Supercharger install

Zitat von fuzzifikation;76254

Did that help? Or was it something completely different that you've asked?

Very well written. Indeed, that was what I was looking for.

In summary, the engine management (ECU) has base fuel/spark maps to tell it how things *should* be and then uses the feedback loop (ie from various sensors including the O2 sensors) to determine how things actually are.

With regards to the O2 sensors, the ECU detects a lean condition and adds more fuel - - but it adds slightly too much fuel causing the ECU to detect a rich condition, which causes it to reduce fuel - - but it reduces too much, which causes a lean condition - - and so on and so on, etc. In short, the ECU is always chasing its own tail.

Of course, this is a gross oversimplification of things but I think the datalog graph (which is just a few seconds across the X-axis) demonstrates this behavior nicely and may help some readers here to gain a more complete understanding of how the O2 sensors work in conjunction with the ECU's to ensure that air/fuel ratios are within the desired ranges.

Rgds...

Zitat von John in DC
Were these numbers taken from the car's on-board-computer?

Zitat von stevep840;76219

Yes always during the 5 years of owing the car, ie before & after conversion hence the quoted figures.

with a BMW V8 M60 / M62 SC kit you have changed the fuel injectors too. this also means your on-board calculation for gas milage is not correct any more with out a manual adjustment (factor in the hidden menue).

So I would not give to much for your quoted values if they are only based on on-board computer reading and not from manual calculations.

firebird

Zitat von Noggie;76160

I spoke to John yesterday and I got some information.

The guy who did the programming for John also altered the timing, looking at the dyno chart this was not the right step, but thats part of the tuning process, you try something and it migh not give the expected result.
He also increased the amount fuel to make it rich, as planned.

A new map will be made now where the timing is set back to its previous setting, and the afr leaned out a little.

Once I get a more functional VL map I was thinking of getting a logging equipment installed and do some logs during normal driving to tune the TL maps.

AFR was measured in the muffler so they told me I could subtract 0.5 from the AFR reading. making it about 13,7 at the leanest, and about 11 at the richest.

No I did not get a boost diagram.

Gerry.
I'm am only on my second map, it's too early to quit now.
It has taken quite some time to get here, but there are reasons for that.
It took a lot of time to determine where in the chip the euro map was.
I was working in China most of last year and the car has been in winter storage for several months.
The car has not been driven much since last June and the rich mix I have now only hurts my wallet. Don't use the car that much anyway since I have the M3 as a daily driver.

Looking forward to receive the package

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Egil,

do you have any chance/possibility to check for leacks in your pressurized section after SC (tubing, manifold, fuel injectors)?

firebird

Zitat von firebird;76588

Zitat von John in DC
Were these numbers taken from the car's on-board-computer?

with a BMW V8 M60 / M62 SC kit you have changed the fuel injectors too. this also means your on-board calculation for gas milage is not correct any more with out a manual adjustment (factor in the hidden menue).

So I would not give to much for your quoted values if they are only based on on-board computer reading and not from manual calculations.

firebird

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Yes the injectors were changed for larger ones, but fail to agree with your point, Hey I added a Supercharger & the car recorded more MPG,even ESS said this was achievable

Occasionally when starting a journey I did verify the cars ecconomy by topping the tank then calculating the driven milage by the fuel used it was never far off the cars computed calcs.

Have more faith old Chap.

Zitat von Noggie;76592

I have no fluid leaks, smell, or fumes that I know of.
The crankhouse ventilation vents into the engine bay right now instead of into the exhaust so I get the occational drop of oil on my exhaust manifold.

I have driven the car some miles now and havent seen any issues with the engine so far.
We are running about 7psi (0,5bar) at about 6000rpm.
at normal driving rpm I'm probably having less than 4-5psi boost, so there is really not much pressure at all.

If you would have a leackage after SC / HMM (Air Mass Meter) your DME would still adjust to the reported air flow. Under low boost not to much of a problem but with increasing boost the reported air flow would vary more from the air that gets into the angine. This would mean the car runs to rich on higher rpm and loosing power since no max boost.

Your car does not have knock sensors - so even if your timing got advanced by 1 or 2° in higher rpm and it may knocks it will not retare timing (like the newer M73 that will take back actually 5-6° in that case).

How did you measure the quoted boost numbers (7PSi @ 6000rpm).

cheers
firebird

Zitat von stevep840;76590

Yes the injectors were changed for larger ones, but fail to agree with your point, Hey I added a Supercharger & the car recorded more MPG,even ESS said this was achievable

Occasionally when starting a journey I did verify the cars ecconomy by topping the tank then calculating the driven milage by the fuel used it was never far off the cars computed calcs.

Have more faith old Chap.

