Looking to buy 1984 Audi Quattro 4000 S and 1986 q 5000
07-05-2012, 11:19 AM
#31
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If I remember correctly, that sound is the compressor stalling because they didn't have a BPV/BOV. There's probably a reason they did it that way, but it's definitely hard on the turbo.
Since CIS is a closed system from the airbox to the exhaust, it doesn't like when air exits prematurely, such as with a straight BOV. So, if you want some sound, you'll have to look into what's called a 50/50 or hybrid BOV. It recirculates half the air like a BPV and then lets the rest out. I hear that if the car is tuned perfectly you can run a straight BOV with no ill effects, but otherwise the engine can stall when you let off because it's venting too much air that's already been measured.
I'm trying a 50/50 valve myself. I think the sound is an easy way to tell how the system is behaving, but I'm hoping the 50/50 will be a lot less obnoxious. Of course mine doesn't have any "whistlers" or amplification, so there's that too. Personal preference.
-Rog
Since CIS is a closed system from the airbox to the exhaust, it doesn't like when air exits prematurely, such as with a straight BOV. So, if you want some sound, you'll have to look into what's called a 50/50 or hybrid BOV. It recirculates half the air like a BPV and then lets the rest out. I hear that if the car is tuned perfectly you can run a straight BOV with no ill effects, but otherwise the engine can stall when you let off because it's venting too much air that's already been measured.
I'm trying a 50/50 valve myself. I think the sound is an easy way to tell how the system is behaving, but I'm hoping the 50/50 will be a lot less obnoxious. Of course mine doesn't have any "whistlers" or amplification, so there's that too. Personal preference.
-Rog
i was told it was a BOV... and that back then not everyone knew what one was. if i really have to get a 50/50 i just say eff it.
07-09-2012, 01:03 PM
#34
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i read it was at 130mph... but im not sure if the year matters or not. it was on a thread on here or motorgeek. idr which and where... lol. but htere is a track around where i live and would love to have it unlimited! 
07-09-2012, 07:11 PM
#35
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i think the speed limiter you guys are thinking of is just the relative top speed of the vehicle. 130 mph is basically 220 km/h. and thats were my speedo ends. usually if a vehicle is limited, its at a much earlier speed. my friends 2009 ford escape cuts out at 160 km/h
07-09-2012, 11:02 PM
#36
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One time I was at the mall about ten years ago, about to pull out of my parking space, when a strange man and his friend knocked on my window to talk about my car (the '84 4kq that I still own).
I remember two things about the conversation:
One was that he said the W8 engine would fit in the car, which to this day I've never seen anyone do. He really talked it up, too. This was before I knew anything about how easy the 10vt is to swap or how insane you can get with the 20vt or how the 4.2 V8 weighs less than the I5...
The other thing was that he bought a 4kq new and was dismayed that it would only do 115 mph. He talked about searching the car for the speed limiter but never found it, but was convinced that it had one. That conversation and this post are the only two times I've heard mention of it. In fact I haven't thought about it since then.
So thinking about it now, I can't imagine what it would be tied to. The 4kq speedometer is driven by a cable with nothing in between. The fuel pump relay can limit revs since it's connected to the distributor and can thus cut fuel accordingly. But the 4kq isn't like the later cars where the speed is electronic so you can simply snip the wire going to the ECU so it doesn't know how fast you're going.
So how would the 4kq know how fast you're going? It's possible that it's some kind of tricky thing involving some esoteric sensor signals, but it's hard to wrap my head around it. I know there are analog speed governors out there (since the 1970s I believe). Never run across one on these though.
In short, I think that guy was full of it about the W8 (why??) and just may have been about the speed limiter too.
I've barely been up to 100, so I wouldn't know anyway.
-Rog
I remember two things about the conversation:
One was that he said the W8 engine would fit in the car, which to this day I've never seen anyone do. He really talked it up, too. This was before I knew anything about how easy the 10vt is to swap or how insane you can get with the 20vt or how the 4.2 V8 weighs less than the I5...
The other thing was that he bought a 4kq new and was dismayed that it would only do 115 mph. He talked about searching the car for the speed limiter but never found it, but was convinced that it had one. That conversation and this post are the only two times I've heard mention of it. In fact I haven't thought about it since then.
So thinking about it now, I can't imagine what it would be tied to. The 4kq speedometer is driven by a cable with nothing in between. The fuel pump relay can limit revs since it's connected to the distributor and can thus cut fuel accordingly. But the 4kq isn't like the later cars where the speed is electronic so you can simply snip the wire going to the ECU so it doesn't know how fast you're going.
So how would the 4kq know how fast you're going? It's possible that it's some kind of tricky thing involving some esoteric sensor signals, but it's hard to wrap my head around it. I know there are analog speed governors out there (since the 1970s I believe). Never run across one on these though.
In short, I think that guy was full of it about the W8 (why??) and just may have been about the speed limiter too.
I've barely been up to 100, so I wouldn't know anyway.
-Rog
Last edited by Rogviler; 07-09-2012 at 11:13 PM.
07-10-2012, 11:46 AM
#37
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The fastest I've ever driven my 4000s was recently, at 155 km/h which I believe translates to 96 mph. So if that guy was talking about 115 mph limit, that would sound legitimate. That's 185 km/h. I really wish north America had an autobahn!! I long to test this theory
07-14-2012, 02:31 PM
#38
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Finally got some pics of the 4kq! Its dirty but i love it! 
id post more but im on a slow cell tethering connection... maybe sometime next week there will be more. here is the link though...
http://s284.photobucket.com/albums/l...cpZZ1QQtppZZ24
Its dirty but i love it! id post more but im on a slow cell tethering connection...
maybe sometime next week there will be more. here is the link though... http://s284.photobucket.com/albums/l...cpZZ1QQtppZZ24
07-14-2012, 04:52 PM
#39
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That's awesome! That is some wicked petina...looks like moss? I love it.
Looks like it will be fun to mess around with. I've never seen an '84 in white, so that's cool.
-Rog
That is some wicked petina...looks like moss? I love it.Looks like it will be fun to mess around with. I've never seen an '84 in white, so that's cool.
-Rog