1-This is the test motor in...
1-This is the test motor in standard carbureted trim: a freshly built, balanced, and blueprinted 406 with all-Lunati forged internals and port-matched Holley 23-degree heads.
We pit Holley's new StealthRam fuel injection against the venerable 750 double-pumper in a showdown for maximum power and driveability. The results may surprise you.
While fuel injection has been around in various forms for the better part of half a century, functional high-performance systems didn't really become a reality for those of us in the rodding world until 1986. Why 1986, you ask? Because that's the year that Ford introduced its all-new EFI system on the 5.0 Mustang, and Chevrolet switched the Corvette from a complicated cross-ram throttle-body system to a much more elegant and functional TPI arrangement. Suddenly "high performance" and "fuel injection" were phrases that could be uttered in the same sentence, and within months those trick new systems began to show up on street rods and musclecars around the country.
2-The two Mikes, Petralia...
2-The two Mikes, Petralia and Lambert, open up the boxes containing everything needed for the EFI swap. There were a lot of boxes.
Unfortunately, the '80s were still the relative dark ages of aftermarket EFI, so only those willing to take on the task of splicing their own wire looms were able to make the conversion, and then they were very limited in how much actual tuning they could do. Luckily, things have come a long way in the past 15 years, and there are now literally dozens of different fuel-injection systems available for just about any American V-8 you can think of, from small-block Chevys to Y-blocks and Flatheads. However, many street rodders still think of EFI as something of a mystery, so we decided to take a shot at swapping out a tried-and-true carburetor setup for a cutting-edge injection system in an attempt to see how difficult the swap would be and what kind of power changes we would net.
3-This is the StealthRam base...
3-This is the StealthRam base in polished trim, which looked outstanding. Lambert had the tops of the plenums blended, but Holley claims that since strictly dry air is running through the intake at this point and fuel isn't introduced until the very end of the port, this step really isn't necessary.
The first step was to find an appropriate test mule, which turned out to be relatively easy. Mike Lambert, a friend and diehard gearhead, was just putting the finishing touches on a very stout small-block for his daily driver. The engine started out life as a 400, which was then bored to 406 cubes and stuffed with lots of goodies like a Lunati forged crank, Lunati forged 6-inch H-beam rods, forged 9.2:1-compression pistons, port-matched Holley 20-degree aluminum heads that were worked over by Mike Slover at Slover Porting Service in Van Nuys, California, and a healthy Lunati hydraulic roller cam. The motor had never been fired and was fitted with a port-matched Holley Stealth intake manifold and an HEI distributor, so we thought it would be fairly representative of your average, hard-hitting, street small-block.
4-The ports were opened up...
4-The ports were opened up and matched to the gasket. This step was also done on the cylinder heads by Mike Slover at Slover Porting service in Van Nuys, California.
The next step was to find an appropriate fuel injection system to try on our raucous little Mouse motor. Since the engine was already stuffed with Holley and Lunati parts, we figured that would be the best way to go, and as usual, our timing was impeccable. It turns out that Holley recently released their newest street injection system for small-blocks, called the StealthRam MPFI (multi-point fuel injection). This wicked-looking setup is all new and totally high-tech, but it essentially looks like the bottom half of a tunnel-ram mated to the top half of an old mechanical fuel injection "breadbox" intake. What we're trying to say is that thing absolutely screams "LOOK AT ME!" When the box arrived, we were amazed at how complete the kit truly is. Holley packages everything from the intake and injectors to the wiring harness, software, gaskets, bolts, plugs, and other miscellaneous hardware.
5-The base bolted on without...
5-The base bolted on without a problem, and we used Fel-Pro reusable gaskets to hurry the process along.
Finally, a call was made to the horsepower gurus at Vrbancic Brothers Racing in Ontario, California, where we would be doing all of our dyno-testing. George and Bob Vrbancic (who also own The Carburetor Shop) have been involved in this game for a long time, so we knew their expertise would come in handy. We also invited our buddy Mike Petralia, technical editor of our sister magazine Super Chevy, for a little backup tech support. Once the 406 was bolted up to the dyno, George dropped on a Holley HP750 straight out of the box, and we started making pulls. With 34 degrees of initial timing and slightly rich jets in the carburetor (a little too much fuel is better than not enough) we made 423 hp at 5,100 rpm and exactly 500 lb-ft of torque at 3,900 rpm. Those are some pretty stout numbers for a pump-gas small-block, and while we probably could have squeezed an extra pony or two out of the motor with more testing, time was running short and we needed to get cracking on the injection install.
6-Squirting a little WD-40...
6-Squirting a little WD-40 on the rubber grommet at the base of the fuel injector will make it slide into the injector fuel rail and injector boss much more easily.
