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The GTO Devil...
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Discussion Starter #1
Where is the stocker rev limiter set , I think I found it at 6500
 

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Can't help ya, Sorry.
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I thought it was 6200 but it may be 6500
 

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The Anti Dyno Racer
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Should be 6200 for a stock LS1. The stock valvesprings start to float around 5800-5900 so having the limiter that high is not a good thing.
 

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Wooohooo
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NJTorque said:
Should be 6200 for a stock LS1. The stock valvesprings start to float around 5800-5900 so having the limiter that high is not a good thing.
6200 on the 04 ls1
 

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Member #804
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NJTorque said:
Should be 6200 for a stock LS1. The stock valvesprings start to float around 5800-5900 so having the limiter that high is not a good thing.
If the valves could float at all come 5800rpm you would have some serious problems. The rev limter I was told is 6200 and indeed I hit 6200 and it felt like ABS or traction control kicking in, though we know it was in fuel cut.

The valve springs in our GTOs are green stripe "LS6" springs. They are good to 6700rpm on LS6 motors but they also have increased airflow (Z06) and can maintain power to the 6500redline.

When I was trying the 0-60 runs keeping it in second to the redline I could feel it stop accelorating as hard come 6,000rpm onward.
 

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The Anti Dyno Racer
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GMH GTO said:
If the valves could float at all come 5800rpm you would have some serious problems. The rev limter I was told is 6200 and indeed I hit 6200 and it felt like ABS or traction control kicking in, though we know it was in fuel cut.

The valve springs in our GTOs are green stripe "LS6" springs. They are good to 6700rpm on LS6 motors but they also have increased airflow (Z06) and can maintain power to the 6500redline.

When I was trying the 0-60 runs keeping it in second to the redline I could feel it stop accelorating as hard come 6,000rpm onward.
I'm only relaying what's been seen on the dyno. The LS6 spings are blue in color for the LS1 base circle cam in '01 and they are yellow in '02 up(LS6 cam has a smaller base circle in '02 up). My stock LS1 springs have a green stripe on them in my '01 C5 and I know they're not LS6. Your "butt dyno" of the car feeling how it pulls isn't exactly scientific evidence. Do a spring swap and see how it changes your power around 5800 RPM, you'll see less power drop off at the higher RPMs. But I'm sure you all this already. Before you ask me to reference threads created online by others, show me your spring pressures @ installed height and LS6 lift. Unless GM has changed the manufacturing of the LS1 engine, when you compare them to true LS6 spring pressures you may be surprised. Another interesting fact, LS6 springs are not good to 6700 RPM. If they were, then why do all the guys who routinely rev that high need to upgrade valvesprings? I race my LS1 powered car, and am routinely around people who build these motors to race. My statements are rooted in fact, not speculation.
 

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13 year owner
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6,250. Your tach (and the gauges in general) aren't perfectly calibrated. SO you may see it sweep to 6,500. Usually it's the other way around. The tach is slower and you bounce off the limiter.

Our engines don't start valve floating until 6,500'ish. I don't know where you found 5,800! That's where we make our peak power. It'd suck if we all had to shut down there to avoid floating!

I've been around these too and have built a few myself!! I have never seen one float at 5,800!
 

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The Anti Dyno Racer
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CMNTMXR57 said:
6,250. Your tach (and the gauges in general) aren't perfectly calibrated. SO you may see it sweep to 6,500. Usually it's the other way around. The tach is slower and you bounce off the limiter.

Our engines don't start valve floating until 6,500'ish. I don't know where you found 5,800! That's where we make our peak power. It'd suck if we all had to shut down there to avoid floating!

