Grimmer
Well-Known Member
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- #1
I've been reading up on the forced induction options for my 2016 GT Manual. First I want to thank everyone for the incredible amount of information and help available on the forum.
I have kind of a specialized question that I've only been able to pick up indirect bits and pieces of a possible answer here and there...
First my general purpose / goal for forced induction. My car is a "fair weather daily driver", meaning that I'll drive it year round (all 4 seasons around here) so long as there is less than a 20% chance of precipitation, and in winter an adequate length of clear days following a storm to get the snow and wet removed from the roads (to avoid black ice and such). With that said, I would like to see a bump in power (of course, or why else look into FI); however, I am not power hungry and don't plan to race or track or even time runs. In reality, I would probably be just fine with the minimum amount of boost available (offset by cost, of course). And I would in fact like to minimize the additional mods required to "hold up" against the increased power. Which brings me to my question...
The '16 S550 is rated at 435 hp @ sea level on 93 octane. I live at 4,500 feet above sea level. The rule of thumb that I've always heard is a 5% reduction in horsepower for every 1,000 feet of elevation. I take this to mean (0.95^5, or 0.7738 overall). Perhaps one of you tuners out there has a better rule of thumb and can help answer the following questions. Does the same rule of thumb apply after forced induction? For example, if the FI adds 235 hp at sea level, will it also add 235 hp at altitude? Or does it reduce the 5%/1,000 ft losses and actually recover some hp and then add the 235 on top of that? Or does the 5%/1,000 loss also apply to the 235?
The reason I ask is that applying just the rule of thumb to my situation would mean that my car when NA at 4,500 feet actually only produces at best 336 hp. If the FI adds a straight 235 at sea level, and the same rule of thumb is applied for my altitude, that ends up being only 518 hp or an increase of roughly 83 hp over what the NA car does at sea level anyway. Hopefully all parts of the car were originally designed with enough engineering safety factor to handle "an extra 83 hp". If the safety factor perhaps can only absorb an addition 50 hp, is there a way to detune a FI setup to keep it under the original engineering safety factor?
I would like to get a bump in juice, but I want to limit the adverse effects and I'll need a clear idea of what additional costs will be required to keep the car in good health and up to the task of handling the "extra" hp. My car is also still under the new car warranty, so the Ford Performance Racing Supercharger Kit is top of the list for now. Alternatively, I can wait until the powertrain warranty is over (5 years) before installing FI and look at other options.
From what I've picked up so far, I might need to factor in the cost of a billet OPG and crank gear since the potential for failure there sounds like it is more related to vibrations and jarring inherent to most FI systems. Although maybe the pulley vibrations can be handled with a damper and the jarring wouldn't be too severe if only 83 hp above stock. I will probably also have to upgrade the tires because they slip a little too easily even now.
Any thoughts? Especially, does anyone know the rule of thumb for the elevation induced loss of power with forced induction? This could change the whole equation...
I have kind of a specialized question that I've only been able to pick up indirect bits and pieces of a possible answer here and there...
First my general purpose / goal for forced induction. My car is a "fair weather daily driver", meaning that I'll drive it year round (all 4 seasons around here) so long as there is less than a 20% chance of precipitation, and in winter an adequate length of clear days following a storm to get the snow and wet removed from the roads (to avoid black ice and such). With that said, I would like to see a bump in power (of course, or why else look into FI); however, I am not power hungry and don't plan to race or track or even time runs. In reality, I would probably be just fine with the minimum amount of boost available (offset by cost, of course). And I would in fact like to minimize the additional mods required to "hold up" against the increased power. Which brings me to my question...
The '16 S550 is rated at 435 hp @ sea level on 93 octane. I live at 4,500 feet above sea level. The rule of thumb that I've always heard is a 5% reduction in horsepower for every 1,000 feet of elevation. I take this to mean (0.95^5, or 0.7738 overall). Perhaps one of you tuners out there has a better rule of thumb and can help answer the following questions. Does the same rule of thumb apply after forced induction? For example, if the FI adds 235 hp at sea level, will it also add 235 hp at altitude? Or does it reduce the 5%/1,000 ft losses and actually recover some hp and then add the 235 on top of that? Or does the 5%/1,000 loss also apply to the 235?
The reason I ask is that applying just the rule of thumb to my situation would mean that my car when NA at 4,500 feet actually only produces at best 336 hp. If the FI adds a straight 235 at sea level, and the same rule of thumb is applied for my altitude, that ends up being only 518 hp or an increase of roughly 83 hp over what the NA car does at sea level anyway. Hopefully all parts of the car were originally designed with enough engineering safety factor to handle "an extra 83 hp". If the safety factor perhaps can only absorb an addition 50 hp, is there a way to detune a FI setup to keep it under the original engineering safety factor?
I would like to get a bump in juice, but I want to limit the adverse effects and I'll need a clear idea of what additional costs will be required to keep the car in good health and up to the task of handling the "extra" hp. My car is also still under the new car warranty, so the Ford Performance Racing Supercharger Kit is top of the list for now. Alternatively, I can wait until the powertrain warranty is over (5 years) before installing FI and look at other options.
From what I've picked up so far, I might need to factor in the cost of a billet OPG and crank gear since the potential for failure there sounds like it is more related to vibrations and jarring inherent to most FI systems. Although maybe the pulley vibrations can be handled with a damper and the jarring wouldn't be too severe if only 83 hp above stock. I will probably also have to upgrade the tires because they slip a little too easily even now.
Any thoughts? Especially, does anyone know the rule of thumb for the elevation induced loss of power with forced induction? This could change the whole equation...
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