Super Chevy Magazine Homepage Super Chevy
Facebook Click here to find out more!

Holley EFI System - A Stroke Of Efi Genius

We Test The Hye-Tech Performance 391 Stroker With Holley's New EFI

Holley Efi System Seal
Two gaskets are supplied to seal the plenum to the base. Don't use any sealer on them. Just four stainless steel bolts are needed to hold the top down.
Holley Efi System Seal
Two gaskets are supplied to seal the plenum to the base. Don't use any sealer on them. Jus

The cool thing about tuning an EFI motor is that you do it while the engine is running. Also, the perfect tune-up is usually just a few keystrokes away, but it may take a while to get there if you're not careful. That's because it's just as easy to go way off base with your fuel map as it is to get the thing right in a matter of minutes. Holley has gone to great lengths to supply what it feels will be a reasonable fuel map for each particular EFI kit, but just like with a carburetor, there's always some power to be found with tuning somewhere. However, unlike tuning a carb with traditional jets and air bleeds, tuning EFI takes only seconds, and the results can be felt instantly.

In the end, this stroker Mouse made some great power, and the fact that it idled incredibly smooth at just around 600 rpm points to its being a great daily driver.

Holley Efi System Throttle Adjustment
The throttle position sensor (TPS) goes on the side of the throttle body and tells the computer how far the throttle blades are open. This can be roughly translated into how much power your foot wants the engine to make.
Holley Efi System Throttle Adjustment
The throttle position sensor (TPS) goes on the side of the throttle body and tells the com
ENGINE SPECS
Bore/stroke/cid: 4.030/3.832/391 cid
Crank: C.A.T. 4340-steel
Rods: C.A.T. 4340-steel 5.7"
Pistons: JE forged 10.4:1
Rings: Total Seal gapless
Bearings: Clevite "H" series
Camshaft: Lunati hydraulic roller PN 50156
Cam Specs: 232/242 degrees at .050
290/300 degrees advertised
.510/.525 lift
110-degree lobe separation
Oil system: Milodon stroker pan and
HV pump
Heads: Holley Street Avenger
EFI: Holley Stealth Ram
Ignition: Holley Annihilator
  • Holley Efi System Ecu Monitors
    The Holley ECU monitors coolant temp as well as both ambient and manifold air temp. It can also be programmed to turn on or off things like electric fans and bump up idle speed when you turn on your A/C, since it now knows how hot the engine is and how well it idles.
    Holley Efi System Ecu Monitors
    The Holley ECU monitors coolant temp as well as both ambient and manifold air temp. It can
  • Holley Efi System Manual
    Before randomly trying to figure out where each wire goes, sit down and read through the entire instruction manual. You might find it difficult to read at first, but it'll all make sense once you're trying to plug things in.
    Holley Efi System Manual
    Before randomly trying to figure out where each wire goes, sit down and read through the e
  • Holley Efi System Connections
    Not only does EFI have lots of electrical connections, there are also lots of vacuum connections and even some vacuum connections that go to electrical connections! The Manifold Air Pressure (MAP) sensor is one of them. In non-boosted engines like this one, a 1-BAR MAP will always read intake manifold vacuum, instead of pressure.
    Holley Efi System Connections
    Not only does EFI have lots of electrical connections, there are also lots of vacuum conne
  • Holley Efi System Efi Tuning
    Sitting to the left is Holley's EFI expert, Doug Flynn, who flew out to California to help us tune this thing perfectly. Dyno operator and co-owner of Vrbancic Brothers Racing, George Vrbancic, is actually pretty well up to speed on tuning EFI motors and was even able to show Doug a thing or two.
    Holley Efi System Efi Tuning
    Sitting to the left is Holley's EFI expert, Doug Flynn, who flew out to California to help
  • Holley Efi System Timing
    Even though the Holley ECU controls the timing advance curve, you still have to set it first the old-fashioned way. We set ours to a max 36 degrees and tweaked the distributor's curve with the computer to get the best power. There are no springs or advance mechanism in the Holley distributor to wear out, either.
    Holley Efi System Timing
    Even though the Holley ECU controls the timing advance curve, you still have to set it fir
  • Holley Efi System Rockers
    We had to try one old hot rodder's trick to see if we could squeeze out more power. We swapped the Lunati 1.5:1 intake rockers with some 1.6:1-ratio rockers and found just a hair more power.
    Holley Efi System Rockers
    We had to try one old hot rodder's trick to see if we could squeeze out more power. We swa
RPM TQ HP
2600 401 199
2800 424 226
3000 439 251
3200 444 271
3400 444 287
3600 441 302
3800 445 322
4000 455 347
4200 461 368
4400 463* 387
4600 461 403
4800 457 418
5000 449 427
5200 434 430
5400 429 441
5600 416 444*
5800 401 443
6000 383 438
Avg 436 356
Max* 463 444
SOURCES
C.A.T. Power engine parts
345 Cloverleaf Dr., Suite C
Baldwin Park
CA  91706
Lunati Cams A Holley Performance Products Company
4770 Lamar Ave.
Memphis
TN  38118-7403
Holley Performance Products
1801 Russellville Rd.
Bowling Green, KY 42101
KY  42101
270-782-2900
www.holley.com
Total Seal
Phoenix
AZ
800-874-2753
totalseal.com
Hye-Tech Performance
13912 Valley Blvd., Unit A
La Puente
CA  91746
Vrbancic Brothers Racing
1463 E. Philadelphia
Ontario
CA  91761
909-930-9980
JE Pistons
Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!

*Please enter your username

*Please enter your password

*Please enter your comments
Comments:
Not Registered?Signup Here
(1024 character limit)
Super Chevy