Lets all install superchargers - since they will give you a much better gas milage

you have to compare apples with apples - If I reprogram the original fuel and timing maps properly the M60 and M62 will also achieve a better gas millage in specific driving conditions (my 540iA M62 did 11.2L/100km (light foot, mixed driving conditions averaged) with changed maps before changing to SC setup - try to top this).

cheers
firebird

Zitat von firebird;76611

Lets all install superchargers - since they will give you a much better gas milage

you have to compare apples with apples - If I reprogram the original fuel and timing maps properly the M60 and M62 will also achieve a better gas millage in specific driving conditions (my 540iA M62 did 11.2L/100km (light foot, mixed driving conditions averaged) with changed maps before changing to SC setup - try to top this).

cheers
firebird

You do come across as some one who knows what he is talking about, albeit a tad arrogant Do you think I wake up & think to myself "what bull shit can I feed those dudes today" No I don't I've more to do with my time , to that point I won't bother spending any further time trying to explain further

The centrifugal supercharger you are using works like a belt driven turbo. The boost is not linear from idle to max rpm, there is a speed where it will start to boost then boost will rise from there. Knowing your supercharger drive ratio I would expect boost to start around 3000 rpm and then rise quickly to its maximum at your max rpm because you have a 15:1 drive ratio so your supercharger is running at 90,000 rpm when your engine hits 6000.

You are running a 2:1 pulley drive ratio and the charger has an internal drive ratio of 7.5:1. To get boost lower down you need to overdrive the supercharger to increase its airflow but you will overspeed the SC at high rpm and so limit your maximum power.

If you had a positive displacement supercharger, your boost would be the same (approx) from idle to the redline which is why this type of SC gives huge low down power. Trouble with that is fuel economy.

Here is a full explanation from my post on 16/10/2007.............

[FONT=&quot]THE CHARGER[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]OK, so here is the second installment in the "Quest" mini series, entitled The "Charger". [/FONT][FONT=&quot]

I will try and explain to both the beginner and the more knowledgable, how and why I have selected the particular Charger that I have. I have called it this because in the very beginning, I was looking at both Turbo"Chargers" and Super"Chargers".

For the beginners, a very brief description of the differences:

Turbochargers use wasted exhaust gas energy to produce boost by spinning a compressor from the exhaust gases running through the exhaust system using a turbine. Power is almost free!

Superchargers use an engine driven belt to spin a compressor, usually from the crankshaft front pulley. It takes power from the engine to spin the supercharger when producing boost, but only a small percentage of the extra horsepower it is giving.

Turbochargers can be used singly or in multiples, usually twin. Twin turbo's can be arranged in three seperate ways, parallel, staged or sequential.

Twin parallel turbo's are generally used where there is insufficient room to install a single large turbocharger. This is most convenient on the "V" engines. Both turbo's will be identical.

Staged twin turbo's, as on the new 330i and 335D use a small turbo for low rpm boost and a larger turbo that takes over at higher rpm, when the smaller turbo has reached maximum flow. This is a very good arrangement as lag is very low and yet high boost levels are not compromised. 2 different sized turbo's are used in this arrangement.

Finally, the sequential twin turbo uses a similar arrangement to the staged, except it uses one turbo to produce boost, which is then fed directly into the second turbo to produce very high boost pressure levels which are beyond the capability of the pressure ratio of just one unit. In these installs, boost pressures of 60 psi to 100 psi are typical. Not for the faint hearted!

In a single turbo install, many believe that twin turbo's produce less lag because of the inertia in the 2 is less. This is minimal because in the case of an 850 for example, each turbo is only being spun by 2.5 litres whereas a single would receive all 5.0 litres. An advancement of the single turbo such as the twin entry or VGT will surpass this lag.

A twin entry turbo uses two seperate ports to introduce the exhaust gases onto the turbine, therefore changing the force and gas volume to spin it up early without restricting it at higher flow rates, the VGT or "Variable Geometry Turbocharger" does the same thing by varying the angle the gases enter the turbine.

And no, twin turbos DO NOT produce twice the power of single turbo's, although the marketing men would have you believe so!

The supercharger can also be installed singly or in multiples. Again, twin superchargers can be smaller than a single and may be far easier to install spacewise, but will require 2 drives from the crank, although these may be possible from the same belt, generally 2 separate drives are used.

There are a number of supercharger designs, the most common being the positive displacement and the centrifugal types. Most people associate with the positive displacement type which will produce boost ON IDLE speed and has ZERO lag because it pumps air into the engine at any speed at a ratio dependent on supercharger drive ratio.

A centrifugal supercharger is almost a hybrid between a supercharger and a turbocharger and can be described basically as a belt driven turbocharger, producing no boost and little load on the engine at low rpm, but producing boost at higher rpm again dependant on supercharger drive ratio.

Examining all of the above, and considering them all, I decided against the option of the single large turbo due to mounting, relocation of underbonnet components and heat management issues, the twin turbo's involved doubling the cost of a single unit, involves two oil robbing supplies from the engine lubrication system, 2 drains into the sump and glowing red hot turbo's within millimeters of the chassis and wiring components, as well as the manufacture of a pair of exhaust manifolds only suitable for right hand drive cars and difficult maintenance issues around the turbo's.

Remember though that all high power output Japanese tuned cars invariably replace their twin turbo set-ups with a single large turbo.

