Hemi-Head LS Makes 636 HP on Pump Gas

Greg Brown Blan­kets a 416CI LS With Hemi Heads to Make 636 HP on Pump Gas

Hot Rod - - Contents - Jeff Smith John Machaque­iro and Greg Brown


That’s the out­rage we’d ex­pect from the Mopar faith­ful or per­haps even the Ford hemi guys. Af­ter all, their right­eous in­dig­na­tion is aimed di­rectly at a set of hemi heads sit­ting astride an LS short-block.

Al­low that to stew in its own juices for a mo­ment or two. Then ig­nore the au­to­mo­tive the­olo­gians and fo­cus in­stead on the fact that hot rod­ding has al­ways rid­den on the knife’s edge of au­to­mo­tive heresy. It wasn’t all that long ago that hot rod­ders were re­viled hooli­gans.

Still, the two terms “hemi” and “LS” would seem to be mu­tu­ally exclusive, ex­cept to Greg Brown. To him, the two were des­tined to part­ner up to cre­ate the un­like­li­est of per­for­mance en­gines. Brown’s ini­tial foray into the world of hemi heads be­gan when he saw the need—long be­fore per­haps there was a need—for a set of hemi heads on a small-block Ford. Emerg­ing from a rather large pile of alu­minum shav­ings, he pre­sented the world a set of Ham­mer­head hemi cast­ings bang­ing valves up and down on a 351W and later a 427 Ford. That alone was cause for cel­e­bra­tion, but Brown was al­ready look­ing ahead.

Be­ing the cre­ative guy that he is, it oc­curred to him one day that there was but a mere 0.020-inch dif­fer­ence in the bore spac­ing be­tween a small-block Ford (4.380-inch) and GM’s LS en­gine (4.40-inch). This sim­ple ob­ser­va­tion led him to drill a 10-bolt LS head pat­tern into a pair of cast­ings, and with a few other changes, he had what he needed to bolt a set of Ham­mer­heads on an LS en­gine. Align­ing his ducks beak-to-tail wasn’t nearly as easy as that over­sim­pli­fied de­scrip­tion, but a good idea whose time has come is a force that can­not be ig­nored.

Brown has spent the past 18 months deal­ing with all the pesky minu­tiae re­quired to make the valves go up and down with­out is­sues. He in­tro­duced his pre­miere hemi LS at the 2017 PRI Trade Show, and HOT ROD was im­me­di­ately in­trigued. We put the pres­sure on him by record­ing the event as the LS hemi churned up the dyno for its maiden ef­fort. But be­fore we get to the sexy power num­bers, let’s do the equiv­a­lent of au­to­mo­tive cave div­ing into those mas­sive alu­minum ports that started all this crazi­ness.

Brown’s ini­tial ef­fort was aimed at build­ing a set of hemi heads that would bolt di­rectly to a small-block Ford. While the valve ar­range­ment and the mas­sive valve cov­ers cer­tainly ex­ude hemi, look­ing at the cham­ber might lead you to think this is noth­ing more than a wedge cham­ber with big valves. Ac­cord­ing to Brown, that’s ex­actly what it is. “It’s re­ally just a ro­tated wedge cham­ber.” But a nearcentral­ized spark plug and wide, canted valves pointed in make it look like a hemi.

’Nuff said.

The main ad­van­tage of this valve ar­range­ment is that the valves open to­ward the

“I want to be able to bolt my heads on and have them work. Sim­ple as that.” — Greg Brown

cen­ter of the cylin­der bore, as op­posed to wedge heads with in­line valves that open to­ward the cylin­der wall. The dif­fer­ence is all about flow. With a 2.20inch in­take valve, this head with Brown’s street-friendly 45-de­gree valve job will push the nee­dle to 379 cfm on the in­take side and 263 cfm on the ex­haust side, both at 0.700 lift. And those are not the peak num­bers; the in­take can over­achieve beyond 400 cfm at 0.800inch lift.

Brown says he has sev­eral cus­tomers fo­cused on tur­bocharg­ing these cast­ings. With port­ing and a larger valve, Brown has al­ready achieved 470 cfm on the in­take side. The com­bi­na­tion of mas­sive air­flow with boost should be im­pres­sive.

Of course, these ex­pan­sive heads also re­quire their own spe­cific val­ve­train. For this, Brown sought out Je­sel’s as­sis­tance and all Ham­mer­heads come with Je­sel Pro­fes­sional series shaft rock­ers. For this LS en­gine, Brown fit­ted the heads with bee­hive springs for the hy­draulic roller cam.

