DIY OBD-1 Varioram Conversion Step by Step (More or less)
01-02-2009, 04:14 PM
#20
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That is a great write up. My buddy just converted to a supercharger and gave me his intake system. I think I might do it after reading this. Thanks again great pics.
Baron
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01-02-2009, 05:42 PM
#22
Burning Brakes
Damn it! My engine rebuild is completely done, but still sitting on the engine stand. I have a v-ram intake in the basement and I decided not to do the upgrade. But now..........
Very nice job and thanks for the info.
Very nice job and thanks for the info.
01-02-2009, 05:47 PM
#23
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Great work indeed! You have been speaking with a good friend of mine Gerry K. He is doing the same conversion now and really appreciates your insight!
01-02-2009, 06:02 PM
#24
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Thanks for the kind comments everyone. I have not dynoed the car either before or after so I can only describe the change in feel. However, note that in his book "Porsche 911 Story," Paul Frere claims the difference in torque at 4000 rpm is +60 Nm (44 lb/ft) for the v-ram engine. No doubt that this due in part to the slightly larger valves and different cam profiles in the later cars, but the majority of the increase comes from the improved ram effect offered by the v-ram. As we all know, peak tq and hp are only marginally improved.
The feel of the car confirms this. At part throttle and at less than 5K rpm, that car simply feels more responsive. Put another way, there's less need to downshift when street driving. At full throttle or high rpms the difference is minimal. This is why race car owners may find the improvements marginal. However, for those of us who use our cars on the street, the conversion is a distinct improvement.
As our modest friend Tal states, the beauty of this conversion is that it is it can be done with all Porsche parts. In effect, we updated our cars as Porsche did with the Euro OBD-1 cars. Also, I think there's very reasonable bang for the buck with the conversion. And improved torque curve with a +44 lb / ft imcrease at 4K rpm seems reasonable for less than $1500 (assuming you source a reasonably priced manifold and do the work yourself). Frankly, regearing the car (and perhaps even adding a LWF), will provide more noticeably results - but at a much great cost. (Of course, I'll be doing these later too)
One more benefit - I learned tons about my 993 doing conversion. Great fun.
The feel of the car confirms this. At part throttle and at less than 5K rpm, that car simply feels more responsive. Put another way, there's less need to downshift when street driving. At full throttle or high rpms the difference is minimal. This is why race car owners may find the improvements marginal. However, for those of us who use our cars on the street, the conversion is a distinct improvement.
As our modest friend Tal states, the beauty of this conversion is that it is it can be done with all Porsche parts. In effect, we updated our cars as Porsche did with the Euro OBD-1 cars. Also, I think there's very reasonable bang for the buck with the conversion. And improved torque curve with a +44 lb / ft imcrease at 4K rpm seems reasonable for less than $1500 (assuming you source a reasonably priced manifold and do the work yourself). Frankly, regearing the car (and perhaps even adding a LWF), will provide more noticeably results - but at a much great cost. (Of course, I'll be doing these later too)
One more benefit - I learned tons about my 993 doing conversion. Great fun.
01-02-2009, 06:05 PM
#25
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It's not too late! It would have been a lot easier to do the conversion with the engine out.
01-02-2009, 06:06 PM
#26
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01-02-2009, 10:20 PM
#27
Burning Brakes
FYI - there is a varioram intake on eBay for $600, seems like a goods price. There is also a varioram wiring harness for $699, and a DME for $1900 ouch.....but we now know how to get around it.
01-03-2009, 06:41 PM
#29
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You will need to run two wires from the ECU to the engine fuse box.... Carefully open the ECU 55 pin connector and splice into the #1 and #32 wires (the locations are numbered but hard to see – you may need a magnifying glass). FYI - #1 is used to control the resonance flap and #32 is used for the SAI. Next remove the engine fuse box cover and find the 21 pin connector. You can remove this connector by sliding the “drawer” to the side (the drawer lacks the connector in place). Connect ECU wire #1 with a BMW bullet connector to #18 in the 21 pin connector. Connect ECU wire #32 with the other BMW bullet connector to #4 in the 21 pin connector.
I don't have the SAI fault yet, but if it's inevitable, I want as many options as possible to fix, and one of those options I hope is elimination of the system. If this is the way to do it I'd like to know.