As far as twin superchargers were concerned, this was only necessary if a single unit could not flow sufficiently, and as many GMC positive displacement superchargers can flow to 6000 bhp and more, I researched into what would be required for my mere 600 bhp. I found the most popular size/ flow superchargers to be the Vortec range of centrifugal superchargers. With severe space limitations in the "V" above the engine, this pretty much ruled out the use of a positive displacement type, and also whilst boost from idle is an awesome experience, there had to be SOME consideration on fuel economy, and the stress on the engine at all times, not just when required.(90% of the time he he)

Further research here in the UK showed a development being made by Turbo-Technics on a fluid drive high speed centrifugal supercharger, and yet more research showed a Danish company called Rotrex that were already producing these units. I investigated further, only to reveal that they do a unit rated to 640 bhp thats the size of an alternator! And guess what engine runs a second alternator on the Japanese Spec engine?

O YES, That'll be an 850 BMW then!

Well, here we had a supercharger small enough to fit, capable of running to 600 bhp, you only needed one, with a spare mounting area on the car. All that was required was a mounting arrangement and a drive set-up. I guess a few J-Spec owners will be deleting that 2nd alternator then?

The only further options are the trim of the supercharger to use and the drive ratio, and close examination of the flow charts should at least get you close to the correct one for each. I have chosen, so only time will tell.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]My first tasks in relation to this project were to try and cover all aspects of the car that would change due to the installation of a supercharger. So I will be trying to cover all these issues BEFORE I fit the blower, not try and cure problems found afterwards. Issues include cooling (engine, oil and charge), fuelling and control, mounting and drive, lubrication, intercooling/chargecooling, induction and exhaust systems. [/FONT][FONT=&quot]

[/FONT]

8Tech.

Zitat von Noggie;76691

This is based on datasheets.
With this size pulleys at 6000rpm the SC is at 100% RPM = 7-7,5psi boost.

Hi! might I add yet another two cents to the matter.. ?

The spec-sheet of the charger is just one variable... from it alone, one cannot conclude the boost. For further reading (after reading Gerry's post), I recommend this overview.

Here's how to (very roughly) get the boost pressure. Let's look at a typical compressor map (attached; not your compressor, but your's will look similar).

The lines represent pressure over massflow (I made one black). The elliptical stuff is the efficiency and not of any concern here.
Each line represents one constant compressor speed. Let's say we're at the black one:

I there's a lot of massflow going into the engine, the compressor will produce less(!) pressure than if less mass is going into the engine. The point is: It's (a) not linear and (b) dependent on massflow (and not engine speed). The massflow depends, in turn, on engine speed, pressure and intake temperature and air efficiency of the engine.

Well, anyway: I'm sure that the compressor is a good fit for your engine. It's just that to know the boost, you'll need more information than the spec sheet. But: if it's working, it's a good fit and will produce good boost (whatever that might be).

HOWEVER: Are you sure that the flow meters (the two hot wire flow meters in the intakes) can handle (i.e. measure) the amount of massflow that your compressor produces? If not, that would be a nice explanation why you'd be running lean ...

Zitat von fuzzifikation;76786

HOWEVER: Are you sure that the flow meters (the two hot wire flow meters in the intakes) can handle (i.e. measure) the amount of massflow that your compressor produces? If not, that would be a nice explanation why you'd be running lean ...

Guess who's using big 3" MAF's?



He he.

Zitat von 8Tech;76804

Guess who's using big 3" MAF's?

He he.

Good call, that one. I've looked up the specs of the original MAFs. Each can handle about 500 kg/h (I'm waaay to lazy to convert to lb/min).

At 6000 RPM, one bank of the engine will do (roughly) 450 kg/h... so that's already cutting it close!

I deem it unlikely that the original MAFs can handle the additional massflow from the boost!

Zitat von 8Tech;76804

Gerry, slightly OT, but from where can I get those hose clamps???

Zitat von 8Tech;76804

Guess who's using big 3" MAF's?

He he.

Different MAFs or just different housing?

- Wont diff housing skew the readings?
- Diff MAF require custom ECU tuning?

On a related note, anyone ever try insulating the MAFs from engine bay heat? As they (pending type) use air flow for cooling an element, a hotter than ambient environment somewhat messes the calculated values up. Might be hard to test on the 8er, but on other cars with live measurable data you can usually see an improvement in accuracy.

Zitat von Noggie;76807

I'm not running lean anymore, but very, very rich.

ok.. got'cha!

Zitat von 8Harry8;76808

Gerry, slightly OT, but from where can I get those hose clamps???

Can't remember exactly but there are plenty here:

http://shop.ebay.co.uk/i.html?_kw=t&_kw=hose&_kw=clips

Cheers, Gerry.

Zitat von Noggie;76813

did notice that my 4-speed auto and 3.45 diff was 300rpm higher than the CSI at 140kph, but that should not give a difference of 20l ïn about 600km.

There seems to be some guessing in the whole fat/lean matter.. Can you take the car to a testing shop, where they can measure the exhaust oxygen value at the exhaust tip? Then you'd know exactly, what's going on.

I just got my TÜV (MOT) and they check the CO and Oxygen values here.. so, you might have the same thing in your country?
That also would releave Firebird and John from having to guess so much... What do you think?