I've been around these too and have built a few myself!! I have never seen one float at 5,800!
CMNT, I have seen many an LS1 start floating at 5800-5900 as evidenced by the power curve on the dyno. They usually are floating pretty good by 6200. Yes, power does peak around 5800, but that sudden dip shortly thereafter has been proven to flatten out dramatically simply by upgrading to a set of Comp 918s(any more than these w/a stock cam is a waste). Titanium retainers also help a lot as they reduce the weight and are usually worth 2-300 RPM and a couple hp. The beehive springs simply to not hold up for a long time when subjected to a high RPM environment. This has been an ongoing issue with valvesprings, the new Comp springs seem to be the best of the new breed, but their high costs(over $400!) makes them a less popular choice for those who see more street duty than racing. I replaced the springs in my C5 at 10k mile intervals, just to keep the car running perfect all the time. A random sampling would indicate that some springs were beginning to show signs of weakening. I was running stock retainers, pushrods, and rockers. Were I to make changes to the cam or a rocker upgrade, the springs would have been toast in just a few thousand miles. I've seen cars that the owners thought were running fine pick up a tenth at the track just from replacing springs. Perhaps I'm a bit more particular about things than most, but hope that what I have seen firsthand can help somebody down the road.
 

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13 year owner
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If you say so! I don't agree. I think you're about 1,000 rpm off.

I'm well aware fo what springs are in what motor and what needs to be done to eliminate "float".

But the stock ones are sufficient for the RPM range the motor is capable of. ONce you start running more lift, longer duration cams, base circles, increasing push rod length, changing rocker arm ratios, etc, then yes, float becomes an issue. But not a stock cam, with stock pushrods, with stock rockers.
 

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Rev limiter appears to be at around 6200 on the not exactly accurate tach. I hit it once just to see where it is.
 

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Wooohooo
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Adam4356 said:
Rev limiter appears to be at around 6200 on the not exactly accurate tach. I hit it once just to see where it is.
According to LS1edit after we d/l my program out it was factory set at 6200 rpm rev limit.
 

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Member #804
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LS6 springs are not good to 6700 RPM
Then how is the redline on a LS6 6500??? Do a search on LS1tech, normal LS1 springs don't have any stripe. Green stripe is 2003 LS6 spring.

And whats with the personal attack??? :rolleyes: Just cause power dips off at 5700rpm in an LS1 doesn't mean the valves are floating, if they floated at all they would be bent. So what your saying is doing a valve spring swap is going to gain you hp?
 

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The Anti Dyno Racer
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GMH GTO said:
Then how is the redline on a LS6 6500??? Do a search on LS1tech, normal LS1 springs don't have any stripe. Green stripe is 2003 LS6 spring.

And whats with the personal attack??? :rolleyes: Just cause power dips off at 5700rpm in an LS1 doesn't mean the valves are floating, if they floated at all they would be bent. So what your saying is doing a valve spring swap is going to gain you hp?
Look at some dyno graphs, you can see the power dropoff on some stock LS1s beginning around 5800. I have personally changed springs on one stock motor, the power dropped off more progressively after the swap and at a higher RPM. Just my results, verified on a chassis dyno. I apologize if you viewed my statements as a personal attack, I just want to put my findings on the table and point out my findings were gathered from a scientific standpoint, rather than pulling info from other places on the internet that may or may not be true. My stock LS1 springs had the stripe, so that alone does not necessarily mean that the springs used now are LS6 springs. The '02 up LS6 uses longer valves due to the smaller base circle of the cam. If the exact same spring was used in an LS1, the installed height spring pressure would most likely exceed specs. The '01 LS6, which used the blue colored springs, used the same base circle as a standard LS1 engine and the same length valves as well. With regards to gaining power from a spring swap, it won't be a true "gain" from a theoretically perfect LS1 but the degradation of spring rate which costs you hp at the top end will be dramatically reduced. It is also important to note that too much spring pressure for a given application will cost you hp due to the extra load on the valvetrain. With a higher lift/longer duration cam, the gain from more lift/duration far exceeds the losses from having to run more spring pressure. As far as bending valves if they float, that is not necessarily true if you have sufficient PTV clearance and the float is not excessive. The float is the valves "bouncing" against their seats instead of closing properly, if they do not "bounce" into the way of the piston they should not bend unless the guide is worn, allowing too much side to side motion and the valve hitting the seat at an angle instead of concentric to the seat.

