diff --git a/src/collision/Detector.js b/src/collision/Detector.js
index 7b47c9f..a4626e2 100644
--- a/src/collision/Detector.js
+++ b/src/collision/Detector.js
@@ -1,84 +1,133 @@
 /**
-* The `Matter.Detector` module contains methods for detecting collisions given a set of pairs.
+* The `Matter.Detector` module contains methods for efficiently detecting collisions between a list of bodies using a broadphase algorithm.
 *
 * @class Detector
 */
 
-// TODO: speculative contacts
-
 var Detector = {};
 
 module.exports = Detector;
 
-var SAT = require('./SAT');
-var Pair = require('./Pair');
+var Common = require('../core/Common');
+var Collision = require('./Collision');
 
 (function() {
 
     /**
-     * Finds all collisions given a list of pairs.
-     * @method collisions
-     * @param {pair[]} broadphasePairs
-     * @param {engine} engine
-     * @return {array} collisions
+     * Creates a new collision detector.
+     * @method create
+     * @param {} options
+     * @return {detector} A new collision detector
      */
-    Detector.collisions = function(broadphasePairs, engine) {
+    Detector.create = function(options) {
+        var defaults = {
+            bodies: [],
+            pairs: null
+        };
+
+        return Common.extend(defaults, options);
+    };
+
+    /**
+     * Sets the list of bodies in the detector.
+     * @method setBodies
+     * @param {detector} detector
+     * @param {body[]} bodies
+     */
+    Detector.setBodies = function(detector, bodies) {
+        detector.bodies = bodies.slice(0);
+    };
+
+    /**
+     * Clears the detector including its list of bodies.
+     * @method clear
+     * @param {detector} detector
+     */
+    Detector.clear = function(detector) {
+        detector.bodies = [];
+    };
+
+    /**
+     * Efficiently finds all collisions among all the bodies in `detector.bodies` using a broadphase algorithm.
+     * 
+     * _Note:_ The specific ordering of collisions returned is not guaranteed between releases and may change for performance reasons.
+     * If a specific ordering is required then apply a sort to the resulting array.
+     * @method collisions
+     * @param {detector} detector
+     * @return {collision[]} collisions
+     */
+    Detector.collisions = function(detector) {
         var collisions = [],
-            pairs = engine.pairs,
-            broadphasePairsLength = broadphasePairs.length,
+            pairs = detector.pairs,
+            bodies = detector.bodies,
+            bodiesLength = bodies.length,
             canCollide = Detector.canCollide,
-            collides = SAT.collides,
-            i;
+            collides = Collision.collides,
+            i,
+            j;
 
-        for (i = 0; i < broadphasePairsLength; i++) {
-            var broadphasePair = broadphasePairs[i],
-                bodyA = broadphasePair[0], 
-                bodyB = broadphasePair[1];
+        bodies.sort(Detector._compareBoundsX);
 
-            if ((bodyA.isStatic || bodyA.isSleeping) && (bodyB.isStatic || bodyB.isSleeping))
-                continue;
-            
-            if (!canCollide(bodyA.collisionFilter, bodyB.collisionFilter))
-                continue;
+        for (i = 0; i < bodiesLength; i++) {
+            var bodyA = bodies[i],
+                boundsA = bodyA.bounds,
+                boundXMax = bodyA.bounds.max.x,
+                boundYMax = bodyA.bounds.max.y,
+                boundYMin = bodyA.bounds.min.y,
+                bodyAStatic = bodyA.isStatic || bodyA.isSleeping,
+                partsALength = bodyA.parts.length,
+                partsASingle = partsALength === 1;
 
-            var boundsA = bodyA.bounds,
-                boundsB = bodyB.bounds;
+            for (j = i + 1; j < bodiesLength; j++) {
+                var bodyB = bodies[j],
+                    boundsB = bodyB.bounds;
 
