Author Topic: People with modded LDA diaphrams plz read! (Read 6357 times)

Smokey Eddy · « **on:** December 31, 2008, 04:15:35 pm »

Does anyone have theirs at 180 degrees out?

What kind of fuel economy changes can you expect the closer to 180 degrees out you go?

I am talking of course about the dot on the LDA that determines fuel addition under boost.

please people share your details.
I know you have to balance the fuel screw with the LDA right?

Luckypabst · « **Reply #1 on:** December 31, 2008, 04:44:22 pm »

180 out from what? 180 out from the notch on mine gives less fueling than other positions. My reference "notch" is somewhere just above midway on the boost fuel curve so 180 out puts it somewhere just below the midway point. Did that make sense to anyone but me?

It's been a while but as I remember - dot turned furthest toward sprocket = least fueling, dot turned furthest toward injector lines = greatest fueling.

Chris

Smokey Eddy · « **Reply #2 on:** December 31, 2008, 04:48:08 pm »

o

...

THE PLOT THICKENS!

(yes 180 out from the notch. I was told the further away from THAT you go the more fueling you get...)

Luckypabst · « **Reply #3 on:** December 31, 2008, 05:00:24 pm »

I'm not here to argue convention however what I found on my pump is:

The dot on the diaphragm is aligned directly over the "high" side of the eccentric cone - that being the point on the cylinder that the cone is most closely biased toward. When the cone is rotated with the greatest bias toward the feeler pin (sprocket end), you get the least fueling and at this point, the dot will also be closest to the sprocket. Rotate the cone away from the feeler pin (flywheel end) and you get the greatest fueling under boost, with the dot now adjacent to the flywheel end.

If you assign the sprocket end of the LDA the angle of 0 and the flywheel end the angle of 180, the reference notch on mine is at about 110 degrees (hey - you can even see it in one of those pictures on the Audi 5000 pump in the for sale section). So if I spin mine 180 degrees out from that point, the eccentric cone will end up about 40 degrees closer to the feeler pin and give reduced fueling under boost.

Mine currently is turned about 15 degrees beyond the reference notch, to what would be roughly 125 degrees total (this is just approximate - I haven't been in there since summer).

Chris

I'm going backpacking - you all can heckle me and tell me how wrong I am for 4 days before any rebuttal...

Mark(The Miser)UK · « **Reply #4 on:** January 01, 2009, 07:13:29 am »

Quote from: "libbybapa"

There's no positive relationship between the pin and diaphragm and so if anyone has ever loosened the nut and rotated the pin, then the dot is meaningless.

Andrew

Exactly... You need to look at the cone, and use the trace left by the lever for reference
Additionally, neither 'leaning out', nor 'enriching' neccessarily leads to better fuel economy. You need to match it to your driving style... If you are leaving smoooke trals everywhere then it's overfuelling for you. If you 'lean it out' then still want to overtake everything you see in front of you, then you will end up hammering the accelerator and bring out your whip to get past, and still end up with poor mileage. I've tried all options. I find if I keep my eye on the boost gauge, and keep that down to the minimum as much as possible, even though I can easily get it upto the 8 or 9 psi, if I wish, ie constant velocity where possible, that makes for the best economy whatever the settings...

Smokey Eddy · « **Reply #5 on:** January 01, 2009, 03:12:28 pm »

Hmmm
I see.

Thanks guys. I guess I'll just have to change it up to what i want...
For faster LDA access i got some bolts to replace the stupid slotted driver ones. Pretty pimpin performance upgrade if you ask me

jtanguay · « **Reply #6 on:** January 01, 2009, 04:35:09 pm »

Quote from: "Smokey Eddy"

Hmmm
I see.

Thanks guys. I guess I'll just have to change it up to what i want...
For faster LDA access i got some bolts to replace the stupid slotted driver ones. Pretty pimpin performance upgrade if you ask me

also put some anti seize on them as the soft aluminum corrodes, plus its easy to take it off

Luckypabst · « **Reply #7 on:** January 04, 2009, 04:40:21 pm »

Mine has a locating flat on the pin and on the diaphragm. They only assemble in one positive manner. I'll take pictures tomorrow.

Chris

Smokey Eddy · « **Reply #8 on:** January 04, 2009, 04:42:40 pm »

sweet sauce thanks chris!

I can't stress enough how nice it is to have 10mm bolts on it instead of flat head screws

Smokey Eddy · « **Reply #9 on:** January 04, 2009, 10:41:17 pm »

mine, i now understand is totally out of wack...

saurkraut · « **Reply #10 on:** January 05, 2009, 06:26:53 am »

Quote from: "Smokey Eddy"

mine, i now understand is totally out of wack...

Its not a chrises though. Figure out where the dot is in relation to the smallest slope, put a sharpee mark on the houseing to put that shallowest slope in line with the pin. Take it for a drive, and note your EGT and boost.

Pull the top, and rotate the diaphragm towards more slope on the pin in 1/16, 1/8, 1/4 turn (your choise) incriments and repeat the EGT/boost run. Set it where you like it and your done. :wink:

Alternatively, you can start at the depest slope and worke down, but you'll probably see big EGT & boost. And then you'll have to dial it back.

Luckypabst · « **Reply #11 on:** January 05, 2009, 07:25:55 am »

Quote from: "libbybapa"

I'd like to see that. I've taken apart several and although they have a flat part on the pin for using a wrench, the flat has never extended up to index into the large washers or diaphragm. Those have always just been circular without any positive index. Because of that, it's always been a bit of a pain when reinstalling the diaphragm to place the dot in the right location as the diaphragm and washers tend to rotate on the pin as the nut is tightened.

Andrew

I'm over here praying that I wasn't hallucinating now. I hate eating crow.

Checking this afternoon...

CHris

Smokey Eddy · « **Reply #12 on:** January 05, 2009, 07:47:24 am »

eating crow?

Luckypabst · « **Reply #13 on:** January 05, 2009, 05:09:58 pm »

Dang! You're right - I'm wrong. I was hallucinating. Stay away from the pink mushrooms and ignore the hairbrain in CA(lifornia).

I take back some of what I said.
Chris