1/4 miles times for my 84 300SD - ALDA testing
 

Now that my AC is fixed and out of the shop (and my wallet much much lighter), I wanted to see what adjusting the ALDA would do for performance. I don't believe in "seat of the pants" testing. I've dyno'd my Nissan about 30 times testing parts, and I've dyno'd and 1/4 miled the CLK just to keep those guys at AMG honest ;)

So I did cheat a little on this "tuning" session. I used a G-Tech to simulate 1/4 mile runs. Not the most accurate measuring device, but not that un-accurate for something that looks like it came out of the radio shack clearance bin.

So, I cleaned the banjo fitting and the line going from the intake side to the gizmo on the firewall near the brake resevoir (I'm drawing a blank...) and then the line and fitting that runs down to the ALDA.

Someone had evidently tweaked it before, since the locking nut was exposed.

So my first two 1/4 mile runs with the G-Tech (OK - no laughing!!)

71.6 mph 20.28 sec
73 mph 20.15 sec

turned the ALDA out 1/8-1/4 turn

73.3 mph 20.01
second run screwed up on the measurement

turned ALDA out an additional 1/8-1/4 turn

73.2 mph 19.93 sec
71.9 mph 20.28 sec

tried to loosen the ALDA more and discovered it was backed all the way out! So, I turned in clockwise a good two turns just to see what happened

72.5 mph 20.55 sec
73.4 mph 20.48 sec

So... my ALDA is basically not impacting performance at all. The car is a dog until about 2K rpm... the lines are clear, though I did not blow out the thingy on the firewall. No ridiculous amount of smoke in my opinion, though I think it is still slow to boost. 0-60 times I think were in the 14-14.5 range if that tells you anything.

Ummmm - comments? The A/C was off if you were wondering.

That seems about right in performance terms. What PSI of boost do you have? Lighten the load anything removable like seats or extra parts.

ahhhh - I did have a trunk full of tools...
 

....and about half a tank of fuel. I'm about 180lbs....

oh well... I was hoping the ALDA was going to give me a nice performance tweak. I'm wondering if something else is preventing boost.... :(

My overboost sensor (firewall thingy) on the 84 was not working right, connecting the alda directly to the intake manifold made a big difference.

Jerry

bodyart27
How far in can you turn the ALDA?
You should be able to get the injection pump to lean up to the point the acceleration is reduced significantly (and fuel economy increased) by turning the screw in to the factory setpoint. From that point a max of maybe 2 turns out is all that is necessary.
Some mechanics prefer to place a shim or two under the ALDA, where it mounts to the pump, but that takes a thin wrench not normally found in most weekend mechanics' toolbox.
Did you check to see black smoke (well, just smoke!) by looking in the rear view mirror at night (while someone is following you with their headlights on? That is the best way to look for smoke, aside from having a knowledgable (ie. Diesel) person follow you and observe the smoke. If you can see smoke by day you got too much ALDA or not enough boost.

Dieseldiehard
1971 220 (gas) 4-spd manual 104041 or is it 204041?
1979 300TD w/ ’85 turbo engine 288975
1983 300D 237300
1985 300TD 205437

OK - more testing
 

I'm wondering if this is having any impact at all :mad:

OK - adjusted all the way in, and back out 2 full turns:

20.31 sec @ 73.5 mph

3 full turns:

71@20.45
74.8 @ 19.86

3.5 turns

72.6 @20.5
77.5 @ 19.3 (OK- I call fluke on that one)
73 @ 19.93
74.8 @19.83

3.75 turns
75.3 @ 19.64
72.2 @ 20.12
75.4 @ 19.63
(there is a run in here that I bailed out of b/c some jackass actually thinks I'm drag racing! I'm stuck in a lane I'm trying to get out of but the wack-job won't let me over - I bail *hard* out of the run as some construction stuff is coming up fast - the one day old Michelin X-Ones perform awesome just barely starting to lock and yell loud when I've scrubbed enough speed to veer into an empty cosco parking lot - OK - I'm wiggin' out - how did that get so ugly so fast! I start wondering if this is just nuts. After chilling for about 5 minutes I now stop testing off a light like I did that time - and promise myself to wrap things up quick and go home!)

