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2012-2013 Boss 302 Mustang
would the GT intake work better on a BOSS engine? lets find out!
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<blockquote data-quote="pufferfish" data-source="post: 13517398" data-attributes="member: 153725"><p>ok I found some info on how to calculate the optimum shift point from a dyno graph. first, HP is not a factor, except to say that in general, shift 1000 above max hp is the fastest. I would take it at face value, but I have heard the coyote responds best to 1500 above max, so I set out to waste some time in calculating and graphing both.</p><p></p><p>so, torque is what propels the car. the fastest way down the strip (or a track straight section) is to minimize the delta between the torque value of the gear you are leaving to the gear you are going into. the rpm that gives you the closest to equal torque is your theoretical shift point.</p><p></p><p>to plot the graph, you need to find the wheel force for a given gear for the Y and the mph for the X. I started with 500 rpm increments and making my best guess with a ruler to find the torque value at each rpm increment on the dyno graph. then put into the following formula to give me the force the tire exerts to the ground.</p><p></p><p>(trans gear ratio)X(diff ratio)X(torque value)/1.083</p><p></p><p>the 1.083 represents the wheel as the lever arm. I use a 26" tall tire (13" radius) and the divider to achieve 1 foot is 1.083, which is important to get an accurate lb per foot figure. with the force numbers calculated for each rpm increment in each gear, all that's left to figure out before plotting is the mph for the given rpm in the given gear. that formula is as follows.</p><p></p><p>(tire diameter)/2/168X(rpm)/(diff ratio)/(trans gear ratio)</p><p></p><p>whew! then the fun part, plotting the force at the mph increment in each gear. putting all of these on the same graph shows where each gear parabolic shape intersects. this is the theoretical equilibrium torque value when upshifting.</p><p></p><p><img src="http://imageshack.com/scaled/thumb320x240/202/mefv.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>if I was able to plot these electronically, I could have seen how diff gear ratios effect the shift points, but you all can feel free to do it yourselves...I am stopping here.</p><p></p><p>each coordinate plotted for each gear represents a 500 rpm increment starting at 2500 and finishing at 8000. the arrows at the 8000rpm coordinate point shows the jump in torque when upshifting. the GT graph is clear that 8000rpm shifts are useless. take the 1-2 gear change for example. at 7500rpm, 1st gear is outputting 3000lb/ft. shifting here starts you off with 3000lb/ft to begin 2nd gear in. stretching to 8000 ends at 2400lb/ft before shifting and getting the same exact 3000lb/ft to start out 2nd. so, the time it takes to get from 7500rpm to 8000rpm is essentially less productive time, which will bring ET's higher.</p><p></p><p>the GT intake on my car with my gear ratio, is optimized at 7500 for 1-2. 7400 for 2-3. 7250 for 3-4. and 7250 for 4-5. but of course, if I was at a drag strip and was able to do better than 120mph, I would stretch 4th to save the time in shifting. so, with max power coming in at 6600, I am actually shifting LESS than 1000 above max horsepower. very surprised by that.</p><p></p><p>the BOSS intake graph shows that the 1-2 shift should occur somewhere north of 8000. maybe 8800? the 2-3 is also higher than 8000. the 3-4 and 4-5 are a tad bit higher than 8000, but it would likely be negligible.</p><p></p><p>what I find very interesting is the force delta you end up with for each intake if you have to short shift as you would likely do on a road course for various reasons. I will stick with 3-4 starting at 5500rpm, since I believe that will be the most common for me.</p><p></p><p>5500: GT = -400lb/ft, BOSS = -475lb/ft</p><p>6000: GT = -310lb/ft, BOSS = -350lb/ft</p><p>6500: GT = -250lb/ft, BOSS = -250lb/ft</p><p>7000: GT = -150lb/ft, BOSS = -150lb/ft</p><p></p><p>at 7250, where the GT shifts, is where the BOSS maintains higher force values, over the GT in the next higher gear. at 7250, the BOSS has and additional 150lb/ft. at 7500, +100lb/ft. at 8000, +25lb/ft. </p><p></p><p>so, carrying a gear higher indisputably allows for more acceleration. and it appears that shifting anywhere above 6000rpm can allow the BOSS intake to never see its low end deficiencies.</p><p></p><p>its clear to me from this little math exercise, that on paper the BOSS is king for track and drag, with the exception of the short end of the track. up to about 25mph, the GT is supreme.</p><p></p><p>so, the choice to use the GT intake for road racers has to be because of the hp to weight rules. if you can't wind the BOSS out above 7000rpm (where it bests the GT in HP), its no better than a GT intake. now, on the street, the GT intake is definitely the better choice...but I don't think anyone was arguing that.</p><p></p><p>the force losses at 5500 are significant, but again, would probably improve for the boss mani with a steeper diff gear ratio.</p></blockquote><p></p>
