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700R4 Swap | AN Thread Sizes | Cold Air Induction | Fuels | LS1 Info & Specs | Turbo Tech 101 | Weather Correction | Feature Car - 86 Vette

1986 Corvette



The Story Of One L98
Corvette

The Purchase
The ’86 Corvette was purchased in 1990 from a dealership. The body appeared in good condition and the compression checked above average for 48K miles and the color was my 1st choice, so the deal was completed and my mid-life crisis acted on. I was quite impressed with the power this car imparts on the senses. The first full throttle acceleration provoked a “holy shit” and an ear to ear smile you just hoped no one else saw - unbelievable.

The Seduction
The next six years were spent learning about corvettes so performance enhancements could be made while tailoring the operating characteristics to suit my needs. Going to car shows and subscribing to the many mag’s and parts/accessories catalogs was an important part of this process. I guess reading about performance success stories plants a subliminal desire in one to run with the big guns.

About this time, my son asked me to follow him to Epping one Wednesday evening so he could race his Corvette. He had just completed an engine transplant and was anxious to see what it would do, all-the-while being cautiously optimistic. So we head up there and before the night ended I was talked into the staging lanes. I made two runs that night and was hooked. I ran 97 mph @ 14.8 secs, 60 ft time was 2.19 - pretty average, but the obsession for speed would intensify over the coming months.

SmokemUP

Modifications - Phase 1
Making the car go faster is a logical development in the evolution of drag racing. If you have done it you know what I’m talking about. The only non-stock items on the car to this point were the GS-Cs and the Borla mufflers. 96 and 97 were spent doing the common catalog bolt-ons. Good logs were not kept so I can’t document objectively what gains can be made incrementally. I can say the BFG Drag Radials were the best cost effective purchase, added at the recommendation of my neighbor Gary who races an 11 sec GN. Prior to the end of the ’97 season, my best time was 14.126 @ 99.45 mph. The addition of the BFG’s brought my 60’ time down to 1.82 1st time out. The season ended with my best performance of 13.670 @ 100.24 and a 60’ time of 1.814.

Modifications - Phase 2
Ending the race season on a good note leaves one vulnerable to making questionable decisions. Combine this with 100K miles on the odometer and an article published in PHR by Dave Emanuel on 11/97 “Hard Rock Camaro” that addresses all of your concerns, and your well on your way to upping the excitement level a notch. I decided to have the engine done over and live the experience of managing a major modification project. Those around me wondered if too much nitro-methane got inhaled during walks through the pit area. My wife couldn’t understand why I didn’t upgrade to a new vette but I had a goal to be solidly in the 12s. So I had the engine pulled in February ’98 and delivered to Hess Machine & Balance in Fitchburg, MA. Four months later the car was back together but another two months would go by before the car would operate satisfactorily. The very 1st pass on a hot August evening was 12.566 @ 110.68 and a 60’ time of 1.786. I bettered this later in the season with a 12.415 @ 110.61 with a 1.655sec 60’.

Early in the ’99 season with cool temperatures and good air I recorded my best to date performance - 12.126 @ 111.15, 60’ was 1.629. This exceeded my 12.3 goal at the onset and has made all the planning, worrying, cost, and time consumed worth it. I recently monitored the engine parameters with the assistance of a friend’s Diacom software. The air/fuel ratio indicated was 12.2. The plan is to record data for normal road and WOT runs in order to have a new chip burned. With the air/fuel closer to 12.9 and good air, who knows the 11s may be in sight.

I’ll keep you posted. See below for details on the phase I/II build-ups

Corvette

Modifications Phase I: (Best time 13.67 @ 100.24)

  • Transmission Performance Rebuild in May, '96 by SRA in Portsmouth, RI
  • Hypertech Stage II PROM modified to turn fan on at 196·, off at 185·
  • Air foil in throttle body
  • Borla mufflers & front y-pipe (eliminating pre-catalytic converters)
  • Mass air flow sensor with screens removed
  • Air filter housing with enlarged open area and K&N filter
  • Fuel pressure regulator set to 47 psi
  • 180· Thermostat & 200· secondary fan turn-on switch
  • TPI ignition wires, Accel distributor & rotor, AC Rapid Fire Plugs
  • Heated O2 Sensor
  • BF Goodrich Drag Radials - 255-50R16

Modifications Phase II: (Best time 12.12 @ 111)

