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404CI LS2 Carburetor Engine Build - High Winder

Pumping Up A Gen IV LS2 For Serious Motor-Only Duty

Over the years we've been involved with a number of Gen III and IV engine builds and for longtime readers, you may even recognize the current LS2 that we've recently rebuilt. If so, then you'll know that this will be the third incarnation since the January '07 issue.

chp_01_o 1003chp_404ci_ls2_carburetor_engine_build Crankshaft 2/17

Back then we had a friendly in-house competition to find out how a 402ci LS2 would fare against a conventional 406ci small-block ("Old School Meets New," page 20). All said and done, both engines generated a tick over 580 horsepower with costs being nearly identical; the biggest difference was in how docile the Gen IV was in comparison to the traditional mill. Either way, there was no clear-cut winner; instead it went to show that fairly aggressive LS engines could be built more attuned for the street at a very reasonable price.

Just under two years later, we reintroduced our mill with a completely different top end package and were able to push the power levels even higher by eclipsing the 600hp barrier with a solid-roller Comp camshaft and a set of Trick Flow 235cc cathedral port cylinder heads ("Thumper," Dec. '08, page 28). While those numbers were plenty to write home about, we went on to try the then new Zex Perimeter plate; the net results showed 780 hp and 801 lb-ft of torque!

With another year down the road, we decided to take our 402ci to the next level. Rather than topping it off with a supercharger, we wanted to see the results to be had in a naturally aspirated configuration. We'll tell you up front that this is not a street-friendly powerplant, instead it's heavily geared for the weekend dragstrip jockey with a thirst for high-test fuel.

chp_02_o 1003chp_404ci_ls2_carburetor_engine_build Aluminum_engine_block 3/17

For the third round, we maintained a mostly similar package, only we opted for maximum compression by utilizing a set of AutoTec pistons and rings, a larger valve package by stepping up to a set of 2.10-inch on the intake side over the previous 2.08-inch valves, and made way for one of the largest Comp solid-rollers we've ever seen for an LS engine with all the supporting valvetrain, including robust springs and their shaft-mount-style rockers. For induction duties, we swapped the Edelbrock Victor Jr. manifold for a much larger Super Victor and topped it off with Quick Fuel Technology's latest three-circuit 1,050-cfm carburetor with a 4150-style base. We even borrowed a Peterson Fluid Systems oil/vacuum pump setup in order to make sure we would extrapolate every bit of power from this combination.

At the heart of our project, the credit for this creation goes to Rocco Acerrio from A.R.E. Performance & Machine in Simi Valley, California. This is a one-stop shop that offers everything from detailed machining to complete engine assembly. We're absolutely pleased with his work and if you're looking to build something similar; he's certainly the man to get the job handled.

If you thought the previous combos were something, you're gonna get a kick out of this one. For now, we're going to introduce the build, but be sure to keep an eye for the results in an upcoming issue as we put it to the test at Westech Performance in Mira Loma, California.

Quick Notes

What We Did
Put together a rowdy 404ci Gen IV

Bottom Line
Swapping a few select components can get you under way to a potent combination

Price (Approx)

404ci ls2 Buildsheet
Specifications not listed are the same as stock. Except as noted, all dimensions are in inches or fractions thereof.

Displacement 404 ci
Bore x Stroke 4.010 x 4.000
Compression 15.3:1
Rod, Center to Center 6.125
Piston Deck Height 0.008
Chamber Volume 60cc
Rod Bearing Clearance 0.0025
Main Bearing Clearance 0.0025
Crank Endplay 0.006
Piston Ring Endgap 0.022 top
  0.026 second
Main Cap Torque 60 ft-lb inner
  50 ft-lb outer (moly)
Cross-bolt 18 ft-lb (sealant)
Rod bolt torque 65 ft-lb (moly)
Head bolt torque 70 ft-lb (moly

Lift Intake Exhaust
0.100 73 58
0.200 152 130
0.300 237 204
0.400 294 248
0.500 328 263
0.600 352 270
0.700 358 274
0.800 360 274
*cfm at 28 inches H2O

Manufacturer Comp Cams
Part Number 54-000-12
Grind Number LS1 1724R/ 1860R R 113
Type Mechanical roller
Valve Lift 0.834/0.800-inch intake/exhaust
Duration at 0.050 277°/288° intake/exhaust
Lobe Separation 113°

Clevite MS-2199H H-series main bearings (set) $153
  CB-663HN H-series rod bearings (each) 9
Comp Cams 54-000-12 Camshaft 400
  8904-16 3/8-inch Hi-Tech pushrods 160
  875-16 Pro Magnum lifters 208
  947-16 Triple valvesprings 326
  632-16 Super valve locks 32
  4786-16 Spring locators 34
  620-16 Valve lash caps 34
  1500 Gen III aluminum shaft rockers 1,030
  735-16 1.625-inch Titanium retainers 290
Edelbrock 28097 Super Victor LS1 manifold 444
Fel-Pro 1161R/1161L Head gaskets (each) 72
Quick Fuel Technology P-1050-3 3-circuit 1,050-cfm carburetor 940
Moroso 20141 LS1 conversion pan 274
  24840 Oil pump pickup 42
AutoTec 1001783-C Pistons Call for pricing


Quick Fuel Technology
Bowling Green, KY 42101



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