Why do LS1s rev down so slowly?
04-07-2004, 10:34 PM
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Why do LS1s rev down so slowly? Why do LS1 motors deccelerate/rev down so slowly? Like when you rev it up it takes a long time to get back down to near idle. Is it the flywheel or the balancer or what?
04-08-2004, 12:15 AM
#4
Originally Posted by BadAndy
Why do LS1 motors deccelerate/rev down so slowly? Like when you rev it up it takes a long time to get back down to near idle. Is it the flywheel or the balancer or what?
04-08-2004, 02:57 AM
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Originally Posted by SMOKIN01TA
computer controled crap. thats all it is as far as i know
And that's the first time i've ever heard reving your car was bad
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04-08-2004, 06:16 AM
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Yeah - driving your car is bad for it too - but we're all going to do it anyway.
Continual revving to the redline or holding a car 'free revved' at high rpm's can be bad for an engine. A quick little rev up to hear the exhaust note is not going to cause any problems more than any normal driving.
And I'm not sure about the 'rev decelleration' speed.
Dan
Continual revving to the redline or holding a car 'free revved' at high rpm's can be bad for an engine. A quick little rev up to hear the exhaust note is not going to cause any problems more than any normal driving.
And I'm not sure about the 'rev decelleration' speed.
Dan
04-08-2004, 08:27 AM
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There is a throttle follower / throttle cracker set of
params that are meant to keep the motor from
down-revving too fast and overrunning the IAC and
crashing. It makes a "soft landing". Yeah, you don't
really need to start soft landing at 6000 feet. The
settings can be tuned but they have no performance
impact so most don't bother.
Unloaded revving is said to cause pistons to flutter
in their bore and because of the light rings this leads
to excessive oil consumption. At least that's GM's
story. Yeah, you probably gotta do it once in a
while. But just like scratching any other itch, you
keep at it, you make a mess eventually.
params that are meant to keep the motor from
down-revving too fast and overrunning the IAC and
crashing. It makes a "soft landing". Yeah, you don't
really need to start soft landing at 6000 feet. The
settings can be tuned but they have no performance
impact so most don't bother.
Unloaded revving is said to cause pistons to flutter
in their bore and because of the light rings this leads
to excessive oil consumption. At least that's GM's
story. Yeah, you probably gotta do it once in a
while. But just like scratching any other itch, you
keep at it, you make a mess eventually.
04-08-2004, 09:31 AM
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the real reason your car revs down so slow is because the flywheel is so damn heavy(rotational mass),
as far as free reving being bad for your engine- free reving streatch's connecting rods because there is no load on the pistons, so the violent change in direction streatch's them which intern makes them weaker and prone to snapping and putting a piston in your cylinder head.
as far as free reving being bad for your engine- free reving streatch's connecting rods because there is no load on the pistons, so the violent change in direction streatch's them which intern makes them weaker and prone to snapping and putting a piston in your cylinder head.
04-08-2004, 07:26 PM
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Mine doesn't seem to take a long time, a second or two mostly. You also have to remember that these aren't little rice burner sewing machine motors here. 
They do have some rotational mass and size to them which is why we love them
They do have some rotational mass and size to them which is why we love them
04-08-2004, 07:32 PM
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I'm not 100% sure what causes it but I did notice a HUGE difference in the rev down speed when I went from true duals to GMMG. With the duals, the speed dropped really quick but now its much slower. 
I'm guessing a Y pipe has something to do with it as well.
I'm guessing a Y pipe has something to do with it as well.
04-08-2004, 07:39 PM
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Originally Posted by Rice Eater 316
or it could be the computer relearning something???
Maybe so but the GMMG has been installed for a couple of months now and it hasnt changed a bit. BTW it wasnt a little change in speed.... it was a very very noticeable amount.
04-08-2004, 08:05 PM
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Originally Posted by Rice Eater 316
hmm I just had mine installed and maybe i'm just not as picky I don't know. I"ll have to pay more attention to it.
04-11-2004, 11:54 AM
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Rev ramp-down has to do with emissions and fuel consumption. It's in the computer, and on quite a lot of cars, newer ones suffer from it worse then ours. Honestly it's not that large of a problem, but like many on here said, you can get it de-programmed or changed to your likeing. If you doubt this, I can list any number of other car-specific forums that address this exact issue. It's an emissions feature on the car, put there by GM. For the most part be glad it's there, or you'd have more constrictive exhausts and cat's to make up for the gap a free rev-down motor would have lost in emissions.