Can anyone send me what AFR you are running on turboed vw?

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dunebuggyjay
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Can anyone send me what AFR you are running on turboed vw?

Post by dunebuggyjay » Wed Jul 31, 2013 8:12 am

Hi Guys,

I have a 2276 running a t3/t4 hybrid turbo. Im running MegaSquirt2 in a fiberglass buggy.

I seem to have VERY high CHT. I also seem to get some surging at certain area, and am having a heck of time with throttle tip in. It just stumbles no matter what I try. (I was kind of contributing that to my large single throttle though..5L mustang throttle body)

I am trying some changes in megasquirt to make tip in better, and it seems to be helping a tiny bit.

But I am really wondering if I am targeting the wrong AFR. I just took the buggy to work this morning, but didnt have my laptop with me. If I could somehow manage to get better fuel economy in this thing I would be happy. It smells very rich, and I get about about 10 miles per gallon. But it seems if I were to try and lean things up a bit, it usually runs like crap. Just wondering if my target afr chart are way out of whack.

Thanks
Jay

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Chip Birks
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Re: Can anyone send me what AFR you are running on turboed v

Post by Chip Birks » Wed Jul 31, 2013 9:39 am

Post up your target afr table when you have access, we might be able to help you better. What heads/cam/compression are you running?

dunebuggyjay
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Re: Can anyone send me what AFR you are running on turboed v

Post by dunebuggyjay » Wed Jul 31, 2013 12:07 pm

Im running a Webcam 86b. this is not a turbo grind cam. (at some point i will swap this out) Heads are welded up stockers. Forget the valve size off the top of my head, but big. I think the next step up from these were race only heads. Compression is 8 to 1 i believe (Its been almost 15 years since I built the engine)

I have tunerstudio on my work computer, so I'm 99% sure this is what my afr setting are in the car.

Do these look out to lunch to you guys?

Thanks
Jay
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Chip Birks
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Re: Can anyone send me what AFR you are running on turboed v

Post by Chip Birks » Wed Jul 31, 2013 6:39 pm

If i decide i hate my current cam, i will be going with the 86b. You are way too rich under boost, assuming gasoline. I'm shooting for 12:1 or so under boost. Your table looks pretty rich everywhere though.

vw1970
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Re: Can anyone send me what AFR you are running on turboed v

Post by vw1970 » Wed Jul 31, 2013 11:22 pm

my map looks pretty darn similar to yours on my 1776cc T4. but like stated above, i'm around 12.5 under boost and it runns great!

Lets see your VE table? maybe even spark maps..

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TouringBubble
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Re: Can anyone send me what AFR you are running on turboed v

Post by TouringBubble » Fri Aug 02, 2013 8:07 am

I haven't tuned turbo air cooleds, but I usually aim for low to mid 11's under boost (when using pump fuel), depending on the car and boost level. I've found that I can make a little more power, safely with this method as the slower burn can help keep knock at bay. In terms of power production, timing advance and boost make a lot more power than a leaner fuel mix.

Anywhere from 11:1 to 12.5:1 is fine until you start to push the limits. Below 11:1, as you have, is a little too rich. You'll have some smoke and lose some power/response. Below 10:1 and you'll start to wash the cylinder and likely cause damage over time. Over 13:1 and you're getting a lot more heat than the engine will like.
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davidt
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Re: Can anyone send me what AFR you are running on turboed vw?

Post by davidt » Fri Aug 24, 2018 4:06 am

This is my AFR map for my 1915 Scat engine running 13psi.
Turbo 1915 AFR.JPG
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