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Eddles 02-22-2011 11:07 PM

Advice req - Differences between similar diesel cars & chipping
 
Hello all,

Sorry for the long post and the use of UK units, but wanted some of your opinions... I know it's all UK stuff, but the theory should be the same no matter where you live so please bear with me.... ;)

I used to have a 2001 Opel Astra ECO4 which was specially designed to reduce fuel consumption through an underbelly pan, skinny and really big fuel saver tyres (175/80/14) on steel rims, spoiler and wide ratio 4th and 5th gears. I found mention that Opel *might* have programmed the computer to use less fuel and had lowered the suspension but I couldn't find firm confirmation of this.

It had a 1.7 Isuzu DTI engine with a distributor type fuel pump with simple injectors giving 75 BHP. I got an average combined fuel consumption of 74 MPGuk out of that compared to a rated combined figure of 64.3 MPGuk - see my sig below. Someone pulled out in front of me and I ran into her, writing off the car. Oh well. Eventually, I decided to buy another Astra, but due to the extreme rarity of the ECO4 and that it doesn't come with ABS as standard, I decided to get a non ECO4 diesel Astra with ABS. This car comes with the exactly the same engine as my ECO4, but with common rail injection and, I believe, a lower pressure turbo. The engine produces 80 BHP and much cleaner emissions. However, I'm getting about 61 MPGuk out of that out of a rated combined figure of 61.4 MPGuk, so I'm rather disappointed with this.

Now, I haven't driven an Astra DTI or an Astra ECO4 CDTI so it is difficult to tell whether the higher fuel consumption is due to the common rail injection system or the modifications Opel did for the ECO4. I have been seeing reports online that the CDTI engine uses up more fuel than the DTI engine but I tend to be suspicious of those sort of reports[1], however if this is true, I suspect that Opel increased the power of the CDTI engine as it's much cleaner than the DTI at the expense of fuel consumption mainly because, to be honest, the engine is pathetically weak[2], and 80 BHP "sounds" better than 75.

The government says that the CDTI engine gets *exactly* the same fuel consumption than the DTI which lends credence to the fact that the ECO4 modifications helps a lot, however the government figures show little difference between the ECO4 and the standard Astra - only 3 MPGuk combined, but I am getting 13 MPGuk combined less on my new Astra.

I have already planned to swop the alloy wheels (195/55/15) on my new Astra to have exactly the same wheel setup on the ECO4, that should gain a couple MPG. Unfortunately it won't be realistic for me to get the wide ratio 4th and 5th gears from the ECO4 and fit them on my car. I'm not bothering with the spoiler as I'm not really convinced that it really helps.

I am seriously considering getting the engine chipped to attempt to reduce the power and hopefully increase fuel consumption but I wanted your opinions. I can't see much options beyond getting an standard Astra engine pan however it's rather pricey second hand. The additional ECO4 underbelly pan bits will be next to impossible to get as no-one know about those.

Thanks for reading this far! :D

[1]"I only get 50 MPG out of my car, while the government tells me I can get 75 MPG!" "You've been doing 90 MPH on the motorway, haven't you?" "Err... yes? So?"
[2]The 68 BHP Fiat 1.2 diesel engine found in some Opels run rings around the Isuzu 1.7 diesel engine.

euromodder 02-23-2011 05:16 PM

Did you get to keep the eco-parts of the ECO4 Astra ?

Arragonis 02-23-2011 05:55 PM

Be careful of the wheel swap because of Insurance. :D

What is the engine in the new car, i.e. what model exactly ?

Do you know if it has fully synth oil in it ?

Eddles 02-24-2011 06:35 AM

Quote:

Originally Posted by euromodder (Post 221713)
Did you get to keep the eco-parts of the ECO4 Astra ?

Unfortunately there were a miscommunication between me and the insurance company - they towed the car straight to a scrapyard - I thought they were going to tow it to a garage for repair. Because of this confusion, my insurance company allowed me to see the car again, but I was only allowed to take off the parts that wasn't OEM - the towbar, cruise control and radio. I didn't get a chance to remove the eco parts, didn't really think of it, to be honest!

Quote:

Originally Posted by Arragonis (Post 221720)
Be careful of the wheel swap because of Insurance. :D

"I brought the car without alloy wheels, I didn't know alloy wheels were standard for this variant? I guess the previous owner sold off the alloy wheels before selling the car to me maybe? There were 3 previous owners, I don't know what they've done to it."

Quote:

What is the engine in the new car, i.e. what model exactly ?
Not sure what you're looking for, but the Opel code is Z17DTL, I believe. Is this the code/model you're looking for?

Quote:

Do you know if it has fully synth oil in it ?
Don't know - the garage who sold the car to me changed the oil (so they claim). When the oil next need changing in 4,000 miles time, I will be using 5w30 oil which is the minimum recommended by the manual and what I was using on my old ECO4.

Piwoslaw 02-24-2011 06:50 AM

Hi Eddles,

Sorry to hear about the ECO4 getting trashed, I hope no-one was hurt. Did you get to keep any parts? That'd be awesome, since ECO4 parts are so rare.

Look on the bright side - you have a unique opportunity to compare, almost side-to-side, two versions of the same car. Yes, a few parameters have changed, but most are very close (weight, frontal area, etc.).

When did you get the "new" Astra, and how old was it, how many miles on it? Has it been checked and tuned up yet? Maybe an oil and filter change will help, maybe alignment should be checked.

If you do swap the wheels/tires then maybe try a roll-down test to see the difference in RR.

Quote:

Originally Posted by Eddles (Post 221594)
This car comes with the exactly the same engine as my ECO4, but with common rail injection and, I believe, a lower pressure turbo.

