Help needed with Eco-mods for VW AAZ Diesel engine!
 

I've recently become a custodian of a 1996 Mk3 Golf fitted with the 1.9 TD aaz engine and 5 speed manual gearbox.

The engine has 75 bhp/110 ft/lb torque

has a bosch mechanical pump and a mechanical wastegate on the Turbo. No intercooler is fitted

I'm fairly clueless in the way of the devils fuel, and wondered if memebers here could help me enhance my knowledge regarding getting the best MPG from this engine?

Things I "think" I know:

The AAZ engine is Indirect injection (i.e. NOT a TDI)

Diesels are not throttled- unlike petrols

Cold Air Intakes are beneficial on Diesels- more complete burn of fuel

Keeping the engine as warm as possible (within operating limits!) also helps with ignition and complete burn.


Questions

I can find lots of info on altering max fuel on the pump and altering turbo boost pressures to improve performance- e.g. to circa 90-100bhp without intercooler.

Would these be beneficial from an eco-mod point of view? I.e. smaller throttle pedal opening for a given power/torque?

Anyone have any experience of running the AAZ lump on Veg oil/waste oil?
i.e organic rather than fossil?

Anyone got any specific AAZ or VW diesel Eco-mod tips?


I'm also looking at aero mods, as the car spends most of its time on the Motorway- any suggestions for grill block sizing?


Thanks for reading, and I'll be grateful of any help you may have!

C'mon people!

are my assumptions at least right? cold air, hot lump = best for a diesel?

Sorry, Man. I was at work.

Cold air intake is better for diesels. More oxygen per volume.

Warm engine is good. There is a thread around here somewhere that describes how to make your thermostat open a 200 degrees f instead of 185/192. I'll try to find it.

No throttle body or ventury( except for more modern engines that have a DPF( diesel particulate filter) that has to regenerate itself from time to time, but that doesn't concern us here.

I've heard good things about your and my engines for veggie oil conversions, but I think we both need to research more in that area. I haven't started yet, so I don't have much info there. I do know that used ATF( automatic transmission fluid) mixes with diesel and burns quite good.

My suggestions for aero would be; upper grill block, belly pan( removable for MOT inspections), and rear wheel skirts( done tastefully, of course). Maybe a kamm-back if it doesn't attract any unwanted attention from the highway patrol.

Does your fresh air intake hose connect behind the right( as sitting in the drivers seat) head light? Mine does, but I'm thinking of moving it...haven't decided.

K&N Airfilter - less restriction - better for a diesel. Keep intake as cold as possible. Pump up tires.
If you mod engine you want a tourque curve to be as flat as possible. Moving max tourque down in rpm v will tens to improve Fe if gearing is right.

Tourque can be moved up or down a bit by making intake funnel longer or shorter, changing the standing wave in the intake.

you're excused- dont make a habit of it:D

On the casual glances I've had at the air-filter area (yes, its behind the RHS headlight) I reckon it'd be fairly easy to fabricate an enclosure to force it to draw air only from outside the engine bay- effectively building a CAI

I'd envisaged controlling the engine temp by increasing insulation in the engine bay, e.g.

Thicker Insulation on the bonnet/hood

An under tray below the car to seal off the compartment

Upper/Lower grill blocks

I believe my car may have an EGR- I may have a raid at the weekend and clean/clear whatever I can in the engine bay- can't do much harm!

Some googling, and conversations with mates suggest that the Bosch fuelpump on our lumps is happy with veg.

Key seems to be starting off with low concentrations (10/20/30%) and slowly ramp it up. Additionally fuel filter changes to catch any crud flushed out would be a plan. Filters are cheap..

Once I get past 30% veg, I'd see a significant decrease in fuel costs per mile..

I like the upper grill block/belly pan combo.

Rear wheel skirts and Kamm back would attract (unwanted) attention.

I could, however, possibly go for wheel covers, and possibly "spats" to deflect air round the tyres?

I'll investigate reducing restrictions in the intake system- I imagine there's some scope for re-routing the turbo pipework/installing an intercooler etc.

I know what you mean re the torque- about 2000-2500 rpm would be ideal for my commute, as it'd cover 50-60mph

does a longer intake= more torque lower down?

Thanks!

Yes cold air is good, rammed air is better but the air can get too cold.
Depending on the compression ratio of the engine once air starts to get in to the 20'F to 40'F range it can delay injection ignition timing.
IDI diesels tend to run higher compression so the ignition delay effect would be restricted to below freezing.

Oh and if it has an EGR, make sure it doesn't when you are done with it.

Yes cold air is good, rammed air is better but the air can get too cold.
Depending on the compression ratio of the engine once air starts to get in to the 20'F to 40'F range it can delay injection ignition timing.
IDI diesels tend to run higher compression so the ignition delay effect would be restricted to below freezing.

Oh and if it has an EGR, make sure it doesn't when you are done with it.

I hear you re "too cold"- I'll certainly try to avoid that, as can quite often be below 0 degrees C here over autumn/winter

compression ration on the AAZ lump is 22.5:1- so should be fairly resilliant!

I'm away to google EGR removal:)

I do not believe this is an IDI, the TD engines like the AAZ are direct injected and would suffer using vegetable oil. A far better fossil-free fuel is biodiesel, I have been burning B100 in my direct injected diesels since 2007. I even get better mileage on it and blends than straight diesel.

I think I am wrong, the AAZ is indiect, which makes it more tolerant of vegetable oil. To me, this would only make sense on long commutes or trips where you can keep the engine hot for long periods of time as vegetable oil needs more heat than diesel or biodiesel to completely combust.