring is too small would be to measure the amperage at the pump during a dyno run.If the amps are low (due to the wire being too small) the pump would run too slow.The specs of the pump i.e. on the box or papers should show how many amps the pump pulls.You should have that as a minimum value.

Wally April 11th 2011 03:27

Not too much credits to me pls Mark, give them to the type 4 engine instead ;)
The 044 pump alone can pull 15A and the low pressure Carter feed pump probably between 5 and 10A as well. I just had time yesterday to change the wiring to much bigger (3x) and put and extra relais in the trunk next to the battery, feed straight from battery plus its own fuse. Short test drive revealed the same low fuel pressure (from 3,5 bar to 2,5 bar FP) on boost instead of rising with boost... not good still.
Tested FPR again and with air pressure from the air compressor, fuel pressure rose nicely while engine was idling. So the FPR-rising-rate works, it just doesn' t kick in for some reason.
My remaining thought is that the boost reference line for the FPR is not giving it boost. I have that boost reference line Tee'd from a line where it also feeds the boost control relais. Since that one is now circulating with the top and bottom port of the external gate, maybe the boost reference line looses pressure when waste-gate kicks in(?).
At least thats my latest thought, so I have changed the T to another location and hope to test it somewhere this week...

70Turbobug April 11th 2011 06:12

Quote:

Since that one is now circulating with the top and bottom port of the external gate, maybe the boost reference line looses pressure when waste-gate kicks in(?).
That's possible but if your FP is decreasing at 1.3 bar and you were hoping for 1.6 then I am assuming that you have your EBC set above 1.3 bar correct? So it would only steal pressure when the WG opens and not before?
Also, you didn't have this problem before at higher boost levels.Maybe your alternator is too weak to support the increased load that the pump and injectors are demanding? Just an idea, but I think the problem is actually elsewhere.Does your ECU control the fuel pump also? Is it possible that you may need a larger or an additional feed pump?

Wally April 11th 2011 13:04

Runs:
http://www.youtube.com/watch?v=97SNAq1e9gY

and warm-up on dyno (turbo whistle):
http://www.youtube.com/watch?v=IfBpkJnZgbc

effvee April 11th 2011 14:31

Boost senitive regualtor
 
Walter, you are running a boost senitive fuel regulator arn't you? Is you fuel system looped? I have seen boost senitive regulators in a looped fuel system where the fulel pump pumps the same pressure all of the time, as boost demand are needed. It is the responsibility of the regulator to up fuel pressure. Amp and wire size can come into play if the pump is worn and tired, thus the need for more amps. Can you ECM log fuel pressuee and you not at what boost pressure?

Humble April 12th 2011 01:02

Your car is an animal, 418hp and still going! Hopefully you can sort out the fuel problem soon, sounds like you're on the right track with the boost tee.

As for the fuel pump, I believe you might be nearing it's limits. When I calculated my fuel needs at 100% duty cycle i got 3.8bar (55psi) flows about 230 LPH from the 044 pump and with 4x750cc injectors is 3 liters a minute or 180 LPH, which leaves me a good buffer. IIRC, you had 4x1000 injectors, 4 LPM or 240 LPH but the pump running at 3.5 bar can only supply around 237 LPH. Again, that's assuming 100% duty cycle but it looks like you may need more fuel in the future if you keep going.

Edit: That thought was half baked it seems, I just got back from Vegas so give me a break :)

I forgot to factor in the rising rate FPR, so here's a couple of quick numbers.
yours: initial fuel pressure 3.5 bar + 1.3 of added boost = 4.8 bar from the pump which is about 210 LPH and you need 237 LPH (again assuming 100% duty cycle)
mine: initial fuel pressure 3.8 bar + 1.7 of added boost = 5.5 bar from the pump which is about 175 LPH and I need 180 LPH (again assuming 100% duty cycle)

damn, I guess we will both need more fuel ;)

Wally April 12th 2011 03:25

Good post Humble!
I actually had similar thoughts, but some things I see IRL at the car just don't add up for me atm: I still do not see _any_ rise in fuel pressure when its comming on boost.
Did another test run last night and there's no increase in FP over the base 3.5 bar when on boost. On the contrary, FP still drops a bit to 3.25 or 3.0 bar with ~ 1 bar boost.
That was with the rerouted boost reference line.
Remember that I tested the FPR at idle with applying boost and it worked then, also matched by the log reading. So the FPR and the fuel pressure sensor read accurately (enough anyways).

