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beepbeep beepbeep is offline
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Join Date: Jun 2001
Location: Sweden
Posts: 5,567
Hmm, so you are planing to keep CIS? I didn't understand that until now. I believed all this time that you were to use EFI.

Unfortunately, I find decision to keep CIS very unwise. CIS is one of first things to ditch when tuning 930 motors. All this talk about picking state of the art turbochargers and well-formed headers goes trough the window if you attach it to CIS.

I find your build budget somewhat skewed in that case. Trying to get more power from CIS is flogging the dead horse. It won't flow much more than 400 - 450hp no matter what you do. Porsche knew this all the time and build dual parallel K-Jet systems in their 934's in order to get them to breathe easier, and they didn't get so impressive power anyway. (They had to retain same fuel injection as in production cars for homologation reasons) It's not it's ability to provide fuel that is limiting, it's its construction. Airflow-measuring barn door will be there no matter what.

More or less stock 930 engine will provide 400hp all day long with modern (but not state-of-the-art) turbo and EFI. You went the other way and specced whiz-bang engine with costly parts but somehow decided not to correct this inherent 930 weakness.

With other words, you can probably achieve same HP goal with (considerably) less money if you start with EFI first. I believe that single-plugged 3.3L engine with K27- turbo and EFI will dyno as much power as your 3.4L dual-plugged GT35 mill with costly headers and CIS.

You have specced impressive mechanical base to build on, I suggest that you try to save some money on turbo-choice to begin with and use that to try to convert the engine to EFI+computerized ignition from first begining.

Decent EFI like SDS will cost around 1000$, including injectors, MAP-sensors, direct-fire coils and whole sheebang. Otherwise it would be such pity to build a monster engine just to choke it with such substandard fuel system. I would rather save some money on turbo side in order to convert it than go for best turbo and keeping the CIS.

I understand you allready bought the ingition parts, so it's nothing to argue about. I'm just saying that EFI will make a huge difference performance and performance per dollar-wise, proportionally bigger than other trick parts you have in your engine.

Thank you for your time,

Last edited by beepbeep; 10-13-2004 at 09:43 AM..
Old 10-13-2004, 09:40 AM
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