Please let me know which portion of my post(s) offended you, and I will be happy to remove it(them). The goal we are all seeking is to get the most out of the cars and engines we love, I just want to make sure that those who read this post have enough information to form their own opinions on the subject. I realize that not everybody will agree with me, but I hope that I can help somebody with their decision. If you're interested, I'll try to get my hands on a set of comp 918s and some titanium retainers and send them to you for testing. Then you can put the car on a dyno, and see for yourself. Let me know via PM and I'll see what I can do for you. It may take a little while as I am pretty busy on my end trying to get my Goat by the end of next week and have some issues to resolve on the home front.

Artie
 

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Member #804
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If the exact same spring was used in an LS1, the installed height spring pressure would most likely exceed specs
Not totally true not totally wrong. The valves are taller by .050".

As far as bending valves if they float, that is not necessarily true if you have sufficient PTV clearance and the float is not excessive
I'm gonna disagree with you on that, the PTV is very small in a GEN III motors some performance camshafts even cause problems with stock un machined heads. Its not just the possibility the valve bends. During valve float, part of the spring is attempting to compress while another portion is trying to expand. The spring gets overheated and looses its tension. When that happens valves will float at maybe 4000rpm or the springs will break as 918s are accustomed too(in the past). So for their to be any valve float at 5800 rpm, you would have a difficult time obtaining that continually.

If you knew so much about LS1 power development, you'd be a bit quicker than mid 13s, and the results would have been verified at an actual track instead of relying on a g-tech.
was that neeeded? thanks but no thanks for the springs. No hard feelings. I actually work night shift and have minimal opprotunitys to go to the track, but I do have plenty of 1 mile streatchs of level expressway that are abandon at 2am, Gtech works well on them:)
 

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The Anti Dyno Racer
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GMH, I removed the portion of my post that you found offensive. It is more and more obvious that we're both set in stone on our positions on this, I love a good debate on technical issues as it appears you do as well. We've provided enough info for most others, if you want we can take this to email/PM as not to potentially cloud the judgement of others with too much information. I'm not looking to make enemies, I just enjoy meeting a formidable adversary with regards to technical debates:) You and CMNT have proven more than worthy opponents. :cool:

P.S. Perhaps we can discuss the beehive type spring design next :D
 

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Member #804
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Not opponets; we just didn't share the same view.
 

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Can't help ya, Sorry.
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If this conversation goes on, this audiance member would like you to keep it on the board. I have learned a bit and it has been interesting.

Especialy (and only) if you guys can dissagree without resorting to cutdowns and name calling. I personaly know GMH he is a good and knowlagable (ASE cert) guy who is willing to help anyone local work on their cars. NJT seems like a good guy except for the early dig. I too thought "WTF was that?" when I read the Gtech comment. 13.9 isn't bad for a stock car on stock rubber. It isn't great but I don't see how engine knowlage translates into driving ability anyway. Then I figured he hadn't been around here long enough to see that for the most part we don't jump people like that unless they are being dumb-asp's.

On one hand, the valve float @ 5800 makes some sense to me because of the dyno drop off. That is taking into consideration that changing the springs adds HP or moves the drop off point further up the RPM band. This may or may not be the case but I do beleive from experiance in other feilds that springs do loose their tension over time.

On the other hand, why would GM set a red line higher than the point of float? Maybe they condsider it "acceptable float" and the damage chance is low. Either way this has been interesting and I would like to thank both of you and CMNT for the conversation.

We really need a good R&D shop with a Dyno and some Money.
 

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13 year owner
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Thank you NJ Torque, but I wish not to be an opponent. :D

We're together in the LS1 community, just that we disagree where a certain condition happens. :)
 

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Member #804
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On one hand, the valve float @ 5800 makes some sense to me because of the dyno drop off.
The valves floating isn't whats contributing to the drop off, the air flowing abilitys of the cylinder heads and camshaft's ability to let them breath have alot to do with it. If hp drops off at 5600 why does torque drop off sooner?

This may or may not be the case but I do beleive from experiance in other feilds that springs do loose their tension over time
certainly is the case.
 
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