2002Scoob

Your Mileage May Vary?

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FWIW: DCOE 45s (not sure of the choke size or jetting), Schrick 292s, Stahl headers, MDS ignition, 4  spd tranny...

 

- High speed run on I-5 from Sacramento CA to Grants Pass OR saw 15-16 mpg on steady 75-80 mph straight flat runs; barely making 200 miles to the tank.

- Easy run back south along the windy coast on Hwy 101 through the the redwoods and coastal towns, top speed no more than 65mph, average speed probably 40 mph, saw 24-25 mpg

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Oh, doing a bit of math, figuring an 8-9 gal/hr burn rate on the race car, that works out to about 10 mpg.

Figuring an average distance of 90 miles/ hour.

 

the 2002 is an aerodynamic dirty brick

t

 

oh, here's a simplification of the E46 ignition mapping

 

Ignition curve.jpg

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Hi Toby,

Thanks, that model looks like something er I didn't do well in in high school.

One thing I was good at during high school, was watching the fuel gauge drop as I was always short on gas money to get it to go back to full. Now I never could figure out then or even now if my Triumph Spitfire with weber DCOE carbs consumed more fuel with the top up or the top down. I do recall that when there were female occupants, or other cars involved in a social activity of sorts, the gas guage generally moved faster... Odd.

I can also now say with certainty that when I go to a track day and drive the 02 full out, the tank empties quite quickly, not in 60 miles but fast enough. I know that I can rarely do the entirety of a regularity rally on one tank. I also know that when I am driving home from an event on a late evening, when the needle gets close to 0, I can still drive for a looong time at low RPMs using nothing and I have never run out of gas. Am I happy doing that? Definitely not, I all all for going fast an dumping 98 octane in it as often as possible. The AFR gauge tells me when I'm not doing the "right thing", my butt tells me when I am. Smile.

Andrew

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That E46 map looks ridiculous, but I suspect that has a lot to do with VANOS being in the equation.  For a 2002, I suggest starting out with an advance map that looks something like this:

image.png.3cb512ec0e855a30f8417c8ff723e2b5.png

image.png.5b3223a653e41ae716d458a6f480cf34.png

 

But back to @2002Scoob's original topic, here's a few tidbits I have for sidedraft fuel economy:

 

1.) Your idle AFR looks pretty good, but you may want to try a smaller idle jet.  At cruising, there's still a lot of overlap from the idle circuit.  My guess your idle will start to get too lean too quickly for that to help you much though.

 

2.) Also might want to play with your pump jets a bit. Again you'll want to not compromise good throttle response, but those accel pumps dump a LOT of fuel whenever you start moving the pedal around; might be surprised how much difference that can make.

 

3.) When I had sidedrafts I had DCOMs, which had much smaller/more numerous progression holes.  I think they had like 7 compared to the DCOEs 4? Anyway, this is specifically to help with part throttle cruising fuel economy, so if that stays a goal of yours, you might want to consider trying some Ms.  (Other difference is the Ms have a diaphragm accel pump instead of the piston pump like in the Es, but I have no idea if/why this matters).

 

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Oh man, thanks for all the great replies. I've been on Vacation in Rome the last week and haven't been active. 

 

On 3/5/2019 at 5:05 PM, AustrianVespaGuy said:

1.) Your idle AFR looks pretty good, but you may want to try a smaller idle jet.  At cruising, there's still a lot of overlap from the idle circuit.  My guess your idle will start to get too lean too quickly for that to help you much though.

 

I might revisit this... I've gotten the Idle to lean-up a bit by tweaking the adjustment screws, and have between a 12.8-13.5 AFR. That's with 55 F9's. That of course is dependent on a handful of variables like engine and atmospheric temperatures.

 

I feel that so much is dependent upon everything be up-to-temp and adjusted for temp. I have suspicions of the throttle linkage expanding/twisting/relaxing that leads to super rich, low RPM idle at startup/cold temps. If I wanted to devote even more time to this setup, I'd look at making my own throttle linkage with more stable metals to help negate this. More on that later...

 

In the past when I was first trying to nail down jetting, I think I had tried to go one-step smaller, and while I got it to idle fine, it went super lean on the progressions. 

 

On 3/5/2019 at 5:05 PM, AustrianVespaGuy said:

3.) When I had sidedrafts I had DCOMs, which had much smaller/more numerous progression holes.  I think they had like 7 compared to the DCOEs 4? Anyway, this is specifically to help with part throttle cruising fuel economy, so if that stays a goal of yours, you might want to consider trying some Ms.  (Other difference is the Ms have a diaphragm accel pump instead of the piston pump like in the Es, but I have no idea if/why this matters).

 

My DCOE's have 3 progression holes, and I can't say that I feel any separation, but i could see where more, and smaller holes could make for a smoother, leaner curve. 

 

On 3/5/2019 at 5:05 PM, AustrianVespaGuy said:

2.) Also might want to play with your pump jets a bit. Again you'll want to not compromise good throttle response, but those accel pumps dump a LOT of fuel whenever you start moving the pedal around; might be surprised how much difference that can make.

 

^^^ This is the area that I have the most suspicions about... Pump jets, and bleed/spill valves. Depending on the application of throttle and where, Things can get kinda rich (10.5-11.5) or pretty lean (15-16) on quicker throttle openings.  I need to do some attentive driving to the what and where, so I can come back with relevant information. 

