2.4 MPI upgrade & A/C update?

[joetiii]

I'm thinking about doing an upgrade to my '72 T. The original A/C compressor was missing when I bought the car and I want to update the whole thing to 134A. Worthwhile project? approx. cost?

Once complete, I figure the A/c will rob me of a few HP so I am considering a few motor tweaks as well. I've read good things about an MSD ignition upgrade. Though I'm not a racer and the car is not a concours queen I value opinions of those that go before me. I read that idle speed and low rpm engine performance will improve.

The second improvement I'm considering is updating the T cam. I only have experience with domestic cars so forgive me. A mopar cam upgrade is relatively easy. On a flat 6 I know nothing about so years of experience is why I'm posting to this group. What are the pros and cons?

I imagine the MPI will need to be adjusted if/when a cam change is made. Are these problematic?

Cost? and other recommendations are certainly appreciated.

joe

[Grady Clay]

Joe,

Welcome to the Forum. You will find a lot of help here.

Depending on where you live the A/C may not be useful or may be absolutely necessary. There are several things you can do to improve its performance. An easy one is to change the fan and crank pulley at the engine. This turns the fan 1.82:1 ratio in place of the original 1.3:1. This not only pulls more air through the deck lid condenser but it helps keep the engine cool (longevity issue.)

There are also many improvements to the A/C system. Some might include the improved hoses, an extra condenser in the LR fender, larger capacity evaporator and fan and a heat exchanger in the return line to before the expansion valve.


Your 2.4 911T engine is probably best maintained in original condition. Yes the later ignition technology helps. The engine and Mechanical Fuel Injection (MFI) are a complete system. Each sub-system was designed to work in concert with the others. It is unreasonable to change some components and have satisfactory performance.

Let’s take the cams for example. The cam profile is matched to the size of the intake stacks, throttle bodies and intake ports in the heads. They are different T, E, S, RS and RSR. The MFI pump has the engine characteristics ground onto the 3D “space cam” that determines the fuel flow vs. RPM and throttle position – a mechanical computer. The distributor advance curve is different among the different versions. Even the compression ratio is different. If you try and install “S” cams in a T, the valves will hit the pistons.

I recommend you put your effort into having the T run the best possible in original condition. There are plenty of good maintenance items to occupy all your time. Chain tensioners and chain ramps come to mind.

Best,
Grady

[Jim Sims]

If this car doesn't have a external oil cooler in the right front fender one should be added if A/C is being restored.

If the A/C compressor bracket is that "kludge" mounted off the passenger side chain case cover studs then it should be changed out to a 1973 or later model bracket that mounts from the engine rear console.

DIY cost to upgrade your A/C system so it works well is likely around $1500 to $2000 assuming you retain the existing rear deck lid condenser and some other already installed parts.

If you have the under dash A/C ducts they do a reasonable job of distributing the cool air.

[David E. Clark]

Joe,

Get yourself a copy of 101 Projects for your Porsche 911. There are loads of great ideas for maintenance and upgrades in there and - if you are like me this is a huge bonus - GREAT pictures showing how everything is done!

There is a companion book called How to rebuild and modify your Porsche 911 engine that is also quite useful and will probably answer all of your engine modification questions.

Both of these books are available at most Barnes and Noble or Borders bookstores. Or you can get them here from our host. Welcome to the board.