Fix the little things - PERFORMANCE MODS
09-18-2006, 01:58 PM
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Originally Posted by John Speake
In fact the "K" in K-Jet does not indicate "knock" - i found this info.....
QUOTE
"The designation K-Jetronic stems from this fact ("K" stands for the German word for "continuous"). "
QUOTE
"The designation K-Jetronic stems from this fact ("K" stands for the German word for "continuous"). "
09-18-2006, 02:19 PM
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Originally Posted by John Speake
Hello Glenn,
I see it the opposite :-)
If more air flows into the engine at a particualr RPM and throttle position, then that would move the LH operating point on the map up to a higher value, and would result in more fuel being added.....
I see it the opposite :-)
If more air flows into the engine at a particualr RPM and throttle position, then that would move the LH operating point on the map up to a higher value, and would result in more fuel being added.....
Please bear with me as I try to bend my mind around this.
From your description, I thought that at WOT the only thing determing fuel flow to the engine was the "map" in the LH. I imagined this as a table with a given fuel value attached to the given RPM. There is no input from the MAF or O2 sensor("open loop"). So if more air gets into the engine at a given RPM (say due to a less restrictive air filter) how does the LH realize this and move up the map to a higher value? What am I missing out of the equation?Glenn
09-18-2006, 02:20 PM
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Worf, you are simply getting the Bosch EZK ignition system confused with Bosch K-Jetronic fuel injection.
K-Jetronic is what is usually known in these parts as "CIS", and the "K" stands for the German word "kontinurlich" or continuous. This is a PURELY mechanical fuel injection system- however two versions had electronic add ons:
K-Lambda, which added an O2 loop to control a "frequency" valve, which opened and closed rapidly to fine-tune fuel pressure [mixture], and
KE-Jetronic, which had a different fuel distributor block that incorporates an electronic solenoid that helps fine tune the mixture via altered control pressure.
NO K-jetronic sytem ever involved any form of integrated ignition/injection, such as in the Motronic sytems.
L-Jetronic and LH-jetronic, on the other hand are true electronic fuel injection and use a central brain to manage mixture control. Pure K has no brains whatsoever. Like several of my former girlfriends.
N!
K-Jetronic is what is usually known in these parts as "CIS", and the "K" stands for the German word "kontinurlich" or continuous. This is a PURELY mechanical fuel injection system- however two versions had electronic add ons:
K-Lambda, which added an O2 loop to control a "frequency" valve, which opened and closed rapidly to fine-tune fuel pressure [mixture], and
KE-Jetronic, which had a different fuel distributor block that incorporates an electronic solenoid that helps fine tune the mixture via altered control pressure.
NO K-jetronic sytem ever involved any form of integrated ignition/injection, such as in the Motronic sytems.
L-Jetronic and LH-jetronic, on the other hand are true electronic fuel injection and use a central brain to manage mixture control. Pure K has no brains whatsoever. Like several of my former girlfriends.
N!
09-18-2006, 02:22 PM
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Originally Posted by sharkmeister85
John,
Please bear with me as I try to bend my mind around this. From your description, I thought that at WOT the only thing determing fuel flow to the engine was the "map" in the LH. I imagined this as a table with a given fuel value attached to the given RPM. There is no input from the MAF or O2 sensor("open loop"). So if more air gets into the engine at a given RPM (say due to a less restrictive air filter) how does the LH realize this and move up the map to a higher value? What am I missing out of the equation?
Glenn
Please bear with me as I try to bend my mind around this.
From your description, I thought that at WOT the only thing determing fuel flow to the engine was the "map" in the LH. I imagined this as a table with a given fuel value attached to the given RPM. There is no input from the MAF or O2 sensor("open loop"). So if more air gets into the engine at a given RPM (say due to a less restrictive air filter) how does the LH realize this and move up the map to a higher value? What am I missing out of the equation?Glenn
N!
09-18-2006, 02:26 PM
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Originally Posted by heinrich
John my theory the past 6 years has been number two. The mesh over the vanes of the filter causes a mess in airflow.
Glenn
09-18-2006, 02:30 PM
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Originally Posted by heinrich
John my theory the past 6 years has been number two. The mesh over the vanes of the filter causes a mess in airflow.
Lol...in which case ..please explain what the 2 MAF screens on top and bottom of the MAF do ???
And they have a much smaller mesh than a K&N.....
Also for what its worth...
When I had my Nitrous explosion where the airflow was REVERSED and about 1000 times stronger than normal.....
It went through the lower MAF screen without damaging it in any way.....BUT...the top screen it blew into a tiny ball , a little smaller than a golf ball...
