I'll be writing specifically about the pre-Magnum 239 engine, an engine that is quite neglected across the board for anything performance oriented. We'll touch on the free modifications to going forced induction.
Engine performance boils down to a few things; cold air, more fuel, substantial spark. The colder the air you have entering the engine the more fuel will be needed. The more fuel you have the better spark you'll need. Combine all of these together with the "all things equal" plugged in, you'll have more horsepower and torque. An easy formula that is very complex, but that might be for further down.
Free Modifications
Removing components, both in the cab, bed, and in the engine bay can help free up horsepower and make the vehicle faster by reducing weight.
-Change bench seat to single or double captain chairs.
-Remove spare tire.
-Remove A/C compressor, components, and AIR pump. You will need an idler pulley, its bracket, and belts to replace the A/C compressor. Removing the A/C compressor and the AIR pump will free up rotational mass on the engine allowing for the engine to gain RPM faster, start easier, and require less fuel to run.
-Remove EGR valve so hot air does not recirculate back into the intake manifold, hot air equates to less fuel. For this purpose we'll need to remove the EGR valve to keep the air cooler.
-Clean up all your ground points to take more stress off of the alternator and engine as a whole. This is a minimal 'gain' if anything, but it will help in the long run when diagnosing other problems.
Cheap Modifications
-Switch to a lower temperature thermostat: 180* Fail Safe. Lower temperature thermostats is an old trick to increase the amount of fuel going to the engine; colder the engine the more fuel.
-Add Redline WaterWetter to reduce the temperature of your coolant even further.
-Instead of the Autolite copper ATO65, switch to a single platinum Autolite AP65, double platinum Autolite APP65, or NGK Iridium GR41X. The better the spark, the better the fuel burn mixture.
-Most performance ignition wire sets are decently cheap, especially for domestic vehicle. Going with 8.5MM or thicker ignition leads will help shield out all the interference and help give better spark.
-Change out the OEM ignition coil for an MSD Blaster 2 or equivalent.
-Change distributor cap and rotor out so the contact points are brass, not aluminum. Brass is a much better conductor of current.
-Remove the factory air cleaner and components and switch to a Short Ram Intake or Cold Air Intake. Remember, these intakes will not give you 10-20 horsepower increase, that would be with other major supporting modifications. These intakes will give you around 2-5 horsepower, but can be made on a budget or purchased online.
-Remove and clean your throttle body. With the amount of gunk and varnish that will be covering the inside of the throttle body, now is a good time to remove and clean, and if you can, port match to the intake plenum. While the throttle body is removed, remove the butter fly plates and give them a knife edging to decrease the amount of tumbling the air will do over the plates.
-Purchase an underdrive pulley to further reduce the rotational mass on the engine.
-Change out all fluids to synthetics; engine, transmission, transfer case, differentials.
-
Moderate Modifications
-Headers will definitely help increase the flow for the engine and thus increase the horsepower and torque. JBA, OBX and other 'eBay' brands are out there ranging in price from $200-$700.
-Replace your exhaust system with a much more free flowing mandrel bent system. If you can, you may be able to remove the catalytic converter and replace it with a test pipe, for race day only, to help reduce the amount of restriction. Design your exhaust system after the 318/360 systems available using a higher flowing muffler, retain the Y-Pipe style collector as it will add more horsepower than straight dual exhaust or H/X-Pipe. Remove resonator altogether if you don't mind a drone at cruising speeds.
-Swap out the OEM rockers with the 318 higher lift rockers. The further the valves open, the more air/fuel enters and the more exhaust leaves leading to better flow.
-Get your camshaft re-ground at a performance shop or machine shop for a longer duration or opening sooner/closing later. Take into account if you replace the rockers with 1.7 lift or longer. Copy 318/360 camshafts.
-Bring intake manifold to a reputable machine shop to have it port and polished/send it off to be extrude honed. P&P will run anywhere from $100-$200 and will help increase HP/TQ, extrude honing runs $400 plus, but will yield even better figures. (Extrude honing basically makes your good flowing intake manifold that was tuned for the powerband flow even better and make power where you would need it.
-Change out valve springs for stiffer springs. Stiffer springs means less likely of valve float at higher RPMs, and now you can reach higher RPMs with the increased pressure.
-Polyurethane bushings for suspension at the control arms, sway bar links, sway bar frame bushings, and engine mounts (if engine mounts can't be found in polyurethane, a quick way to increase their rigidness is to fill the holes with caulking).
Expensive Modifications
-Getting a better hold on the torque and horsepower with a new clutch kit in a few different stages; for the time being, a Stage 1 clutch kit should do just fine; pedal pressure will be near the same and holding power will be increased. But, since you're in there and have gone this far for modifications and intend on going further, put in at least a Stage 2 clutch kit or better.
-Have the flywheel machined so it can be as light as possible while still retaining its ability to last. Have it resurfaced as well.
-Swap the rear end to a Limited Slip Differential, this will give better take off and cornering.
-Wideband O2 Sensor(s)
-Piggy Back Fuel System or MegaSquirt (which will need a lot of customization, but gives you full engine control)
-Engine Building Naturally Aspirated
-Engine Building Turbocharged
*Not absolutely necessary, but couldn't hurt for added security.
Engine performance boils down to a few things; cold air, more fuel, substantial spark. The colder the air you have entering the engine the more fuel will be needed. The more fuel you have the better spark you'll need. Combine all of these together with the "all things equal" plugged in, you'll have more horsepower and torque. An easy formula that is very complex, but that might be for further down.
Free Modifications
Removing components, both in the cab, bed, and in the engine bay can help free up horsepower and make the vehicle faster by reducing weight.
