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Eye of the Toiger
 
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To MFI or not to MFI

I'm planning my rebuild of my 2.7 L CIS 74.

I'm not sure weather I should go for MFI or Webbers.
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1973 911 RSR clone powered by 77 3.0 turbo
Old 11-01-2005, 07:47 PM
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3 restos WIP = psycho
 
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Why not go TBitz EFI? The MFI retrofit will cost you A LOT more money than carbs or EFI and the EFI can be bolted onto your existing CIS for the same price as a used set of carbs. Do a search; there's a lot of info out there.
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- 1979 930
Old 11-01-2005, 07:51 PM
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Eye of the Toiger
 
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will this give me the performance of webers, i'm going s cams and JE pistons
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1973 911 RSR clone powered by 77 3.0 turbo
Old 11-01-2005, 07:55 PM
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Frankly, it should be better, since it has a wideband O2 sensor which adjusts F/A ratio on the fly. Throttle response is supposely similar to MFI as well. I frankly dislike carbs, so take the biases for what they are. All of the cars I own with carbs are all in process of conversion to fuel injection.
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- 1979 930
Old 11-01-2005, 08:16 PM
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Try not, Do or Do not
 
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..........The MFI retrofit will cost you A LOT more money than carbs or EFI and the EFI can be bolted onto your existing CIS for the same price as a used set of carbs.............

Old 2.7 40mm Webers 200 hp? $1200 to $2000 old school
New PMO 200 hp? $2600 to $3000 new version old school
Rebuilt MFI 200 hp? $2500-$3000 tractor parts but so cool
EFI? 200hp? Most cost $3500 + modern just like a Toyota

How is an MFI more expensive? A'm I missing something?
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Old 11-01-2005, 08:22 PM
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Eye of the Toiger
 
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Henry,

Do you do gearboxes and engines for Aussies?

I have a 915 4 speed I want to update to a 5 speed I just want to exchange for rebuilt one but no one here really does this.

Not to mention what I want to do with the motor, I want an RS spec 2.7
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1973 911 RSR clone powered by 77 3.0 turbo
Old 11-01-2005, 08:27 PM
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Quote:
Originally posted by Henry Schmidt
[B]..........

How is an MFI more expensive? A'm I missing something?
Tony's kit that is specifically for converting CIS cars to EFI is MegaSquirt based and costs $1700, soup to nuts. Motec EFI, etc. are another ball of wax and MFI is actually cheaper there.
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Old 11-01-2005, 08:37 PM
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Do you do gearboxes and engines for Aussies?

I have a 915 4 speed I want to update to a 5 speed I just want to exchange for rebuilt one but no one here really does this.

Not to mention what I want to do with the motor, I want an RS spec 2.7


We send engines all around the world.

Early gear boxes are our specialty.

Instead of an RS spec engine I would recommend something with a little more pop. Perhaps a little more compression and a more modern cam from DR cams.
We do an intake port/manifold conversion that offers great flow and still delivers low end performance.

Email or call and I'll make something work for both of us.
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Old 11-01-2005, 08:40 PM
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Matt

I'm in Sydney and have a spare MFI setup I would consider selling if you decide to go with MFI.

I have a 2.7RS++ spec motor (MFI, 10.5:1 pistons, GE80 cams, twin plug etc) in my RS replica track/rally car and it is simply fantastic.

Also, performance 9 or perhaps one of the bigger porsche wreckers or parts places might do a gearbox exchange. However, i wouldn't expect much for your 4 speed.
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Old 11-01-2005, 09:39 PM
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Ryan,

I have spoken to Dave at P9, although they are great blokes I get my parts from them he can't help me with a rebuilt box.

who else is there?

BTW I'm interested in your MFI, what do you want for it?
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Old 11-01-2005, 09:59 PM
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Matt,

Re. MFI - I PM'd you a price.

Re. gearbox - maybe call exoticars at silverwater, swan in WA or aporschapart in VIC. there's also some guy in rural WA that advertises in unique cars who has engines and gearboxes.
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1969 911E (historic racer)
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Old 11-01-2005, 10:20 PM
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Quote:
Why not go TBitz EFI? The MFI retrofit will cost you A LOT more money than carbs or EFI and the EFI can be bolted onto your existing CIS for the same price as a used set of carbs.
Quote:
will this give me the performance of webers, i'm going s cams and JE pistons
Shared plenum and agressive cams like S cams don't work well together. The CIS setup has a shared plenum and even with EFI it will be hard to get it to run smooth.

Cheapest bang for the buck is still a used set of carbs in this scenerio but if you can swing it money wise the MFI requires less maintenance and performs better once it's set up right.

I love the novelty of MFI and it's relationship to Porsche in it's heyday when 917s were trouncing the competition. Those were the days....
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Old 11-02-2005, 12:23 AM
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On a stock 2.7 If I put on MFI what type of cam shafts can I use to gain performance with out having to change pistons?
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Old 11-02-2005, 03:15 AM
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Stock CIS pistons offer a number of challenges. Valve to piston clearance being the major on.

In the past we have placed valve pockets in CIS pistons and the results were acceptable. (be it lower compression and only done to accommodate a customers budget).
If your project is (as most projects are) governed by budget concerns, I would look to our host for some very reasonably priced JEs and build and engine that will run on CIS, MFI, carbs or EFI and add the new induction later.

What engine configuration will run with all these intakes?
I'm not sure, what is certain is that it will be a compromise, but what engine isn't?
The key will be the cams. I would ask our resident expert John Dougherty what he would use. http://forums.pelicanparts.com/drcamshafts.com
Perhaps a version of a S Cup cam?
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Last edited by Henry Schmidt; 11-02-2005 at 10:32 AM..
Old 11-02-2005, 08:15 AM
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By all means contact John. I wanted to install a different cam on my 3.0. I want to keep the stack pistons and run the webers and SSIs that are currently on the motor. He advised a special intake and exhaust grind with the correct lobe center to maximize my existing compression ratio and induction while maintaining clearance. He also helped it fit my budget by suggesting specs that could be reground, not welded. The cams are nearly ready to be sent off for grind work.

What great service! We are very fortunate to have these experts helping out us enthusiasts. Thanks John and Henry and everyone else that contributes.
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Old 11-02-2005, 09:50 AM
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I'll go with Henry's excellent advice and do the pistons first
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Old 11-02-2005, 10:57 PM
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Matt,

When do you plan on doing your conversion and what will you primarily use the car for?

Mark,

914/6 2.7
Old 11-03-2005, 03:53 PM
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Early next year street use
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Old 11-03-2005, 04:02 PM
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Hmmm...

I run a set of JE 9.5:1 in my current engine. Finished in mid 2003, it's done four tarmac rallys and a couple of seasons of club sprints.

After Rally Tasmania in Feb I'll be building a new (smaller) engine and will probably sell most everything except the heads and ancilliarys of my current engine.

The timeframe may or may not suit. Just a thought.

Mark
Old 11-03-2005, 04:46 PM
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I have sent you PM
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Old 11-03-2005, 05:15 PM
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