EFI & Supercharger Project (Phase I)
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The current state of affairs...
After I successfully completed the Keisler 5-Speed Transmission Project in March 2002, I started the next big project for the Challenger. The freshly rebuilt sixpack motor was running well and had good power, but not the kind of power that would put me in the upper echelon of street cars. I took the car to a chassis dyno and it pulled 341 horsepower at the rear wheels, which is roughly 410 horsepower at the flywheel. Like I said, not bad, but not King Kong power either. The cam I was running was a Hughes hydraulic with 230 degrees intake duration at .050 lift. Even though this cam was not huge, it had quite a bit of overlap, which gave it a relatively bumpy idle and, together with 9.5 to 1 compression pistons, made for kind of a mushy bottom end as far as torque and throttle response goes. The cam and the ported 906 heads I was running makes this a mid-to-upper range motor as far as street-driven big blocks go; it wouldn't really start pulling hard until you got close to 3,000 rpm, and would pull like mad from there on up to 6,000 rpm. As we all know, this made for a fun car when you are getting busy with it, but for all-around regular cruising it's not that great. With the performance cam, the vacuum signal at low-rpm was pretty weak (about 12 inches at idle), which contributed to the mushy slow throttle response. Another anoyance was the finicky cold-weather starting/warmup behavior that comes with a performance cam and sixpack carbs with the old style choke setup. Most people simply accept this as part of owning a 60's era muscle car, and they learn to live with it, or more likely they simply don't drive the car when it gets cold out. I, however, like to enjoy driving my car in all seasons (provided the roads are clear and clean). Cold weather shouldn't mean I automatically have to put the car in storage until winter is over.
The Problems...
So I had solved the high-rpm highway crusing problem by installing the 5-speed, but now I needed to address all of these street-drivability issues that come with the typical high performance carbureted engines built using 1960's technology. Owners of present-day muscle cars (Corvettes, Mustangs, Camaros, etc.) don't have to put up with this crap because of advances in modern electronic engine management systems and fuel injection. We (owners of older muscle cars) used to take consolation in the fact that, although we lacked many of the nice drivability characteristics of newer cars, we still out-horsepowered them and could whip most of them in a stop-light drag or 1/4 mile run. In recent years however this has changed. The new machines are now every bit the equal in terms of power that the average 60's muscle cars were, but with vastly improved driving manners. Now, they can keep up with (and in many cases pass) us in the stoplight drags, plus they enjoy all of the niceties afforded by the new technology. I decided that it would be too much for me to bear to be driving one of the hottest 60's muscle cars and to be drubbed by some young kid in a new Boss Mustang. I wanted to maintain the performance advantage we have always had in the past. Obviously, I could achieve this goal by simply pumping up the 440 some more with traditional hop-ups like a bigger cam and higher compression. But doing this would mean making my driveability problems even worse. No, what I wanted was the best of both worlds.
The Goals...
I wanted Mondo-power and better all-around driving manners. I wanted a car that wears 1960's muscle car sheetmetal, but has 1990's drivetrain technology underneath. I wanted a car that idles at 700 rpm, has crisp instantaneous throttle response, can get better than 15 miles per gallon fuel mileage, can start instantly with one turn of the key in any temperature and be driven immediately with no fuss, can produce well over 700 horsepower and 800 lb-ft of torque at less than 5,500 rpm, and can turn low 11's in the quarter on street tires and high 9's in the quarter on slicks in a 3,500 lb car. Wow, that's a tall order!
The Solution...
