Hide EFI in Your Next Project

Has Hol­ley Nailed the Per­fect Mix of Nos­tal­gia Style and Mod­ern Per­for­mance?

Hot Rod - - Everyday - Phillip Thomas Phillip Thomas and Mike Mor­gan

With the ad­vent of bolt-on EFI, we knew this day was com­ing; they didn’t just come for the car­bu­re­tor to re­place it as a fu­el­ing sys­tem, they came and stole ev­ery bit of the car­bu­re­tor’s retro-cool looks, too. As much as carbs were cho­sen for their prac­ti­cal strengths, to some folks, their look called back to the right pe­riod for many projects. Hol­ley un­der­stood this and ma­chined up a throt­tle-body that took all the tech­nol­ogy it has de­vel­oped with the Terminator and Dom­i­na­tor EFI sys­tems and packed them into a dou­ble-pumper dop­pel­gänger. This is where Dale Snoke’s 1964 Mercury Comet— a tra­di­tional A/FX Gasser that runs nos­tal­gia races all over Socal—comes into play. Car Craft read­ers might rec­og­nize Dale’s Comet from the 2016 car­bu­re­tor test siz­ing up which cfm of Hol­ley dou­ble-pumper was ideal—ironic that we’re here to erase all that hard work with Hol­ley’s self-learn­ing EFI.

As a quick re­fresher, The Rocket is pow­ered by a 425ci Wind­sor (4.060 bore with a 4.100-inch stroke) topped by a set of 195cc AFR Rene­gade heads that are stuffed with 2.05/1.60-inch valves, which all tap to the rhythm of an Isky roller cam (260/260 with 0.620-inch lift and a 110-de­gree LSA). The wild, through-the-fender head­ers are home­built by Dale, an elec­tri­cian and welder by trade, and he’s fab­ri­cated two sep­a­rate ex­haust sys­tems, one muf­fled and one baf­fled, de­pend­ing on the noise re­stric­tions for the day’s ac­tiv­i­ties. This is no­table in our EFI test, as open head­ers with an O2 sen­sor in the col­lec­tor need ex­tra ex­haust length to en­sure an ac­cu­rate fuel-ra­tio read­out; with­out some kind of ex­ten­sion, am­bi­ent air can get pulled into the col­lec­tor be­tween pulses, skew­ing O2 sen­sor read­ings—this is avoided in Dale’s con­fig­u­ra­tion. Out back, a C4 built by Nick Ma­gana, han­dles the gear shuf­fling and a Ford 9-inch with 4.30 gears lays down the power with a set of plain, old leaf springs. This is a bare-bones, street-ready combo that churns miles to a cruise night across Los An­ge­les as well as it churns out 6-sec­ond eighth-mile passes.

We’ve observed many EFI bap­tisms over the years, but this one is spe­cial: with Dale’s Comet stay­ing true to its al­tered-wheel­base roots, could we build an EFI sys­tem that blended right into the vin­tage un­der­hood land­scape of gold Moroso valve cov­ers, wild­hair head­ers, and prom­i­nent MSD dizzy? And bet­ter yet, would EFI’s closed-loop self­tun­ing for conditions make the car quicker, if not more con­sis­tent? With a week­end’s worth of ef­fort, we found out.

Hol­ley’s new Terminator Stealth EFI is a vari­a­tion of its other four-bar­rel, throt­tle­body–in­jected EFI sys­tems. Thanks to Moore’s Law—the one that states tech­nol­ogy shrinks and be­comes more ca­pa­ble on an ex­po­nen­tial rate—Hol­ley has squeezed four in­jec­tors, a throt­tle po­si­tion sen­sor, idle air con­trol valve, MAP sen­sor, and in­take air-temp sen­sor un­der the façade of a clas­sic dou­ble-pumper. This means the only ex­ter­nal sen­sors that you have to think about are for coolant temp, air/fuel (A/F) ra­tio, and rpm. Hol­ley was mind­ful to sheathe its wir­ing in a sim­i­lar braid­ing as its fuel lines, so the har­ness quickly blends into the en­vi­ron­ment if routed ap­pro­pri­ately. For con­trol,

Terminator Stealth uses a vari­a­tion of the fa­mil­iar HP-se­ries ECU with four in­put/out­put chan­nels for ad­di­tional con­trols, such as fans, a shift light, or nearly any­thing else you can dream up to be trig­gered or read by the unit. This also means com­plete lap­top tun­ing when needed, though for this test we wanted to put all the weight on the ECU’s shoul­ders in fig­ur­ing out this nos­tal­gia combo. Hol­ley also included an ex­ter­nal high-pres­sure fuel pump for our kit (PN 526-5), which we’ll test in this combo.