-            if (boundsA.min.x > boundsB.max.x || boundsA.max.x < boundsB.min.x
-                || boundsA.max.y < boundsB.min.y || boundsA.min.y > boundsB.max.y) {
-                continue;
-            }
-
-            var partsALength = bodyA.parts.length,
-                partsBLength = bodyB.parts.length;
-
-            if (partsALength === 1 && partsBLength === 1) {
-                var collision = collides(bodyA, bodyB, pairs);
-
-                if (collision) {
-                    collisions.push(collision);
+                if (boundsB.min.x > boundXMax) {
+                    break;
                 }
-            } else {
-                var partsAStart = partsALength > 1 ? 1 : 0,
-                    partsBStart = partsBLength > 1 ? 1 : 0;
-                
-                for (var j = partsAStart; j < partsALength; j++) {
-                    var partA = bodyA.parts[j],
-                        boundsA = partA.bounds;
 
-                    for (var k = partsBStart; k < partsBLength; k++) {
-                        var partB = bodyB.parts[k],
-                            boundsB = partB.bounds;
+                if (boundYMax < boundsB.min.y || boundYMin > boundsB.max.y) {
+                    continue;
+                }
 
-                        if (boundsA.min.x > boundsB.max.x || boundsA.max.x < boundsB.min.x
-                            || boundsA.max.y < boundsB.min.y || boundsA.min.y > boundsB.max.y) {
-                            continue;
-                        }
+                if (bodyAStatic && (bodyB.isStatic || bodyB.isSleeping)) {
+                    continue;
+                }
 
-                        var collision = collides(partA, partB, pairs);
+                if (!canCollide(bodyA.collisionFilter, bodyB.collisionFilter)) {
+                    continue;
+                }
 
-                        if (collision) {
-                            collisions.push(collision);
+                var partsBLength = bodyB.parts.length;
+
+                if (partsASingle && partsBLength === 1) {
+                    var collision = collides(bodyA, bodyB, pairs);
+
+                    if (collision) {
+                        collisions.push(collision);
+                    }
+                } else {
+                    var partsAStart = partsALength > 1 ? 1 : 0,
+                        partsBStart = partsBLength > 1 ? 1 : 0;
+                    
+                    for (var k = partsAStart; k < partsALength; k++) {
+                        var partA = bodyA.parts[k],
+                            boundsA = partA.bounds;
+
+                        for (var z = partsBStart; z < partsBLength; z++) {
+                            var partB = bodyB.parts[z],
+                                boundsB = partB.bounds;
+
+                            if (boundsA.min.x > boundsB.max.x || boundsA.max.x < boundsB.min.x
+                                || boundsA.max.y < boundsB.min.y || boundsA.min.y > boundsB.max.y) {
+                                continue;
+                            }
+
+                            var collision = collides(partA, partB, pairs);
+
+                            if (collision) {
+                                collisions.push(collision);
+                            }
                         }
                     }
                 }
@@ -103,4 +152,39 @@ var Pair = require('./Pair');
         return (filterA.mask & filterB.category) !== 0 && (filterB.mask & filterA.category) !== 0;
     };
 
