Putting the 911 on a weight loss program

Now that the 911 has its kill switch installed and is all sorted out and running, it is time to start adding lightness to the vehicle.  I’m first going for the free to cheap lightness adding methods.  I’ve already done some of it such as: going to a lightweight battery, stripping out the interior of the vehicle, backdating the heat, and removing the windshield washer reservoir.  However, it has come to lose some more weight off the car; but, I’m not going to remove the most obvious: the air conditioner.  I love my A/C — especially in the summer and especially while I still drive the car on the streets.

Of course, you ask, why would one want to reduce the weight of their vehicle?  There are lots of reasons for reducing weight on the 911 (and any other car).  First, the less weight you have to push around the track the faster you can accelerate and take corners.  It also makes other components in the car last longer like brakes, brake pads, and tires.  It can also help increase fuel economy, and finally, the best reason of all: a 10% reduction in weight is roughly equivalent to a 10% increase in horsepower.  The most common places to begin removing weight are from the unsprung items like brakes, wheels, trailing arms, etc.  Next comes weight from high up on the car (sunroof, etc).  After that, weight at the rear of the car, then weight from the front of the vehicle.

The cheap ones I am working on are: stereo system removal, remove of the rest of the windshield washer system, removal of the oil cooler fan in the front passenger side fender, and installation of headers (removal of the stock exhaust system).  With the exception of the headers, I don’t believe the other items will amount to a lot of weight saved initially; perhaps 10lbs to 15lbs total, but every bit helps.  The headers will knock a fair amount of weight off the vehicle since the stock exhaust parts are quite heavy and not exactly optimal for getting the most power out of the engine.

Once these easy ones are complete, then comes the harder and/or more expensive parts: replacing body panels with fiberglass or carbon fiber body panels.  At this point, it becomes a how much do you want to spend proposition.  The carbon fiber parts add about $300 over the price of the fiberglass part while weighing a pound or two lighter in most cases.  Replace the glass windows with Lexan is another place where weight can be lost but I’m not at that point yet.  Once the car is a full track vehicle, Lexan windows are in.  Removal of the sunroof and the associated electronics can drop a good 40lbs off of the top of the car, lowering the center of gravity.  Taking it a step further and replacing the steel roof with a carbon fiber or fiberglass roof can reduce the overhead weight even more.  Like I said, it becomes “how much do you want to spend to be lighter?” question.

For me, when this is all said and done, my end goal is to have the car weigh in at a maximum of 2400lbs with A/C and an empty gas tank.  As of right now my car weighs 2588lbs, so can I find an additional 188lbs to drop off the car while still maintaining an ability to drive the car on the street on the weekends?

Installation of the Kill Switch and heater backdate for the 911

This weekend I finished the install of the kill switch and the heater backdate for my 911.  When it was all said and done, the kill switch was made out to be a lot harder than it was since none of the instructions online seem to have been made for a car that wasn’t a purpose-built track car.  What I had to do was use the set of connections that was marked ignition switch and power to coil or ecu, I used for the fuel pump.  The picture below is how I wired up the kill switch.

The wire for the power to the fuel pump is located at the fuse panel in the trunk and is red with a green stripe (at least in the ’84 911). I removed it from the fuse and extended to the kill switch, then fed a wire back to the fuse from the kill switch.  The power wires that were connected to the battery all had to be modified.  I purchased a new batter cable 3/8″ ring terminal and used that to connect the wires to the kill switch power stud.  The smaller wires that were attached the battery, I did the same thing to except used a ring terminal that was meant for the higher gauge wires.

And since no one really explains how the kill switch works, I’ll give a quick run down.  When the switch is in the ‘on’ position there is power flowing from the battery to the electrical connection on the other side of the switch.  The set of spade terminals 2 make a circuit and the other set of terminals are an open circuit.  When the switch is turned to the ‘off’ position, power is cut from the battery, the terminals marked 2 become an open circuit and 1 makes a circuit.  The set of spade terminals 1 is called an Alternator protection circuit, so when the engine stops running the voltage won’t surge back into the alternator and fry it, instead it will go through the resistor to ground.  The circuit made with ‘2’ must be something that when power is cut, the engine will stop running.  I chose the fuel pump as stated earlier since all the wires were right there.  However, now that I think about it, I probably could have done the same thing with the ECU’s power cable.

The second project I took on this weekend was the backdating of the heater in the engine bay.  Earlier 911s lacked the large blower motor in the engine bay to push air over the heat exchangers to the cabin.  However, my heat has always been pretty crappy and I live in Texas.  Heat isn’t super important, but it is nice to have.  So the pluses outweighed the minuses in my mind and I decided to do it.  Removing the heater blower motor was a pretty simple job, but if you have large hands it could be kind of hard since the screws and nuts are in some awkward places.  Once the blower motor and the associated tubing are removed, the backdate heater duct can go on.  You’ll probably want a hammer or mallet to persuade the piece to fit around the distributor.

I installed the piece, saw where it was going to be interfering with the distributor and took a hammer to it to make it fit.  Once I did that a few times, I put it back into the engine bay, screwed and it in.  I think cut some high-temp silicon hose that was 2.5″ diameter and forced it over the output of the piece then rammed the other side of the tube into the input for the heat exchanger and clamped it down with the clamps on the heat exchanger input side.

A close-up of the finished product.

The full, somewhat cleaner looking engine bay

Now that all of this is complete, I’m beginning my week-long project of Liquid Wrenching the exhaust nuts in order to install the headers onto my vehicle in the coming week or two.

