K-Jet - Interesting Metering Heads & Air Weighing Valves

Now I am in 'metering head mode' here are the details from my Merc.

1984 Mercedes 280GE 6 cylinder 2.8l G-Wagen
Metering head: 0438 120 115
Fuel distributor: 0438 100 069

 

Spot the deliberate mistakes?

1 - ≃ 9 should read ≃ 7. It is ≃ 9 at the other side!

2 - 0 438 100 150

Paul.

I have not got the foggiest how much they did machine out bore, or what shape it was.

From what I read in Bosch injection manuals, all standard K-Jets had the three steps in the funnel.

The 80/84mm in the lower Cone are for Idle and Transition.

The 84/100mm Cone is for Part-Load.

The 100/101mm Cone is for Full-Load.

Now, it would appear that sometimes there were only two or just one cone. This may have only been in KE-Jet Systems.

 

James.

I wonder if a chart with flow cone shapes would prove useful?

Something like the image below could be used to identify the relevant data points.

I can produce a better one.

It appears that the Throat Dia. 'A' is what Bosch use to define the reference 'Size' of a AMH. This would be called a 80mm AMH.



This is my Bosch Injection book. This book and a copy of the VW Dealers 16v KE-Motronic Training Manual helped me sort out my Audi 100.



What is nice they use VW and **** a lot as featured systems.

For example:

Below are examples of K-Jet AMHs for Early Rabbits - 60mm Throat and Later - 80mm Throat.



The top left picture shows alternative possibilities for Rabbit Throttle Bodies.

Standard - Polished - Opened Out Aftermarket - Single Throat

The conclusions were that it made small differences unless work was done on the AM and FD Heads.

 

Sorry to break the excitement but I took a set of calipers out today and it would appear the VWMS 8v AMH metering head bits are same as above, 101mm at the top, standard aperture at the bottom, same depths and a 3 angle cut. Booooring!

 

James.

This thread's title is not what you think!

I started the thread for you in the hopes you would collect and collate all datas for the K-Jet Heads.

I was going to take the FMH (aka FDH), from my EV and AAD, apart, to check metering slot sizes, etc.

I shall try to scale the images that Chris has posted and thence attempt to determine the cone shapes.

I note from the image on your post that you have the pukka Bosch K-Jet Manual. Lucky you as I guess it goes a lot deeper into the subject than my own manual? I was stuck with buying the Bentely one as I needed KE and LH information as well!

Sincerely,

Dave.

 

I recon that we can scale off this one!

16v CIS VW Motorsport.


And off this one!

This is the one Idorap posted and I recon. that they are the same!

 

Have a VWMS 16V metering head to measure here if this thread still requires that info ??

 

Better late than never Andrew!


Now we await roccodingo's dimns to compare!

 

Thank you Dave

An extra step / throat over most others then plus an additional 10 / 20mm at the top

Not sure of the model years that the details below refer to hence possible pub figures

1600GTI - 80 / 100 / 110

1800GTI - 80 / 100

1800GTI16v - 80 / 102 / 110

Motorsport - 80 / 90 / 105 / 120

 

VWMS 16V metering head. Bosch # B438 122 028








The underside of the VWMS air plate has the round ali attachment, maybe to smooth out the airflow ???





Seems to be pretty close to the dimensions posted earlier.

US spec air boot is ~ 5 mil smaller on the inside diameter than the KR unit, has a few extra breather holes also.

KR boot VW # 027 133 357.


PL Boot VW # 027 133 357C.

 

I have a volvo 2l kjet one in my MK1- 0438 120 043 and 0438 100 005. Also on the top is cast 056 which I believe is the same as the very early MK1 1.6 higher flow rate heads. ????

 

I thought I'd resurrect this thread as I've recently found a 1.6 air metering head in the garage and am going to be fitting it to the track car after a recent dissapointing visit to the rolling road and in an attempt to improve my fueling issues.....will update this thread after I have had it re-setup.....anyway I thought I'd post some pics and measurements I've taken. You'll see that the measurements are far closer to those of the VWMS item than a standard 1.8 metering head so hoping for good things along with the 16v WUR fitted


......next to a standard 1.8 jobbie......


.....and finally the all important measurements

 

That's interesting.

I await the results with interest. I have not fitted the VWMS unit as I assumed the motor would be over fueled without a cam change, porting and high comp. pistons?

Also. I wonder how the fuel metering slots, etc., compared?

 

Daved,

This is the very reason I intend fitting this as I have a 1900cc engine with a stage 3 8v head and 300deg cam running 11.25:1 CR

The current issue I have is overfueling mid range and then under fueling top end, my assumption is that fitting this metering head will smooth out the fueling curve as there will be less opening of the air flap to acheive the same airflow which in turn will lead to less opening of the plunger in the fuel distribution head.

Unfortunately I don't think the fuel distribution head will be servicable as the plunger is stuck in position and as it has been sitting for many many years I have no idea of the condition of it internally

The plan will be to use the 1.8L fuel distribution head as my understanding of this component is that it does exactly 'what it says on the tin' and just distrubutes the fuel based on the position of the plunger and therefore has a minimal effect on the fueling curve as such. By 'tweaking' system and control pressures overall fuel delivery across the range can be adjusted as this in essence shifts the whole profile of the fuelling curve either richer or leaner.

