Budget Ford Mustang Build - Back-To-Basics Budget 5.0 Buildup Part 4 - Tech

Electrical Stuff
The main items on our agenda are the battery and a master cut-off switch. What was done here comes under safety and performance. First, the battery location was moved from the front to the back to help weight balance. Secondly, a dry cell-style of battery was chosen.

In this instance, we used two of Performance Distributors' Dyna-Batt units. The reason for two batteries was because of the electric water pump and no alternator. These batteries are about half the weight of a regular battery and provide high initial cranking voltage, which is great for starting.

A Dyna-Batt from Performance Distributors costs $119-and that's on-sale. We realize this is a little more expensive than a regular battery, but as such we have added $240 into the cost breakdown. If you are following this build, you will need only one battery, and the price difference to ensure that no acid will fly around the interior of your car in the event of a crash is well worth the difference between a Dyna-Batt and a $50 battery. If you are interested in drag racing only, then instead of making up a battery-retention system as we did, use a Mr. Gasket battery box kit. This comes with the box, all the cable you will need, and most everything else.

Suspension Mods
Suspension mods for a 5.0 come under two distinct headings: those that seek to stabilize pickup/pivot points on the suspension so they don't move and those that are intended to improve the geometry. Before you can do too much to the geometry, it's necessary to make sure the pivot points stay where they should be. Rubber is good at isolating road noise, but its inherent flexibility is not so good at keeping the geometry consistent.

We will address the excessive compliance of the stock rubber bushings. The simplest and most effective way is to use Energy Suspension's urethane bushings. These work well on the track while still being more than civilized for the road. Remember the supporting project car that owner Jason Peck is doing alongside our project? We had him install a set of Energy Suspension bushings just to get a second opinion. Jason told us, "It's almost like going from night to day." Your author is glad he felt that way because that's about what his response was when he first installed some of these a few years back. These days, the results are likely to be better because the cars being so equipped are having older, and consequently softer, bushings replaced by the Energy bushings.

Installing these bushes is straightforward enough but can be somewhat time-consuming unless you have all the right tools in hand. It can be done in the driveway over a weekend, but you'll need some tall jackstands, and an air-impact wrench will certainly make life easier. A special tool is needed and can be rented for a fully refundable $100 deposit from the good guys at AutoZone.

Dyno Time
In racing, the real moment of truth comes when the car rides the dyno or goes to the track. Such was the case with our Comp Cams Special. Tests were done at Custom Performance late one night. Essentially, we made one run and found the mixture to be really lean. We aborted the run at 4,000 rpm as the average mixture ratio recorded was a thread-bare 17:1 instead of the 13:1 we were looking for. That was the bad news. The good news was that in spite of this way too lean condition, the engine still cranked out over 330 lb-ft of torque as seen at the rear wheels.

That's about 10 percent above what is typically seen by a warmed-over and optimally calibrated engine (which ours essentially is) with bolt-on heads and a moderate street-cam upgrade. The prospects of our engine producing good results when the mixture is fixed and the timing optimized are, at this point, looking extremely good.

Now about this time some of you knowledge-able guys are going to be asking what happened to the 5.0's famous ability to correct the mixture and thus compensate for engine mods. Well, that ability is still there, but obviously there's a problem with the hot-wire sensor in the mass airflow unit. Whatever it may be, this is causing it to read less air than is really passing through.

This could actually play into our hands and save us a bunch of cash. Here's the deal: The stock injectors deliver 19 pounds of fuel an hour at a shade under 40 psi. At a brake-specific fuel consumption of 0.45 lbs/hr/hp, the most power the injectors will allow the engine to deliver before being maxed out at 100 percent duty cycle is 338 hp. That's assuming everything is right on the money. In reality, it's likely to be a little less than that-but no matter, this capacity puts the injector right on or just over what's needed for fuel flow for our engine as it's expected to peak at about 320 flywheel horsepower. What we can do is up the pressure supplied to the injectors. Normally this would be only a fine-tuning measure but because of a fault in the system, we can use more pressure to not only fix the mixture ratio but also-at this stage at least-up the injector capacity to stave off the need to spend relatively big bucks on bigger injectors. A little math here shows that to get the mixture to 13:1 will call for the fuel pressure to be increased to about 64 psi. This will make the injectors good for 386 hp. With the pressure number in mind, the next move was to check Accel's catalog for an adjustable pressure regulator. When that arrives, we'll get back on the dyno and check out the results.

On the Scales-the Final Verdict
As can be seen from the nearby photo, our car is beginning to look a little more like a decent (at this time) road racer. We still have brake upgrades and shocks to do, but that's for an upcoming issue. Right now the question here is, how much have we lightened it? We had anticipated eliminating some 280-300 pounds from the car, but our efforts here came as a pleasant surprise to us all. The weight, less driver, dropped from 3,127 pounds to 2,692 pounds, for a savings of 435 pounds. In round terms that's a reduction of 14 percent. That means our 302 will appear 14 percent torquier, and that equates to about what you could expect from installing a 347-inch motor in place of the 302 and leaving the weight as is.

Dropping all that weight cost us nothing more than about six cans of spray paint to cover the marks made while scraping off the sound-deadening goop that Ford lathers onto everything under the carpet and upholstery. As good as that is for more go, it has even bigger implications on stopping. Taking out that weight means more brake for the weight involved. The big 13-inch disks normally used cost more than our budget at present allows. But taking out the 435 pounds means the brakes will now react as if the size has been increased from 11 inches to 12.4 inches, and that is one big step in the right direction.

If we could get the weight of the car down another 160 pounds, the brakes would have the same swept area per pound of car as 13-inch ones on a stock-weight car and would brake about as well-if the calipers were up to the job, that is. As it happens they are not, but we'll address that in the next installment by showing how to get close to 50 percent more clamping force out of some retrofit low-cost calipers. Couple this to some good brake pads, sensibly priced slotted rotors, and budget high-temp brake fluid, and we'll have a brake upgrade that, though still not as good as 13 inchers, will, for a fraction of the cost, be pretty awesome.

OK, back to the weight issue. Take a look at Fig. 1 showing the before and after weight distribution with a 200-pound driver in place. Although a stack of weight came off the front of the car, so much came out of the interior that the weight bias front to rear favored the rear by only 0.6 percent more than when we started. This is in spite of the fact that we moved the battery back to the trunk and left in the rear crash-absorbing bumper. The truth of the matter is that though we sucked a lot of weight out of this car, there's still much that can be done in this direction. A glass hood and door lightening could amount to another 75 pounds removed. A tubular K-member and tubular front A-arms would take close to another 100 pounds off the front. Plastic windows and a glass rear deck can account for about another 100 pounds. As far as lightening goes, we're not done yet, but from here on, it's likely to cost money.

Regarding the power-to-weight ratio, if our car hits 300 at the wheels it will run like a stock weight car having 342 rwhp. To us, that's the same as a gift of 42 free horsepower. In terms of performance, the weight reduction alone will be worth 0.4 and 5 mph in the quarter with a stock engine. With the 100 or so extra horsepower our engine makes, we should be looking at a fast ride. Given the tires, we should be able to run in the bottom of the 12s in the quarter with trap speeds in the region of 112 mph-and we still have the Zex nitrous kit in hand.

OK, now for the cost to date: As you see the car in the nearby photo, we spent $6,579.