Performance Trends, Inc.

Producing Quality Computer Tools for Racers and Engine Builders since 1986

Tumble Fixture

Swirl and Tumble are 2 different types of motion the air/fuel charge can exhibit as it enters the cylinder on the intake stroke.  Generally, swirl is measured on 2 valve engines and tumble is measured on 4 valve engines.  However, if you are looking for that extra 0.5% power and want to completely measure differences between different Head modifications, you would want to measure both.

Illustration of Swirl Motion               Illustration of Tumble Motion


(+ directions shown are not necessarily an industry standard)


Tumble fixture shown above with separate head and bore adapter,  Serial # 1.


Current Design, as of April 2005.


Close up of optional Swivel Adapter, to measure tumble in 360 degrees of head orientation.  Note: This is a small 65mm bore.

You need our Swirl Meter to measure tumble.  The tumble fixture lets you mount the swirl meter sideways so you can measure tumble motion.  Tumble fixtures are all custom for different bore sizes and head bolt patterns, and are quoted individually.  Several options are available for the tumble fixture, including:

Individual, changable bore sleeves and head bolt adapters so one tumble adapter can be used for several engine designs.

Piston Adjuster to see if Piston Dome/top shape influences tumble.

Swivel Adapter to check tumble at several different orientations (and it changes "big time" in different orientations).

Call 248-473-9230 to discuss these options.