I will certainly update everyone with my findings

 

I have just checked the part numbers on all the fuel distribution heads I have and they are all 0438 100 100 with the exception of one......which is the one I robbed off of my Campaign in order to get the Red Trackcar up and running originally! This was one that I had previously given a bit of a fettle and painted some years ago when I was tidying up the Campaign and was a spare I had....it only turns out that it's a 1.6L one To be honest like many others I never paid much attention to the part numbers on the fuel distribution head! Anyway the part number on it is 0438 100 079 for those that are interested and it will be being used with the matching 1.6L air metering head shown in my earlier post

I wish I had the time and money to do back to back testing of the fuel distribution heads on the rollers but for now we'll just have to make do with the back to back of the different air metering heads using the same 1.6L fuel distribution head.....what I can tell you is that with this 1.6L fuel head the normal rich mid range dip and then going lean at the top end trend is still exhibited, so I don't really believe that the fuel head plays much of a part in the issue

 

I have 16v WUR fitted, however I don't know if it is because of the duration of cam I am running but the fueling profile exhibits even more of a dip mid range than with a standard car, or at least so it seems.

To give you an idea of the sort of levels I am seeing....with the AFR adjusted by tweaking the control pressure at the WUR to give the correct fueling for max power at the top end of the rev range (12.5-12.8:1 AFR or 0.85-0.87 lambda) the AFR between 4000-5400rpm is less than 11:1 or 0.75 lambda which is way too rich under load and is in rich missfire territory. It has been previously proven that all adjusting the control pressure up and down does is shift the fueling curve profile up and down, it does not change the shape of the profile to any real extent. It seems, from everything I have read, the only component that will chenge the shape of the fueling curve profile is the air metering head itself due to the different shape of the cone. We will find out for certain next week when I get it back on the rollers with the 1.6L fuel metering head

 

11:1 is "rich" but certainly not at misfire levels. Yes you will loose some torque in the speed range this level of fuel mixture will occur. However if the upper rpm range is displaying the exhaust lambda you stated then there is very little to be gained for a "peak power" measurement on this setup.

I can back up jamesa's suggestion, by own experience, If the 16v WUR is adjusted to enlean the mixture in the mid speed range you can achieve closer to best torque fuel mixture and not much delta for WOT when the engine vaccum heads to atmos. A good compromise to the K-Jet system.

Some non-**** advice....12.5-12.8 is not the best torque fuel mixture on these engines

To back up Mike H, to seriously wake up these engines and on your case a non standard motor, you need an SEM and a matching calibration. Unless there is a limitation for racing, the less mechanical controls you have the better.

Kind regards.

Toyotwhat

 

I appreciate the feedback However this thread is not really about my engine but more about comparisons between the different air metering heads available and their impact. Let's see what gives next week with empirical back to back data of one air metering head vs another

But in brief reply to a couple of the points you have made, I was not meaning that the 11:1 figure was missfire territory but rather it is heading that way, apologies if this is not how it reads and for any missunderstanding caused. I stated that in the rpm range shown this was the highest the AFR reached.....in actual fact the mean of the AFR within this range was 10.8:1 with a low of 10.5:1!

I know that adjusting using a 16v WUR will provide a decent compromise, however I feel that using the 1.6L air metering head and 16v WUR will provide an even better compromise....clearly if you have tried this previously and can provide empirical data to prove this is not the case I'm sure we would all love to see it?

As I replied to Mike I have no intention of switching to SEM on this car as I will ultimately be selling it and do not want to throw money at it that I will never recover

Cheers

 

Right then....

I managed to get an hour on some rollers local to me yesterday afternoon, as I wasn't able to get on the rollers I had car on a few weeks ago until second 1/2 of July. This is far from ideal I appreciate and doesn't provide the most accurate of comparisons I know....however assuming that both sets of rollers are correctly calibrated and the AFR equipment being used is also correctly calibrated the comparison should be valid for what we are discussing as there are no calculation factors to be considered and it is all 'raw' data The fact that both sets of rollers gave the same max wheel power to within 0.5 bhp, once fueling was optimised, leads me to think the stated results are valid

I have requested the raw data from the rolling road used yesterday so that I can plot AFR vs engine speed represented by the change in air metering head. What I can report is that on the intial power run with exactly the same settings on the 16v WUR as was optimum for the original 1800 air metering we were running lean all the way through the rev range at in excess of 14.0:1 AFR, so this shows that the 1600 air metering head flows significantly more air than the 1800 item.

Next step was to increase the fueling by reducing the control pressure via adjustment of the 16v WUR. After several runs, adjusting after each, we reached the point where additional fuel was having no effect on the power curve and it started to drop off, at this point we returned to the previous control pressure and re-ran to validate it. For best torque and power spread we ended up with an AFR of between 12.4-12.8:1 across the range, the guys on the rollers were quite surprised that this is where we saw the best results as they expected to see it around the 13-13.5:1 AFR range, the conclusion was that the extent of head work and the long duration (300deg) cam may be needing the additional fueling to work to it's optimum. As a result of the better fueling throughout the mid range pick up was drastically improved and torque came up a little as well, idle quality was improved and more stable, all in all not a bad result and i think this verifies what has always been suspected that the early 1600 air metering head when combined with a 16v WUR allows for a far better fueling curve throughout the rev range

 

The VWMS cars ran twin pumps and a manually adjustable pressure regulator, insead of the WUR!

What are peoples thoughts on this set-up?

Reasons? Advantages? Disadvantages?