Why are my MPH so low?
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From: Baltimore, maryland, usa
Re: (Honda-Pilot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda-Pilot »</TD></TR><TR><TD CLASS="quote">
The distance of the quarter mile doesn't change. The only thing that has changed is the rate at which you accelerate through the first 60 feet. Weather you accelerate fast or slow through the first 60 feet, you still 1260 feet left to accelerate. So if you went fast through the first 60 feet you would think it would be a good head start on MPH for the 1260 feet you have remainder.
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I know the distance doesnt change, I was just making an example.. And you have a good head start on the ET not the MPH..
The distance of the quarter mile doesn't change. The only thing that has changed is the rate at which you accelerate through the first 60 feet. Weather you accelerate fast or slow through the first 60 feet, you still 1260 feet left to accelerate. So if you went fast through the first 60 feet you would think it would be a good head start on MPH for the 1260 feet you have remainder.
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I know the distance doesnt change, I was just making an example.. And you have a good head start on the ET not the MPH..
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Joined: May 2004
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From: Santa Margarita, CA, 93453
Re: (1316130057)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1316130057 »</TD></TR><TR><TD CLASS="quote">The reason slicks produce lower MPH's is because of more rolling resistance. They hook more why? A: because the grade of rubber used has a higher coefficient of friction than other tires, and B: their sidewalls are softer so they dull the effect of immediate torque transfer and change it into sidewall wrap.
As a result, the same things that give you more traction at low speed is the same thing that works against you at high speed. The tires like to be stuck to the asphault, so they'll give you traction down low. The tires like to be stuck to the asphault, so they'll fight you up high.
BTW, cars also dyno at less power with the more driveline slack there is (which sidewwall wrap could definitely be considered as) because more work is being done and less force transmitted.
<----just read "Devine's" response. My fault.
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Okay, now this is the best response I have heard yet. I figured the tire pressure theory was on the right track but the pressure alone wasn't enough to make me believe. I'll have to think about this one and get back to you.
As a result, the same things that give you more traction at low speed is the same thing that works against you at high speed. The tires like to be stuck to the asphault, so they'll give you traction down low. The tires like to be stuck to the asphault, so they'll fight you up high.
BTW, cars also dyno at less power with the more driveline slack there is (which sidewwall wrap could definitely be considered as) because more work is being done and less force transmitted.
<----just read "Devine's" response. My fault.
</TD></TR></TABLE>Okay, now this is the best response I have heard yet. I figured the tire pressure theory was on the right track but the pressure alone wasn't enough to make me believe. I'll have to think about this one and get back to you.
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From: Santa Margarita, CA, 93453
Re: (tgreaves)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tgreaves »</TD></TR><TR><TD CLASS="quote">
I know the distance doesnt change, I was just making an example.. And you have a good head start on the ET not the MPH..</TD></TR></TABLE>
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32
I know the distance doesnt change, I was just making an example.. And you have a good head start on the ET not the MPH..</TD></TR></TABLE>
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32
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From: It says BIGBOOST
Re: (Honda-Pilot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda-Pilot »</TD></TR><TR><TD CLASS="quote">
Okay, now this is the best response I have heard yet. I figured the tire pressure theory was on the right track but the pressure alone wasn't enough to make me believe. I'll have to think about this one and get back to you. </TD></TR></TABLE>
lol, no, the pressure just creates more sidewall wrap (driveline slack). You wanna think about it and get back to me? No prob. I'm not going anywhere.
Okay, now this is the best response I have heard yet. I figured the tire pressure theory was on the right track but the pressure alone wasn't enough to make me believe. I'll have to think about this one and get back to you. </TD></TR></TABLE>
lol, no, the pressure just creates more sidewall wrap (driveline slack). You wanna think about it and get back to me? No prob. I'm not going anywhere.
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From: It says BIGBOOST
Re: (Honda-Pilot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda-Pilot »</TD></TR><TR><TD CLASS="quote">
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32</TD></TR></TABLE>
Yeah. You're 100% right. But..you already answered your own question (kinda), with this:<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">The only thing that has changed is the rate at which you accelerate through the first 60 feet. Weather you accelerate fast or slow through the first 60 feet, you still 1260 feet left to accelerate. </TD></TR></TABLE>
The QM should be divided into two parts. The first 60 feet and the second 1260 feet. In the first 60' with slicks on you pick up more MPH, so you travelled that portion in comparitively less time. In the next 1260' you travelled it in a comparatively slower time (due to the rolling resistance) so your mph turns out slower. The thing that throws people off here is that 0.1XX lower in the 60' = 2-3 tenths in the QM.
