Build a Twin Turbo Big Block Chevy 502
Do you need 1400 horsepower and want it to run on E-85 fuel? Just grab 2 turbochargers off of a 3.8 Buick Grand National, and you can achieve this goal. The single turbo from the 231 cubic inch V6 is perfect when you put one on each side of a 502 cubic inch monster.
- Buy a 502 crate motor 8.75:1 compression ratio. Re-clearance the rotation assembly - extra clearance in the bearings for additional crank flex, and open up the ring gaps for the additional heat of the turbocharger.
- Learn how to read a turbo map, decide what your horsepower goal is, and buy the correct turbos. For an old school 800hp setup - a pair of T04B V1/V2 compressors, P trim turbine with about a 1.2A/R is a good start. For a more modern setup, a pair of GT4094's would be a powerful combo with low RPM spool up.
- Spend the money on your fuel system to keep up with the horsepower and boost levels. A boost referenced FPR is a must. I would use either a Racepumps mechanical pump, Aeromotive, Holley Performance Products or similar. Blow through carb, fuel injection, will both work. CSU makes a nice Blowthrough carb setup.
- Tune it fat to start, and with low boost. Keep the timing low to avoid detonation. Tune it for whatever fuel you will be running most of the time. A wideband 02 monitor is a must.
- Always use fresh fuel since fresh E-85 is 108 octane.
- If you are not sure or have questions, check online forums for advice or if you know somebody with a turbo setup ask them for their opinions.
- Never put something together you are not 100% sure is correct. This could lead to more expenses and a loss of time.
- Be prepared for significant power gains. If you have never driven a car/truck with this amount of power don't go out your first time and floor it.
- Tire wear can be a real problem if you are running the Harmon Systems 502 twin-turbo system.
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