What makes a car really fun to drive for general street-cruising is good low-end torque and super crisp throttle response and lots of vacuum. Normally, if you build an engine to work in this performance range you have to sacrifice top-end horsepower. I already had the key ingredient to making low-end torque... lots of cubic inches! To get the good vacuum and good low-rpm idle characteristics I would have to get rid of the traditional hi-po cam and go with a milder cam. But how was I going to get the top-end power that I also wanted? Nitrous was out because I want the power-on-demand all the time and not just at full throttle; plus I don't like the idea of always refilling the bottle. Turbocharging was out because I didn't like the idea of all that extra exhaust tubing that would have to be fabricated to drive the turbo. So the answer had to be Supercharging! But wait a minute... I didn't want to cut a big hole in the middle of my beautiful Challenger R/T ralleye hood! Hmm... ok, it would have to be a centrifugal supercharger that fits entirely beneath the hood line. The centrifugal supercharger,as opposed to a Roots-type, would compliment the large cubic inch motor beautifully because this type of supercharger builds boost as a function of rpm. In other words, it hits very softly at the beginning but then comes on strong as the rpm's go up. In fact, the centrifugal supercharger works exactly like a turbocharger, only it's driven by a belt instead of the complicated exhaust tubing needed for a turbo. So the big 440 with a mild cam would do the job of providing the brute low-end torque, but then the centrifugal supercharger would come on in the mid and upper rpm range just when the mild cam is starting to run out of ooomph... so the additional power is coming in right when it is most needed!Ok, the solution was starting to come together in my mind now, but there's a problem. To use a centrifugal supercharger you have to blow air into the intake manifold, which would mean blowing it through the carb(s). Well, I didn't want to mess with all the tubing fabrication it would take to plumb air into all three carbs of the sixpack, so those were going to have to go. Ok, so get a single four barrel and manifold, right? Wrong! Blow through set-ups like this are notoriously problematic. This stems from the fact that the typical carburetor was not designed to be pressurized like this, so you can wind up blowing fuel past the various seals, some of which can be vary difficult to remedy (such as around the throttle shafts). There is also the fact that I have not yet solved all of the driveability problems (the cold starting, the throttle response, the fuel mileage, etc.). The answer, of course, was to use fuel injection. With a modern electronic fuel injection system I would solve both the blow-through problem and the driveability problems. The reason is that modern efi systems use some form of throttle body instead of a carburetor. No fuel passes through the throttle body; it's sole job is to meter air. This elminates the blow-through leakage problems of using a centrifugal supercharger with a carburetor. A fully programmable EFI system with sequential multi-point injection would provide outstanding throttle response at every point throughout the entire rpm range. Such a system also automatically compensates for atmospheric conditions such as ambient air temperature and pressure.
So... an intercooled centrifugal supercharger on a large displacement engine with a mild cam and fully programmable sequential multi-point fuel injection system would be the solution to my problems and this is how I intended to reach my goals laid out in the paragraph above.
The Parts...
Now that I had formulated the solution, I needed to figure out where I was going to get all of this stuff. Sheesh!The Fuel Injection System...
The first part of the puzzle was the EFI system. I did some research and decided to go with a brand new fully programmable EFI system manufactured by Accel (a division of Mr. Gasket). The system is called Accel/DFI Generation7. I contacted Rance Baxter, the same fellow who set up the EFI system on the Flying Green Brick that Rick Ehrenberg has campaigned in the One Lap of America racing series. If you read Mopar Action magazine you should be familiar with these guys. Rance set me up with a complete Accel/DFI system, which included the ECU (engine control unit, or computer), the software to program it with (called CalMap), throttle body, fuel rails and injectors, specially-modified Edelbrock Performer RPM manifold, high-volume electric fuel pump, fuel pressure regulator, MAP (Manifold Absolute Pressure) sensor, Wide-Band Oxygen sensor, manifold surface temperature sensor, throttle position sensor, coolant temperature sensor, braided steel fuel lines, AN fittings, knock sensor, and of course the giant octopus-like wiring harness to tie it all together.
The Centrifugal Supercharger...
Here was a problem. There are several well established manufacturers of centrifugal blowers out there: Vortech, Paxton, ATI Procharger, and Powerdyne just to name a few. They make all kinds of complete bolt-on kits. They have kits for everything from corvettes, camaros, mustangs, to luxury SUV's. A few of them even offer kits for older Chevy muscle cars. But NONE of them made a kit for any kind of big block Chrysler! They do sell kits for the Magnum trucks with the new fuel injected 360 v8 engines, but that's as close as you'll find.Well, I could have purchased one of these kits to get the supercharger head unit, but all of the mounting braketry and air tubing would have to be fabricated from scratch. Outch! That would take a lot more time than I had budgeted for this project. I needed to find something as close to bolt-on as I could. After a lot of digging around I finaly found the answer. The answer is SD-Concepts Engineering run by a fellow named Scott Dickson and located in Warwick Rhode Island. Scott has been custom fitting centrifugal superchargers to Mopars for many years and has complete bolt-on kits for both small and big block Chrysler engines! He set me up with a complete kit including the new ATI Procharger P1SC model supercharger which has a self-contained oiling system. The kit came complete with custom mounting brackets for both the supercharger head unit and the alternator, which as you will see later gets relocated to the other side of the engine. The kit also included a Huge custom aluminum intercooler and all of the necessary tubing parts, as well as a blow-off (surge) valve. Scott has engineered into the main mounting bracket a very nice automatic belt tensioning idler, which virtually eliminates belt slippage and allows the use of an un-cogged belt. Also included in the kit is a custom made aluminum crank pulley with the necessary groove for the belt. Scott actually custom fabricates each kit and pre-fits it to an engine in his shop prior to shipping it out, so your kit bolts right on with no trouble at all.
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| Here I am at the start of the project with many of the parts laid out in front of me. You can see the Edelbrock aluminum cylinder heads, the new cam in my right hand, the new efi throttle body in my left hand, the intake manifold is sitting on top of the Accel/DFI kit, and you can see the aluminum intercooler laying on a box to my left. The main pieces you can't see in this shot are the supercharger head unit and braketry, which I would receive a couple days later. |