Effectiveness of Penetrating Oils

This information has been posted on numerous bulletin boards and passed around in emails for a long time and somehow I keep deleting it every time I see it.  Well, no more.  I’m posting it here so I can see it and anyone else who is interested in it can as well.

Penetrating Oils Compared

Machinist’s Workshop magazine actually tested penetrants for break out torque on rusted nuts. Significant results! They arranged a subjective test of all the popular penetrants with the control being the torque required to remove the nut from a “scientifically rusted” environment.

Penetrating oil           Average load

None ………………… 516 pounds

WD-40 ……………… 238 pounds

PB Blaster …………..214 pounds

Liquid Wrench …… 127 pounds

Kano Kroil ………… 106 pounds

ATF-Acetone mix… 53 pounds

The ATF-Acetone mix was a “home brew” mix of 50 – 50 automatic transmission fluid and acetone.

Note:   The “home brew” was better than any commercial product in this one particular test. A local machinist group mixed up a batch and all now use it with equally good results. Note also that “Liquid Wrench” is about as good as “Kroil” for about 20% of the price.

I’ll be testing out some Liquid Wrench and PB Blaster and maybe even the home-brew ATF-Acetone mix in the near future since I’ll be trying to remove the exhaust system from my 911 in the near future.  Can you say 24+ years of dirt, grime, and maybe a little rust on them there exhaust nuts?  If we go by how bad the stuff is for you, I’m not surprised the ATF-Acetone mix is #1.

Another 911 part arrives..

A new part for my 911 has arrived: a left side heater duct for backdating the heating system on the 911 to the early 911 style.  Why is this important and why is it a good idea to backdate the heat?  First, backdating the heat makes it much easier to work in the engine compartment.  It removes a decent amount of plastic piping and removes a large blower motor that honestly gets in the way when you try and work on the engine.  Secondly, backdating the heating system is just cool (pun not intended) since we already have a large fan blowing air across the entire engine diverting a little bit to blow air through the heater boxes around the headers isn’t that big of a deal.  The heat will still get to the front of the car with no issues.  And lastly, it is all in my steps toward rebuilding my engine into something more spectacular than the 3.2L boxer six sitting back there now.

Left Side Heating Duct

I still need to purchase the high temperature silicone hose used to route the heater duct air to the heater boxes, but I didn’t want to purchase it until I had the part in hand and could confirm the size that I needed.  As luck would have it however, Pegasus Auto Racing Supplies is out of the hose when I really want to order it.  Maybe I’ll get lucky and Austin Performance has some in stock.

And, just before I was about to publish this post another thing I’d been waiting for showed up on my doorstep.

Yes, a bag from Simpson Racing.. what could be in this bag?  Could it be this?

Yes, my racing suit, in the flesh, so to speak.  However, after trying it on there is going to be no gaining weight in the wrong areas or it won’t fit at all.  But, now I’ve got all the racing gear I need sans a cool shirt — now I just need my car so I can get to rocking and rolling out on the track again.

The 911’s headers and mufflers have arrived

Well, they didn’t arrive today, they arrived on Thursday and I haven’t had time to truly look at them until now.  I had spent a lot of time debating on which set of headers to buy.  Did I want to have completely custom made ones, or an off-the-shelf model like the ones from Instant-G, B&B, Fabspeed, Buckley Racing, SCARGO Racing, or SSI, etc.  After looking and reading over the various forums, specification pages and pouring over the pictures I decided on the Fabspeed headers and muffler.  The primaries on the headers were 1 5/8″ which should be good for up to a 3.8L motor or so according to what I have read.

The headers from what I can tell are well made with full mandrel-bent tubes and the ability to run either a track exhaust or a muffled exhaust.  It also came with the heater boxes so I can still use the defroster in my car.. if the need ever arises.  In addition to this, I also had to order a new cross-over oil pipe for the engine to replace the oil line that would interfere with the install of the headers.  I’m also going to see about backdating the heater in my car to remove a large extra fan and ducting from the rear of my car and simplify the engine bay a little bit more. Oh, and of course, two cans of PB Blaster to help get the nuts off of the exhaust studs so I can actually install the new system.

Once my DME arrives back from California it should be a happy fun time.  I’ll get the headers installed, the heater backdated, the DME reinstalled and then begin to troubleshoot why the car still isn’t getting spark or fuel to the engine.  And if I can’t get it sorted out… maybe I decide to rewire the entire car?

Kill Switch Adventures

As I’ve written about before, my 911 needed a kill switch installed to be truly safe for the race track.  This weekend I decided for sure I’d install it on Saturday and it’d be done in a few hours and there would be nothing else to worry about.  As you can tell with the name of the post, it did not go quite as easily as expected.

Most of the installation was straight forward, the kill switch gets installed between the main battery and the rest of the electronics in the car.  So, you simply cut the main battery cable, fab up a shorter one to make it from the battery to the kill switch, wire up what needs to be wired up and call it a day.  A quick and easy hour or so job.  Obviously, not the case.

The kill switch needed a bracket mounted to it to hold the kill switch remote pull wiring.  The piece holding the kill switch itself needed to have some holes oblonged so that then kill switch would not rub against other brackets and everything would fit into the vehicle.  The supplied wiring diagram was not very good at all (and I think this is where I managed to release the magic smoke from the system).  After two days of working on installation, the kill switch is now wired up and hopefully working, but, I ended up with a dead engine control unit in return.

The DME (engine control box) has been shipped out to 911CHIPS to be repaired and have a different performance chip installed and I’m looking at installing  set of headers on the engine to open it up a little bit more and get some more horsepower out of the engine.  Although this is a minor setback, the addition of headers onto the car should help lessen the pain of being without the car for over a week :).