| Stock exit size port. 195 cfm @ .7" lift Excellent mid lift flow and no filling of floor This port would be great for a hot street combo. With a good 3 angle seat 200 cfm is realistic. Further bench work has shown that 200 to 210 cfm at .600" lift is very possible with proper short turn shape and a 1.76" exhaust valve. 12-23-02 SMJ/RHP |
| Large port done as in guide. CJ size valve |
62
112
144
168
182
187
191
191
112
144
168
182
187
191
191
| The left wall and bowl areas are very similar on both of these ports. The right side is essentially untouched. The t-bump / roof is left as cast. Raising the exit height .070" and recontouring the corners helped marginally. |
| Port comparison Stock exit vs raised and widened exit |
| Three ports were done in this style. In every port removal of the thermactor roof bump and the exhaust bolt bump hurt flow. Widening right wall and raising roof bring back flow but increase width and height by .1" to .125". Bigger port = lower velocity. |
| Because the distance from seat to roof above is limited in these ports a back cut valve helps flow by up to 10 cfm. This back cut helps pull the flow cone tighter to the back of the valve |
| The addition of a CJ valve and the bowl and short turn mods to accomodate it netted the second higher set of flow figures above. A good 3 angle seat should exceed 210 cfm. This with a STOCK sized exit. No sealing and flange fit issues + 1/3 less work. No floor filling necessary. |
| 65 108 136 160 178 196 201 204 |
| The shape of the short turn radius and the height of the crest are critical for good flow without floor filling |
| Full stock exit pic set coming soon. Stay tuned for updates... |