neat idea

perhaps these pics from an unmolested rubber will help ?







don't forget , the design of the rubber is to interface the throttle body inside diameter to the inlet port

generally without too much change in diameter (although one can see that bmw did do some change in diameter )

the diameter of the port side should match the head  and on the rubber adaptor this is easy to achieve



good luck

You need the slight internal cone shape because it accelerates the mixture into the combustion chamber.

Thank you Charlie, i really apreciate your effort with the measurements and pictures! And i Think Everyone like unmolested rubber better

I think the only messurement i need is the total height and Also from the top down to the groove where the throttlebody sits om top of (internally)
If you have the time to do it i can’t thank you enough

Maybe you misunderstood me dai, i’m going to change the coneshape to different angle which should help the engine pulse

hope this helps





cheers

Thank you, this is a big help! I really appreciate the effort

charlie99 wrote:hope this helps





cheers

Charlie do yo know the diameter of the inlet port? I might adjust the diameter so I fit directly on to the inlet port to achieve a good flow. Also do you know the diameter of the o-ring which is seated under the inlet manifold?

best regards

there is no ring under the rubber on k100 8 valve types .that I have seen ..I think there is one under k1100 - k100 16 valve types , because the rubber integrates the injector as well .

if you look at one of the earlier pics I posted in this thread ...you could guess the port diameter ....the one shown maybe about 1/2 a mm larger than stock  because I rework the inlet path to take out irregularities , get rid of the short turn lip and mod the valve guide  for better flow , which works well .

charlie99 wrote:there is no ring under the rubber on k100 8 valve types .that I have seen ..I think there is one under k1100 - k100 16 valve types , because the rubber integrates the injector as well .

if you look at one of the earlier pics I posted in this thread ...you could guess the port diameter ....the one shown maybe about 1/2 a mm larger than stock  because I rework the inlet path to take out irregularities , get rid of the short turn lip and mod the valve guide  for better flow , which works well .

Okay Thank you. I might make these ones with a o ring under the bottom. But I think I will make the smaller diameter in the inlet manifold around 30.50 mm then, to avoid having a big edge which will prevent flow.

that sounds about right

So here is a quick update on the manifolds, all four are milled in aluminum. They still need some work and which can only be done when I have the correct measurements of the inlet port. 

I will keep updates coming

charlie99 wrote:that sounds about right

I saw your thread with you build and it is really amazing Charlie... The part with the throttle bodies airflow measuring was very interesting and I might improve mine as well. Do you think removing the ridge inside the throttle body will be worth it maybe with a bit of polishing? or will it lean out the mixture if the engine breaths more air in?

I don't think that the ridge removal will lean out the mix , but will act as some disturbance to flow with the change in diameters at that one point

I guess the ideal would be to have a nice smooth internal tube of constant diameter , rather than a gap between diameters , if that makes sense .

the machining looks great in your pic,  well done , wish I had the skills and resources for something similar .

Beautiful work, Tommy.  That's real eye - candy!

Changing the venturi angle will affect the engine, probably in a bad way. There's no chance it improves its performance if you don't adapt the following tube in shape and diameter to fit these new features - and if you don't use a flow bench to test it.
Anyway, as on your K100 has an injection port very close to the valve, it's pointless to create turbulences before in the inlet manifold as there's no fuel to be mixed with air at this place.
Besides this, the rubber manifold provides vibration insulation to the whole injection system. Expect rapid wear and problems with the internal card of the flowmeter.

charlie99 wrote:I don't think that the ridge removal will lean out the mix , but will act as some disturbance to flow with the change in diameters at that one point

I guess the ideal would be to have a nice smooth internal tube of constant diameter , rather than a gap between diameters , if that makes sense .

the machining looks great in your pic,  well done , wish I had the skills and resources for something similar .

Thanks, it is never too late to learn  I haven't pulled the throttlebodies of yet, but I'm able to mill out that ridge if I decide and then lightly polish it to make it smooth. I guess that's more accurate than with a Dremel. I will make everything as smooth as possible with no ridges or edges which will prevent flow.

jbt wrote:Changing the venturi angle will affect the engine, probably in a bad way. There's no chance it improves its performance if you don't adapt the following tube in shape and diameter to fit these new features - and if you don't use a flow bench to test it.
Anyway, as on your K100 has an injection port very close to the valve, it's pointless to create turbulences before in the inlet manifold as there's no fuel to be mixed with air at this place.
Besides this, the rubber manifold provides vibration insulation to the whole injection system. Expect rapid wear and problems with the internal card of the flowmeter.

I'm not focusing on the flowmeter for now, not sure if that's restrictive anyway. My goal is not to create turbulens, but better breathing.
When looking down in the original inlet manifold you can see the inlet port is slightly smaller than the inlet manifolds exit, which create an edge which result in "bad" flow. 
The plan is simply to make the internals smooth all over since I have nothing better to do. 