With the better wiring (I assume I now have a few Volts more), the test drive last night actually showed the problem to be even worse, even at lower rpm and boost I experienced misfires from lean spikes (log showed very uneven lambda and high spikes).

My thoughts now are that the whole catch tank may be more of a restriction then a help, so I will by-pass that tomorrow and see if a direct feed from a full tank will help.
I am really puzzled so far...

Bruce. April 12th 2011 05:50

A few thoughs to be helpful.

If you can set up a voltmeter to measure the volts across the pump it will confirm if you have a problem with wiring (or a connector). If the volts drop across the pump when it is flowing lots of amps, there is another source of electrical resistance between the pump and the Bat/alternator.

I'm also guessing you have a genuine 044 from a known seller? Apparently there are copies on Ebay which look good but don't perform.

Is the supply to the pump (pipe sizes and tank port) big enough? A fuel pressure sensor at the 044 input would show if there is always positive pressure at the input. If the 044 has to suck the fuel at high flow rates, the output pressure would drop.

good luck!

Wally April 12th 2011 17:14

Thanks Bruce!

I just removed the catch tank and Carter feed pump and now I can maintain my target lambda all the way to redline under 20 psi of boost. Now that was fun :D

You were probably close with the feed to the 044 not being optimal. The intake line is 1/2" internal from the tank to the feed pump, so plenty big, but entrence into catch tank is only 7mm internal, so almost half that size. For the low pressure Carter pump probably a little too much of a restruction to get to full flow.
Feed to the 044 itself from the catch tank is 1/2" or about -12 iirc, but if there's only one restriction...

Now the 044 sucking straight from the 1/2" from under the tank works well, but at higher boost, the rising rate pressure suffers a little and doesn;t follow the boost pressure quite. That leads me to believe the 044 is somehow running a little on the edge in my set-up.
For now it will do, but maybe a second pump may be wise in the long run.

Thanks for thinking along all!

70Turbobug April 13th 2011 04:39

Glad to hear you found the problem, Wally.Will you modify the catch tank and continue to use it or is there no need for it?
I'm exited now what you pull on the dyno - then again I might get jealous:D

Wally April 13th 2011 05:36

Quote:

Originally Posted by 70Turbobug (Post 80386)
Glad to hear you found the problem, Wally.Will you modify the catch tank and continue to use it or is there no need for it?

Good question. Right now I have no hurry to change it. There is a need for it however when I start circuit driving it again. At Spa-francorchamp and on the Ring, when the fueltank level only dropped to half full, I already started having fuel deprivation in long high spee corners... that was/is my reason for the catch tank.

I hope to run one or two Time Attack events, but those are only 20 minutes track time, so I might just be ok for now till end of season? We'll see.
Quote:

I'm exited now what you pull on the dyno - then again I might get jealous:D
Maybe end of season a dynorun again if everything is still in one piece by then :rolleyes:

Steve Arndt April 13th 2011 15:09

What fuel pressure sensor and gauge do you have?

When I was having miss fires under load I needed to check fuel pressure. My only option at the time was a long hose from rear to front, and a gauge taped to the windshield. That is a bit unnerving!

s

Wally April 13th 2011 15:30

Quote:

Originally Posted by Steve Arndt (Post 80393)
What fuel pressure sensor and gauge do you have?

When I was having miss fires under load I needed to check fuel pressure. My only option at the time was a long hose from rear to front, and a gauge taped to the windshield. That is a bit unnerving!

s

I don't have a gauge, I just run a VDO 0-5 bar oil press. sensor just after the pump inline and log the values :cool:. In hindsight the 0-10 bar would have been more appropiate, but I haven't run out of range yet. Unfortunately...
DTA has already the VDO sensor's calibrations as stock in the ecu, amongst many other press. sensors and I just have to click the right one and it knows what and how to measure.


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