All the best Brett
PORSCHE 928 S2 AUTO V8 4.7 LTR 1986 IRIS METALLIC BLUE WITH X-PIPES ,RMB ,PROMAX CHIPS, KICKDOWN SWITCH.K&N.NITROUS KIT 150 HP.
PCGB UK 928 FORUM MODERATOR - Email managingdirector@pchealthcare.co.uk
09-18-2006, 02:37 PM
#68
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Ok, I think i understand what you are saying now, because of ebbs and flows in the way the air goes past the hot wire in the MAS, you can and will have kind of a "eddy current" where the air flow is not 100% laminar past the wire.
Originally Posted by John Speake
Hello Greg,
Perhaps I didn't explain very well.....
The MAF hot wire takes a sample of the total airflow into the engine and converrts that into a voltage. That voltage (or more correctly a modified and processed version of it) coresponds to a "load" value on the main fuel map. The other axis of the map is rpm. The map tells the LH how long to open the injectors for (they are all fired simmultaneously).
If you changed the airflow into the MAF, then it may indicate a different voltage at a particular throttle opening than it did before. So this will mess up the fuelling to a greater or lesser extent. A small change may not cause a problem at cruise with a cat equipped car running closed O2 loop, but when you're at WOT, then it's open loop time, and an accurate airflow reading into the engine is critical.
In a perfect world the airflow into the MAF would be laminar, and then it would be easy to change things without upsetting something. But life ain't like that...
The implication of a small drop in power/torque at WOT with a K&N is that it is the result of a weaker mixture than stock. I wonder if anyone has checked this ? Louie ?
Hope this helps.....
Perhaps I didn't explain very well.....
The MAF hot wire takes a sample of the total airflow into the engine and converrts that into a voltage. That voltage (or more correctly a modified and processed version of it) coresponds to a "load" value on the main fuel map. The other axis of the map is rpm. The map tells the LH how long to open the injectors for (they are all fired simmultaneously).
If you changed the airflow into the MAF, then it may indicate a different voltage at a particular throttle opening than it did before. So this will mess up the fuelling to a greater or lesser extent. A small change may not cause a problem at cruise with a cat equipped car running closed O2 loop, but when you're at WOT, then it's open loop time, and an accurate airflow reading into the engine is critical.
In a perfect world the airflow into the MAF would be laminar, and then it would be easy to change things without upsetting something. But life ain't like that...
The implication of a small drop in power/torque at WOT with a K&N is that it is the result of a weaker mixture than stock. I wonder if anyone has checked this ? Louie ?
Hope this helps.....
09-18-2006, 02:40 PM
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Originally Posted by Normy
I think what he was saying is that when the LH brain receives a signal from the WOT switch on the throttle body, that it engages a separate subroutine that adds a pre-programmed amount of time to the injector-open period that the MAF is advocating = more dino juice.
N!
N!
Glenn
09-18-2006, 03:25 PM
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, I like the way you put that.As far as CIS-E, they had that on MB and others.
Like they used to say in the old tarzan movies "Bad JuJu country, Bawana, dont go there".
Complex system, To me any way, maybe I have not worked on enough of the to be very good with them, and I hope I never do.
Originally Posted by worf928
You didn't learn $ht+t from me except that I can post crap everyonce in a while esspecially when I'm stuck in hotel room...
I know in the VW world there was CIS-E and CIS-K. The 'K' was a CIS system with knock detection. The Porsche literature maps the 'K' in EZK to knock detection.
09-18-2006, 03:27 PM
#71
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sharkmeister85 ( on K&N) - performance auto parts stores often have a display for K&N -vs- standard paper filters, where you can see a ping-pong ball floats high in a closed chamber with the K&N, but sits idle on the bottom with the paper filter. Looks great and sells a lot of K&N's.
However, we're talking significantly greater velocities in real world 928 useage. Consider as well that the surface area also makes a difference, opposed to the little display sample the marketing guys came up with. Throw in the path of flow etc, and the test gets rather complex.
On a bench, the K&N would likely flow more in a straight forward push air through the element test, but that higher flow doesn't traslate to application specific useage either. So, it leads to Louis/Heinrich's dyno scenario to identify differences in application specific normal useage. Seems to not offer any improvement.
Most importantly <for me at least> - IMHO, the K&N higher flow is due to less filtering, hence the requirement for oil to assist capturing what the gauze isn't. This oiling requirement begs the question, "Did you oil it too much? or too little?" Let's not kid ourselves here, the idea of "correct oiling" is easier spoken than replicated. If correct oiling means oil isn't getting to the hot wire, then it would seem quite easy to under-oil and think you did it correctly --> ah, but then you're letting more crap through the gauze. So you experiment with the oiling application (trial and error over 20mi, or 100mi, or 500mi intervals???) to arrive at the "correct oiling" amount and coverage, such that you'd be right on the verge of oil getting through to the hot wire but it can't quite. K&N does NOT provide you with a guideline for "how to accurately do trial and error to get the oil application correct", you have to create a logical one on your own. OR YOU COULD USE THE BETTER FILTERING STOCK ELEMENT
Personally, a K&N makes sense for a racer only, where you change the filter every race and doing so with a stock filter would be too costly. You can slightly overoil the K&N to get the desired filtering from all the track dust and smog, yet clean/reuse it before the oil ever gets a chance to drip through to the hot wire. Rather cheap if you require constant changing and can keep reusing it.