The Ham­mer­head in­take-port lay­out was orig­i­nally de­signed to al­low Ford Wind­sor in­takes to bolt right on. We’ll get to how Brown solved that for the LS a lit­tle later. The ex­haust ports were a bit more of a chal­lenge, with Brown set­tling on the Ford/Yates C3 lay­out. This al­lows an en­gine builder to at least buy the ex­haust flanges to fa­cil­i­tate cus­tom head­ers.

To be­gin this hemi LS odyssey, Brown’s ini­tial cus­tomer, Ricky Tucker, wanted this unique com­bi­na­tion stuffed into a Pro Tour­ing 1969 Ca­maro. Brown started with a pro­duc­tion LS3 block at a 4.165-inch bore and honed the cylin­ders an­other 0.005 inch and pumped the dis­place­ment with a

4.00-inch Lu­nati forged-steel crank and 6.125-inch Lu­nati H-beam rods.

An ef­fort like this re­quires some help from solid sources, like the guys at Di­a­mond, who had al­ready helped Brown with hemi pis­tons for his ini­tial Ford ef­fort. The pis­tons are re­ally just a set of LS stro­kers with a crown con­fig­ured to ac­com­mo­date the hemi valve lay­out and larger 2.200-inch in­take valves. Brown told us that bore spac­ing is mea­sured from the cen­ter out­ward, so the out­board valves would be skewed slightly in­board com­pared to a stock valve po­si­tion on an LS en­gine.

For pis­ton-to-valve clear­ance, Brown came up with a sim­ple so­lu­tion. While a stan­dard valve-re­lief pat­tern would sup­ply a 0.050-inch ra­dial clear­ance (given

01] This is what the hemi heads look like be­fore they start pro­duc­ing some se­ri­ous air­flow. Greg Brown dis­cov­ered that his orig­i­nal Ford small-block hemi cast­ings would also fit a large-bore, LS3-style en­gine with a few tweaks.

02] These cast­ings were treated to the same pro­duc­tion valve job and valve sizes as any stan­dard Ham­mer­head heads with no special port work added. Valve sizes are 2.200/1.65-inch with a 62cc com­bus­tion cham­ber. 03] The cast­ings also re­quire a ded­i­cated set of Je­sel Pro alu­minum rock­ers. The hemi valve lay­out re­quires the long ex­haust rocker, but with mild hy­draulic roller camshaft valve tim­ing, rocker de­flec­tion is min­i­mal.

04] The big­gest chal­lenge was cre­at­ing a man­i­fold to meet his cus­tomer’s re­quire­ments. Brown chose a Chevro­let Rac­ing SB2 man­i­fold that he cut down the cen­ter, adding two 5⁄8- inch-thick lengths of alu­minum to cre­ate the proper width and run­ner po­si­tions.

the 2.200-inch valve size) be­tween the valve edge and the pis­ton, that would be­come tighter with the out­board cylin­ders due to the hemi heads’ shorter bore spac­ing. So Brown had Di­a­mond ma­chine the valve pock­ets for a 2.250inch valve di­am­e­ter, cre­at­ing the ad­di­tional ra­dial clear­ance.

Brown says that while these Di­a­mond pis­tons were cus­tom-ma­chined and there­fore ex­pen­sive, he’s work­ing with a cou­ple of pis­ton com­pa­nies to come up with pro­duc­tion parts that would be more af­ford­ably priced. For seal­ing, Brown went with a set of 1.5/1.5/3.0mm To­tal Seal duc­tile-iron top and Napier sec­ond ring set with a stan­dard ten­sion oil ring set.

The next big hur­dle was a bit more chal­leng­ing. Brown’s Ham­mer­head cast­ings re­verse the nor­mal LS valve lay­out,

mean­ing that an LS en­gine ori­ents the valves start­ing with the in­take while the hemi heads lead with an ex­haust valve. This de­mands a re­ori­ented camshaft that re­verses the in­take and ex­haust lobes. At the time, Brown em­ployed a bil­let LS cam core to cre­ate his camshaft. This clearly isn’t an off-the-shelf cam, even though the specs are still very mild at 238/246 de­grees at 0.050 with 0.595-inch lift on both the in­take and ex­haust ground on a 112-de­gree lobe­sep­a­ra­tion an­gle (LSA).

In­ter­est­ingly, Brown later dis­cov­ered al­most by ac­ci­dent that the new Gen V LT1 and LT4 en­gines switched the valve ori­en­ta­tion and now place the ex­haust valve at the front of the cham­ber in­stead of the in­take. He im­me­di­ately rec­og­nized he could use a Gen V cam blank for fu­ture LS hemi builds, saving con­sid­er­able ex­pense over a bil­let core. The Gen V en­gines use a sin­gle-bolt cam drive, but other than that, it is an easy retro-fit to any LS en­gine. Some­times the world just de­liv­ers an un­ex­pected present right to your shop door. Greg Brown must live right.