The new intake base bolted on easily, and within an hour most of the hardware (including injectors, injector rails, distributor, top plenum, throttle body, and fuel lines) had been installed. This step was fairly easy and the directions were quite clear. After that it was time to do the wiring, which took a little more thinking. Thankfully, Holley designed this wiring harness in such a way that each plug will only fit in its designated receptacle, so wires cannot be crossed and things cannot be hooked up incorrectly. The electronic distributor, fuel injectors, throttle body, temperature probes, and more all attach to a main computer box, which is about three times the size of a pack of cigarettes. Unfortunately, one plug that ran from the distributor to the ignition box was missing, but Petralia figured out that it was identical to the coolant temperature-sending-unit plug found on late-model Chevy pickups, so a quick run to the dealership around the corner remedied the problem.
7-Once the injectors are in...
7-Once the injectors are in the rail, the entire unit can be pressed into the bosses in the intake manifold.
Finally, it was time for the magic to happen, and this is when it became apparent that having Petralia along was an excellent idea. The StealthRam comes complete with its own software, which we loaded into a laptop that was plugged into the EFI computer through a supplied USB cable. The software allows the user to select a baseline program just to get the motor started, but since there was no baseline for a 406, we selected a 383, which was the next best thing. George was able to get the engine started, but it popped and crackled and didn't run very well at first. After a few minutes of looking, it appeared that it was very lean. This was most likely a result of using the 383 baseline. The provided software allows the user to look at either a 2-D or 3-D map of the fuel curve as the engine is running, and a small cursor bounces around the rpm range where the motor is running, telling you how much fuel is being provided. With George manning the dyno computer and Mike Petralia working the laptop, we were slowly able to get the curves dialed in, and the 406 began to purr like the proverbial kitten. Essentially the process involved looking at the fuel, rpm, and exhaust gas temperatures on the dyno and using those to determine where and how much more fuel was needed. At that point Mike could simply highlight the area and hit the "up" key on the computer to increase fuel flow. After about two hours' worth of tuning, the revs were snappier than ever and power numbers came up. Horsepower peaked at 445 at 5,300 rpm, while peak torque actually dropped a miniscule amount to 498.2 at 4,100 rpm. It's important to note, however, that while peak torque didn't really change, the overall torque curve was much flatter with the EFI, as it began to drop off at 4,200 rpm with the carburetor but continued on right until redline with the injection. That kind of difference is what you feel in the seat of your pants on the street.
8-There is a threaded hole...
8-There is a threaded hole in the base of the upper plenum, in case you need an extra port for vacuum. We did not, so it was plugged.
So after a full day of dyno thrashing one thing we determined is that aftermarket fuel injection technology has come a long way in the past decade. Horsepower was increased significantly, and the torque curve flattened out for better street driving. Plus, the unit looks absolutely wicked. However, keep in mind that we had two experienced professionals lending helping hands with this swap, so a two-hour install should not be expected. Plan on spending the better part of a long weekend bolting this thing up, and unless you have access to a dyno, it will probably take another week or two of driving around to get it running flawlessly. Add a modern overdrive trans and you may just end up with the ultimate high-tech / high-performance street rod!
