Turbocharged Engine Guide - How To Install Your First Turbo

Here is the complete system...        read full caption Here is the complete system as we would set it up for a blow-through carburetor-type system and no intercooler. As a rule, the inlet ducting should be 1 inch larger in outer diameter than the compressor outlet.	Because the turbo is clockable,...        read full caption Because the turbo is clockable, we also test-fit the system with the included air-to-air intercooler to blow into an EFI manifold.	The upgrade for this system...        read full caption The upgrade for this system could be the Turbonetics GT-K. The machined slots are called map enhancement porting, which essentially moves the compressor map surge line to the left for a better efficiency range. They are available from 46 to 76 mm with A/R ratios of 0.48 to 0.96.
For combos that make 500 hp...        read full caption For combos that make 500 hp or less, use the Evolution wastegate. Turbonetics also offers three others that can handle up to 1,000 hp or more. The blue-and-white springs are for 5- and 7-psi settings, respectively.	This is an example of an internal...        read full caption This is an example of an internal wastegate often seen on OE vehicles. Note the size of the exhaust port. In a big-boost situation, it might not be able to vent enough boost to slow the turbine, causing overboost, detonation, or worse.

Junkyard Turbo
Junkyard heroes claim you can slap on a set of Thunderbird turbos and go to town. That may be true, but you will be giving up a lot in doing so. Aside from the improvements in bearing technology that add longevity and performance to the turbo, the compressor efficiency maps on newer compressors are much wider, allowing you to run more boost in a wider rpm range than the OE stuff. You can also get away with running a single turbo to achieve the same power levels.

This is the map from the "good"...        read full caption This is the map from the "good" '85 to '86 Ford Thunderbird. Note that the surge line narrows the maps usable area and the turbo needs to spin about 40,000 rpm faster than the 60-1 to get the job done.

This is the 60-1 compressor...        read full caption This is the 60-1 compressor map from Turbonetics. Note the agreeable shape of the surge line and the size of the compressor's usable area. As you upgrade, it gets even better. The center island is where the turbo is most efficient at making boost while creating the least amount of heat.

Turbo Terms
Boost: Any pressure above atmosphere measured in the intake manifold.

Boost threshold: The lowest engine rpm where the turbo can produce usable boost.

Compressor map: A grid of numbers used as a tool to evaluate the efficiency of a turbo in relation to an engine.

Compressor surge: Air that backs up, causing the speed of the turbo to become unstable when the throttle is suddenly closed.

Lag: The delay between the change of throttle position and the production of usable boost.

Surge line: The line that follows the far left of the efficiency island on a compressor map where the turbo becomes unstable.