Author Topic: blown 6.9 in perth  (Read 4109 times)

Big_Richard

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blown 6.9 in perth
« on: 17 February 2006, 06:41 PM »
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« Last Edit: 25 October 2012, 01:38 AM by Major Tom 6.9 »

Mforcer

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Re: blown 6.9 in perth
« Reply #1 on: 17 February 2006, 06:50 PM »
Sounds impressive. Where did you find out about this? Any more details?
Michael
1977 450SE [Brilliant Red]
2006 B200

AMG69

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Re: blown 6.9 in perth
« Reply #2 on: 17 February 2006, 08:20 PM »
Hmm. Well, when i last made enquiries about that car (I called JRT, Jaguar Rover Tech in Perth who that guy (posted on the M100 site - name escapes me) said did all the work.  JRT were not complimentary.  They said he never actually finished the car and they made it sound like he was "grossly exagerating" in his posts; so, I didnt enquire further.  If there is a 6.9 Blown in Perth - its the first I know of it and I do know most of them now and all the top Merc mechanics here. 

Next Sunday we have almost all the 6.9 Owners I know in Perth ALL meeting for the first time as a Group; I tried to organise this last year and it fell thru so we are trying again; we are meeting for a chat then a drive then lunch; naturally we'll post photos on this site afterwards; I think we have about 6-7 cars; a couple of guys cant make it; if its a success we'll no doubt do it again;  I'll ask everyone about the blown 6.9 - I assume its been at teh new Kwinana Motorplex.

Chris Munday
sigh....sitting back contemplating the next purchase..!

John Hubertz

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Re: blown 6.9 in perth
« Reply #3 on: 18 February 2006, 03:00 AM »
Speaking of blown.....


Anyone own or know of a blown 450SEL or 280SE model?  Strikes me that a turbo would be possible....and a paxton-style centrifugal supercharger would be downright "easy" on a d-jet.

Here's a pic of the type of unit I mean....



The beauty of these Paxton units is they can be placed anywhere in the engine compartment - nice little bolt on replacement for the fat-hog OEM air conditioning compressor, methinks.
« Last Edit: 18 February 2006, 03:02 AM by John Hubertz »
John Hubertz
"When the going gets weird, the weird turn pro."
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1977 450SEL (Max Headroom)

oscar

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Re: blown 6.9 in perth
« Reply #4 on: 18 February 2006, 10:24 AM »
Sometime's I wish I had setup another user name to ask questions like this:  What does "blown" mean?  I was under the impression a 6.9 had paid the ultimate sacrifice and was no longer with us.
1973 350SE, my first & fave

Mforcer

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Re: blown 6.9 in perth
« Reply #5 on: 18 February 2006, 12:17 PM »
Sometime's I wish I had setup another user name to ask questions like this:  What does "blown" mean?  I was under the impression a 6.9 had paid the ultimate sacrifice and was no longer with us.

In this case blown engine is simply one that has a turbo.
Michael
1977 450SE [Brilliant Red]
2006 B200

AMG69

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Re: blown 6.9 in perth
« Reply #6 on: 18 February 2006, 10:39 PM »
....or a supercharger ("blower")!!
sigh....sitting back contemplating the next purchase..!

John Hubertz

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Re: blown 6.9 in perth
« Reply #7 on: 19 February 2006, 03:59 AM »
The supercharger would bolt up - and enrichment wouldn't be that big a deal - one could either put on a high-output fuel pump or modify injectors - diesel guys do it all the time.

The metering plate would maximize flow - and the low end improvements of HP and torque off the line would be massive.

Superchargers aren't really efficient at sustained high speeds - thus the turbocharger on most applications used that way.

Drag vs rally - its a question of what type of driving you want.
John Hubertz
"When the going gets weird, the weird turn pro."
(Hunter S. Thompson) 

1977 450SEL (Max Headroom)

Nutz

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Re: blown 6.9 in perth
« Reply #8 on: 26 February 2006, 06:46 AM »

Adding my $.02 and a bit long winded but here it goes...

Choosing the right charger

Because of their physical differences,positive-displacement and centrifugal blowers move air at different rates and at varying levels of efficiency.Neither system is perfect but each has advantages to counter its disadvantages.Following are some features for each type.

