Hood scoop to lower diesel smoke?

Juanito84

The reason:

I own a 1985 Golf 1.6L non-turbo Diesel and live at 8,000ft above sea level and have to drive up to 12,000ft to get out of town. I've noticed that it smokes more black smoke the higher in elevation. At 2,000ft I have to floor it to get some smoke. At 6,000 it starts to smoke around 3/4 throttle. At 10,000 it smokes around 1/2 throttle.

I've come to the conclusion it has to do with the lack of air up here. I've contemplated adding a turbo or supercharger, but don't want to shell out that kind of money.

Would adding a hood scoop lower exhaust smoke? Obviously it wouldn't work at slow speeds. I was thinking of something adjustable so I could eliminate the pressure at low altittude and throttle.

According to my calculations even 3psi would help.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

ps2375 · Posted: Tue May 27, 2014 11:29 pm Post subject:

Do your calculations tell you how fast you'd need to be going for the scoop(of any size) to generate any positive pressure in the intake?

Juanito84 · Posted: Tue May 27, 2014 11:59 pm Post subject:

No

. Good idea to start there. I wonder how size would affect pressure too.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

Juanito84 · Posted: Wed May 28, 2014 12:16 am Post subject:

Well as long as I can get to 400mph. Shocked

Image may have been reduced in size. Click image to view fullscreen.

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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

stewardc · Samba Member Joined: August 06, 2005 Posts: 73

The proper way to compensate for the higher altitude is called a "turbocharger". It packs in more air.

ps2375 · Posted: Wed May 28, 2014 5:19 am Post subject:

I'm pretty sure it couldn't even fall off a cliff and reach that speed...ever.

Juanito84 · Posted: Wed May 28, 2014 9:38 am Post subject:

crsmp5 · Posted: Wed May 28, 2014 11:08 am Post subject:

Ahhh imo even w turbo it smoke

Can try later 89 era alt compensation stuff...
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ps2375 · Posted: Wed May 28, 2014 7:16 pm Post subject:

I'm no expert on diesels, but, if you have enough air going in, the smoke will be lessened. But there will be a lag and smoke till turbo spools. The TDI's with their O2 sensors and other electronics reduced the smoke and added power, but at a cost($$).

Juanito84 · Posted: Wed May 28, 2014 9:05 pm Post subject:

A stock pre TDI turbo, like the option my car had available, has a boost enriching mechanism so still inject more fuel than air causing smoke.

If I were going for boost, I'd get this:

http://superchargersunlimited.com/index.html

For $1,000 and all boost I need. But still, that's a lot of money!
_________________
If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

ps2375 · Posted: Wed May 28, 2014 9:20 pm Post subject:

Smoke from an oil burner is hard to eliminate. Just think of it as Prius Repellant. A local TDI has that on his bumper above the tailpipe.. Wink

Juanito84 · Posted: Wed May 28, 2014 10:29 pm Post subject:

Oil yes. That's when only new rings, bore finish, perhaps oversized pistons as well as new valve guides and valve stem seals will fix it. I'm talking about excess fuel smoke (actally particulate ash) due to lack off oxygen.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

ps2375 · Posted: Thu May 29, 2014 6:59 am Post subject:

I was using the term "oil burner" in place of diesel. With a mechanical injection pump w/ or w/o boost, you will have a hard time eliminating smoke. The belt driven charger might give you your best chance, as then you won't have to wait for the turbo to catch up with power demand and thus fuel injected.

crsmp5 · Posted: Thu May 29, 2014 12:41 pm Post subject:

Just look at how in 89 jetta na got turbo pumps, alt compensation thinggy on fuel filter, but turbo-eco versions had na pumps....