...then again, if the K&N is slightly over oiled per the above situation, wouldn't that indicate that if the oil 'can' get sucked through the gauze (oil applied to the outside of the filter), then the oil itself has become a restriction to the <proposed> increased airflow of the unit and thereby cancelled any intended benefits? Stock air filter for me please.
Just my opinion
However, we're talking significantly greater velocities in real world 928 useage. Consider as well that the surface area also makes a difference, opposed to the little display sample the marketing guys came up with. Throw in the path of flow etc, and the test gets rather complex.
On a bench, the K&N would likely flow more in a straight forward push air through the element test, but that higher flow doesn't traslate to application specific useage either. So, it leads to Louis/Heinrich's dyno scenario to identify differences in application specific normal useage. Seems to not offer any improvement.
Most importantly <for me at least> - IMHO, the K&N higher flow is due to less filtering, hence the requirement for oil to assist capturing what the gauze isn't. This oiling requirement begs the question, "Did you oil it too much? or too little?" Let's not kid ourselves here, the idea of "correct oiling" is easier spoken than replicated. If correct oiling means oil isn't getting to the hot wire, then it would seem quite easy to under-oil and think you did it correctly --> ah, but then you're letting more crap through the gauze. So you experiment with the oiling application (trial and error over 20mi, or 100mi, or 500mi intervals???) to arrive at the "correct oiling" amount and coverage, such that you'd be right on the verge of oil getting through to the hot wire but it can't quite. K&N does NOT provide you with a guideline for "how to accurately do trial and error to get the oil application correct", you have to create a logical one on your own. OR YOU COULD USE THE BETTER FILTERING STOCK ELEMENT
Personally, a K&N makes sense for a racer only, where you change the filter every race and doing so with a stock filter would be too costly. You can slightly overoil the K&N to get the desired filtering from all the track dust and smog, yet clean/reuse it before the oil ever gets a chance to drip through to the hot wire. Rather cheap if you require constant changing and can keep reusing it.
...then again, if the K&N is slightly over oiled per the above situation, wouldn't that indicate that if the oil 'can' get sucked through the gauze (oil applied to the outside of the filter), then the oil itself has become a restriction to the <proposed> increased airflow of the unit and thereby cancelled any intended benefits? Stock air filter for me please.
Just my opinion
09-18-2006, 03:38 PM
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Originally Posted by sharkmeister85
Correct (I think). And that is what I was saying(I think). But if more air goes into the engine than the "subroutine that adds a pre-programmed amount of time to the injector-open period" was expecting, what moves the fuel point to a higher value. At WOT the MAF and O2 sensor are no longer factoring in, correct?
Glenn
Glenn
N!
09-18-2006, 04:11 PM
#74
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Hello Glenn
The mistake in your understanding that although the O2 loop is disabled at WOT, the MAF signal isn't because its readings are used on the cruise fuelling map - based on rpm and MAF volts.
The cruise map is the main factor in determining the basic fuel injector on time.
The rpm only WOT map just adds a little more juice.
When you put the pedal to the metal, the engine takes more air, the MAF measures this, the higher load values are used on the map which give the exttra fuel required
It is easier to understand when you see pictures of the maps.
The SharkTuner LH User Manual is available on line form DR's webiste. It is listed under "tools". Scroll down the page and you will see that the USer Manual is available as a PDF download.
There's lots of pictures and descriptions of remapping in there !
The rpm only WOT map just adds a little more juice.
The mistake in your understanding that although the O2 loop is disabled at WOT, the MAF signal isn't because its readings are used on the cruise fuelling map - based on rpm and MAF volts.
The cruise map is the main factor in determining the basic fuel injector on time.
The rpm only WOT map just adds a little more juice.
When you put the pedal to the metal, the engine takes more air, the MAF measures this, the higher load values are used on the map which give the exttra fuel required
It is easier to understand when you see pictures of the maps.
The SharkTuner LH User Manual is available on line form DR's webiste. It is listed under "tools". Scroll down the page and you will see that the USer Manual is available as a PDF download.
There's lots of pictures and descriptions of remapping in there !
The rpm only WOT map just adds a little more juice.
