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Update on Tunnel Wedge test, Bottleneck on Dyno Mule

December 6 2006 at 9:18 PM

Jay Brown  (Login jaybnve)

Got a chance to get out to the shop tonight, rejet the carbs on the dyno motor, and run another test on the tunnel wedge intake. I went up from 63s to 65/66 jets (only had two of each), and after the warmup the engine made 403 HP. And surprisingly, it also made over 450 ft-lbs of torque, which is much better than I expected. A/F is still a tad lean, running around 13.0 to 13.2. I think I'll go to 68s and make one more pull. Betcha this intake will make 410 HP just like the other heavy hitters on this engine.

I also ran some Engine Analyzer Pro simulations tonight on the dyno mule. I have the actual head flow numbers, compression ratio, etc. for this engine, and so I adjusted the other parameters such as flow coefficient for the intake and header efficiency so that with a single four dual plane intake like the Performer RPM I got the tested HP and torque outputs. So, the simulation matched the dyno results nearly perfectly.

Then I started changing components. I have some figures for stock Edelbrock head flows, and they are only slightly better than the mildly ported CJ heads that are on the engine. The simulator said I'd pick up about 10 HP with the Edelbrock heads. Then, I swapped in a bigger cam, a 248/248@.050", .600" lift Comp solid (existing cam is 236/236@.050", .572" lift hydraulic). With the CJ heads, the engine was up about 15 HP, and with the Ed heads it was up about 25 HP. Still not a big improvement.

I also have flow data on a set of street/strip ported Edelbrock heads. Just for comparison, my factory CJ heads flow about 250 cfm @ .600" lift on the intake side, and the stock Edelbrocks flow about 260 cfm @ .600" lift (according to the data I have, which is not mine, by the way...). The street/strip ported Edelbrocks (which were mine) flowed about 300 cfm @ .600" lift. I added these flow numbers into the simulation, and ran the engine with the existing cam. HP jumped up by 80, to 485! With the bigger cam, the engine went up another 30 HP to 515 HP. Torque results were similarly improved.

So, if you believe the video game, the heads are the big bottleneck in my dyno mule combination. I think I might slap on a stock set of Edelbrock heads and that solid cam and try a couple of dyno pulls to test this theory out...

Jay Brown
1968 Shelby GT 500 Convertible, all aluminum 489" 1030 HP Supercharged FE
1969 XL Convertible, 460
1969 R code Mach 1, 706 HP 511" all aluminum FE, 10.457 @ 127.47, 2005 Drag Week Winner, Naturally Aspirated Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver

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