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32</TD></TR></TABLE>
Yeah. You're 100% right. But..you already answered your own question (kinda), with this:<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">The only thing that has changed is the rate at which you accelerate through the first 60 feet. Weather you accelerate fast or slow through the first 60 feet, you still 1260 feet left to accelerate. </TD></TR></TABLE>
The QM should be divided into two parts. The first 60 feet and the second 1260 feet. In the first 60' with slicks on you pick up more MPH, so you travelled that portion in comparitively less time. In the next 1260' you travelled it in a comparatively slower time (due to the rolling resistance) so your mph turns out slower. The thing that throws people off here is that 0.1XX lower in the 60' = 2-3 tenths in the QM.
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From: Manchester, NH, USA
Re: (Honda-Pilot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda-Pilot »</TD></TR><TR><TD CLASS="quote">
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32</TD></TR></TABLE>
Speed only equals distance divided by time for a constant speed, or at an instantaneous moment. That's not the case in a quarter mile.
Think about it this way: Next time you are at the track, watch something like a DSM or an S4 race, and watch something like a Honda on crappy tires race. Pay special attention where they shift to second gear.
The DSM comes out of the hole hard, but it isn't actually moving that fast. It just gets to 10 mph, like, now. The Honda, on the other hand, just kind of "sits" there and then starts to go.
I bet you money the DSM is shifting to second gear earlier, but also further down the track. That gives the lower traction car more distance to accelerate in the higher gears.
Or, consider it on your own car. When you wheelspin a launch, you might take a while to shift to second, but you haven't gone far at all. When you hook up, the car lunges off the line and you can go pretty far before you have to shift.
MPH = DISTANCE/TIME. Doesn't this mean if your TIME is less then the MPH is higher? Example 60ft/2.3sec = 26 and 60ft/1.9sec = 32</TD></TR></TABLE>
Speed only equals distance divided by time for a constant speed, or at an instantaneous moment. That's not the case in a quarter mile.
Think about it this way: Next time you are at the track, watch something like a DSM or an S4 race, and watch something like a Honda on crappy tires race. Pay special attention where they shift to second gear.
The DSM comes out of the hole hard, but it isn't actually moving that fast. It just gets to 10 mph, like, now. The Honda, on the other hand, just kind of "sits" there and then starts to go.
I bet you money the DSM is shifting to second gear earlier, but also further down the track. That gives the lower traction car more distance to accelerate in the higher gears.
Or, consider it on your own car. When you wheelspin a launch, you might take a while to shift to second, but you haven't gone far at all. When you hook up, the car lunges off the line and you can go pretty far before you have to shift.
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From: Santa Margarita, CA, 93453
Re: (kpt4321)
I agree with the tire sidewall, compound, and pressure giving traction, but killing acceleration. I'm still not satisfied though.
Maybe thats enough to to slow me down 4 mph but what about my co-worker. He added about 100 Hp and dropped 200 pounds of weight. He dropped his ET from 12.12 @ 120 to 10.88 @ 119. Thats a lot of power for his slicks to eat up to make him loose a MPH.
Maybe thats enough to to slow me down 4 mph but what about my co-worker. He added about 100 Hp and dropped 200 pounds of weight. He dropped his ET from 12.12 @ 120 to 10.88 @ 119. Thats a lot of power for his slicks to eat up to make him loose a MPH.
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From: It says BIGBOOST
Re: (Honda-Pilot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda-Pilot »</TD></TR><TR><TD CLASS="quote">I agree with the tire sidewall, compound, and pressure giving traction, but killing acceleration. I'm still not satisfied though.
Maybe thats enough to to slow me down 4 mph but what about my co-worker. He added about 100 Hp and dropped 200 pounds of weight. He dropped his ET from 12.12 @ 120 to 10.88 @ 119. Thats a lot of power for his slicks to eat up to make him loose a MPH. </TD></TR></TABLE>
You're absolutely right. It most certainly is. You also have to consider that lighter cars are more radically affected by things like rolling resistance, aerodynamic drag, down/upforce etc. The lighter something is, the easier it is to alter its momentum or change its trajectory.
Maybe thats enough to to slow me down 4 mph but what about my co-worker. He added about 100 Hp and dropped 200 pounds of weight. He dropped his ET from 12.12 @ 120 to 10.88 @ 119. Thats a lot of power for his slicks to eat up to make him loose a MPH. </TD></TR></TABLE>
You're absolutely right. It most certainly is. You also have to consider that lighter cars are more radically affected by things like rolling resistance, aerodynamic drag, down/upforce etc. The lighter something is, the easier it is to alter its momentum or change its trajectory.
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