+    /**
+     * The comparison function used in the broadphase algorithm.
+     * Returns the signed delta of the bodies bounds on the x-axis.
+     * @private
+     * @method _sortCompare
+     * @param {body} bodyA
+     * @param {body} bodyB
+     * @return {number} The signed delta used for sorting
+     */
+    Detector._compareBoundsX = function(bodyA, bodyB) {
+        return bodyA.bounds.min.x - bodyB.bounds.min.x;
+    };
+
+    /*
+    *
+    *  Properties Documentation
+    *
+    */
+
+    /**
+     * The array of `Matter.Body` between which the detector finds collisions.
+     * 
+     * _Note:_ The order of bodies in this array _is not fixed_ and will be continually managed by the detector.
+     * @property bodies
+     * @type body[]
+     * @default []
+     */
+
+    /**
+     * Optional. A `Matter.Pairs` object from which previous collision objects may be reused. Intended for internal `Matter.Engine` usage.
+     * @property pairs
+     * @type {pairs|null}
+     * @default null
+     */
+
 })();
diff --git a/src/core/Engine.js b/src/core/Engine.js
index bb98b55..7d15e4c 100644
--- a/src/core/Engine.js
+++ b/src/core/Engine.js
@@ -16,7 +16,6 @@ var Sleeping = require('./Sleeping');
 var Resolver = require('../collision/Resolver');
 var Detector = require('../collision/Detector');
 var Pairs = require('../collision/Pairs');
-var Grid = require('../collision/Grid');
 var Events = require('./Events');
 var Composite = require('../body/Composite');
 var Constraint = require('../constraint/Constraint');
@@ -43,7 +42,6 @@ var Body = require('../body/Body');
             enableSleeping: false,
             events: [],
             plugin: {},
-            grid: null,
             gravity: {
                 x: 0,
                 y: 1,
@@ -60,10 +58,11 @@ var Body = require('../body/Body');
         var engine = Common.extend(defaults, options);
 
         engine.world = options.world || Composite.create({ label: 'World' });
-        engine.grid = Grid.create(options.grid || options.broadphase);
-        engine.pairs = Pairs.create();
+        engine.pairs = options.pairs || Pairs.create();
+        engine.detector = options.detector || Detector.create();
 
-        // temporary back compatibility
+        // for temporary back compatibility only
+        engine.grid = { buckets: [] };
         engine.world.gravity = engine.gravity;
         engine.broadphase = engine.grid;
         engine.metrics = {};
@@ -93,9 +92,10 @@ var Body = require('../body/Body');
         correction = correction || 1;
 
         var world = engine.world,
+            detector = engine.detector,
+            pairs = engine.pairs,
             timing = engine.timing,
-            grid = engine.grid,
-            gridPairs = [],
+            timestamp = timing.timestamp,
             i;
 
         // increment timestamp
@@ -109,15 +109,25 @@ var Body = require('../body/Body');
 
         Events.trigger(engine, 'beforeUpdate', event);
 
-        // get lists of all bodies and constraints, no matter what composites they are in
+        // get all bodies and all constraints in the world
         var allBodies = Composite.allBodies(world),
             allConstraints = Composite.allConstraints(world);
 
-        // if sleeping enabled, call the sleeping controller
+        // update the detector bodies if they have changed
+        if (world.isModified) {
+            Detector.setBodies(detector, allBodies);
+        }
+
+        // reset all composite modified flags
+        if (world.isModified) {
+            Composite.setModified(world, false, false, true);
+        }
+
+        // update sleeping if enabled
         if (engine.enableSleeping)
             Sleeping.update(allBodies, timing.timeScale);
 
-        // applies gravity to all bodies
+        // apply gravity to all bodies
         Engine._bodiesApplyGravity(allBodies, engine.gravity);
 
         // update all body position and rotation by integration
@@ -130,27 +140,11 @@ var Body = require('../body/Body');
         }
         Constraint.postSolveAll(allBodies);
 
-        // broadphase pass: find potential collision pairs
-
-        // if world is dirty, we must flush the whole grid
-        if (world.isModified)
-            Grid.clear(grid);
-
-        // update the grid buckets based on current bodies
-        Grid.update(grid, allBodies, engine, world.isModified);
-        gridPairs = grid.pairsList;
-
-        // clear all composite modified flags
-        if (world.isModified) {
-            Composite.setModified(world, false, false, true);
-        }
-
-        // narrowphase pass: find actual collisions, then create or update collision pairs
-        var collisions = Detector.collisions(gridPairs, engine);
+        // find all collisions
+        detector.pairs = engine.pairs;
+        var collisions = Detector.collisions(detector);
 
         // update collision pairs
-        var pairs = engine.pairs,
-            timestamp = timing.timestamp;
         Pairs.update(pairs, collisions, timestamp);
 
