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Observations: NA pump vs TD pump with a vnt15.
by
hamradio
on 12 Mar, 2009 15:40
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So, I recently swapped from an old worn out NA pump to a "condition unknown" 1.6td pump from an '84 jetta. It doesn't leak...I'm happy...$60 well spent. I previously had an NA pump with the fuel screw turned in enough to not be able to get the idle any lower.
Anyway, some observations-
Upon free revving, it revs down much slower than it did with the na pump. It seems like the boost falls at the same time the engine revs down...maybe boost is still built and it's fueling it a little extra?
If one holds their foot on the throttle and gives it enough throttle input to slowly build 3 or 4 psi, once the boost is built, it will start revving more. Is this due to the enrichment?
Also, it now builds boost ridiculously quickly...I can feel the vanes open in 1st like it is nothing...I feel it long long before I hit the governor on the pump.
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#1
by
jtanguay
on 12 Mar, 2009 18:22
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i think theoretically you can get more fuel out of a TD pump with the enrichment device. you can screw in the fuel screw to where the car just wants to run away, and then the enrichment device on the pump should add even more fuel under boost.
so hamradio, what would your advice be to anyone who would want to get a VNT turbo, but is worried that it'll break? how long have you been running yours? i'm guessing you're not gentle with it :lol:
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#2
by
Rabbit on Roids
on 12 Mar, 2009 20:20
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ive had my vnt on my car for almost a year now. and that thing sees full boost pretty much whenever i drive the car. it seems to be a very reliable turbo.
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#3
by
jtanguay
on 12 Mar, 2009 20:27
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ive had my vnt on my car for almost a year now. and that thing sees full boost pretty much whenever i drive the car. it seems to be a very reliable turbo.
good to hear!
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#4
by
hamradio
on 13 Mar, 2009 05:02
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Hmmm...it's not due to enrichment. I unhooked the tube, and the revs would hang in the same way. I'm thinking the fuel screw is turned in too far...it was up against the collar when I bought it. I also have crappy old worn out injectors.
Come to think of it, I don't think I've ever driven my car without hitting full boost...it's natural, it seems. Usually by the time I'm through first and 2nd gear, not even revving hard, it has hit full boost. I also can hit full boost in 5th on the freeway just by flooring it.
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#5
by
subsonic
on 13 Mar, 2009 05:52
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What kind of boost levels are you talking about. Any problems so far with high boost at lower rpm?
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#6
by
Hey
on 13 Mar, 2009 06:55
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i think theoretically you can get more fuel out of a TD pump with the enrichment device.
In fact, IF the pump is very well adjusted (which is VERY VERY rare), you will have the same quantity because it is not en enrichment device but a "cutting" device. If the pump is not well adjusted (often) you will have less.
It doesn't give you fuel, it just makes the pump wait for some boost before giving you more... it serves to prevent fumes.
LDA might be: Limiting Device Actuator
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#7
by
Golf/Jetta
on 14 Mar, 2009 02:00
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i don't know if this will work, an Air tank
i was going to say an Air Regulator, i wonder if that stalls.
ideas
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#8
by
Rabbit on Roids
on 14 Mar, 2009 10:10
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i don't know if this will work, an Air tank
i was going to say an Air Regulator, i wonder if that stalls.
ideas
?!?! what? randomness about air tanks and regulators? making a pneumatic turbo spooling device?
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#9
by
jtanguay
on 14 Mar, 2009 11:20
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i think theoretically you can get more fuel out of a TD pump with the enrichment device.
In fact, IF the pump is very well adjusted (which is VERY VERY rare), you will have the same quantity because it is not en enrichment device but a "cutting" device. If the pump is not well adjusted (often) you will have less.
It doesn't give you fuel, it just makes the pump wait for some boost before giving you more... it serves to prevent fumes.
LDA might be: Limiting Device Actuator
but the LDA itself does the same as screwing in the fuel screw under boost. so in actuality it does increase fueling, and more so than you could without it (and have a good stable idle)
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#10
by
Hey
on 14 Mar, 2009 12:47
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You are correct... but let me clarify my point of view.
If you just remove the boost-pin... you will have more fuel.
If you put a boost-pin you have less fuel when there is no boost.
Then it's a Limiting device since you have less with it.
A NA pump is a pump without this limiting device. So this is why the guy may see faster boost building up without it.
The LDA only shorten the throttle lever movement. So even if you put the pedal to the floor, in fact you are ¾ full throttle until there is some boost.
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#11
by
hamradio
on 15 Mar, 2009 20:03
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OK, here's an issue that's driving me bonkers.
The car started and ran great with my old worn out 1.6na pump. The engine started immediately when about 30* outside...with the new 1.6td pump, cold starts are much harder and smokier. I do have old worn out injectors, but it's as if the car is running on 2 cylinders at idle until I actually drive it a little distance, and blue smoke pours from it. Timing is reasonable...sounds right, but I need to get to a dial indicator to check it. Fuel screw is cranked to the collar and idle corrected (changing fuel screw had no effect on this missing issue).
After the car has been driven a little, even 1/4 mile, it runs fine.
Any thoughts?
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#12
by
Rabbit on Roids
on 15 Mar, 2009 22:56
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OK, here's an issue that's driving me bonkers.
The car started and ran great with my old worn out 1.6na pump. The engine started immediately when about 30* outside...with the new 1.6td pump, cold starts are much harder and smokier. I do have old worn out injectors, but it's as if the car is running on 2 cylinders at idle until I actually drive it a little distance, and blue smoke pours from it. Timing is reasonable...sounds right, but I need to get to a dial indicator to check it. Fuel screw is cranked to the collar and idle corrected (changing fuel screw had no effect on this missing issue).
After the car has been driven a little, even 1/4 mile, it runs fine.
Any thoughts?
yea, this is the same thing my car is doing. POURS blue smoke when your cold.
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#13
by
Hey
on 16 Mar, 2009 06:32
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I think a timing issue would be the most probable cause.