One Member’s Mods and his Results
LG4 "low performance 305" Typically run low 17’s at about 80mph stock,never ran car stock at track. Mods:in detail Edelbrock micro-plus timing computer (I think it is discontinued) Car Craft Nov 1987 Auto Specialities crank underdrive pulley HO Z28 dual snorkel air cleaner with ducting and K&N filter Edelbrock Performer EGR #3701 intake manifold Dual Fans from a GTA-stock is a crank driven clutch fan Banks exhaust including y-pipe,full 3" exhaust,cat from a 1987 350 IROC 3.42 Posi 10 bolt rear-stock was 3.08 Car Weight 3300lbs no driver
15.1s at 91.5mph consistently 60ft time:2.25s In all,for about $900,the car went about 2 seconds and 12mph faster than stock without ripping into the motor,the motor made about 205hp,up from 150 stock,top end was about 140,up from 120,car mileage remained the same.I wonder now how fast it could have been with the 305,if I added good headers,a mild cam,and ported the heads,I feel the car could have run 14.50.
This motor was out of a wrecked 1990 L98 Corvette,complete with aluminum heads.I installed the motor without ripping into it,just to see how fast it could make the car go.I decided to not use the TPI that it came with,using the stock carb instead.
Arizona Speed and Marine headers,1-5/8"-banks y-pipe was not used. SLP oil pan-stock Corvette pan would not fit with the headers. Fluidamper harmonic balancer-stock balancer was cracked and was unuseable. Rejetted stock carb secondaries from CH rods to CK rods,primary jets remained stock. Trans was redone(motor burnt it),with 2400rpm converter,modified by Level 10. NOS 150hp nitrous kit Carter 7psi fuel pump mounted near fuel tank,holley pressure regulator under hood.
Car weighed 3650lbs with driver.
Motor only 14.0 at 98mph consistently 150hp nitrous 12.8-13.0 at 113mph,depending on traction Changing the 305 to a stock 350 brought the hp from 205 to 270.The car was faster at all rpms because of the motor’s superior torque.Top speed was 150-155mph(never tested past 140).The motor cost $500,headers $525,Balancer $225,oil pan $225,I had a friend help me put the motor in,god rest his soul(Paul Stone).
Driving the car for 2 years with the above combo,it became boring even though I was never beaten(nitrous insurance policy).I decided to have the heads ported,new cam,1.6 roller rockers,raise compression,and new intake manifold.
Lingenfelter CNC ported L98 Heads $1500 Accel 219/219 roller cam $300 Double roller timing chain $75 1.6 ratio Crane Gold roller rockers $300 Edelbrock Performer RPM Q-jet intake manifold $150 Thinner head gaskets,raised compression to 9.8:1 $50 ARP head bolts,new intake and header gaskets $100 Had Carburetor Shop redo carb,primaries rejetted,secondaries now CL
Motor 13.30 at 108mph consisently.
150hp nitrous 12.20 at 121mph consistently.
By changing the cam,intake,rockers and having ported heads put on the motor,it gained about 85hp,but more importantly the torque curve is better because the heads and cam are a perfect match,engine efficiency also went from 76% to 90% which is impressive for a carb motor.The motor now makes about 355hp at 5500rpm,up from 270 at 4900.I shift the motor at 5900rpm always,before it was 5200rpm.The car is traction limited,I hit the nitrous as soon as I shift into second and it doesn’t break loose.I know the car is capable of 11.50’s on slicks,but since when I run the car on the street it is always on street tires,besides the rear couldn’t handle a 11.50 run.The best part of this combo is that it idles exactly as it did before the mods were done,mileage went down slightly.I would guess the car has enough power and is geared to go 165mph top end.The 3.42 gears also put the car at its power peak of 5500rpm while passing through the traps on nitrous.
I was looking at a 383,but it costs $7000 for the long block with bulletproof parts from Lingenfelter,it would make about 425hp at 6000rpm with my heads,intake,and carb.It would probably run 12.0 at 115mph on the motor,and in the 10’s at 130mph on the bottle,but I would need a new rear,headers,and fuel system.
I decided to go with Lingenfelter’s 420 motor,it uses the same type of parts as the 383,but costs $8000,and it includes a bowtie block;the 383 uses a converted stock block.
It would make 470hp in a combo like mine,using the same headers,rear,and fuel system that the 383 would.making it obvious the 420 is better for me.The 420 also makes a ton more torque and the power peak is 5700rpm.My car with the 420 should run 11.50 at 119mph on the motor and 10’s at 140mph with a 2 stage nitrous system.I should say prayers for my trans!I will run 3.25 gears in a Ford 9",and seperate fuel pumps for the motor and nitrous systems.Total cost is estimated at $11,000 for the motor,rear,headers,fuel system,and nitrous systems.
Unfortunately,I don’t want to rip the motor out so soon after doing it once,I’ll wait untill next winter and then do it.In the meanwhile,I want to address all of the cars other weaknesses in 1997.The brakes will be upgraded to Baer 13"/12" PBR setup,the wheels will be 17" with 275-40ZR17 SP8000 tires,Global West Torque arm,Edelbrock strut tower brace.