[QUOTE="pufferfish, post: 13517398, member: 153725"] ok I found some info on how to calculate the optimum shift point from a dyno graph. first, HP is not a factor, except to say that in general, shift 1000 above max hp is the fastest. I would take it at face value, but I have heard the coyote responds best to 1500 above max, so I set out to waste some time in calculating and graphing both. so, torque is what propels the car. the fastest way down the strip (or a track straight section) is to minimize the delta between the torque value of the gear you are leaving to the gear you are going into. the rpm that gives you the closest to equal torque is your theoretical shift point. to plot the graph, you need to find the wheel force for a given gear for the Y and the mph for the X. I started with 500 rpm increments and making my best guess with a ruler to find the torque value at each rpm increment on the dyno graph. then put into the following formula to give me the force the tire exerts to the ground. (trans gear ratio)X(diff ratio)X(torque value)/1.083 the 1.083 represents the wheel as the lever arm. I use a 26" tall tire (13" radius) and the divider to achieve 1 foot is 1.083, which is important to get an accurate lb per foot figure. with the force numbers calculated for each rpm increment in each gear, all that's left to figure out before plotting is the mph for the given rpm in the given gear. that formula is as follows. (tire diameter)/2/168X(rpm)/(diff ratio)/(trans gear ratio) whew! then the fun part, plotting the force at the mph increment in each gear. putting all of these on the same graph shows where each gear parabolic shape intersects. this is the theoretical equilibrium torque value when upshifting. [IMG]http://imageshack.com/scaled/thumb320x240/202/mefv.jpg[/IMG] if I was able to plot these electronically, I could have seen how diff gear ratios effect the shift points, but you all can feel free to do it yourselves...I am stopping here. each coordinate plotted for each gear represents a 500 rpm increment starting at 2500 and finishing at 8000. the arrows at the 8000rpm coordinate point shows the jump in torque when upshifting. the GT graph is clear that 8000rpm shifts are useless. take the 1-2 gear change for example. at 7500rpm, 1st gear is outputting 3000lb/ft. shifting here starts you off with 3000lb/ft to begin 2nd gear in. stretching to 8000 ends at 2400lb/ft before shifting and getting the same exact 3000lb/ft to start out 2nd. so, the time it takes to get from 7500rpm to 8000rpm is essentially less productive time, which will bring ET's higher. the GT intake on my car with my gear ratio, is optimized at 7500 for 1-2. 7400 for 2-3. 7250 for 3-4. and 7250 for 4-5. but of course, if I was at a drag strip and was able to do better than 120mph, I would stretch 4th to save the time in shifting. so, with max power coming in at 6600, I am actually shifting LESS than 1000 above max horsepower. very surprised by that. the BOSS intake graph shows that the 1-2 shift should occur somewhere north of 8000. maybe 8800? the 2-3 is also higher than 8000. the 3-4 and 4-5 are a tad bit higher than 8000, but it would likely be negligible. what I find very interesting is the force delta you end up with for each intake if you have to short shift as you would likely do on a road course for various reasons. I will stick with 3-4 starting at 5500rpm, since I believe that will be the most common for me. 5500: GT = -400lb/ft, BOSS = -475lb/ft 6000: GT = -310lb/ft, BOSS = -350lb/ft 6500: GT = -250lb/ft, BOSS = -250lb/ft 7000: GT = -150lb/ft, BOSS = -150lb/ft at 7250, where the GT shifts, is where the BOSS maintains higher force values, over the GT in the next higher gear. at 7250, the BOSS has and additional 150lb/ft. at 7500, +100lb/ft. at 8000, +25lb/ft. so, carrying a gear higher indisputably allows for more acceleration. and it appears that shifting anywhere above 6000rpm can allow the BOSS intake to never see its low end deficiencies. its clear to me from this little math exercise, that on paper the BOSS is king for track and drag, with the exception of the short end of the track. up to about 25mph, the GT is supreme. so, the choice to use the GT intake for road racers has to be because of the hp to weight rules. if you can't wind the BOSS out above 7000rpm (where it bests the GT in HP), its no better than a GT intake. now, on the street, the GT intake is definitely the better choice...but I don't think anyone was arguing that. the force losses at 5500 are significant, but again, would probably improve for the boss mani with a steeper diff gear ratio. [/QUOTE]
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would the GT intake work better on a BOSS engine? lets find out!
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