         // wake up bodies involved in collisions
@@ -224,17 +218,13 @@ var Body = require('../body/Body');
     };
 
     /**
-     * Clears the engine including the world, pairs and broadphase.
+     * Clears the engine pairs and detector.
      * @method clear
      * @param {engine} engine
      */
     Engine.clear = function(engine) {
-        var world = engine.world,
-            bodies = Composite.allBodies(world);
-
         Pairs.clear(engine.pairs);
-        Grid.clear(engine.grid);
-        Grid.update(engine.grid, bodies, engine, true);
+        Detector.clear(engine.detector);
     };
 
     /**
@@ -314,53 +304,53 @@ var Body = require('../body/Body');
     * Fired just before an update
     *
     * @event beforeUpdate
-    * @param {} event An event object
+    * @param {object} event An event object
     * @param {number} event.timestamp The engine.timing.timestamp of the event
-    * @param {} event.source The source object of the event
-    * @param {} event.name The name of the event
+    * @param {engine} event.source The source object of the event
+    * @param {string} event.name The name of the event
     */
 
     /**
     * Fired after engine update and all collision events
     *
     * @event afterUpdate
-    * @param {} event An event object
+    * @param {object} event An event object
     * @param {number} event.timestamp The engine.timing.timestamp of the event
-    * @param {} event.source The source object of the event
-    * @param {} event.name The name of the event
+    * @param {engine} event.source The source object of the event
+    * @param {string} event.name The name of the event
     */
 
     /**
     * Fired after engine update, provides a list of all pairs that have started to collide in the current tick (if any)
     *
     * @event collisionStart
-    * @param {} event An event object
-    * @param {} event.pairs List of affected pairs
+    * @param {object} event An event object
+    * @param {pair[]} event.pairs List of affected pairs
     * @param {number} event.timestamp The engine.timing.timestamp of the event
-    * @param {} event.source The source object of the event
-    * @param {} event.name The name of the event
+    * @param {engine} event.source The source object of the event
+    * @param {string} event.name The name of the event
     */
 
     /**
     * Fired after engine update, provides a list of all pairs that are colliding in the current tick (if any)
     *
     * @event collisionActive
-    * @param {} event An event object
-    * @param {} event.pairs List of affected pairs
+    * @param {object} event An event object
+    * @param {pair[]} event.pairs List of affected pairs
     * @param {number} event.timestamp The engine.timing.timestamp of the event
-    * @param {} event.source The source object of the event
-    * @param {} event.name The name of the event
+    * @param {engine} event.source The source object of the event
+    * @param {string} event.name The name of the event
     */
 
     /**
     * Fired after engine update, provides a list of all pairs that have ended collision in the current tick (if any)
     *
     * @event collisionEnd
-    * @param {} event An event object
-    * @param {} event.pairs List of affected pairs
+    * @param {object} event An event object
+    * @param {pair[]} event.pairs List of affected pairs
     * @param {number} event.timestamp The engine.timing.timestamp of the event
-    * @param {} event.source The source object of the event
-    * @param {} event.name The name of the event
+    * @param {engine} event.source The source object of the event
+    * @param {string} event.name The name of the event
     */
 
     /*
@@ -452,9 +442,18 @@ var Body = require('../body/Body');
      * @default 0
      */
 
+    /**
+     * A `Matter.Detector` instance.
+     *
+     * @property detector
+     * @type detector
+     * @default a Matter.Detector instance
+     */
+
     /**
      * A `Matter.Grid` instance.
      *
+     * @deprecated replaced by `engine.detector`
      * @property grid
      * @type grid
      * @default a Matter.Grid instance
@@ -463,7 +462,7 @@ var Body = require('../body/Body');
     /**
      * Replaced by and now alias for `engine.grid`.
      *
-     * @deprecated use `engine.grid`
+     * @deprecated replaced by `engine.detector`
      * @property broadphase
      * @type grid
      * @default a Matter.Grid instance