Ah, ok the Sullivan on a 4.6 kills the low end power, gotcha. Yes I met Jason at MIR last year. Nice of you to remember. I'll be running my M/T street ets next time. I should gain a couple of tenths. Happy building!
The Sullivan does kill torque on both the 4.6 and 5.4. However, the 5.4 has enough CI that it still make more than a stock 4.6 even with the single plane intake manifold. Installing a cobra/mach 1 intake would add more power than you can imagine under 5000rpm. That intake alone would probably have your car running 13.0 or even high 12s.
The navi cams are the same as those in the 03/04 Cobra, Marauder, Aviator and Mach 1; very mild in 4.6 and even more so in a 5.4. These would be the reason that the tq suffered little with the Sullivan, but also why the peak power suffers.
If building a 5.4 4v for a street car that is staying under 7000rpm, the 99-04 heads would be the best option by far.
with the short runners I do understand and agree it is better at higher rpm. My thoughts are there is more usable torque if it were a dual plane intake. But I have never seen any real tq/hp numbers with what you describe, cobra intake/ heads. there is also a big port mismatch with the cobra intake on a Navi head witch can negate any theoretical gains. Do you have any data on this other combo? even with the adapter plates for a 302 performer intake? I only have seen pictures no dyno or track data.
I saw a post about the 302 manifold in passing, searching something else; with our limited room, and aluminum blocks being cheap, I'll be staying with a 4.6; y'all can spend your cash however you see fit.
I just want to see one in properly and run well; dyno sheets and 1/4 mile times are gravy.
found a horse power calculator, with my et 13.62 @ 100mph, 4000lb with me in it, I get 312hp at the rear wheels. not to shabby considering Navi's were rated at 305hp at the crank. I'd be interested in hearing about a 5.4 with Cobra intake and heads works out, sounds like it would be a stump puller. keep me posted
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