Author Topic: Audi Turbo Diesel (Read 5006 times)

TW · « **on:** July 13, 2006, 05:25:45 pm »

I just found this forum today, finally someone else that understands these engines. My project this winter was putting together a 5 cylinder turbo diesel engine with components from 6 or 7 sources and placing it in my 1980 Audi 5000 originally equiped with a NA diesel and manual 5 speed. I've put about 6000 miles on it, the power and acceleration are great, but it only averages 32 mpg with my 80 mile round trip on the highway to work and back. I have slightly oversized tires on to make up for the differences with the final drive ratios of the automatic versus manual. Should I expect better milage, and if so what should I do?

QuickTD · « **Reply #1 on:** July 13, 2006, 06:47:35 pm »

The audi 5000 is a tank, 32 sounds respectable. the gasser audi's were probably lucky to stay in the low 20's. I used to drive lincoln mark 7 turbo diesel (BMW 524 drivetrain) and it averaged an honest 28-32 in combined driving. The gas powered lincolns got about 16-18mpg,

RabbitJockey · « **Reply #2 on:** July 13, 2006, 06:49:36 pm »

i dunno about all that, a guy i know has an audi 4k with a 4 cyl n/a diesel, and he said it runs good and gets 50mpg easily

RabbitJockey · « **Reply #3 on:** July 13, 2006, 06:50:11 pm »

and he can even get 36mpg in his turbo diesel vanagon westfalia

houseofdiesel · « **Reply #4 on:** July 14, 2006, 08:54:26 am »

32 mpg in the Audi sounds fine, they weight a lot and the 5 bangers are not known for economy. I am planning on dropping the 2.0 td in my quattro later this summer. What did you do over the flywheel, was it the same manual/auto or different?
Greg

TW · « **Reply #5 on:** July 14, 2006, 10:01:50 am »

The flywheel from the NA bolted up to the crank on the turbo just fine. I'm hoping to find a donor Quattro sometime soon to put this TD engine in. In a Quattro it would be relativly easy to hook up the intercooler. The gear ratios would be better for MPGs with enough low end torque, so I would have a 3" exhaust system installed too. Let us know how your project works.

regcheeseman · « **Reply #6 on:** July 18, 2006, 08:02:37 am »

Get 36 mpg out of my T4 (Eurovan) camper 2.4 D N/A no bother. - doesn't drop much running at 85mph for hours either :wink:

veeman · « **Reply #7 on:** July 18, 2006, 09:11:23 am »

Quote

The flywheel from the NA bolted up to the crank on the turbo just fine.

In the gasser 5-cyl world, there's a "bushing" in the end of the crank that's different from the autos to the manual transmissions. Did you find one in your engine when you switched flywheels?

Quote

The gear ratios would be better for MPGs with enough low end torque, so I would have a 3" exhaust system installed too

.

Hmmm..... Do you mean the quattro trans will be better for mileage? I thought that the quattro transmissions were geared too tight for any kind of highway speed with a diesel. This was the case when I looked into doing a 4000 quattro TD which has essentially the same trans as the 5000 except a slightly higher final drive.

Regardless, sounds like a great project...keep us informed.

TW · « **Reply #8 on:** July 18, 2006, 11:03:48 am »

I bought a new pilot bearing to put in the end of the crank, I used the same one as for a 1980 5000 5 cyl NA.

As far as the gears go, I might be calculating wrong, but the final drive on the manual transmission in the car now has a ratio of 4.78, and 5th gear has a ratio of .68 to 1. This means to me that the drive axel rotates onc time for every 3.25 engine rpm.

The automatic transmission for a 1983 5000 with a turbodiesel has a final drive of 3.08and high gear is one to one, or the axel rotates once for every 3.08 engine rpm.

On a 5000 Quattro the final drive is 3.89 and 5th gear is .73 to one, so the axel rotates one for every 2.84 engine rpm.

It would take greater low end tourque to drive the quattro than a NA diesel has, unless you never shifted above 4th gear. That's why I think with a turbocharged engine with a 3" exhaust and an intercooler would handle the load fine

veeman · « **Reply #9 on:** July 18, 2006, 11:13:18 am »

Hmmm.... Interesting. I use this page to determine road speed / engine speed at different levels.

http://www.scirocco.org/gears/

I assumed a 195/60/14 inch tire and a 3500 "limit" for highway cruising. Not sure what the 5-cyl TD's like as far as revving, but on my 4-cyl, that rpm is probably about as high/buzzy as I'd like to go on the highway.

Using that page and assuming the gearing data is accurate, it appears that your impressions are correct. The quattro should have slightly taller gearing and result in a higher road speed with the same engine speed as in the auto/fwd trans.

I'd love to hear how the TD feels on a quattro drivetrain. Should be near unstoppable in the bad weather.

TW · « **Reply #10 on:** July 18, 2006, 11:26:32 am »

I dont have a tach. Now I'm runnung 185/75-14s. I have room for 205/75-14s but don't know if the ride will be firm enough. These tires cause my speedometer and odometer to be 5% off. A comfortable cruising speed without too much noise is 62 on the speedometer (65). If I drive faster than 75 my mpgs get worse and the engine runs a little warmer than I like.

http://www.audiworld.com/model/

houseofdiesel · « **Reply #11 on:** July 20, 2006, 06:35:24 am »

Depends on the quattro running gear-the turbo cars had a really low number final drive, the non turbos did not (called "sport" transmissions). I have both. The turbo quattro runs around 2000 rpm @ 60mph, the non turbo 3000 rpms @60mph. One is great for towing and winter snow rallying but totally sucks for top end, the other is terrible in the city but awesome on the highway (If I remember right 100mph was around 3200-3400rpms). I am a bit worried the turbo gearing might be a little slow in the city with a diesel, however it would keep the engine happy on the highway. I am still on the fence-I think I will install the diesel in my 89 100Q, which has the close ratio, it is my tow vehicle, hence I need the short gearing (tow up to 5000 pounds every month, move cars with it). I would have to limit myself to around 65mph with the diesel then...I don't want to kill the engine too soon. Plus the gas enigne is over 220k miles, it has a hard time passing emmission for stupid reasons, uses minor amounts of oil, runs poor in the winter (too rich, gas gets in the oil) and the timing belt is overdue.I plan on intercooling, GTD nozzles, full engine rebuild, maybe a pump rebuild by superior if I can find some funds, oil cooler (factory), turbo not sure yet I have a couple good stock ones, it was plenty fast in the automatic donor car once tuned properly...
So I need to change the crank pilot bearing? These are things not detailed in the parts program...it shows the same flywheel for all diesels manual or auto and I know that cannot be true! What else have I not thought about???

Greg

jackbombay · « **Reply #12 on:** July 20, 2006, 07:11:56 am »

Quote from: "houseofdiesel"

So I need to change the crank pilot bearing?

The Auto 5 banger Diesel had a bushing in the end of the crank, not a bearing, mine was hard to remove, I had to tap it and then run a bolt through it which pushed it right out. I tried several varieties of bearing pullers and none worked.

TW · « **Reply #13 on:** July 20, 2006, 08:29:49 am »

I've used a torch to remove one bearing, and a cold chisel to remove the other.