Can the boost be increased?

Quote:

Originally Posted by Eddles (Post 221594)
[2]The 68 BHP Fiat 1.2 diesel engine found in some Opels run rings around the Isuzu 1.7 diesel engine.

An engine swap is out of the question, I guess?

Arragonis 02-24-2011 09:21 AM

Quote:

Originally Posted by Eddles (Post 221826)
"I brought the car without alloy wheels, I didn't know alloy wheels were standard for this variant? I guess the previous owner sold off the alloy wheels before selling the car to me maybe? There were 3 previous owners, I don't know what they've done to it."

Ah - I see. I thought you were going to swap the eco4 wheels - which I think were narrower - to the replacement car. Insurance people can get picky :D

Quote:

Originally Posted by Eddles (Post 221826)
Not sure what you're looking for, but the Opel code is Z17DTL, I believe. Is this the code/model you're looking for?

Chippable ?

Arragonis 02-24-2011 09:34 AM

Minimal googling suggests the L suffix means low pressure and H would mean high - maybe plus an intercooller. Not sure if there are other differences but an "upgrade" may be possible?

This place has a box which takes it to 100hp - bolt on so can be removed and I think it has an adjustment allowing you to turn it down.

Eddles 02-24-2011 10:13 AM

Quote:

Originally Posted by Piwoslaw (Post 221827)
Sorry to hear about the ECO4 getting trashed, I hope no-one was hurt. Did you get to keep any parts? That'd be awesome, since ECO4 parts are so rare.

It happens. Was just a minor fender-bender, but the insurance company wrote off the car without looking at it. I did think about buying it back and repairing it myself, however I saw how the scrapyard moved cars around with a forklift, that put me off. Someone contacted me on Facebook and it turned out that they brought the car for 600 and repaired it for 100 - the insurance company paid me 1,700 for it - so I'm glad it's back on the road and saving someone money. I'm not confident enough in deciding whether the shell wasn't damaged, so it's safer all around to walk away for me, so I'm happy with my decision.

I only got the non-OEM parts off it, unfortunately, I wasn't allowed to get the OEM parts.

Quote:

When did you get the "new" Astra, and how old was it, how many miles on it? Has it been checked and tuned up yet? Maybe an oil and filter change will help, maybe alignment should be checked.
It has 104,000 miles on it. The dealer claimed that they did a full service on it, but it turned out that they only changed the oil, and nothing else. I will be finishing off the service myself next week/2 weeks time. The air filter is a bit black, so it'd certainly help to change that. Will get alignment checked when I get the new wheels on, it's definitely slightly off.

Quote:

If you do swap the wheels/tires then maybe try a roll-down test to see the difference in RR.
I'll see if I can get the time to do that.

Quote:

Can the boost be increased?
I'd guess so but I'd be wary about doing so for 2 reasons - 1) I don't want to damage the engine or shorten its life and 2) the engine with the high pressure turbo has higher fuel consumption, so I'm not quite sure if it's benefitical.

Quote:

An engine swap is out of the question, I guess?
Unfortunately the Fiat engine is only rated at 120,000 miles, while the Isuzu engine is rated at 250,000 miles, probably partly because of the power difference - 120lb/ft torque for the Isuzu and 175lb/ft for the Fiat despite being 450cc smaller - and partly probably because the Isuzu engine was designed 30 years before the Fiat engine. And it'd probably be more money & time than it's worth - I mean, it'd be better and easier to buy a Smart diesel if I'm serious about fuel consumption! I expect to put at least 100,000 miles on the Astra in 5 years before considering a new car.

Actually... this made me think, and I know the newer Astra model has a choice between the Fiat 1.2 engine and the Isuzu 1.7 engine so I decided to look at the government ratings for both, and it's 58.8mpg combined for the 1.2, and 56.4mpg for the 1.7. Very poor compared to the older model, but this shows that the Fiat engine is more efficient than the Isuzu CDTI, but don't know about the older DTI version. Another interesting note is that the 1.2 in the Astra is 80bhp, while the 1.2 I know was 68bhp, so I'd guess the Fiat 1.2 68bhp engine in an ECO4 would give excellent fuel consumption if a bit slow?

Quote:

Originally Posted by Arragonis (Post 221831)
Ah - I see. I thought you were going to swap the eco4 wheels - which I think were narrower - to the replacement car. Insurance people can get picky :D

You thought correct. Look at the quotation marks I put on...

Quote:

Chippable ?
Think so, yes, though I'd want them to decrease the power, not increase it, but not sure if that'd work. If I'm wrong and increasing the power will improve fuel consumption, then I'd be worried about shortening the life of the engine.

Thanks to everyone for your comments so far! Interesting discussion...

Arragonis 02-24-2011 05:58 PM

The box I linked to has a dial so you can select less performance rather than more for eco if you wish. I had one on my 206 2.0 HDi and it worked on lower settings to get more MPG but it was sluggish. But the 2.0 HDi was not great for go unless turned up to '11', which is why I bought Helga :D

Eddles 02-25-2011 08:15 AM

Quote:

Originally Posted by Arragonis (Post 221833)
Minimal googling suggests the L suffix means low pressure and H would mean high - maybe plus an intercooller. Not sure if there are other differences but an "upgrade" may be possible?

Yup, correct. My engine already has an intercooler. It's not clear what other differences there are - is the turbo the same? Are the innards the same, etc etc. Don't think it's worth the effort.

Quote:

This place has a box which takes it to 100hp - bolt on so can be removed and I think it has an adjustment allowing you to turn it down.
Looks good! I'll think about it, but of course, the ugly face of insurance rears up again...


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