But the chal­lenges of build­ing an LS hemi were far from re­solved. The stock LS en­gine deck height is 9.240 inches, while the Ham­mer­heads were orig­i­nally de­signed for ei­ther a short-deck Wind­sor at 8.206 or the taller 351W deck of 9.48. Since Brown had de­signed his orig­i­nal Ham­mer­heads to ac­com­mo­date ei­ther of the

Ford in­take man­i­folds, the LS pre­sented a sig­nif­i­cant de­sign im­ped­i­ment.

His so­lu­tion for this first

LS hemi ef­fort fo­cused on a NASCAR re­stric­tor-plate ver­sion of the SB2 in­take. “That wasn’t my first choice, but the cus­tomer re­quired that the en­gine fit un­der the flat, stock hood of a ’69 Ca­maro.

That made it tough.” The re­stric­tor-plate ver­sion SB2 was a solid 2 inches shorter and pro­vided the real es­tate to fit it with a Hol­ley 1,000-cfm throt­tle-body. But that doesn’t mean this in­take bolted right up.

When asked how much time he had in­vested in this in­take, Brown just sighed and ad­mit­ted he eas­ily had more than 40 hours in this cast­ing just to make it fit. To start, he sawed it right down the mid­dle, adding a pair of 5/8-inch-thick plates. Plus, the cus­tomer wanted the en­gine to look car­bu­reted, so the short DeatschWerks

50-lb/hr in­jec­tors were placed on the in­board side of the in­take run­ners. With the fi­nal weld­ing of the now two-piece in­take com­plete, it’s dif­fi­cult to fully ap­pre­ci­ate the ef­fort that went into its cre­ation.

Brown says he’s ini­ti­ated a plan with Tyler Ho­gan at Ho­gan’s Rac­ing Man­i­folds to build a sheet­metal base for the LS hemi en­gines that would ac­com­mo­date the mul­ti­ple top half Hol­ley cast­ings that would al­low both a sin­gle or dual four-bar­rel mount or a front­mounted EFI-style throt­tle-body that will also make this a much more af­ford­able in­duc­tion. Brown said that if he had been able to use the taller man­i­fold, the en­gine would have gained sig­nif­i­cant torque, but pack­ag­ing con­straints dic­tated the shorter ver­sion. All that means is there is plenty of power still avail­able, given fewer tun­ing re­straints.

With the en­gine as­sem­bled, Brown de­liv­ered the en­gine to Pro Mo­tor En­gines in Mooresville, North Carolina, where Den­nis Borem and com­pany bolted the hemi on the dyno while Hol­ley’s Robin Lawrence lent his con­sid­er­able tun­ing skills to the Hol­ley HP EFI sys­tem. In a short pe­riod of time, the wide­body LS churned out a peak torque of 545 lb-ft at 5,500 rpm and 636 hp at a very man­age­able 6,500. This is a 10.5:1-com­pres­sion, pump-gas en­gine that would run all day at these el­e­vated num­bers. De­spite the large, sin­gle-plane in­take and big-tube head­ers, this 416 was still ca­pa­ble of more than 400 lb-ft, even at 2,800 rpm.

With all this in­no­va­tion, Ham­mer­head prices a pair of these cast­ings for a hy­draulic roller cam at only $5,995. There’s far more to a com­plete en­gine, of course, but it’s not as pricey as it first

10] A Vin­tage Air front drive spins the ac­ces­sories like A/C, wa­ter pump, al­ter­na­tor, and power steer­ing. Brown added an Edel­brock wa­ter pump that re­quired a small amount of ma­chin­ing and fea­tures a sim­ple-tore­place im­peller car­tridge. 11] It took Brown ( right) about 14 months to make the ini­tial pack­ag­ing hap­pen for this hemi LS with help from Ch­ester Arm­strong ( left).

12] All the dyno test­ing was per­formed at Pro Mo­tor En­gines (PME) in Mooresville, North Carolina, with help from Den­nis Borem.

13] Con­trol over spark and se­quen­tial fuel was as­signed to Hol­ley’s HP EFI sys­tem.

14] To make sure it all went smoothly, Hol­ley’s Robin Lawrence made a trip to Mooresville to en­sure that all the tun­ing was op­ti­mized.

ap­pears. There you have it, LS ir­rev­er­ence on a grand scale that will soon find its way un­der the hood of a Detroit Speed–built 1969 Ca­maro. We can only imag­ine the ques­tions that will crowd around the en­gine com­part­ment every time Tucker pops the hood.

Comp Cams

05] This is the fi­nal­ized man­i­fold that is now a bolt-to­gether, two-piece man­i­fold. With­out the prior photo, you’d never know this man­i­fold had been ex­ten­sively mod­i­fied. 06] From un­der­neath, the ro­tat­ing assem­bly is much more tra­di­tional LS with a...

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