To adapt the Terminator Stealth Kit to the Comet, we also or­dered a pair of Hol­ley’s -8 AN bil­let 175-gph fuel fil­ters (10 and 100 mi­cron; PN 162-554 and 162-564, re­spec­tively) as a pre- and post-fil­ter, though we stuck with the included pump for this test. The bil­let fil­ters al­lowed for a tidy adap­ta­tion to the ex­ist­ing -8 plumb­ing, and we’ll test other pumps in this combo down the road with full AN con­nec­tions. We also de­cided to go with Earl’s braided fuel line given the track us­age (and tech-in­spec­tor eye­balls) here, though the included Va­por Guard fuel hose is more than up to the task in a street­driven project and tech­ni­cally meets NHRA ap­proval. We paired a Hol­ley 15- to 65-psi (PN 12-846) fuel pres­sure reg­u­la­tor with the sys­tem to main­tain the rec­om­mended 43 psi of fuel pres­sure.

It’s at this point that we’ll de­lin­eate some terms, sep­a­rat­ing self-learn­ing from the closed-loop, self-tun­ing as­pects of Hol­ley’s EFI. Hol­ley’s lauded self-learn­ing is the process in which the ECU ad­justs its own base cal­i­bra­tion (an X/Y ta­ble that com­pares load ver­sus rpm, re­sult­ing in a tar­get A/F ra­tio, de­pend­ing on that con­di­tion) around the en­gine combo you’ve told it to run. This is be­cause ev­ery en­gine will re­act dif­fer­ently to throt­tle, tim­ing, and fu­el­ing ad­just­ments in nor­mal use, and the self-learn­ing ad­justs the base cal­i­bra­tion so there’s less and less com­pen­sa­tion to hit the tar­get A/F ra­tio. What this step re­places is that ini­tial cal­i­bra­tion that was a ma­jor bar­rier of en­try to many stand-alone EFI sys­tems.

Build­ing and di­al­ing in a base cal­i­bra­tion was ei­ther a rel­a­tively ex­pen­sive (though very valu­able) stop at a tun­ing shop or re­quired a wealth of up­front knowl­edge to DIY. With Hol­ley’s self-learn­ing, that ini­tial cal­i­bra­tion is en­tirely han­dled by the ECU while driv­ing—and it must be trained. This is done by driv­ing the car across the rpm range at dif­fer­ent throt­tle po­si­tions, work­ing it through that Load vs. RPM ta­ble in as many ar­eas as pos­si­ble. We rec­om­mend start­ing with drives around the block and mov­ing on to high­way trips. This will build out the low- to medium-load ranges of the base cal­i­bra­tion, which help the ECU pre­dict what to do with full-throt­tle loads. We had

to fat­ten up the cruis­ing tar­get A/F ra­tio, but within about 50 road miles, the self­learn­ing had got­ten the hang of Dale’s stro­ker.

Self-tun­ing is what we’ll re­fer to as the closed-loop con­di­tion of EFI, where the car is us­ing the base map and cal­cu­lat­ing the amount of fuel nec­es­sary based on the at­mo­spheric conditions read by its var­i­ous en­gine sen­sors—this is the real ad­van­tage of EFI. In gen­eral, the magic of carb tun­ing isn’t in mak­ing a big dyno num­ber, it’s in ad­just­ing the carb to am­bi­ent conditions to op­ti­mize the fuel curve. This meant a trial-and-er­ror process of tak­ing a pass and mak­ing a messy jet change be­tween rounds—goldilocks with times­lips. This is the magic of EFI; since the ECU does this on the fly dur­ing the run—en­sur­ing that you not only max­i­mize power out­put but also keep the en­gine in a safer en­ve­lope of tun­ing—the car won’t suf­fer as much from bad air, and we the­o­rized that most of the per­for­mance ad­van­tage on track would come from this sec­ond-by-sec­ond con­sis­tency.

[ If it weren’t for the gi­ant EFI let­ter­ing, you’d be right to pick up this box ex­pect­ing a four-bar­rel carb. The Terminator Stealth EFI comes in a pol­ished, black, and gold fin­ish to match your com­mon car­bu­re­tor looks.

[ We cut down the vi­bra­tion in­su­la­tion of our pump to ex­pose the body. Given the heat ra­di­ated off Cal­i­for­nia high­ways, we had heard this can pre­vent fuel boil­ing.

[ Hol­ley’s 15- to 65-psi bil­let fuel pres­sure reg­u­la­tor was the key­stone of this build, giv­ing us a port for our re­turn line while also ad­just­ing for EFI’s higher pres­sure over a car­bu­reted fuel sys­tem.

[ A mount­ing bracket was cut out of3⁄16- inch steel, which housed the in­let fil­ter (10 mi­cron) and pump. The down­stream fil­ter (100 mi­cron) was mounted in place of the for­mer Hol­ley Black Pump.

[ A short piece of fuel hose was used as our re­turn to pre­vent the fuel from “wa­ter­falling” into the fuel cell, cre­at­ing cav­i­ta­tion-in­duc­ing bumpers.

Newspapers in English

Newspapers from USA

© PressReader. All rights reserved.