-Change bench seat to single or double captain chairs.
-Remove spare tire.
-Remove A/C compressor, components, and AIR pump. You will need an idler pulley, its bracket, and belts to replace the A/C compressor. Removing the A/C compressor and the AIR pump will free up rotational mass on the engine allowing for the engine to gain RPM faster, start easier, and require less fuel to run.
-Remove EGR valve so hot air does not recirculate back into the intake manifold, hot air equates to less fuel. For this purpose we'll need to remove the EGR valve to keep the air cooler.
-Clean up all your ground points to take more stress off of the alternator and engine as a whole. This is a minimal 'gain' if anything, but it will help in the long run when diagnosing other problems.
Cheap Modifications
-Switch to a lower temperature thermostat: 180* Fail Safe. Lower temperature thermostats is an old trick to increase the amount of fuel going to the engine; colder the engine the more fuel.
-Add Redline WaterWetter to reduce the temperature of your coolant even further.
-Instead of the Autolite copper ATO65, switch to a single platinum Autolite AP65, double platinum Autolite APP65, or NGK Iridium GR41X. The better the spark, the better the fuel burn mixture.
-Most performance ignition wire sets are decently cheap, especially for domestic vehicle. Going with 8.5MM or thicker ignition leads will help shield out all the interference and help give better spark.
-Change out the OEM ignition coil for an MSD Blaster 2 or equivalent.
-Change distributor cap and rotor out so the contact points are brass, not aluminum. Brass is a much better conductor of current.
-Remove the factory air cleaner and components and switch to a Short Ram Intake or Cold Air Intake. Remember, these intakes will not give you 10-20 horsepower increase, that would be with other major supporting modifications. These intakes will give you around 2-5 horsepower, but can be made on a budget or purchased online.
-Remove and clean your throttle body. With the amount of gunk and varnish that will be covering the inside of the throttle body, now is a good time to remove and clean, and if you can, port match to the intake plenum. While the throttle body is removed, remove the butter fly plates and give them a knife edging to decrease the amount of tumbling the air will do over the plates.
-Purchase an underdrive pulley to further reduce the rotational mass on the engine.
-Change out all fluids to synthetics; engine, transmission, transfer case, differentials.
-
Moderate Modifications
-Headers will definitely help increase the flow for the engine and thus increase the horsepower and torque. JBA, OBX and other 'eBay' brands are out there ranging in price from $200-$700.
-Replace your exhaust system with a much more free flowing mandrel bent system. If you can, you may be able to remove the catalytic converter and replace it with a test pipe, for race day only, to help reduce the amount of restriction. Design your exhaust system after the 318/360 systems available using a higher flowing muffler, retain the Y-Pipe style collector as it will add more horsepower than straight dual exhaust or H/X-Pipe. Remove resonator altogether if you don't mind a drone at cruising speeds.
-Swap out the OEM rockers with the 318 higher lift rockers. The further the valves open, the more air/fuel enters and the more exhaust leaves leading to better flow.
-Get your camshaft re-ground at a performance shop or machine shop for a longer duration or opening sooner/closing later. Take into account if you replace the rockers with 1.7 lift or longer. Copy 318/360 camshafts.
-Bring intake manifold to a reputable machine shop to have it port and polished/send it off to be extrude honed. P&P will run anywhere from $100-$200 and will help increase HP/TQ, extrude honing runs $400 plus, but will yield even better figures. (Extrude honing basically makes your good flowing intake manifold that was tuned for the powerband flow even better and make power where you would need it.
-Change out valve springs for stiffer springs. Stiffer springs means less likely of valve float at higher RPMs, and now you can reach higher RPMs with the increased pressure.
-Polyurethane bushings for suspension at the control arms, sway bar links, sway bar frame bushings, and engine mounts (if engine mounts can't be found in polyurethane, a quick way to increase their rigidness is to fill the holes with caulking).
Expensive Modifications
-Getting a better hold on the torque and horsepower with a new clutch kit in a few different stages; for the time being, a Stage 1 clutch kit should do just fine; pedal pressure will be near the same and holding power will be increased. But, since you're in there and have gone this far for modifications and intend on going further, put in at least a Stage 2 clutch kit or better.
-Have the flywheel machined so it can be as light as possible while still retaining its ability to last. Have it resurfaced as well.
-Swap the rear end to a Limited Slip Differential, this will give better take off and cornering.
-Wideband O2 Sensor(s)
-Piggy Back Fuel System or MegaSquirt (which will need a lot of customization, but gives you full engine control)
-Engine Building Naturally Aspirated
- Bored over Engine Block*
- High Compression Forged Pistons
- Higher Flow Fuel Injectors
- Higher Flow Fuel Pump
- Fuel Pressure Regulator
- Knife Edged Crankshaft*
- Oil Baffle
- Forged Connecting Rods*
- Race Connecting Rod and Main Bearings
- Multi Layer Steel head gasket
- ARP Studs
- ARP Bearing Caps
- 318 Throttle Body
-Engine Building Turbocharged
- Bored Over Engine Block*
- Low Compression Forged Pistons
- Higher Flow Fuel Injectors
- Higher Flow Fuel Pump
- Fuel Pressure Regulator
- Knife Edged Crankshaft*
- Forged Connecting Rods*
- Race Connecting Rod and Main Bearings
- MSL Head Gasket
- ARP Studs
- ARP Bearing Caps
- Oil Cooler
- Turbocharger
- Front Mount Intercooler
- Intercooler Piping
- Blow Off Valve
- Custom Turbo Hotside Pipe
- 318 Throttle Body
*Not absolutely necessary, but couldn't hurt for added security.
