shall i buy vanos ?

i have a 520i 1991 automatic , and am thinking of getting a new engine and gear box , actually i have two options , the vanos engine ,and a normal one ,both are 25, i want to know which is better and more convenient ,ive read about the vanos system and its effects , and ive read that the vanos system got some issues on long use , so which option shall i get ?
the second point is the gas mileage ,my mileage is 14.11 mixed and my o2 sensor is removed , if i purchase a new one(o2 sensor) what is the percentage (approx) that i will get ?
the third point is about transmission , I drive automatic , and i have been told that manual will give the car an advantage in speed and mileage , is this true ?
thanks in advance..

Check this out first ..

http://www.bimmerfest.com/forums/sho...d.php?t=597282

and change your thread's title (click edit then go advanced).

I would just stick with a non vanos engine for simplicity.

When in proper running condition, with the O2 sensor installed, the car should get better than 14 mpg. How much better depends on a lot of things.

I would never own one of these cars with an automatic trans. They become very unreliable and expensive to repair with age. They do not transmit power to the wheels like a manual, and the torque convertor sucks power and milage from the already small engine.

So, with a 2.5L M50 engine, five speed manual trans, proper gear ratio, driven sensibly, the car should get 18 city 25+ highway.

I would go for the vanos engine any day. Its a better engine, more torque in the lower ranges, and provides better fuel economy overall. The car would also be more saleable. The issues with vanos are well understood, the seals etc for the vanos unit can be changed for under US$100 in parts and pretty easily done by hand (see Beisan Systems' website), and you can do this before you install your engine in the car.

Go for a manual tranny for the following reasons :

1. It is lighter...perhaps up to 100lbs lighter than an auto box. This is significant for a 525, as the engine's power to weight ratio is lower, and so increases in weight will affect hold it back more.
2. The lockup clutch will only engage in the top gear. This means that your torque convertor will suck anything from 4-7% of your engine's power up till you get to that speed.
3. #1 and #2 means that your fuel economy will suffer with an automatic. You're looking at -10% or higher off a manual tranny.
3. It is much cheaper in terms of parts, oil and labour, to service a manual tranny than an automatic.
4. Auto tranny's are far more expensive when they go bust, and their state of wear and tear cannot be inspected before purchase. As for a manual, you just need to change the clutches and oil at the correct intervals, and you're fine.

Your fuel economy is extremely bad. You not having the O2 sensor in there is probably the reason why, although there may be other issues as well. 18 city and 25 highway are good baseline numbers to shoot for. Another reason why your fuel economy is so poor is because your engine is a 520. The 2 litre consumes more gasoline to get up to speed than a 2.5 litre (it needs to work harder to push the car), while both engines weigh almost exactly the same so there is no compromise in weight when your switch to a 525.

Just one thing...if your get an auto gearbox, make sure you get one that is built for a 525 or higher engine. The 520's engine's torque convertor is not designed to handle a 525's power, and will fail prematurely or so I've been told on good authority.


rgds,
Roberto

I would go for the vanos engine any day. Its a better engine, more torque in the lower ranges, and provides better fuel economy overall. The car would also be more saleable. The issues with vanos are well understood, the seals etc for the vanos unit can be changed for under US$100 in parts and pretty easily done by hand (see Beisan Systems' website), and you can do this before you install your engine in the car.

Go for a manual tranny for the following reasons :

1. It is lighter...perhaps up to 100lbs lighter than an auto box. This is significant for a 525, as the engine's power to weight ratio is lower, and so increases in weight will affect hold it back more.
2. The lockup clutch will only engage in the top gear. This means that your torque convertor will suck anything from 4-7% of your engine's power up till you get to that speed.
3. #1 and #2 means that your fuel economy will suffer with an automatic. You're looking at -10% or higher off a manual tranny.
3. It is much cheaper in terms of parts, oil and labour, to service a manual tranny than an automatic.
4. Auto tranny's are far more expensive when they go bust, and their state of wear and tear cannot be inspected before purchase. As for a manual, you just need to change the clutches and oil at the correct intervals, and you're fine.

Your fuel economy is extremely bad. You not having the O2 sensor in there is probably the reason why, although there may be other issues as well. 18 city and 25 highway are good baseline numbers to shoot for. Another reason why your fuel economy is so poor is because your engine is a 520. The 2 litre consumes more gasoline to get up to speed than a 2.5 litre (it needs to work harder to push the car), while both engines weigh almost exactly the same so there is no increase in the car's weight but a 25% increase in its power, when you switch to a 525.

Just one thing...if you get an auto gearbox, make sure you get one that is built for a 525 or higher engine. The 520's engine's torque convertor is not designed to handle a 525's power, and will fail prematurely or so I've been told on good authority.