4.0 turns

72.9 @ 19.97
74.6 @ 19.80

4.25 turns

75.6@19.55
73.5 @ 19.81

(OK - took a break as I've literally been running back to back runs for 30 minutes - the temp gauge is starting to move up - the turbo must be hot as hell and the oil has to be darn hot - I take her for a "cool" down lap of about 55 for about a mile or so - she quickly gets back to her normal 85*C range - I exit the freeway and try one more blast)

74.2 @ 19.65

Thats a wrap. I'm not sure if I'm get any closer to "optimal," but I'm out of the 20 sec range for 1/4 mile times..... 0-60 time is "flashing" during the G-Tech runs in the 13.5-14 range

thoughts?

:confused:

Sounds like your car is running the way it's supposed to. A couple of other things to check would be the valves and timing chain stretch. I doubt that they'd have a significant effect on your performance though. A less retrictive air filter and exhaust system MIGHT help the turbo to spool up faster. Turn the ALDA out enough so that you don't waste too much fuel (in other words, don't spew too much black smoke). :)

Check your boost -- if you aren't getting much boost, it won't matter what the ALDA is set to, it still won't give you any more power since it isn't doing anything.

0-60 in 15 sec is a bit slow, should be about 12, I think.

Also check to make sure it holds pressure....

If you adjust the output of the turbo, don't go over 13 psi. Factory spec is 10-12, usually 10.5 or 11, and may be lower than that by now, the spring in the boost controller goes soft with age.

Peter

One thing I've wondered for a little while is when people say to check your boost how do they expect you to tap into the lines? I don't care to cut the plastic between the intake manifold and IP, nor do I like the idea of drilling a hole in my intake manifold for an barb. So where am I supposed to go?

There should be a little hole/fitting near with a plug in it near the oil drain/overboost sensor area (Atleast on the 617 turbo), I used the kit from my sunpro boost gauge and that fit perfect with one of the kits adaptors.

Where is this fitting? Oil drain?! The oil drain in the air filter housing? Overboost sensor is on the firewall by the brake booster.

Thanks,

BoostnBenz,

The fitting is a tapped hole in the intake manifold plugged with a small, flush, hex head bolt (8-10 mm. hex head? can't remember exactly). The hex on the bolt is thin; starboard side of the intake manifold, towards the firewall end of it, maybe a little towards the lower side, if memory serves me. It indeed takes one of the adapters from a SunPro gauge metric adapter kit and adapts to a SAE compression fitting for a hose to your boost gauge. This is where I have my boost gauge hose hooked up permanently.

I also cut the hose between the banjo fitting and the overboost protection valve and placed a metal aquarium gang valve there so I could tap in a vinyl hose to a shop vacuum gauge to check and calibrate my homemade boost gauge, made from reversing the "economy" gauge from a 126 gasser instrument panel. I actually prefer the cut hose technique, particularly if you are just going to check occasionally versus having a permanent boost gauge, because you can shut off the gang valve with it's little lever and tap in whenever you want.

bodyart27,

Because the boost pressure and ALDA controlled fuel supply form a "lambda" circuit, in it's looser definition, I don't think much can be said about your cars performance without knowing your current boost pressure. If it's not ~10- 13psi, I think you need to adjust the wastegate first, remembering that it works synergistically with the ALDA adjustment. FWIW

wastegate
 

so I'm gathering to tweak the wastegate I'm going to need to install a boost gauge.... hmmmm

I have a LOT of little tweaks to deal with (valve adjustment, maybe timing chain?!?!) first before going that extreme.

Thanks everyone for responding. I'm just going to live with a less than "perky" car off the line for now while I recover $$$ from my A/C repair!

This car is proving still to be a lot of fun to wrench on though....

I've had good luck using the Dawes Devices manual boost controller.

http://www.dawesdevices.com

It's one of the better manual boost controllers out there. The benefit of using one of these as opposed to adjusting the wastegate nut is that it's MUCH easier to tweak in between test runs. Piece of cake to install too.

Re: wastegate
 

If it takes a few second to get going after you hit the throttle you can just do what JerryBro did, bypass the overboost sensor and run that line from the intake manifold directly to the IP. There is a world of difference doing this if the overboost valve is getting slow. My 84 will go the instant I tell it to, it burns a little rubber, I can make the rear end slide around and such if desired. My 83 though, it is a strategy almost to hit the throttle before the light turns green so I can take off in time. ;) It pauses for a second or two then starts going, simply bypassing the overboost valve would give it much more 'perk' if your valve is slow. This may be worth looking into.