The Engine Builder’s Part - Hess Machine & Balance, Fitchburg, MA

  • Disassembly, cleaning, magnafluxing
  • 4-bolt mains added
  • Align bore w/ deck plates installed, align bore/hone mains, install cam bearings, deck surfaces machined in reference to the crank centerline for a 10.3:1 compression ratio
  • Keith Black Hypereutectic flat-top pistons fit with Total Seal Moly Max gapless rings
  • Crank reconditioned, sized, nitrided, & rotating assembly precision balanced
  • Eagle Sportsman 4340 connecting rods
  • ARP Hardware
  • Hydraulic roller cam - Lingenfelter #74219 - 219º/219º @ .050 Lift = .525 & .525, (.560 & .560 with 1.6:1 rockers)
  • Comp Cams hydraulic roller lifters and valve springs
  • Cloyes roller timing chain and gear set
  • Competition Cams Pro Magnum 1.6:1 roller rockers with ARP 7/16" screw-in studs.
  • Competition Cams Pushrods 4130 sized to fit application
  • Fel-Pro head gasket, p/n 1010 .039 thk
  • Machine Head surfaces flat. Modify cylinder heads to accept springs for 0.560 total valve lift. Match spring load to within 5%. Check combustion chambers for 64cc; Install Viton rubber valve seals; Match port interfaces
  • Rework GM HEI distributor to eliminate axial float
  • Rework Headers for uniform tube protrusion & co-planarity w/ flange. Minimize air tube penetration into exhaust passage
  • Modify flywheel to accept new torque converter and balance
  • Install new High Flow - Normal Pressure oil pump and oil pan
  • Install new oil filter and cooling adapter housing
  • Assembly, Painting, Cam Degreeing

The Major Components

  • TrickFlow Heads #31400001
  • Lingenfelter Valve Covers
  • Lingenfelter Headers 15/8" #74413
  • TPIS Ported Plenum
  • TPIS Bigmouth Intake Manifold Base
  • TPIS High Flow Runners
  • TPIS 52mm Throttle Body
  • TPIS Nippondenso Fuel Injectors, 23 lb
  • TPIS Ignition Wires
  • TPIS Level 5 Chip
  • TPIS Fuel Pump
  • Accel 300+ Ignition
  • Heated O2 Sensor
  • Fluid Damper 6¼"
  • GM Performance Parts Starter Motor - 88-91 Corvetts
  • Random Technologies Catalytic Converter
  • Precision Industries Vigilante Torque Converter
  • Secondary Fan thermoswitch circuit reworked to be manually operated
  • K&N Air Filter
  • Powder Coat Induction System Furboil Silver & Ferro Clear


Performance Highlights
  • July 1996: 14.8 @ 97 mph, 60 ft time was 2.199 (stock except Borlas & GS-Cs)
  • Oct 1, 1997: 14.126 @ 99.45 mph, 60' time was 2.199 (Mods I except BFGs)
  • Oct 19, 1997: 13.670 @ 100.24mph, 60’ time was 1.814 (Mods I)
  • Aug 5, 1998: 110.68 mph @ 12.566 ET, 1.786 sec 60 ft (1st time out, Mods II)
  • Sep 4, 1998: 110.65 mph @ 12.415 ET, 1.655 sec 60 ft (Racer’s Day)
  • Apr 24, 1999: 111.15 mph @ 12.126 ET, 1.629 sec 60 ft (Cat removed due to failure)
  • May 15, 1999: 109.69 mph @ 12.316 ET, 1.688 sec 60 ft (Corvette Day)


Afterthoughts

The thrill of speed is rewarding. On some runs the adrenaline is pumping so fast that my back hurts on route to the pit area. It is expensive and consumes time - a lot of it, but as hobbies go you can do a lot worse. I’ve made new friends and learned a lot along the way. Phase II mods cost me $15K but that includes labor. Those with the time and accommodations could reduce that significantly.

Special thanks are in order for:

SRA Performance Transmissions

Hess Machine and Balance

BF Goodrich for their drag radials & commitment to racing

Precision Industries for their awesome Vigilante Torque Converter

Lingenfelter & TPI Specialties

My son Paul for his technical help and enthusiasm

The Bay State Corvette Club Members (Everybody has an opinion and were offering it to Ken Smith, President of the BSCC, on Dyno-Day 5/1/99)

Corvette Club


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