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<blockquote data-quote="tt335ci03cobra" data-source="post: 12726895" data-attributes="member: 68944"><p>Ya the 5.4 have sweeping potential as power levels climb, it's not a fixed gain, like 30-40whp, but more so an algorithm. At low power na levels its 30~40whp in most cases, but higher power changes things a lot. All variables being the exact same, a 5.4 has greater potential for power production in any comparable scenario vs the 4.6, I'd guess in my scenario, an identical 4.6 from cr, to heads/cams/ rpm/Sullivan intake etc would be 70-80whp lower at 20psi and atleast 100whp lower at 25psi. For comparison, the 5.4 setup made 815whp on 15psi way back before the last set of spark/fuel/maf/tuning mods and the original stock 4.6 made 756whp on 15psi. I think 03's have 9.2/1 stock cr so I was a bit higher but 69whp was the difference just at 15psi. At just 18-20psi, the 5.4 combo made 898-915whp (turbos maxed out for the 5.4) while it took 23-24psi to get 87xwhp out of the stock longblock 4.6, in essence with 5-6psi less boost, it made 15-45+whp, I think at 20psi, the 4.6 was making 825~ but I can't honestly remember. If it was, that 90whp alone there but also, the 5.4 is more sensitive to 2.5" down pipes restriction than the smaller 4.6 is. Little difference also go the other way though like the newer/tune friendlier maf was on the 5.4 when it made 915, but not on the 4.6 when it made 87x, better fuel and spark system too on the 5.4 etc but then again the 5.4 is 20% bigger so it also demands more fuel/spark so its hard to say what those mods would have gained on the 4.6 since its apples/oranges.</p><p></p><p>In my application, the 5.4 showed to be torquier by upto 100+ wtq in certain parts of the powerband which necessitated 3.08's and 28" tires for a semblance of traction just on pump gas under 80-100mph. </p><p></p><p>Here's an old graph comparing the two combos on 15psi. This is before the fuel/spark/maf mods on the 5.4, it now makes I believe 830-840whp on 15-16psi. We had a pull that showed 845~?whp on 16.xpsi but never got anything in the 15psi range on the newest setup. Boost creep maybe? Hope not haha. </p><p></p><p><img src="http://img.tapatalk.com/d/13/02/11/e6u7a4ep.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>I think the graph shows how the stock spark tables (pre boost a spark) and 2.5" down pipes choke off power production as hp is still climbing well then studders off, but torque falls off quickly after peaking and decidedly affects the hp curves ramp. At 3500-4500rpms, it's easily 80-120+whp more with gobs more torque, but then it reaches the restriction of the factory spark tables and 2.5" downs. It's goofy that it only picked up 70whp going from 15/16psi to 20psi haha. On the same day it made these numbers, it made 860-885 on 18-20psi. From 15psi up, the 57/48's are every bit and more so a restriction than even the 2.5" downs/previous spark and maf issues were IMO. Really incongruent combo efficiency wise.</p><p></p><p><img src="http://img.tapatalk.com/d/13/02/11/y3e6u9eq.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="http://img.tapatalk.com/d/13/02/11/nedyhu3y.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>This one shows the spark cut off/issues. I think this 869whp was on 18psi, it made 87x's on 19 and 885 on 20 but we didn't do many pulls up there because of the spark issues.</p><p></p><p>Extra boost was literally just cooking up 20+wtq with like 3-5whp from 19-20psi.</p><p></p><p>Intake wise I'm running an accufab single blade into Sullivan upper/lower but the cold side leading in is dual in dual out modified fmic 4+" (4.5"?)</p><p></p><p><img src="http://img.tapatalk.com/d/13/02/11/jyhu6y4y.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>Na 5.4 it made 380-400wtq at 2000-4500~ and never dropped below 350wtq after that. It peaked 355-365whp@55-6200 with factory 03 cobra exhaust manifolds, heads and cams (stock 03) on 9.5:1 cr with a really safe break in tune. It was good for 12.9's at 112 na with crappy tires (2.1 60ft) but a spec stage 3+, 4.10's, full suspension and powershifts. I know of some full bolt on 01 cobras getting upto 330whp but its very rare. The 365 it made na would be 35whp alone but also, the 9.5:1 compression is probably lower than the 9.8?-10.0?:1 cr of an na 4.6 cobra mill and my 5.4 had cast factory 03 cobra manifolds while 330whp teksids have to be running headers, so it's not exactly that simple to say what the exact difference is. I'd guess 40whp na is a good rule of thumb on a low if all parts/compression/healthiness/etc are the same but displacement is the only real difference. </p><p></p><p>-----any ways, I can't think of much else frame of reference wise to explain the differences I've seen 4.6 vs 5.4 but if you have a specific question, I can try and answer it if I know anything that pertains-----</p><p></p><p>A/r wise they recommended the .63 3" vband which I also thought was small. I was thinking of running atleast a .85-.90~ a/r but they said the 60/62 would feel laggier with that but I'm still on the fence. Time will tell. I think it's interchangeable relatively easily so I can probably switch them if the .63's are too restrictive. </p><p></p><p>Those links are awesome, I love seeing "small" turbo cobras make 4 digit power. So much epic win. Keeps me very hopeful. Thanks for sharing those!!</p></blockquote><p></p>
