Thread: MFI vs CIS
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javadog javadog is online now
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Quote:
Originally Posted by Flieger View Post
Most of my statements were opinions, which are not provable or dis-provable therefore.
Ahh, not so fast, whippersnapper. Let's have a look...

Quote:
Originally Posted by Flieger View Post
I disagree that CIS is more environmentally friendly.
Well, Porsche went to CIS beacuse it enabled them to meet economy and emissions standards that they didn't feel they could meet with MFI, so I guess they would disagree with your statement, as do I.

Quote:
Originally Posted by Flieger View Post
MFI injects fuel into only the cylinders that want it.
Yeah, I've studied MFI but this statement really makes no sense.

Quote:
Originally Posted by Flieger View Post
It is a high pressure injection, too, so the power you get out of the fuel I would say could be double the CIS.
Double? Ahh, no. In fact, recall that the first CIS car, the 1973 T, made the same power with CIS as it did with MFI. The CISs car actually had a half a pound foot of torque more, or 3, depending on which numbers you believe, so...

Quote:
Originally Posted by Flieger View Post
The difference is that CIS cars are slow and slow cars are not going to need as much energy to go slow. MFI cars are fast so they need more energy. If you made a CIS car as fast as an MFI car the MFI car would get better mileage.
This also makes no sense, so I'll go on.

Quote:
Originally Posted by Flieger View Post
I venture that since MFI has much more precise fuel control as far as pulsed injection that MFI has lower brake specific fuel consumption.
No. ANybody that has spent much time with MFI realizes that those systems don't offer near as fine fuel metering control as CIS. They make great power and sound nice, but they aren't frugal with fuel. Not even close. The CIS cars were eventually developed to the point that they got fuel mileage an MFI car couldn't even dream about.

And, if you look at the BSFC curves, CIS cars yielded 20% better numbers, give or take.

Cheers,
JR
Old 10-07-2011, 04:53 PM
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