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Stock ignition and fuel injection matched to K27 and SC cams?

I am not satisfied with the partial load, low rpm driveability of my 77 3.0 turbo. It is worse, now that we have some cold weather. On boost, the performance is great. It is easy to hit the 7200 rpm rev limiter running through 1st and 2d gears.

I have Euro exhaust, SC cams and K27-7200. Ignition and fuel injection are stock. The WUR is the later 054 from the 78 and 79 3.3 liter cars. I have left the top (vacuum) hose off the WUR.

My question is whether I should expect the stock ignition and fuel injection to work with the modified cams and turbocharger. In other words, does the ignition distributor need to be recurved to go with the modifications, or does the fuel injection need some adaptation?

Fuel mileage is not so great either.

The engine is in excellent shape, otherwise.
Old 11-21-2006, 11:01 AM
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When I got into my rebuild, 3.4L, SC cams, B&B headers, Eletromotive XDi twin plug, K27-7200, etc. Stephen mentioned that once you begin the mods, especially cams, it's easy to run out of fuel. Of course my fuel head was a non-Euro type. At any rate I went ahead and installed Imagine Auto fuel head, just to be safe.
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Old 11-21-2006, 01:40 PM
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My engine is similar to yours.
3.3L 930
Euro Exhaust
SC Cams
K27-7200
Euro CIS, 112 WUR
B&B Intercooler
0.75bar

You do not need any added fuel or ignition.
You do need to connect the Vac and Boost hoses to the WUR.
If your fuel mileage is bad (less than 18mpg highway) you likely need to adjust your WUR or clean your fuel head or both.
Wild guess is that your CO is high and you are running rich.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 11-21-2006, 04:58 PM
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Quote:
Originally posted by RarlyL8
My engine is similar to yours.
3.3L 930
Euro Exhaust
SC Cams
K27-7200
Euro CIS, 112 WUR
B&B Intercooler
0.75bar

You do not need any added fuel or ignition.
You do need to connect the Vac and Boost hoses to the WUR.
If your fuel mileage is bad (less than 18mpg highway) you likely need to adjust your WUR or clean your fuel head or both.
Wild guess is that your CO is high and you are running rich.
My car is actually running a little lean, or a little too much advance, at low load, low speed. The symptom is surging, or occasionally spitting back. The vacuum is not high enough to open the auxiliary air valve (valve opens around 20 in. mg., highest measured vaccuum I've been able to measure is around 18 in. mg.), so I'm getting occasional light backfire on overrun. (I don't have any vacuuum leaks, however.) I suspect my poor fuel mileage (around 16 highway mpg) is from the boost enrichment coming on too early (the K27). When Brian Leask's kit is available, I may try that. The car has great high rpm, high load performance.
Old 11-22-2006, 01:52 AM
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Crotchety Old Bastard
 
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Have you tried swapping out your WUR?
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 11-22-2006, 12:15 PM
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I have put the WUR on a fuel pressure gauge, and it checks out. I am not trying to troubleshoot on this board - I think that would be difficult. I'm just trying to get an idea of whether I CAN troubleshoot this car, or whether a different ignition advance, for instance, is needed for the modifications. In other words, am I wasting my time hoping for perfect driveability with these mods? The car drives pretty well as it is, and I have plenty of power.

By the way, Rarlyl8, I share your thoughts about the WUR, but come at it a little differently. My car originally came with a WUR part no. ending in "022," which has a vacuum control. The car now has an "054" WUR, which has boost enrichment. Evidently, only the 054 is available as a spare. I would like to find a working 022, and see if that helps.

Thanks for your ideas.

Last edited by Tom F2; 11-23-2006 at 03:18 AM..
Old 11-23-2006, 02:55 AM
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Re: Stock ignition and fuel injection matched to K27 and SC cams?

Quote:
Originally posted by Tom F2
[B]
My question is whether I should expect the stock ignition and fuel injection to work with the modified cams and turbocharger. In other words, does the ignition distributor need to be recurved to go with the modifications, or does the fuel injection need some adaptation?
/B]
In a word; yes.
The CIS is a mechanical system and will adjust to changes in increased air flow through the metering plate. The important thing is to baseline your CIS system. First with cold and warm control fuel pressures and system pressure. Then get a baseline of your fuel mixture at operating temperature. If you are lean, your can adjust your idle fuel mixture. This will effect the whole fuel mixture curve the engine runs under.
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Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, 8:41 R&P
Old 11-23-2006, 06:59 AM
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