LKN Speeds Vortec 350 TBI

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LKNSPEED2.jpg (50401 bytes)           1992 Silverado Sport ‘SS454 clone’

      Scott @ LKN Speed set out to build a  potent, low-budget Vortec TBI smallblock package for customers and used his own work    truck as the test mule.  The goal was 200hp/300tq at the rear wheels and 20mpg- all on 87 octane fuel!  The engine package is very basic- just a good combination of parts that work well together:

GM ‘010’ 2 bolt block, bored .060-over, HME coated bearings Speed Pro flat top pistons, stock rods and crank- balanced 9.7:1 compression

Vortec ‘906’ heads, with  ‘street port’ special, 3 angle seats + summit 1.94/1.5 valves

Comp 212/218, .449/.458 flat tappet cam and matching valve springs

stock GM rocker arms, Summit stage-1 intake + trans-dapt center mount TBI adapter     UNPORTED stock 42mm 450cfm GM 5.7 throttle  body

Custom chip/fuel pump/spring kit from Brian @TBIchips

Summit 1.5/2.5 shorty headers, flowmaster collector, magnaflow 3″ hi flow cat, and    flowmaster super44 muffler.

Stock GM air cleaner with Holley element and lid     Auto Specialties underdrive crank pulley     stock 700-R4 trans, stock converter, and 3.08 gears.

the dyno sheet shows a run with factory manifolds and y-pipe, as well as a run with the    headers and flowmaster collector. ALL runs were on 87 octane fuel!!!!!

Here is a video of the truck on the dyno:           This truck is a blast to drive!  A true ‘sleeper’, with a throaty    exhaust note and barely noticeable idle. Smoke shows arent a problem, and a rolling    punch will easily put those newer trucks (and a few musclecars) in the rear view mirror!  Driven with a light right foot, this combination sees 17mpg city and19-20mpg highway on a regular basis, and is very happy on 87 octane!

I must say that 245hp and 308lbs torque at the rear wheels are some impressive numbers for small headers, stock throttle body bore and stock air cleaner base.  Also note that Scott gained 18hp and 21lbs of torque by changing out that Y pipe    piece and that is a significant gain for not much $$.  I believe this combo still has at least another 20hp or so even with 87 octane fuel.

Using a conservative 20% drivetrain loss that calculates to 308hp and    385lbs of torque at the flywheel which are some good truck numbers and I feel 20% is a    little low for drivetrain loss but we don’t want to exaggerate numbers either.  The    fact that it runs very smooth with 100hp more than a stock TBI truck and 85lbs more torque    is the important thing here. This engine has great low end torque and is the reason Scott can still get away with running those wimpy 3.08 gears.

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