My tdi has no o2 sensor.... Mist be those new junk ones cause good tdis, 96-03 do not
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Juanito84 · Posted: Thu May 29, 2014 2:02 pm Post subject:

This whole theory is not new. The higher the altittude (also the hotter the air) the less dense it is and therefore less oxygen. So either you lessen the fuel intake or increase air intake through boost. On gasoline engines you change out jets or modern EFI senses your altittude, with or without and O2 sensor. I bet TDI has some sort of air pressure sensor to lessen fuel until boost kicks in. No real need for an O2 sensor unless you want to get even pickier than just eliminating smoke.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

WestyPop · Posted: Thu May 29, 2014 8:36 pm Post subject:

If you spend lots of time (key requirement) at higher altitudes, you could try backing out the pump’s max. fuel screw a bit, maybe a ¼ turn [edit.] or so. Of course, that will definitely reduce your engine’s max. power once you’re back at sea level.

OTOH you can look around for a used oem Mk2 TD setup for manifolds, ex. down pipe, turbo, oil supply & drain lines, air cleaner, and just continue to use your NA pump. That’s essentially what the ‘Eco-Diesel’ engines had, and not really a bad idea for yours, since you wouldn’t have fuel enrichment on boost to destroy your NA block, internals & head with any extra heat. You’d probably see a bit of extra power & an increase in MPG. Also that might cut the conversion cost by some, by not getting the TD injection pump.
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Never underestimate the power of stupid people in large groups.
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J.R.
68 Westy
(+ others)

Juanito84 · Posted: Thu May 29, 2014 9:18 pm Post subject:

WestyPop · Posted: Fri May 30, 2014 6:18 am Post subject:

Hope this link posts...
http://i492.photobucket.com/albums/rr281/regcheeseman/PUMP/pump002.jpg

(Of course this is a pic of a TD pump, but just ignore the boost-sensing fuel enrichment canister on top of the pump body) The max. fuel screw has a jam nut on it to keep it at your chosen setting. Be fairly conservative in your settings... a little adjustment usually makes a noticeable difference.

[edit.] May be obvious to some folks, but... Adjust screw IN for more fuel @ WOT ; OUT for less max. fuel @ WOT.

[edit.] just saw this link to an official Bosch VE pump manual:
http://www.k-jet.org/files/other/Bosch_VE_Diesel_Injection_Pumps.pdf
_________________
Never underestimate the power of stupid people in large groups.
______________________________________
J.R.
68 Westy
(+ others)

Juanito84 · Posted: Wed Jun 18, 2014 8:48 pm Post subject:

Thanks for the replies!

Adjusting the injection max quantity screw made a huge difference!

At first I screwed it out way too much. It was sluggish even out of gear! Next I screwed it in until smoke just barely started to come out when I floored it. It still has a bit less power than before but there's no smoke that I can see while driving! This is a huge improovement over the billowing black fog I'd leave behind me everytime I accelerated or climbed a hill.

I might screw it back in just a tad more and compromise between a little smoke and full power. But then again I might just prefer this lack of smoke over the little extra power I had before. Plus it may make someone robbing my car ask himself if it's really worth it.

Just a note, when adjusting this screw it unadjusts the idle and max RPM. So what I did, since I don't have a tach, is lift the wheels off the ground, put it in gear, and note where the needle falls at idle and full throttle. Then, once I adjusted the max fuel quantity screw I reset the idle and full throttle RPMs to the same "speed" as before I adjusted the fuel quantity.
_________________
If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

Juanito84 · Posted: Mon Jun 23, 2014 7:36 am Post subject:

Well I adjusted it again and still can't see smoke in any of the mirrors. It actually seems to have more power now than originally. When it smoked bad before, I noticed that there was allways a small drop in power once at full load (and smoking like a buring oil field). I guess it's adjusted perfect now. Took it up over 11,000ft and no smoke. I went up a long 8% grade in 4th gear with no problem. And cruises along just fine at 75mph.

One thing I didn't think about is that I adjusted it right before I had to drive down clear to sea level. I could adjust it back and get more power down here. But I'm not going to mess with it because as soon as I'm on my way back home I'd have to readjust again. And plus I'm just amazed at how effective the adjustment was.
_________________
If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?


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