Nosing over at high rpm.
02-14-2007, 07:22 AM
#43
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Originally Posted by BLKWS.6
https://ls1tech.com/forums/dynamometer-results-comparisons/647214-my-first-dyno-run.html
^All I am saying is LOOK! That is a 10whp drop roughly from 5500 to 6K. I guess I must be uber-sensetive to feel that. Seems normal to me. I think the people who don't sense it are also the same people who never use any oil and who claim their differentials are dead silent and who say F-bodies dont rattle over bumps. I for one can feel a big difference when the car has been steadily making hp up to 5500-5700 and then all of a sudden it isnt giving me anything to add to that curve and is actually LOSING (albeit 5-10whp) power.
^All I am saying is LOOK! That is a 10whp drop roughly from 5500 to 6K. I guess I must be uber-sensetive to feel that. Seems normal to me. I think the people who don't sense it are also the same people who never use any oil and who claim their differentials are dead silent and who say F-bodies dont rattle over bumps. I for one can feel a big difference when the car has been steadily making hp up to 5500-5700 and then all of a sudden it isnt giving me anything to add to that curve and is actually LOSING (albeit 5-10whp) power.
My '98 uses no oil, and the diff is also very quiet. But yes, I do hear some rattles over really big bumps, like every other F-body. The diff on my '00 car made a tad bit of noise, and it burned a decent amount of oil, so yes not all LS1 cars will be the same and don't assume that all others will be just like yours. I've owned 3, and they've all had slight differences due to production tolerances.
Just because some of our cars don't have certain issues, doesn't mean we don't notice stuff. Stop being jealous that some cars don't burn oil man.
As for the power loss at high rpm, in 1st and 2nd gear, the 5600-6000rpm window happens so fast that I really don't see how anyone could notice much with only a ~10hp drop off in such a short time. If the drop is big enough to be very noticable, then you're probably losing more than just 10hp and you should get your car fixed. Or buy a cam. Or a blower. Or N2O.
In 3rd gear, yes the rpms should climb slower, and you might notice stuff like that more. But for me, I have 2.73 gears. To reach 5600-6000rpm in 3rd would have me at speeds that I rarely ever reach in this car. Should be well past 130mph. So frankly I can't tell you if the cars "feels" like it's droping back power at 5600-6000rpm in 3rd, because I haven't done that often enough to remember.
Originally Posted by ROuND6
so you made this thread ASKING if this happens to any of us... now your TELLING us that it happens to everybody?
Why even bother asking if you already have your mind made up?I never disputed the dyno numbers. In fact, I stated that I've never dynoed this car so I don't have any numbers to discuss on it. But all I can tell you is, I think most people don't notice much difference in power from 5600-6000rpm on a stock or mild bolt-on LS1. If you have a very noticeable drop off in power before redline, there may be something wrong that needs attention.
02-14-2007, 08:28 AM
#45
I think after you read it, you became sensitive to it.
10hp+ is something that you gain or lose every damn day depending on what time you drive your car. You could have 325hp on a cool evening and be running only 305hp around noon on a sunny day. I've had my trap speeds as low as 99mph on a 100degree day, and seen 106mph in the cool evening.
As for the LS1 missing a bit of HP... yeah so what? 10hp or 10/ftlb is peanuts compared to the 300+ you have on tap. we're talking about a 3-7% dip in power from peak??? That's still 300 ft/lb of pull up top near hp peak that most engine types would loose already 15-30% of their torque at or near HP peak.
You should also note that up top, unlike other engine designs, the hp peak isn't just a peak, it plateaus for a bit until it hits rev limiter. Other dynos of other engines I've seen will hit peak and then it's downhill, acceleration now decreases and is necessary to change gears. On our cars though means that while it is not gaining in "acceleration" it is STILL gaining speed at a more constant acceleration while previously it was gaining in acceleration and speed. Result is that until you bounce off the limiter, you acceleration is not dropping. Just bounce off the rev limiter just to see how much acceleration you actually lost when fuel is cut. It's pretty dramatic compared to most cars.
10hp+ is something that you gain or lose every damn day depending on what time you drive your car. You could have 325hp on a cool evening and be running only 305hp around noon on a sunny day. I've had my trap speeds as low as 99mph on a 100degree day, and seen 106mph in the cool evening.
As for the LS1 missing a bit of HP... yeah so what? 10hp or 10/ftlb is peanuts compared to the 300+ you have on tap. we're talking about a 3-7% dip in power from peak??? That's still 300 ft/lb of pull up top near hp peak that most engine types would loose already 15-30% of their torque at or near HP peak.
You should also note that up top, unlike other engine designs, the hp peak isn't just a peak, it plateaus for a bit until it hits rev limiter. Other dynos of other engines I've seen will hit peak and then it's downhill, acceleration now decreases and is necessary to change gears. On our cars though means that while it is not gaining in "acceleration" it is STILL gaining speed at a more constant acceleration while previously it was gaining in acceleration and speed. Result is that until you bounce off the limiter, you acceleration is not dropping. Just bounce off the rev limiter just to see how much acceleration you actually lost when fuel is cut. It's pretty dramatic compared to most cars.
02-14-2007, 12:16 PM
#52
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Originally Posted by NDFORSPD
lol, Im just wonderin what tonights post is gonna be about!... 
..."my car JUST consumed 25mL of oil, where'd it go?!!!!"
..."my car JUST consumed 25mL of oil, where'd it go?!!!!" 
02-14-2007, 04:43 PM
#54
Made a WOT run to 5900 in 3rd today. No nosing over. I think what it was is me pussing out before and letting up on the pedal a tad. Pulled like a freak! LOVE IT! (the new tint kicks *** too!)
Before
After
^Sorry, had to ***** it up!
(the new tint kicks *** too!)Before
After
^Sorry, had to ***** it up!
02-14-2007, 06:19 PM
#55
I'm guessing most the people that say they pull to the redline are probably driving 6 spds where with a good driver they are going shift right at that point where it's just about to level off which is essentially the redline to them. The automatic at WOT will shift a slight bit later than a good manual driver so it's more noticeable to us. With a built tranny you probably will not notice it as much.
02-14-2007, 06:24 PM
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Originally Posted by BLKWS.6
Made a WOT run to 5900 in 3rd today. No nosing over.
02-14-2007, 06:25 PM
#57
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Originally Posted by BLKWS.6
Made a WOT run to 5900 in 3rd today. No nosing over. I think what it was is me pussing out before and letting up on the pedal a tad. Pulled like a freak! LOVE IT! (the new tint kicks *** too!)
Before
After
^Sorry, had to ***** it up!
(the new tint kicks *** too!)Before
After
^Sorry, had to ***** it up!
you've got to be kidding me....
02-14-2007, 06:25 PM
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Originally Posted by Spink
I'm guessing most the people that say they pull to the redline are probably driving 6 spds where with a good driver they are going shift right at that point where it's just about to level off which is essentially the redline to them. The automatic at WOT will shift a slight bit later than a good manual driver so it's more noticeable to us. With a built tranny you probably will not notice it as much.
02-14-2007, 09:55 PM
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Originally Posted by BLKWS.6
I guess I am just more perceptive than a lot of people on here. The ***-dyno confirms the real-dyno curve for me and a coupld people owned up to it as well
Im good! But on a serious note, I've never really noticed it drop off at 5800 rpms, I always shift at about 6300 & it seems to pull all the way up.....FWIW, you're not gonna believe what I have experienced anyways