MFI vs CIS

[Flieger]

Originally Posted by javadog

Ha ha...

I never endorsed CIS as "better" for power than MFI. And, I never even mentioned carbs. Quit putting words in my mouth.

I just think that you and Flieger ought to do a little fact checking before you write stuff. You can have any opinion you want, just stick to the facts.

JR

PS: The funny thing about the 934 (remember those?) is that the Group 4 rules also limited the amount of tire that Porsche could stuff under the rear fenders. The tires were too small for the amount of power the 934 made and the cars were a handful to drive. Imagine the irony... a race car using CIS that made too much power to suit the drivers...

I could make a garden hose big enough to spray 500hp of fuel into the intake. When you are racing like that, just add more fuel and get a bigger barn door. It won't be very efficient but it will make power. The CIS poor throttle response was masked by the equally bad turbo lag.

[javadog]

Originally Posted by Flieger

Notice he said factory race cars. The factory never raced 934s. .

The factory built the damn things. That's the point of "factory" as opposed to a car built by a private team.

I give up. Believe what you want. CIS was a logical step between MFI and EFI. I've owned Porsches that had essentially every type of fuel metering they ever used. They all have good points and bad points. My sunglasses aren't rose-tinted and my memory is still good enough to remember all the downsides to carbs, MFI, etc. so I won't lose any sleep over any of this.

I also like PCA, Cayennes and Panameras don't bother me, etc. I'm not you.

JR

[Flieger]

Geez, Panameras and Cayennes, too? Your case is hopeless.

Anyway, when I hear "factory race car" I take it to mean raced by the factory (or a factory supported team like the Penske 917.30). So, for example, the Kremer cars- 911ST and 935s are not factory cars to me. The Martini cars are, though, in my definition. Salzburg 917s are the factory team, Gulf gets 1/2 credit.

I still believe CIS was a step backwards. The only thing that would get me to switch from MFI is DFI or a DFI injector in the MFI position.

[Flieger]

I bet you like your 911s with SBC V8s in them too.

[Zeke]

Corvettes used CIS as far back as '57 and continued to use it until the 350 CU engine came out.

CIS is much easier to turbo charge or supercharge. I've dicked around with the Corvette system. Porsche MFI and CIS and Motronic EFI. No doubt they are dirtier in the reverse order.

[enzo1]

great thread, I learned something. Don't like CIS probably cause i'm coming off a cracked air box and got a air leak....