 

--All in all, the carbs do work fantastically, as long as you understand that they're 50-60 year-old Italian mechanical technology. Meaning, fussy but fantastic, like all good things Italian. I love how my car drives, I'd just like it to be more efficient/consistent. I'm going to enjoy them for this driving season, and look into where I go from there. Maybe sell them for a set of Jenevy DCOE's, or start looking to sell the motor complete to do an electric conversion. Very much on the fence.  

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11 hours ago, 2002Scoob said:

or start looking to sell the motor complete to do an electric conversion. Very much on the fence.

Wait, what?!? Not that I'm wholly opposed to electric cars or anything, but I feel spending an already well-running 2002 on this endeavor is. . .not a good fit.  At least find a beater that already doesn't have an engine in or something, bitte!

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There's a cheap-ish Golf squaretail on ebay that's already been converted.

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9 hours ago, AustrianVespaGuy said:

Wait, what?!? Not that I'm wholly opposed to electric cars or anything, but I feel spending an already well-running 2002 on this endeavor is. . .not a good fit.  At least find a beater that already doesn't have an engine in or something, bitte!

 

Eh.... I'm a glutton for pain and experiences. It's not of huge consequence.... And I want to be able to drive my little car guilt free for a long time. Or at least something old with allot character, and i'd like it to be an 02.  

 

And financially/space wise I can only afford one vehicle at at time. I've been mulling it over for a while now, and feel I could do it without any real serious modification to the body or frame. Plus, the motor that's in there is a whole lot of fancy stuff, but not the original block... so It doesn't necessarily need to live with the car. I have the numbers matching block in the basement that I've thought to slowly build back up into something special in my living room for decoration, haha. 

 

-New subframe, modified and beefed up to accept a motor. 

-Tube or Alloy front suspension arms

-02 Underground rear end/Diff

-Big-ol-brakes

-Electric motor in the ballpark of 200hp/300ftlbs torque

-Replace the tank/spare tire well with a battery tray, and a few extra under the rear-seats perhaps...

-Melt tires, make smiles, help save the planet.

 

Simple-ish? But that's for another thread... :)

 

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(edited)
On 3/13/2019 at 10:41 AM, 2002Scoob said:

 

On 3/5/2019 at 5:05 PM, AustrianVespaGuy said:

2.) Also might want to play with your pump jets a bit. Again you'll want to not compromise good throttle response, but those accel pumps dump a LOT of fuel whenever you start moving the pedal around; might be surprised how much difference that can make.

 

^^^ This is the area that I have the most suspicions about... Pump jets, and bleed/spill valves. Depending on the application of throttle and where, Things can get kinda rich (10.5-11.5) or pretty lean (15-16) on quicker throttle openings.  I need to do some attentive driving to the what and where, so I can come back with relevant information. 

 

 

What's people's thoughts on the above? What are others running as a pump jet/spill valve combo? 

 

I'm currently running #40 Pump Jets, paired with #70 Spill Valves. 

Edited by 2002Scoob

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I am running 45's so probably not comparable. vgs is selling the g variant for the 45 with 4 bypass holes, the 40 dcoe 151 as well (with ? bypass holes). When you order one from vgs, they will preconfigure it for the m10 but you can't see on their website what that config is (the stock parameters are visible).  So even looking at their standard pump and spill valves/jets won't shed much light....sooo many variables. Wouldn't the exact float level and pump /spill combo affect this too, making the search for comparable combos of limited value?

You could probably search on the 02 club site in Germany for the config of recently delivered vgs carbs if you just want "more" reference data. My invoice from vgs showed the exact config of the carbs.

Andrew

 

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I've got the float-height set to spec... The time I spent spent tweaking the two to be matched and dialed was ridiculous, so even if I don't remember what i set it at, it should be good. I'd assume a higher float equals richer overall, and lower is leaner? 

 

Tweaking this, if an intelligent path to go down, would be an easy experiment. But I'm a bit hesitant. how much is too much, or enough with such things? half mm, 1mm, .1mm? I've got a full metric drill-bit set I typically use that is scaled in tenths of a mm.

 

-J 

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Hi,

Not suggesting to tweak, only suggesting that your "to spec" might vary from my "to spec" and hence with the jetting, volumetric attributes of the motor etc.,  you approach the law of diminishing returns when comparing with others. You are beyond basic setup, the differences to your peers engines limit the value of pump jet and spill valve data....

Andrew

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I think I'll re-read the tuning books and see what I can find :) 

 

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13 hours ago, 2002Scoob said:

What's people's thoughts on the above? What are others running as a pump jet/spill valve combo? 

 

I'm currently running #40 Pump Jets, paired with #70 Spill Valves

 

Thought about this more for you, and here's what I've concluded:

1.) If it's cruising economy you're after, the idle jet is the most significant component.  Remember, true 'idle' is actually tuned from the mixture screw as much as the jet itself. But part throttle and slow progression (what you use most at cruise) are BOTH directly controlled by the idle jet.  So I think first step would be to try a smaller idle jet, re-adjust mixture for a good idle, and see where that gets you.

 

2.) 40 pump jets are already on the smaller end of the spectrum, and if you no-load revving of the engine is nice and crisp already, maybe it'd be better not to mess with this one.  On the other hand, jets are pretty cheap when it comes to parts, so if you're ordering new idle jets anyway (per above), I don't think you could do much harm in trying out some smaller pump jets.  You can always go back to the 40s later if you don't like them.  I would STRONGLY suggest however that you only make one change at a time and test it out for a few days, rather than putting in both smaller idle and pump jets and then re-tuning with two variables!

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