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Randy Blaylock Randy Blaylock is offline
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Join Date: Nov 2004
Location: Pacific Northwest
Posts: 342
I agree 100% that for most people, the CIS is just fine, assuming all the hardware is in good condition and operating within spec. There is no compelling reason whatsoever to do anything beyond verifying that you have a sufficiently fat AFR plot to satisfy your application.

Regarding CIS "tuning", if that means something beyond ensuring that the hardware is in good condition and operating within spec, it must be more of an intellectual exercise than anything, which to inquisitive people is worth the time itself. I'm guilty myself of spending 4 hours on a 10 minute task, as are we all I suspect given the good discussions and frequency of topics on this and other forums. It's a good thing.

Having said that, I personally think that trying to effect a small change in the AFR plot somewhere along the line with piggybacked utilities is not going to net a change in torque or drivability that most people will be able to discern, and most certainly simply will not deliver the performance that a legitimate EFI system will. Not to mention that systems are being introduced that are another potential point of failure or maladjustment, with unknown and potentially serious consequences. The risks and expenses outweight the benefits to me, but that's my analysis and I'll readily concede that others have different priorities that are just as compelling. Doesn't mean that it's not worth doing, it's just not a substitute for EFI for obvious reasons.

For example, it's ignition timing events, not a precise AFR that affects maximum cylinder pressure, which represents itself as torque. There's not much that can be done with a distributor in this regard. Once again, it does a fine job under most circumstances, but it's not even in the same ballpark relative to electronic control.

Having said that, and given the airflow restriction of CIS, plus the superior fuel economy, and for many reasons already beat to death, EFI is without a doubt vastly superior in every respect, both intellectually and in practical terms. The thing is, it is not a casual affair to implement a conversion. It takes a lot of cash, time, experience and testing equipment. This is the key, and where/why most conversions fall short.

Maybe it's just semantics, but to me comparing even a "tuned" CIS, whatever that is, to EFI, is like comparing a gold plated slide rule to a contemporary PC. It's not a judgment, just an observation. I got by with the slide rule quite successfully for years, and accepted the compromises that go with it. I had planned to convert to EFI before my plans changed simply because given the way I used the car, it made economic sense. In almost all cases it doesn't.
Bullet Racing #22 GT3 Cup
Old 03-01-2007, 08:04 AM
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