Downshifting a cammed car (M6)
10-04-2011, 12:00 PM
#1
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Downshifting a cammed car (M6) Hi guys,
I have no idea if this is in the right forum or not...
My question revolves around downshifting my WS6, M6, cammed LS2, no headers, 3.42's, etc. When I am coming up on a stop sign/light I rev match downshift through the gears, I have done this on every manual trans car that I have driven. This seems to be the only car that does not slow down when I downshift. Can anyone tell me why? I would love it if the car would slow down on the downshift.
Anyway i can make this possible? I am not looking to mod any further, I am thinking it might be something that can be adjusted in the tune perhaps. The car is tuned by Slowhawk if that matters.
Thanks,
Bryan
I have no idea if this is in the right forum or not...
My question revolves around downshifting my WS6, M6, cammed LS2, no headers, 3.42's, etc. When I am coming up on a stop sign/light I rev match downshift through the gears, I have done this on every manual trans car that I have driven. This seems to be the only car that does not slow down when I downshift. Can anyone tell me why? I would love it if the car would slow down on the downshift.
Anyway i can make this possible? I am not looking to mod any further, I am thinking it might be something that can be adjusted in the tune perhaps. The car is tuned by Slowhawk if that matters.
Thanks,
Bryan
10-04-2011, 01:40 PM
#6
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I think it depends on what rpm you downshift to. I know if you dowshift from 5 grand in fourth into third obviously braking in between itll sure as hell slow you down. But going from 1500 in sixth to 2500 in fifth wont do much no
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10-04-2011, 03:53 PM
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I seem to remember it slowing down more before the engine/cam swap. I am thinking it is vacuum related but can't quite figure out how in my head...that is why I posted the question.
I have been paying attention to this for several weeks...while it will do it in all gears, I have been able to pinpoint that downshifting into second at about 40mph (rev matched at about 3k of course), the car almost seems to free wheel. Like I am in neutral. I am clearly not in neutral, but the car is just very slow to slow down.
For example, if I were to do that in my Cobra, the car come to almost a complete stop in 300-400ft. That car has 4.10 gears, but it shouldn't affect it that much, would it?
I have been paying attention to this for several weeks...while it will do it in all gears, I have been able to pinpoint that downshifting into second at about 40mph (rev matched at about 3k of course), the car almost seems to free wheel. Like I am in neutral. I am clearly not in neutral, but the car is just very slow to slow down.
For example, if I were to do that in my Cobra, the car come to almost a complete stop in 300-400ft. That car has 4.10 gears, but it shouldn't affect it that much, would it?
10-04-2011, 04:21 PM
#9
so your saying if your going 40-50 miles an hour in 3rd (lets say @2,500rpms) then you downshift into 2nd @ 40-45 miles an hour (your rpms should jump up quite a bit), the car doesnt slow down... hell unless you have a slipper clutch depending on your speed you should hear a squeak from the tires if you shift to a lower gear at to high of a speed
10-04-2011, 04:25 PM
#10
I seem to remember it slowing down more before the engine/cam swap. I am thinking it is vacuum related but can't quite figure out how in my head...that is why I posted the question.
I have been paying attention to this for several weeks...while it will do it in all gears, I have been able to pinpoint that downshifting into second at about 40mph (rev matched at about 3k of course), the car almost seems to free wheel. Like I am in neutral. I am clearly not in neutral, but the car is just very slow to slow down.
For example, if I were to do that in my Cobra, the car come to almost a complete stop in 300-400ft. That car has 4.10 gears, but it shouldn't affect it that much, would it?
I have been paying attention to this for several weeks...while it will do it in all gears, I have been able to pinpoint that downshifting into second at about 40mph (rev matched at about 3k of course), the car almost seems to free wheel. Like I am in neutral. I am clearly not in neutral, but the car is just very slow to slow down.
For example, if I were to do that in my Cobra, the car come to almost a complete stop in 300-400ft. That car has 4.10 gears, but it shouldn't affect it that much, would it?
10-04-2011, 08:32 PM
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I understand what you guys are saying about the gears, but I have driven a fox 5.0L mustang with 2.73 gears that slowed down quicker than this thing.
Slowhawk suggested closing up the throttle blade a bit. I will try that and report back.
Slowhawk suggested closing up the throttle blade a bit. I will try that and report back.
10-04-2011, 11:26 PM
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sounds like a great way to wear things out faster and waste gas. Why not coast in neutral to a stop? And if you are rev matching when you downshift how is that slowing anything down?
Last edited by gmmusclecarman; 10-04-2011 at 11:34 PM.
10-05-2011, 01:40 AM
#18
I'll have to look back which parameters were screwy with my tune that was causing the idle to hang up and screwing with downshifting, very possible it's something with the idle
http://www.popularmechanics.com/cars...l-fuel-economy
just for anyone who is interested
http://www.popularmechanics.com/cars...l-fuel-economy
just for anyone who is interested
10-05-2011, 11:29 AM
#19
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I am going to mess with the throttle screw tomorrow, no time today.
To the guy a few posts up that doesn't understand why I am downshifting a manual transmission, you may want to take the time and read that popular mechanics article...
To the guy a few posts up that doesn't understand why I am downshifting a manual transmission, you may want to take the time and read that popular mechanics article...
