How does the Taurus SHO's dual-port intake system work?

It draws from a pair of common plenum chambers so each port draws from the opposite side of the engine. Long primary runners provide low-speed efficiency, while short "throttled" secondary runners provide high-speed power. The throttle valves in the secondary ports are controlled by the ECM.

Why isn't the transition to the secondary intake runners felt while driving?

The throttling point was selected at an engine speed where the torque output of single intake valve and double intake valve operation are the same, giving constant power flow without a hiccup.

What valve lash adjustment interval does the SHO engine require?

The valvetrain uses direct-acting bucket-style tappets with shimmed lash adjusters that call for adjustment at 60,000 miles.

Why weren't hydraulic lifters used in the SHO engine?

Designers discarded hydraulic tappets because their larger diameter caused a packaging problem, and the oil would foam at high rpm, causing the lifters to collapse.

Home/ Registry/ Ford/ Taurus/ 1992-1995/ “Taurus SHO”/ Photo supermotors.net/registry/media/551293

1989 Ford Taurus SHO Yamaha V6 Engine Article - Hot Rod Dec 1988, Page 70

Hot Rod magazine article page titled SHO of Force with engine cutaways and photos

‹ ›

Hot Rod magazine article page about the Ford SHO engine with prose columns, cutaway illustrations, and photos.

AI caption August 2007 · Photo 981 of 1028

This is page 70 of the December 1988 issue of Hot Rod magazine, part of an article titled "SHO of Force" covering the Ford Taurus SHO's Yamaha-built V6 engine. The page features cutaway engine illustrations and photographs with detailed captions. It explains the dual-port inlet system, which draws air from a pair of common plenum chambers with long primary runners for low-speed efficiency and short "throttled" secondary runners for high-speed power, with the secondary throttle valves controlled by the ECM. The illustrations also depict the die-cast aluminum oil pan, windage baffles, forged crankshaft, four-valve-per-cylinder layout, and tuned inlet system. The body text describes how the transition to the secondary runners is seamless because it occurs where torque from single- and dual-valve operation is equal. The intake cams are belt-driven off the crank at the front of the engine, while exhaust cams are chain-driven off the intake cams at the rear, keeping the engine compact for transverse mounting. The valvetrain uses direct-acting bucket tappets with shimmed lash adjusters requiring adjustment at 60,000 miles; hydraulic lifters were rejected due to packaging and high-rpm oil foaming. Yamaha handled engine mechanicals while Ford developed the electronics, based on the EEC-IV ECM and distributorless ignition (DIS) with crank, camshaft, and throttle position sensors.

Is this accurate? Sign in to help verify it.

Frequently asked questions

How does the Taurus SHO's dual-port intake system work?: It draws from a pair of common plenum chambers so each port draws from the opposite side of the engine. Long primary runners provide low-speed efficiency, while short "throttled" secondary runners provide high-speed power. The throttle valves in the secondary ports are controlled by the ECM.
Why isn't the transition to the secondary intake runners felt while driving?: The throttling point was selected at an engine speed where the torque output of single intake valve and double intake valve operation are the same, giving constant power flow without a hiccup.
How are the SHO engine's camshafts driven?: The intake cams are belt-driven off the crank at the front of the engine, while the exhaust cams are chain-driven off the intake cams at the rear of the engine, which keeps the engine compact for transverse mounting.
What valve lash adjustment interval does the SHO engine require?: The valvetrain uses direct-acting bucket-style tappets with shimmed lash adjusters that call for adjustment at 60,000 miles.
Why weren't hydraulic lifters used in the SHO engine?: Designers discarded hydraulic tappets because their larger diameter caused a packaging problem, and the oil would foam at high rpm, causing the lifters to collapse.