[QUOTE="tt335ci03cobra, post: 12726895, member: 68944"] Ya the 5.4 have sweeping potential as power levels climb, it's not a fixed gain, like 30-40whp, but more so an algorithm. At low power na levels its 30~40whp in most cases, but higher power changes things a lot. All variables being the exact same, a 5.4 has greater potential for power production in any comparable scenario vs the 4.6, I'd guess in my scenario, an identical 4.6 from cr, to heads/cams/ rpm/Sullivan intake etc would be 70-80whp lower at 20psi and atleast 100whp lower at 25psi. For comparison, the 5.4 setup made 815whp on 15psi way back before the last set of spark/fuel/maf/tuning mods and the original stock 4.6 made 756whp on 15psi. I think 03's have 9.2/1 stock cr so I was a bit higher but 69whp was the difference just at 15psi. At just 18-20psi, the 5.4 combo made 898-915whp (turbos maxed out for the 5.4) while it took 23-24psi to get 87xwhp out of the stock longblock 4.6, in essence with 5-6psi less boost, it made 15-45+whp, I think at 20psi, the 4.6 was making 825~ but I can't honestly remember. If it was, that 90whp alone there but also, the 5.4 is more sensitive to 2.5" down pipes restriction than the smaller 4.6 is. Little difference also go the other way though like the newer/tune friendlier maf was on the 5.4 when it made 915, but not on the 4.6 when it made 87x, better fuel and spark system too on the 5.4 etc but then again the 5.4 is 20% bigger so it also demands more fuel/spark so its hard to say what those mods would have gained on the 4.6 since its apples/oranges. In my application, the 5.4 showed to be torquier by upto 100+ wtq in certain parts of the powerband which necessitated 3.08's and 28" tires for a semblance of traction just on pump gas under 80-100mph. Here's an old graph comparing the two combos on 15psi. This is before the fuel/spark/maf mods on the 5.4, it now makes I believe 830-840whp on 15-16psi. We had a pull that showed 845~?whp on 16.xpsi but never got anything in the 15psi range on the newest setup. Boost creep maybe? Hope not haha. [IMG]http://img.tapatalk.com/d/13/02/11/e6u7a4ep.jpg[/IMG] I think the graph shows how the stock spark tables (pre boost a spark) and 2.5" down pipes choke off power production as hp is still climbing well then studders off, but torque falls off quickly after peaking and decidedly affects the hp curves ramp. At 3500-4500rpms, it's easily 80-120+whp more with gobs more torque, but then it reaches the restriction of the factory spark tables and 2.5" downs. It's goofy that it only picked up 70whp going from 15/16psi to 20psi haha. On the same day it made these numbers, it made 860-885 on 18-20psi. From 15psi up, the 57/48's are every bit and more so a restriction than even the 2.5" downs/previous spark and maf issues were IMO. Really incongruent combo efficiency wise. [IMG]http://img.tapatalk.com/d/13/02/11/y3e6u9eq.jpg[/IMG] [IMG]http://img.tapatalk.com/d/13/02/11/nedyhu3y.jpg[/IMG] This one shows the spark cut off/issues. I think this 869whp was on 18psi, it made 87x's on 19 and 885 on 20 but we didn't do many pulls up there because of the spark issues. Extra boost was literally just cooking up 20+wtq with like 3-5whp from 19-20psi. Intake wise I'm running an accufab single blade into Sullivan upper/lower but the cold side leading in is dual in dual out modified fmic 4+" (4.5"?) [IMG]http://img.tapatalk.com/d/13/02/11/jyhu6y4y.jpg[/IMG] Na 5.4 it made 380-400wtq at 2000-4500~ and never dropped below 350wtq after that. It peaked 355-365whp@55-6200 with factory 03 cobra exhaust manifolds, heads and cams (stock 03) on 9.5:1 cr with a really safe break in tune. It was good for 12.9's at 112 na with crappy tires (2.1 60ft) but a spec stage 3+, 4.10's, full suspension and powershifts. I know of some full bolt on 01 cobras getting upto 330whp but its very rare. The 365 it made na would be 35whp alone but also, the 9.5:1 compression is probably lower than the 9.8?-10.0?:1 cr of an na 4.6 cobra mill and my 5.4 had cast factory 03 cobra manifolds while 330whp teksids have to be running headers, so it's not exactly that simple to say what the exact difference is. I'd guess 40whp na is a good rule of thumb on a low if all parts/compression/healthiness/etc are the same but displacement is the only real difference. -----any ways, I can't think of much else frame of reference wise to explain the differences I've seen 4.6 vs 5.4 but if you have a specific question, I can try and answer it if I know anything that pertains----- A/r wise they recommended the .63 3" vband which I also thought was small. I was thinking of running atleast a .85-.90~ a/r but they said the 60/62 would feel laggier with that but I'm still on the fence. Time will tell. I think it's interchangeable relatively easily so I can probably switch them if the .63's are too restrictive. Those links are awesome, I love seeing "small" turbo cobras make 4 digit power. So much epic win. Keeps me very hopeful. Thanks for sharing those!! [/QUOTE]
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