To make your engine breath better, first give him big lungs, then you'll consider milling the teeth to enlarge the mouth. This engine is filled only by aspiration and the only restriction is the flowmeter, not the manifolds nor the air filter. It's not because there will be a shiny welcoming manifold that more air will magically run into it, it's all about pressure & couter pressure.
Without flowbench measures, you can be sure to lose more than you gain modifying the intake. And if by chance, you manage to increase the amount or the speed of the air getting inside, how will you adjust the fuel in adequation?
The direct and big admission ports are designed for high rev super square engines. What a k100 engine is definetely not -and will never be.

jbt wrote:To make your engine breath better, first give him big lungs, then you'll consider milling the teeth to enlarge the mouth. This engine is filled only by aspiration and the only restriction is the flowmeter, not the manifolds nor the air filter. It's not because there will be a shiny welcoming manifold that more air will magically run into it, it's all about pressure & couter pressure.
Without flowbench measures, you can be sure to lose more than you gain modifying the intake. And if by chance, you manage to increase the amount or the speed of the air getting inside, how will you adjust the fuel in adequation?
The direct and big admission ports are designed for high rev super square engines. What a k100 engine is definetely not -and will never be.

No one mentioned high revs. Actually i didn't know the flowmeter was the restrictive part, I haven't found that written anywhere. 
As I said in the post, all of this work is done because my intake is leaking, and while I'm at it why not make it shiny and smooth out the internal edges. The changes I'm making are tiny. Very tiny. I'm not expecting any horsepower gain, but a nice running engine.

Tommy2305 wrote:Actually i didn't know the flowmeter was the restrictive part, I haven't found that written anywhere.

That would depend upon how the word restriction is defined.

Tommy2305 wrote:No one mentioned high revs. Actually i didn't know the flowmeter was the restrictive part, I haven't found that written anywhere. 
As I said in the post, all of this work is done because my intake is leaking, and while I'm at it why not make it shiny and smooth out the internal edges. The changes I'm making are tiny. Very tiny. I'm not expecting any horsepower gain, but a nice running engine.

 thats the aim ...to make the intake a smooth flow ...  keep at it !!!

charlie99 wrote:

Tommy2305 wrote:No one mentioned high revs. Actually i didn't know the flowmeter was the restrictive part, I haven't found that written anywhere. 
As I said in the post, all of this work is done because my intake is leaking, and while I'm at it why not make it shiny and smooth out the internal edges. The changes I'm making are tiny. Very tiny. I'm not expecting any horsepower gain, but a nice running engine.

 thats the aim ...to make the intake a smooth flow ...  keep at it !!!

Yes, I will proceed    But I'm thinking that ridge inside the bottom of the throttle body might be made to create turbulens inside the cylinder to mix the air and fuel faster. Maybe it's a bad idea to remove? I'm thinking it is there for a reason

no the rubber is made to adapt the bore of the throttle bodies to the inlet port which are different diameters ...also gives some vibration isolation but not much as the whole plenum and air box and afm are also rubber isolated multiple times

Tommy2305 wrote:But I'm thinking that ridge inside the bottom of the throttle body might be made to create turbulens inside the cylinder to mix the air and fuel faster.

Do you really think that it would create  appropriate turbulens as the butterfly flap just above is much more disturbing for the air flow?
It's nonsens to worry about turbulens when it's only air in the tube at this place. The K100 injector is designed to aim the back of the valve, which is very hot and vaporises instantly the fuel. Once it spits at the optimum instant, once it spits when the valve is closed and the engine is asked to wait the next cycle to swallow the mixture when the valve opens. It's pretty neanderthalian as an injection system, but it works. Yet it will never suit nor allow a performance engine, so don't search any improvement in admission line design, it won't improve anything since this L-jetronic is fitted.

I have been really busy, but here in the Christmas holiday I finally got the chance to work on the bike. 
I finished one manifold, to see how it would fit, and it was pretty good and the diameter goes from Ø35 to Ø31.45. The diameter is a little bit too small so I'm going to mill the smaller diameter up to 31.6, and make room for the injectors, underneath the manifold. 

While making those manifolds, i figured I might have to paint the engine and drivetrain, just to make everything look slick. Even painting the throttlebodies. 

Here is a couple of pictures:


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[url=https://servimg.com/view/20089755/24]
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I see what looks like a Mini in one of those photos.....

Are you planning on pulling the head etc etc off the K an putting it in the Mini?

92KK 84WW Olaf wrote:I see what looks like a Mini in one of those photos.....

Are you planning on pulling the head etc etc off the K an putting it in the Mini?

It would definitely be a good project putting a k100 head on one of the mini's! I've seen a guy pushing 140hp out of the a-series engine with a k100 head    but I don't think I have the time at the moment, but maybe some day