Dyno results - my 930 Sucks!

[beepbeep]

P.S.

Dyno of MB 2.3 16v before and after it has been "liberated" from CIS flapper. CIS body has been kept the same but it has been "gutted" from flapper:

[Maltese Falcon]

Goran, I've also got my CIS biturbo system working great with a pair of Andial 959 (grind) cams...which shouldn't work well at all with CIS . When prices/availability of CIS parts become an issue, I will upgrade to MoTech...until then
So...back on topic for now
Marty

[beamonk]

Goran, tell me more about the liberation of the flapper on the MBZ.

[beepbeep]

Hello!

Car is owned by a gentleman I "know" from local swedish track-racing forum. He converted from CIS to to aftermarket injection system (MAP-sensor speed/density). So it's a basic EFI-conversion where he replaced CIS injectors with EFI-ones but opted to keep gutted K-Jet assembly in order to simplify plumbing and retain stockish looks (important for smog-check here in Sweden). So motor is EFI-converted mill that draws air trough hollow K-Jet. I just opted to use his dyno graph as a interesting example of possible gains attainable by replacing K-Jet with something flapper-less.

I'll try to dig out his thread, there are more pictures of gutted CIS.

Regards,
Goran

[AvonGil]

Originally posted by beepbeep
So motor is EFI-converted mill that draws air trough hollow K-Jet.

It's not the lack of a flapper that caused this huge change in the curves. It's the new fuel injection system. There is a huge variable here and it's a tuned injection map vs the crude K-Jet constant fuel delivery. Way too many variables to show anything conclusive.

[beepbeep]

Originally posted by AvonGil
It's not the lack of a flapper that caused this huge change in the curves. It's the new fuel injection system. There is a huge variable here and it's a tuned injection map vs the crude K-Jet constant fuel delivery. Way too many variables to show anything conclusive.

Yeah, I bet untuned EFI is really bad (possibly even worse than K-Jet).

[rotorhead]

Does anyone know if I can bypass the thermatic valve with the vacuum line and route it directly from the throttle body to the distributer?

[rotorhead]

OK I am ready to put this engine back in. I found and fixed the following problems.

1. Air leaks under intake manifolds repaired (Thanks Maltese Falcon) Due to manifold not torqued down enough.
2. Leaking Vacuum advance line fixed and routed to bypass thermatic valve.
3. Rocker arms now torqued to 25ft/lb with rsr seals (instead of factory 13.2ft/lb)
4. Leaking turbo oil feed line repaired
5. Cam timing was 0.8/0.65 and now set correctly at 0.7/0.7
6. #6 exhaust valve gap was 0.4mm now 0.1mm

I believe that the low power issues were a result of 1,2,5 and 6.


Steve

[acapella8]

As I a newbee, I am thrilled to read posts like these. Sometimes I have to re-read 2 or 3 times, but they are good learning material for me.

-Tom

[KobaltBlau]

Good luck! I am sure you will let us know how it feels or show us the chart if you put it back on the dyno

[rotorhead]

Its been a while since I started this thread, but I finally seem to have found the problem.

It was fouled fuel injectors.

I took the fuel injectors in to a local shop to be tested and they flowed very unevenly, two of them hardly flowed at all. The spray patterns were all over the place at different pressures.

I have now had that tank removed and cleaned, replaced the rear fuel pump, fuel accumulator, fuel filter and put in six new injectors. Apart from dirty fuel this vehicle had sat for some time.

I think I found at least 80 horses.

I am rather relieved.... I'll post a dyno chart when I get a chance to have it done.

[sammyg2]

Not only did you fine extra HP, you prolly saved your pistons. turbos don't like runnig lean under boost and that is exactly what a partially clogged injector will do to a cylinder.
Now go out and enjoy that monster

[Wayne 962]

Originally posted by beepbeep
As far as I remember, they had to use special CIS assy's on 934's to get enough flow. Only reason for CIS on 934 was homologation rules. CIS sucked then and still does.

Yes, that's true. CIS is best made for VW Jettas - not performance sports cars. However, it was the best thing out there at the time...

CIS is limited because it uses relatitvely low-lift cams to avoid fuel reversion affects in the throttle body system. I suppose one *could* somehow make a CIS system that would work on independent throttle bodies, but it would be a lot of work.

-Wayne

[sketchers356]

Originally posted by cgarr
Welcome to the 912 club!

Craig

For some reason the funniest thing that I have ever read on this board.

Good luck on fixing the problem

[Lukesportsman]

Wayne,

Aren't you afraid of ruffling a lot of SCWD club members feathers. This coming from a guy still running tractor injection, but I agree that flapper doors are not conducive to max power.

[sammyg2]

Say what you want, but my CIS works very well and doesn't catch my engine on fire

(ducking)