The S42 Race Engine !!!!

[swiss318is]

Edit: Found a page but only thumbnail photos, the bigger ones does not seem to work? One good pic on the frontpage though http://www.scheel.ch/ its under "Motorsportteile".

poooh... :eek: right know i hate you!!!:D

[mkodama]

Carbon has to be one of the greatest elements.
From it we can get carbon fiber, which has an incredible strength to weight ratio.
Graphite, which is a self lubricating conductive metal
Diamonds, which are the hardest thing on earth
Carbon dioxide used for photosynthesis, although too much Co2 is bad
And a whole host other shit that i cant be bothered listing

Don't forget, carbon is also one of the main parts of gasoline!

Im not sure of the reason why slide throttle dont give as good modulation as butterfly valves, i think it has to do with the shape of the intake port as they are opening up.
Yes, they dont impede the port at all at full throttle, but at part throttle, the entrance into the runner is offset greatly to one side of the intake runner. This might have something to do with it.
Also there is a much large area of friction with the throttle plate running inside the mechanism as opposed to the small pivot area of the butterfly valves.

I dont know about their responsiveness, im sure its pretty good tbh, but its the modulation that id be worried about.
It really depends how you like to apply the throttle.

I remember from an F1 article with ferrari, they were describing how they set up the pedals for schumacher and barracello.
Barracello liked his pedals to be basically on or off, whereas schumacher like his to be really sensitive, with much more resolution in throttle position.
Just shows that two very experienced drivers can have very different tastes for throttle modulation.

I was thinking about the opening being offset to one side, and wondering how that might affect anything, but I still can think of any good theory to why it might cause a problem.

The issue of friction is probably very small if the slide throttle is well designed.

And I'm also wondering if the throttle modulation is really as bad as what it's cracked up to be.  The only sources I've seen it from are people stating it online, but never from anyone with supporting evidence.

The reason that the slide throttle are hard to modulate is because the intake runner area increases/decreases greatly at some positions. Friction shouldn't be much more than a conventional throttle if the slide throttle is designed properly with bearings but maintenance/greasing is much more important. I'll see if I can find a good photo of one design.

Edit: Found a page but only thumbnail photos, the bigger ones does not seem to work? One good pic on the frontpage though http://www.scheel.ch/ its under "Motorsportteile".

Great link! I downloaded all those photos, hehe, might use them for future use.

And I did the math for the area for air to pass through as you increase the throttle.  I found that, when the throttles tubes are circular and the sliding plate has circular openings(just like the M3 slider throttle in the link you posted for example), the area for air to pass through increases directly proportional to the throttle plate movement.  For example, move the the slider plate halfway through it's range of motion, and the throttle opening will have half the area of its maximum.

[RouteZeroDesign]

I think it has to do with the flow around the plate when it is semi-closed.
You see, air flows in onion type layers, This is called laminar flow.
The outer layers will flow slower due to surface friction, whereas the inner layers will flow faster as the friction it receives is allot less then the outer layers.

Without getting into a discussion about thermodynamics, i believe the throttle plate sticking half way across the port creates turbulence as the layers mix and the air tries to squeeze through the gap.
Im not sure exactly why this effects throttle response but i assume it has to do with the time it takes air to get from the plenum to the combustion chamber, and this plate blocking the way acts like a sudo-chicane, to what preferably would be the straght road of your intake runner.

Have a look here for some useful articles:
http://www.profblairandassociates.com/RET_Articles.html

And I'm also wondering if the throttle modulation is really as bad as what it's cracked up to be. The only sources I've seen it from are people stating it online, but never from anyone with supporting evidence.

The problem with slide throttle bodies, is that anybody who can justify the expense of buying them is going to keep information to themselves.
Therefore, for the people who do give information out, the information will generally based on limited experience or word of mouth.
I dont have any hands on experience (yet ) of slide throttle assemblies, so what i know about them is based on things i've heard and theoretical ideas.

