What AFR stuff do I need ? (carb)

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What AFR stuff do I need ? (carb)

Postby Foscora » Wed Jun 29, 2016 6:44 am

Hello guys,

I wish to dial my carb on the 80 (try different jet size, tune it precisely, etc) and I thought it would be easier with proper equipment such as AFR monitoring.

Even tho, I wouldn't permanently need it on this engine, it may be useful on a later build so I wonder what should I get ?

- What AFR Gauge ? I guess the chinese 15$ stuff is to be forgotten but I can't find out what I really need
- What lambda ?
- Do I need CO reading ?
- Do I need exhaust temp ? (I'm running OEM exhaust manifold)

Where should all this stuff be located ?

I thought lambda probe on the red square
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What about the rest (if I really need it).

Thanks in advance ! ;)
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Re: What AFR stuff do I need ? (carb)

Postby loxxrider » Wed Jun 29, 2016 9:42 am

Just get a quality wideband O2 package from a manufacturer like zeitronix. That's my personal choice for a wideband. You don't need anything else. Just the gauge, controller, and sensor. For afr you should shoot for, refer to my fuel tuning guide here in the diy section.

Egt sensor is more for tuning timing. That's not to say an egt can't help with fuel, but it certainly isn't necessary.
-Chris

'91 Audi 200 20v - Revver/BAT project
'91 Audi 200 20v Avant
'01 Anthracite M5
'90 M3
'85 Euro 635csi
'12 X3
E34 530i (maybe rear-mount soon)
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Re: What AFR stuff do I need ? (carb)

Postby loxxrider » Wed Jun 29, 2016 9:43 am

Location of the sensor mainly just determines it's response time, not accuracy, so where you have it should be just fine.
-Chris

'91 Audi 200 20v - Revver/BAT project
'91 Audi 200 20v Avant
'01 Anthracite M5
'90 M3
'85 Euro 635csi
'12 X3
E34 530i (maybe rear-mount soon)
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Re: What AFR stuff do I need ? (carb)

Postby Foscora » Wed Jun 29, 2016 3:00 pm

Wow thanks Chris !

Yep I already went through your DIY, thanks again !
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Re: What AFR stuff do I need ? (carb)

Postby loxxrider » Wed Jun 29, 2016 4:37 pm

No problem. I should say that guide isn't great for naturally aspirated applications. You'll be able to tell when it's running well with the carb and wideband though. It'll be a nice tool to make sure it isn't too lean while you're tuning. 12-13:1 would be a pretty conservative number to shoot for for afr with N/A.
-Chris

'91 Audi 200 20v - Revver/BAT project
'91 Audi 200 20v Avant
'01 Anthracite M5
'90 M3
'85 Euro 635csi
'12 X3
E34 530i (maybe rear-mount soon)
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Re: What AFR stuff do I need ? (carb)

Postby Foscora » Thu Jun 30, 2016 3:18 am

Yep, I already went to the theory, I guess I'm ok on this side.

Now I have to try different jets to match the engine caracteristics, my problem can't only be solved by turning screws : my carb was thrown in the car without proper "engineering" before, that's how/why I need this stuff ;)

Based on my calculations, I'd say my carb size is correct/great but the jets seems way too oversized (to begin with the idle jets)


I can manage to make the car run "correct enough" (I can even pass the emissions tests), but idle is a bit of a mess, as well as 1000-3000 rpm range which is a vast emptiness of torque/power compared to what I should have. Engine works like it's a 20V with sharpy cams on it, works awesome on the 3000-6000 range tho
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Re: What AFR stuff do I need ? (carb)

Postby type85 » Thu Jan 12, 2017 11:04 pm

Foscora wrote:Yep, I already went to the theory, I guess I'm ok on this side.

Now I have to try different jets to match the engine caracteristics, my problem can't only be solved by turning screws : my carb was thrown in the car without proper "engineering" before, that's how/why I need this stuff ;)

Based on my calculations, I'd say my carb size is correct/great but the jets seems way too oversized (to begin with the idle jets)


I can manage to make the car run "correct enough" (I can even pass the emissions tests), but idle is a bit of a mess, as well as 1000-3000 rpm range which is a vast emptiness of torque/power compared to what I should have. Engine works like it's a 20V with sharpy cams on it, works awesome on the 3000-6000 range tho


This is what I've been using on both my Audi's, love them, meter is programmable for different fuels and has logging capability, it's response time is the fastest in the industry too! I run 15:1 at part throttle and cruising and 13:1 @ full throttle.

http://www.innovatemotorsports.com/products/MTXL.php

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