Positive displacement superchargers can generate a high level of boost at relatively low engine speeds.Centrifugal superchargers generate a comparatively small amount of boost early in the RPM range.

Typically,the output of a centrifugal blower will continue to increase gradually with engine speed.For that reason,positive displacement blowers usually generate larger amounts of low RPM torque compared to centrifugal chargers.

Heavier,underpowered vehicles respond well to positive displacement blowers,while lighter,overpowered vehicles favor centrifugal chargers.

Positive displacement blowers are typically limited to smaller compression ratios.The displacement of the blower must be proportional to the displacement of the engine.

Centrifugal superchargers can deliver a comparatively large amount of boost from a considerably smaller package.The speed and shape of the impeller dictate the output of a centrifugal supercharger.

Adiabatic Efficiency

It should be obvious that to match an existing supercharger to to any given application,one needs to evaluate numerous variables in an attempt to zero in on the optimum combination.Physical size and shape are very important factors as are the drive requirements.Airflow requirements,pressure ratio and drive speed must also fit within a comfortable range.And because heat greatly influences the overall effectiveness of a compressor,the amount of heat a compressor generates should be given a high degree of priority.The value that defines the amount of heat a particular compressor generates is called its adiabatic efficiency.

When a volume of gas is compressed and can't escape,pressure rises in proportion to the degree of compression.An adiabatic operation is one in which no gain or loss of heat to or from external sources occurs.When the air charge is compressed in the cylinder it reaches an appreciably higher temperature than it would in a truly adiabatic process.The measure of efficiency of a compressor is how close it comes to the true adiabatic state.As an example,a compressor rated at 50% adiabatic efficiency will deliver compressed gas at a temperature twice the true adiabatic compression.The extra heat corresponds to losses due to the low pumping efficiency.Unfortunately,heat is an enemy of forced induction.

The density of a gas at any given temperaturen is inversely proportional to its temperature.In other words,the heat effectively reduces the rate of charge.Ultimately,it is the weight of the charge that will determine how much energy can be extracted during the combustion process and converted into useful work.Therefore,lowering the temperature of the charge increases its density and a denser charge will generate more work.

A more efficient compressor generates a lower air-charge temperature.Example,assume a compressor with a 50% adiabatic efficiency takes in air at an ambient temperature of 68 degrees F. (20 degree C)and delivers it at a pressure of 1.5 atmospheres (22 psi),the delivery temperature will be 194 degrees F.If the efficiency  of the compressor were 75%,the outlet temperature would be  153 degree F. Even though the pressure is the same,the 153 degree F. air charge will therfore support a greater power output.

The adiabatic efficiency becomes a more important factor as the ambient temperature rises.When it's 100 degrees F. outside,the temperature of the air entering the supercharger will be 100 degrees or more.Adiabatic efficiency becomes critical at this point unless you plan your driving around the weather.Simply put,the higher the adiabatic efficiency the better.

Sorry so long,I'm just fascinated with turbocharging and supercharging ::)

Mforcer

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Re: blown 6.9 in perth
« Reply #9 on: 26 February 2006, 11:52 AM »
Thanks for the informative and detailed post, Nutz. Great reading!
Michael
1977 450SE [Brilliant Red]
2006 B200

Nutz

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Re: blown 6.9 in perth
« Reply #10 on: 04 March 2006, 01:22 PM »



Anyone own or know of a blown 450SEL or 280SE model? 

How about a 6.9?




John Hubertz

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Re: blown 6.9 in perth
« Reply #11 on: 04 March 2006, 03:20 PM »
Whoooooooeeeeeee!

If you want to see a super-clean centrifugal (looks like a giant alternator that mated with a turbo) installation take a look at the "5144" thread at www.m-100.cc

John Hubertz
"When the going gets weird, the weird turn pro."
(Hunter S. Thompson) 

1977 450SEL (Max Headroom)

Nutz

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Re: blown 6.9 in perth
« Reply #12 on: 04 March 2006, 04:26 PM »

Yeah! I like that but that supercharger is too large.Rather than the D 1SC supercharger he should have used either a P600B ,P-1SC or the P-1SCH .Nonetheless,a very sweet setup 8)