Paul

[strypt]

Well I have to admit I have no first hand experience myself of slide TB's and this time only passing on the information that people told me

[mkodama]

Well I have to admit I have no first hand experience myself of slide TB's and this time only passing on the information that people told me

You're not alone!:rolleyes:

I think it has to do with the flow around the plate when it is semi-closed.
You see, air flows in onion type layers, This is called laminar flow.
The outer layers will flow slower due to surface friction, whereas the inner layers will flow faster as the friction it receives is allot less then the outer layers.

Without getting into a discussion about thermodynamics, i believe the throttle plate sticking half way across the port creates turbulence as the layers mix and the air tries to squeeze through the gap.
Im not sure exactly why this effects throttle response but i assume it has to do with the time it takes air to get from the plenum to the combustion chamber, and this plate blocking the way acts like a sudo-chicane, to what preferably would be the straght road of your intake runner.

Have a look here for some useful articles:
http://www.profblairandassociates.com/RET_Articles.html


The problem with slide throttle bodies, is that anybody who can justify the expense of buying them is going to keep information to themselves.
Therefore, for the people who do give information out, the information will generally based on limited experience or word of mouth.
I dont have any hands on experience (yet ) of slide throttle assemblies, so what i know about them is based on things i've heard and theoretical ideas.

Paul

Good info, and thanks for the link to the articles.

And about the turbulence cause by the sliding plate, I wonder what would make it any different than that of a butterfly throttle.  It would be a major disappointment to spend money, research, and time on something that had a major flaw in it.

I'm going to try and ask my neighbor next time I see him since he is an expert when it comes to race cars.  He does the prep work for a PTG E36 M3 and a Renault Formula V6 car, so I would hope he knows what he's doing at least!

[swiss318is]

i see, i see!! i think i have to take some pics of the dtm m3 e30 sliders and talk with my engine-guy...
by the way... on my s42 pics you see a slider throttle too...

[swiss318is]

finally i found a video with the S42 powered e36, from which i took the pics..
enjoy..
http://www.youtube.com/watch?v=fHzH8L9R4Q8&feature=related
a famous hillclimb race in switzerland.. 20min from my home!

[mkodama]

finally i found a video with the S42 powered e36, from which i took the pics..
enjoy..
http://www.youtube.com/watch?v=fHzH8L9R4Q8&feature=related
a famous hillclimb race in switzerland.. 20min from my home!

Damn, that BMW and Opel are fast, especially considering they have "only" 2-liter engines.  Those drivers are also crazy good.

[swiss318is]

i like the sound!!i could fit a s42 in a e30 318is?... hmm.. i have to think about that!!:D

[mkodama]

The S42 is so awesome, I just really wish there was some widely available crankshaft with an 85mm stroke to put in a normal M42 engine.  It seems like just about the only thing that isn't commonly available that you would need to replicate the S42.

86.5mm bore and pistons aren't too hard
carbon intake manifold can be made without too much effort
slide throttle doesn't seem too bad, just a little designing and machining
head needs some porting, larger valves, cams, and solid lifters
engine management, (I'm already working on this )

But that 85mm stroke crankshaft is the hard part.  Anyway to modify a crankshaft to either increase or decrease stroke?  Like add 2mm to the M44 crank or remove 3mm from the M47 crank?

[PaulC]

Great thread great topic great pics. Can't wait to see how things go.

[swiss318is]

i like the sound!!i could fit a s42 in a e30 318is?... hmm.. i have to think about that!!:D

an original one!!!!

[mkodama]

i like the sound!!i could fit a s42 in a e30 318is?... hmm.. i have to think about that!!:D

an original one!!!!

You confuse me. :confused:

[mkodama]

I finally got to see a 320i STW with an S42 engine! I spent a day at the nurburgring and then the night in the nearby town, which had a BMW M Test Center with two race cars in the front.  One of which was an E36 320i STW, the other being a similar race car, but diesel.

[tim_s]

the nearby town you speak of where those pics are taken is nurburg dude. Did you get any laps in? Only been 3 months since last trip in the 2.1, but already really missing the place. Can't wait to get out there again. There's a trip I'd like to join in Oct, I have a new engine to fit and run in if I'm going to make it in mine by then so may have to psgr! I've also been having evil thoughts about swapping to an e36 chassis.