MFI 101 for a newbie / few questions
 

Ok, I have a 3.0 out of 79sc. Recent rebuild to the best of my knowledge and super clean engine. Currently bone stock with CIS. Only upgrade from what I can tell is Carerra tensioners.

I am trying to make a decision between Webers or PMO carbs, PMO EFI, and MFI

This is really the look I am going for
http://forums.pelicanparts.com/uploa...1447777730.jpg

My three main questions:

1. I know the MFI pump is belt driven by a gear on the rear of the cam, do I need to replace cams?

2. In terms of reliability, how is MFI

3. In terms of performance, of the three, which would you choose.

http://forums.pelicanparts.com/porsche-911-technical-forum/386414-mfi-pump-open-heart-surgery.html

http://forums.pelicanparts.com/porsche-911-technical-forum/457766-mfi-open-heart-surgery-ii-fuel-pump.html

http://forums.pelicanparts.com/porsche-911-technical-forum/617039-mfi-open-heart-surgery-iii-reworking-space-cam.html

How far are you planning to go on your rebuild? Your post indicates your 3.0 was recently rebuilt and is "super clean" -- it's my understanding that to get the most our of MFI, you'd need to swap to appropriate pistons/cams/etc.

The engine you posted the photo of is also twinplugged -- again, internal mods needed to twinplug and to optimize for power.

Where do you want to see performance improve (low/midrange for street? top end for track?) It's my understanding that the ITBs in your photo are best for bringing out top end?

May also want to post this in the engine rebuilding forum

Boy that's a broad spectrum and set of questions...to answer

1) yes you will need a MFI cam drive and therefore an MFI pump spec'd to the cam, pistons etc. There are a LOT of pieces required to convert CIS to MFI and some customization (Heads, 2 fuel pumps, etc.) I currently finished making an 3.0 MFI

2) MFI is finicky to set-up and very unique. Otherwise very reliable for a 40+yr system. If period correct is your end game then MFI is fun and kinda cool.

3) Each system can have their own set of performances...all depends on end game...lots of reading you can do in the Engine Rebuild forum.

Simplest and easiest would be Webbers but beyond that you are looking at 'building' an engine and have to make decisions from the short block-up.

As for the engine pictured...I would probably guess that's a 25K+ motor but I'll let some real pro's chime in.

An MFI 3.0 (0r larger) requires a significant amount of work, time and money. Most of the effort is matching the cams, compression and capacity to the induction and fuel delivery system.

Depending on your goals you could do EFI with the MFI stacks. This only requires modification of the heads during a rebuild. Weld up the CIS port and drill for the MFI injectors. Here is my example. Available through our Host.

http://forums.pelicanparts.com/porsche-911-technical-forum/809214-mfi-efi.html

If you just want the look of ITBs you can bolt on a system from Borla (formerly TWM), PMO, Jenvey and a few others and then tune it with a host of EFI controllers.