If you currently have an automatic transmission and wish to switch to a manual, you'll need to get many parts, including the driveshaft. The driveshaft is of different lengths for autos and manuals.

And if you're buying that much stuff, you might as well ask them to throw in a limited slip differential (3.6 or higher) for free. An LSD improves handling in certain situations, and is considered an upgrade for the E34.

While the engine is out, replace the crankshaft position sensor too....$100 oem, and a piece of cake when the engine is hanging out there. Have all the pulleys and tensioners on the new engine inspected, and reuse your old pulleys/tensioners if they are in better shape. Also, have them clean out your idle control valve...also a piece of cake with a suspended engine and just ten minutes work. Might be a good idea to change out your rear main seal, especially if you're dealing with an engine of unknown mileage that has been lying around a yard for awhile, this would not be cheap but it is far far more expensive to do it after the engine has already been installed in your car and you need this. If you intend to keep this car for the next 5 years at least, I would strongly recommend that you do so. And have the clutch inspected and changed if it looks suspect, if you're getting yourself a manual. Its a very good idea to change out the water pump (composite impeller only) and thermostat as well, while the engine is hanging out of your car. Those are usually suspect.

Of course, you don't have to do all the extra stuff I mentioned even though the labour costs would be substantially lower since the engine is out. However, you're Jordanian, and considering the shamefully cheap gasoline you must be getting there, I would say, why not ? You gotta pay to play, and the E34 is a keeper when she's done up right...




rgds,
Roberto

thank you

If you have the spare cash, get yourself a set of M3 cams and s52 headers, its a great upgrade to the engine and would again be much easier (at least for the headers) to do them while the engine is out of the car.

Basically, go to your workshop and ask them about everything that you ought to do to take advantage of the labour savings you'll receive because the engine is simply not in the way. And yes, have your engine and tranny mountings professionally inspected and change them if they look suspect, when the engine and tranny are down on the ground.

Much information to an amateur like me ,, am writing the stuff you mentioned on a paper ,, thanks alot

Originally Posted by robertobaggio20

I would go for the vanos engine any day. Its a better engine, more torque in the lower ranges, and provides better fuel economy overall. The car would also be more saleable. The issues with vanos are well understood, the seals etc for the vanos unit can be changed for under US$100 in parts and pretty easily done by hand (see Beisan Systems' website), and you can do this before you install your engine in the car.

Go for a manual tranny for the following reasons :

1. It is lighter...perhaps up to 100lbs lighter than an auto box. This is significant for a 525, as the engine's power to weight ratio is lower, and so increases in weight will affect hold it back more.
2. The lockup clutch will only engage in the top gear. This means that your torque convertor will suck anything from 4-7% of your engine's power up till you get to that speed.
3. #1 and #2 means that your fuel economy will suffer with an automatic. You're looking at -10% or higher off a manual tranny.
3. It is much cheaper in terms of parts, oil and labour, to service a manual tranny than an automatic.
4. Auto tranny's are far more expensive when they go bust, and their state of wear and tear cannot be inspected before purchase. As for a manual, you just need to change the clutches and oil at the correct intervals, and you're fine.

Your fuel economy is extremely bad. You not having the O2 sensor in there is probably the reason why, although there may be other issues as well. 18 city and 25 highway are good baseline numbers to shoot for. Another reason why your fuel economy is so poor is because your engine is a 520. The 2 litre consumes more gasoline to get up to speed than a 2.5 litre (it needs to work harder to push the car), while both engines weigh almost exactly the same so there is no increase in the car's weight but a 25% increase in its power, when you switch to a 525.

Just one thing...if you get an auto gearbox, make sure you get one that is built for a 525 or higher engine. The 520's engine's torque convertor is not designed to handle a 525's power, and will fail prematurely or so I've been told on good authority.

If you currently have an automatic transmission and wish to switch to a manual, you'll need to get many parts, including the driveshaft. The driveshaft is of different lengths for autos and manuals.

And if you're buying that much stuff, you might as well ask them to throw in a limited slip differential (3.6 or higher) for free. An LSD improves handling in certain situations, and is considered an upgrade for the E34.

While the engine is out, replace the crankshaft position sensor too....$100 oem, and a piece of cake when the engine is hanging out there. Have all the pulleys and tensioners on the new engine inspected, and reuse your old pulleys/tensioners if they are in better shape. Also, have them clean out your idle control valve...also a piece of cake with a suspended engine and just ten minutes work. Might be a good idea to change out your rear main seal, especially if you're dealing with an engine of unknown mileage that has been lying around a yard for awhile, this would not be cheap but it is far far more expensive to do it after the engine has already been installed in your car and you need this. If you intend to keep this car for the next 5 years at least, I would strongly recommend that you do so. And have the clutch inspected and changed if it looks suspect, if you're getting yourself a manual. Its a very good idea to change out the water pump (composite impeller only) and thermostat as well, while the engine is hanging out of your car. Those are usually suspect.

