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Tunnel wedge vs. 2x4 MR vs. RPM......

December 3 2017 at 6:44 AM

Blair Patrick  (Login CaptCobrajet)
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Response to How much motor do you need to effectively use a Tunnel Wedge?

A couple of years ago, I had three engines on the dyno back to back to back. Two 482s and one 464 inch in a 428 block. One 482 had a 2x4 MR, the other had a Ford tunnel wedge. Both .600 lift hyd rollers 248/254 on a 112. The 464 had a 232/238 on a 112. All are custom cams that I use regularly. I put short travel lifters in the Tunnel Wedge engine so it could handle more rpm past peak. In testing the three engines, the 2x4 MR 482 cought up with the single four RPM at 3900 rpm, and steadily pulled away. Both peaked at about the same place, 57-5800, with the bigger engine and 2x4 being about 40 HP better. In comparing the two otherwise identical 482s, the TW caught up with the 2x4 MR at 5300 rpm, and steadily pulled away to peak 20 HP higher, which was only a couple of hundred more rpm for the TW with the same camshaft. I could see that the TW would have been killing the dual plane by 6500 by the trend that was forming. I came away from those three days thinking a lot more of the ED RPM. It outperforms both bigger engines from 2000 to 3900. It outperformed the TW to about 4500. Overall, on those engines, the RPM had much better bottom end, the Ford dual plane MR was better in the middle, and the Tunnel Wedge was better than the RPM from 4500 up, and better than the MR from 5300 up. It just depends on how you want to use it, and how hard you and your camshaft want to turn it. I usually reserve the Tunnel Wedge for big hydraulic rollers with short travel lifters, or solid rollers planned for rpm. I think a big solid flat tappet in a big engine can still benefit from a Tunnel Wedge, but a darn MR 2x4 or an RPM single are HARD to beat below 5K, which is where Street stuff spends the most time.
Blair Patrick

 
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