Reinforced exhaust valves Suzuki Swift GTi G13B

Suzuki engines covered

The G13B is Suzuki's 1.3 litre twin-cam, 16-valve four-cylinder that powers the sporting Swift models: 101 hp in the Swift I GTi from 1985 to 1989, then in the Swift II GTi up to 2001 and in the Swift convertible 1.3 i from 1992 to 1996.

This engine has 8 exhaust valves, two per cylinder. The version offered has a 24.5 mm head, 0.5 mm larger than standard size, a 5.45 mm stem and a length of 104.7 mm. Light and eager, the G13B likes to rev; sharper camshafts, a higher rev limit or forced induction then put heavy demands on its exhaust valves.

FERREA reinforced exhaust valves

Opened on every cycle, the exhaust valve releases the burnt gases when they are at their hottest. The metal of its head climbs to 760 to 870 °C on an unboosted engine such as the standard G13B, and passes 1,000 °C once forced induction is added. The seat removes about 75 % of that heat, the guide roughly 20 %. At these temperatures steel loses strength: an EV8 family steel keeps 550 MPa at 600 °C but holds only 300 MPa at 800 °C. As soon as revs, load or pressure rise, the head runs hotter, fatigues, distorts and ends up leaking.

The FERREA offered belongs to the maker's 6000 series, made from EV8 stainless steel. It is intended for a tuned naturally aspirated G13B, whether driven on the road, in rallies, hill climbs or on track days: sharper camshafts, firmer springs and a higher rev limit stay within its limits as long as the engine breathes unaided. Once the engine is boosted by a turbo or a supercharger, the head would go beyond 1,000 °C, a range where stainless steel loses most of its strength: forced induction then calls for a valve in a material designed for those temperatures.

Its head, 0.5 mm oversize at 24.5 mm, enlarges the flow area: the spent gases leave the cylinder earlier, which then takes in more fresh mixture, to the benefit of power. The exhaust seats are recut to this size when the head is rebuilt.

Exhaust valve technical specification

Valve fitting

Check the original collets before reassembly: they must match the groove profile of the 5.45 mm stem and show no wear.

The 24.5 mm head requires exhaust seats cut to that size, by a machine shop, while the cylinder head is being reconditioned.

Measure the clearance of each stem in its guide and replace the 8 exhaust valve stem seals at every rebuild.

Technical guide

The brand offered

FERREA Racing Components was born in 1978 from the partnership of Horacio Ferrea with Daniel Urrutia. From Florida and Argentina it produces valves in stainless steel, nickel superalloys and titanium, fitted by NASCAR, drag racing and rally engine builders.

How to choose

Only one version exists for the G13B, so the decision concerns the condition of the head's seats and the use of the engine, which set the head preparation needed before the 8 new valves are fitted.

When reinforced valves become necessary

• More aggressive cam profiles, springs firmer than standard
• Rev limit raised by new engine management
• Rally, hill climb or track use
• Head rebuild with exhaust seats already recut
• Original valves burnt, pitted or bent after over-revving

Compatible vehicles

OEM part number (exhaust valve):

Don't forget the inlet valves

G13B head off: take the opportunity to replace the 8 inlet valves as well, in the same oversize, so that the inlet and exhaust sides are renewed together and wear evenly.