Of course, you don't have to do all the extra stuff I mentioned even though the labour costs would be substantially lower since the engine is out. However, you're Jordanian, and considering the shamefully cheap gasoline you must be getting there, I would say, why not ? You gotta pay to play, and the E34 is a keeper when she's done up right...




rgds,
Roberto

........ Non-Vanos

Originally Posted by snowsled7

I would just stick with a non vanos engine for simplicity.
When in proper running condition, with the O2 sensor installed, the car should get better than 14 mpg. How much better depends on a lot of things.

I would never own one of these cars with an automatic trans. They become very unreliable and expensive to repair with age. They do not transmit power to the wheels like a manual, and the torque convertor sucks power and milage from the already small engine.

So, with a 2.5L M50 engine, five speed manual trans, proper gear ratio, driven sensibly, the car should get 18 city 25+ highway.

+1

There is a lot more to switching to a vanos engine than just plonking it in the engine bay. The DME and wiring harness has to be swapped out to match just to name one of the many issues involved.

damati, I would strongly recommend that you think long and hard about what is involved before you take that giant leap.

If you were looking into getting a different car, I'd say yes, but just as a swap, I don't think it's worth it. Better to do 5 speed swap as stated earlier. Doing the swap to a TU engine will give you another second faster to 60 according to internet times, but realistically even though it's not expensive, it's kind of a pain. Really depends on what you're looking to do, I guess.

Originally Posted by BMR_LVR

+1

There is a lot more to switching to a vanos engine than just plonking it in the engine bay. The DME and wiring harness has to be swapped out to match just to name one of the many issues involved.

damati, I would strongly recommend that you think long and hard about what is involved before you take that giant leap.

Yes, I forgot this. Wiring harness issues are involved. Thank you for pointing that out explicitly.

This is a very important one to think about.

Damati, you may have extra sockets in your current wiring harness for the vanos unit. This is a common practice for BMW...they will generate the harness and its sockets for 1-2 revisions ahead if they are already on the drawing board right now. Look carefully under your intake manifold. If you see an empty switch, that might be it.

The vanos engine has 5% extra compression, according to the Bentley manual. Further, vanos gives you better performance and fuel economy. Further, your car would have a slightly higher resale value.

The vanos wiring harness can be had for cheap or free if you're buying an engine and transmission from the yard. With the engine out, it is a far simpler matter (although involved for sure) to swop out wiring harnesses. The new wiring harness sold to you would come with a fuse back and complete fuses, as well as a the entire ecu bank. Its a plug and play affair if your mech has done this before. I'm guessing we're looking at anything from 2-4 hours of labour for this alone.

A far easier method would be to do minor rewiring on your current harness based on the E34's electrical troubleshooting manuals relevant for your current engine (google for the download) and the new vanos unit that you're looking at. Certain wires need to be switched out at the ECU's computer clamp. Pin-out checks can confirm if the wires are for the devices concerned. All of this can be easily done when the engine is out of the car. Of course you need a mechanic who is not frightened of electrical issues (most of them seem to be) but although this sounds difficult, it is not rocket science at all. Using this method, you can reuse your current wiring harness. There will be no compatability issues. Naturally, you'll need a vanos ecu, if not your vanos unit will not work.

I will be doing this very shortly on my car with Ricks help, when I install my vanos unit.

A NV 525 can use your current ecu but it will not be optimised for the 525, so you'll be getting a new one as well anyway.

This is going to be a very expensive and detailed project that involves experts or confident mechanics/diyers. Considering that, I suggest that you do go all out and go for the best version of the options that you have on the table, which is the m50tu. It only requires extra time, effort and research on your part, if you have the right people at your disposal (and you might have to search for it). The cost differences both in terms of parts and labour are not drastically different, and anyway, this is a one-time affair. Make your decision to go NV instead of the vanos, an informed and reluctant one.




rgds,
Roberto

Another simple way to see if your car's wiring harness is vanos ready is to borrow and plug in a vanos ecu from a 325/525 m50tu. If your car starts up fine, then you're on. You probably don't need any modifications, although you need to check pinouts etc for your vanos circuits. If not, you'll need to swop the entire wiring harness, or give the ETM to someone with a polytechnic-level education/performance in wiring and electricals and they should be able to help you generate new wires and rewire existing ones for you without issues.