PorKen

Cylinder - plenum runner length, inside + outside (±1mm)

Right (passenger)
7 - 29
4 - 98
1 - 98
6 - 76

Left (driver)
8 - 84
3 - 29
2 - 29
5 - 111

Firing order
1-3-7-2-6-5-4-8

T ID: ~73mm
Runner ID: ~45mm

Hilton

150 of the low-compression 86's were sold into Australia.

Not sure about switzerland - they didn't have a specific country code in '86 I can search by.

If there was an option code for the smog motor, I can get an exact number (including German cars with the 32V engine).

Hilton

Update - did a search by engine type for M28.45 and M28.46 (the 32V low-compression motor).

Germany (C00) 214
Switzerland (C10) 49
Austria (C11) 2
Australia (C23) 150

Total 415 cars with the low-compression pistons in the early 32V motor. All of these were what the US guys would consider to be 86.5. 306 Auto's, 109 Manuals.

Rick Carter

Thanks, any in a salvage yard?

Darklands

I have one of the 109 manuals! :-) I think a good engine for forced induction.
I think in Germany are ~ < 50 S 3 on the road.
Ken,I have a lot of work on the farm and can´t research the performance loss with the 80 mm tb.

Vilhuer

ROW 32V S use basically US 32S pistons which just have deeper valve pockets etc. Its fairly easy to modify US pistons to ROW spec or even larger cc. I'm currenly building S4/S3 engine hybrid which will have S4 crank, rods and heads while pistons are US model S3 with larger valve cuts for 39mm 968 intake valves. Cams will be S3 with 0.5mm increased lift and CR around 11:1.

Rick Carter

Thanks Erkka, I have an extra engine that at some point I'll modify.

hernanca

Bit of a thread revival, but..

Could it be that as the air races up the T, some of it SLAMS into the top of it and causes a shockwave to come back, instead of the air being split and coerced to go left and right, to the chambers where the horn mouths await?

Lately, I was wondering how easy it might be to modify (or replace) the top of that "T" in the S3 Organ pipes... Wonder if even just cutting a slit* and inserting a splitter at the top (well sealed, of course) would be of help?

(* taking any necessary precautions, since this part is made of Magnesium or Magnesium alloy)

PorKen

I've thought about the 'T' many times. I think it might flow a little better if the entire piece was swapped with a 'Y' shape, or even a molded piece epoxied on to the roof of the 'T'.

AFAIK, the 'T's secondary function is part of the S3 manifold harmonics, so I think at least part of the 'T' has to remain open to both plenums.

I thought it would be interesting too to see if putting in a flappy type valve in the 'T' would work like the S4 manifold.

simos

Interesting discussion... Not even pretending to be expert in these areas, just exited about this stuff..

Following is more_less related article to this discussion:
http://horsepowercalculators.net/int...anifold-design

"
This usually leads to an oddball design by most OEM’s of an over-sized plenum with a smaller throttle body and runners to try to boost gas velocity, or an undersized plenum (that will be consumed faster for better response) but with a larger throttle body that will not bottle neck the engine as it tries to pull in more air from the outside to stay alive at higher flow demands at higher rpm.
"

If S3 is having over-sized plenum, large runners and you'll add larger throttle body, the result may be too slow velocity, which may also hurt higher flow demands...

Haven't also seen any S3 intake and wondered if it does have any trumpets like S4, which are raised from plenum wall, to help speeding up the velocity in runner itself. I have also document, which will explain the effectivenes of various shapes of runner inputs. The difference between worst and best is about 10% IIRC.

Simo

hernanca

Hey Ken - I figured you had pondered it - I made sure to do a search before posting, and half expected to find an existing post from you!

I like the simplicity of epoxying a molded piece to the roof of the 'T' - very do-able!

Along the lines of the flappy idea: maybe alter the configuration of the 'T' roof between a pronounced split (low RPM's) to a less pronounced split (high RPM's). Continuous varying would be ideal, but on/off like the flappy might still yield gains. Interesting stuff. Disrupting the harmonics is a concern, but it could be worthwhile, and not very difficult, to explore these ideas.

Simo - thank you for the link! The S3 intakes do also have trumpets (bell mouths) sticking into the plenums, like the S4. If I find a picture, I will post it, if someone else doesn't.

Darklands

I have a 80mm tb in my S3 and I have the feeling the engine lost power.

PorKen

Karsten,

I think the 80mm may be making it lose torque at lower rpm. If you fully open the Drosselklappe (TB) at low rpm, torque goes down as the airspeed drops. Newer cars with FBW throttles are programmed to open at the ideal amount at different loads/rpm for best airspeed and intake harmonics.

Most people learn this instinctually after driving their cars for some time - how much to open the throttle at what speed for best acceleration. I am often upset initially after a new round of improvements, because I expect to put the pedal to the floor and have it go like crazy at any rpm. It is only over time, as I relearn the pedal dynamics, that it feels 'quick', again.

I think you have to do what I have done with black car, gasket-match the intake, and retard the cam timing a little to take advantage of that 80. But it may only make for more HP at 6000+rpm, where it can only be measured, not felt.

Darklands

Ken,
good advices for this problem.I will match all intake parts next year after the rebuild of the small block.I have so little time for my hobbys but the S 2 is next week on the road again.
On the 7 th of november we will start my "new engine" with 625 KW.It´s a GE Jenbacher 312.After 2 years of bureaucracy and constructing the biogas plant is ready.