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Max boost?
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2004
Location: Somerset, UK

PostPosted: Tue Nov 19, 2019 11:02 pm    Post subject: Reply with quote

ideola wrote:
Carrera RSR wrote:
What do you think is limiting the Clubsport Dan? CR, intake temps, DITC?


Too much fuel is causing detonation. The way the CIS works on that car, AFR goes 8.0:1 on WOT. The theory, from what I've read, goes something like this:
- rich mixture causes uneven concentrations of fuel in the chamber
- this "clumping" leads to a slow broken flame front
- cylinder pressure rises faster than the flame front can propagate through the cylinder
- "fuel clumps" ignite from the increased pressure and explode instead of a nice smooth flame front causing a knock sound

I am convinced it has nothing to do with ignition advance, intake temps, or CR. What I can't figure out is why the Euro-spec S2 CIS setup overfuels so much more than the S1 setup.

I could attempt converting the Club Sport to S1, but even then, I'm still geting 10:1 fat at WOT on the 941, which is still WAY too rich. I've thought about putting a bleeder valve inline with the WUR's boost signal line to see if that might help with managing control pressure, but have not had time to experiment. The problem with that technique is that it would still be very binary, so you'd have to pick a happy medium point where you want to bleed off pressure. It would be interesting to see if just maintaining stock MAP at the WUR (i.e., 10 PSI on a Euro spec car) would help.


Is it detonating early on mid rpm as boost triggers the WUR? Or top end?

The boost enrichment kicks in at circa 0.5bar I was told by KMI injection. This is why I tried to emulate Brian Leasks set up as the mid range is too rich. I have the rpm triggered solenoid valve opening the boost line to WUR at 4600rpm. By then the AFR demands more fuel.

I can't offer advice on DITC. Being an S1 I never needed DITC but I do use several S2 parts like fuel metering head and WUR, both have been opened up to flow more fuel than stock.

You could always turn up the boost to 1.5bar and use all the fuel being dumped in???
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2036
Location: MI

PostPosted: Wed Nov 20, 2019 3:08 am    Post subject: Reply with quote

ideola wrote:
CIS is the gating factor.


A microsquirt, a MAP sensor, and a wideband will allow you to program your fuel map in tunerstudio by taking control of the frequency valve on US lambda cars about the same way as e-cis is manipulated via FD diaphragm differential pressure..

Priority optional extras would be intake air temp sensor, coolant temp, sensor, TPS, and basically any sensor you want to log..

It will do EBC just by wiring in a solenoid, it will fire nitrous and maybe even do a dry shot on CIS imagine that, spray your meth, spray your IC, it will still do many more things while used to map CIS..

It will also control your ignition if you want to give it a real crank signal like those toothed wheels, then you can map your ignition, rev limits, launch control, anti-lag, all sorts of capabilities..
Like EDIS, or GM truck coils (coil near plug)..
I have a sack of GM truck coils off an H2 hummer 6.0 sitting here waiting for me to use them when/if I want..

A long harness microsquirt is $388.00 + a bit for a good MAP sensor and you probably already have a wideband..

That's what I'd do.. But it takes a whole lot of time, and a bit of money for pieces..
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ideola  



Joined: 01 Oct 2004
Posts: 15506
Location: Woodstock IL

PostPosted: Fri Nov 22, 2019 3:22 am    Post subject: Reply with quote

Carrera RSR wrote:
Is it detonating early on mid rpm as boost triggers the WUR? Or top end?

I hear the "rattling / pinging" when it goes past 10:1 AFR, which is from 3/4 to Full throttle.
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morghen  



Joined: 21 Jan 2005
Posts: 8197
Location: Romania

PostPosted: Fri Nov 22, 2019 4:28 am    Post subject: Reply with quote

mine only detonated at WOT above 5000 RPM and over 1.1bar
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