 9-Here, Petralia and David...  9-Here, Petralia and David Kahn bolt the upper plenum on with four long bolts that slide through the top of the intake. |  10-This is how things look...  10-This is how things look with the basic hard parts bolted on. The fun stuff is yet to come. |  11-Next, Holley provided an...  11-Next, Holley provided an electronic, computer-controlled distributor that works hand-in-hand with the EFI system. |
 12-The wiring harness that...  12-The wiring harness that comes in the kit is pre-cut and loomed, and it features individualized connectors so that nothing can be hooked up incorrectly. The first plugs to get hooked up ran to the fuel injectors. |  13-Next, the billet throttle...  13-Next, the billet throttle body was installed. |  14-The throttle position sensor...  14-The throttle position sensor is very sensitive, and it may be necessary to rotate or move the throttle body, once the sensor is hooked up, to gain a perfect reading. |
 15-The new system is all hooked...  15-The new system is all hooked up and ready to run. It certainly looks awesome, and it sounded nearly as cool as it looked once things were dialed in on the computer. |  16-Men at work. Here Mike...  16-Men at work. Here Mike Petralia and George Vrbancic synched up their brains and computers to tweak the EFI into submission. George worked the dyno computer and read off fuel numbers while Mike tuned the actual Holley computer. | |
Vrbancic Bros. Racing
1463 East Philadelphia St., Dept. R&C
Ontario, CA 91761
(909) 930-9980
Fax: 909-923-3950
Date: 03-14-2003
Time: 11:01:02
:MIKE.LAMBERT SB CHEVY 406 CU
:TIMING:34*
:HOLLEY HP 750 CFM
:JETS:74PRI:85SEC
:FUEL UNION 91 OCT :SG725
| Speed | CBTrq | CBPW |
| rpm | lb-ft | CHp |
| 2,500 | 451.1 | 214.7 |
| 2,600 | 463.6 | 229.5 |
| 2,700 | 476 | 244.7 |
| 2,800 | 484.6 | 258.4 |
| 2,900 | 491.7 | 271. 5 |
| 3,000 | 494.9 | 282.7 |
| 3,100 | 495.8 | 292.6 |
| 3,200 | 495.7 | 302 |
| 3,300 | 494.7 | 310.9 |
| 3,400 | 495.2 | 320.5 |
| 3,500 | 495.9 | 330.5 |
| 3,600 | 497 | 340.7 |
| 3,700 | 497.5 | 350.5 |
| 3,800 | 498.4 | 360.6 |
| 3,900 | 499.9 | 371.2 |
| 4,000 | 498.4 | 379.6 |
| 4,100 | 496.3 | 387.4 |
| 4,200 | 493.3 | 394.5 |
| 4300 | 487.1 | 398.8 |
| 4,400 | 481.4 | 403.3 |
| 4,500 | 476 | 407.8 |
| 4,600 | 470.1 | 411.7 |
| 4,700 | 464.2 | 415.4 |
| 4,800 | 458.6 | 419.2 |
| 4,900 | 452.4 | 422.1 |
| 5,000 | 444.9 | 423.5 |
| 5,100 | 436.2 | 423.6 |
| 5,200 | 426.5 | 422.3 |
| 5,300 | 417.4 | 421. 2 |
| 5,400 | 406.3 | 417.7 |
| 5,500 | 394.7 | 413.3 |
| [ Average data] | |
| 4,000 | 472.1 | 356.2 |
Vrbancic Bros. Racing
1463 East Philadelphia St., Dept. R&C
Ontario, CA 91761
(909) 930-9980
Fax: 909-923-3950
Date: 03-14-2003 Time: 16:43:02
:MIKE.LAMBERT SB CHEVY 406 CU
:TIMING:38*
:HOLLEY FUEL INJECTION
:FUEL UNION 91 OCT :SG725
| Speed | CBTrq | CBPwr |
| rpm | lb-ft | CHp |
| 2,500 | 447.2 | 212.9 |
| 2,600 | 458.3 | 226.9 |
| 2,700 | 469.5 | 241.4 |
| 2,800 | 478.7 | 255.2 |
| 2,900 | 484.7 | 267.6 |
| 3,000 | 488.1 | 278.8 |
| 3,100 | 489.7 | 289.1 |
| 3,200 | 490 | 298.6 |
| 3,300 | 489.5 | 307.6 |
| 3,400 | 489.6 | 317 |
| 3,500 | 490.3 | 326.8 |
| 3,600 | 490.7 | 336.4 |
| 3,700 | 491. 6 | 346.3 |
| 3,800 | 493.9 | 357.3 |
| 3,900 | 496.5 | 368.7 |
| 4,000 | 497.4 | 378.9 |
| 4,100 | 498.2 | 388.9 |
| 4,200 | 497.3 | 397.7 |
| 4,300 | 495.7 | 405.9 |
| 4,400 | 493.7 | 413.6 |
| 4,500 | 491.6 | 421. 2 |
| 4,600 | 488.4 | 427.8 |
| 4,700 | 483.4 | 432.6 |
| 4,800 | 477.9 | 436.8 |
| 4,900 | 471. 2 | 439.6 |
| 5,000 | 464.8 | 442.5 |
| 5,100 | 457.2 | 444 |
| 5,200 | 449.8 | 445.3 |
| 5,300 | 441.7 | 445.7 |
| 5,400 | 432.1 | 444.3 |
| 5,500 | 420.2 | 440.1 |
| [ Average data] | |
| 4,000 | 477.7 | 362.4 |
Holley Performance Products
1801 Russellville Rd., Dept. R&C
Bowling Green, KY. 42101
Tech: (270) 781-9741
Nearest Dealer: (800) HOLLEY-1, Ext. 8530
www.holley.com
Lunati
Tech: (901) 365-0950
Nearest Dealer: (800) HOLLEY-1, Ext. 8530
www.lunaticamshafts.com
Vrbancic Bros. Racing
1463 East Philadelphia St., Dept. R&C
Ontario, CA 91761
(909) 930-9980
www.customcarbs.com