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Discussion Starter #1
Does anyone know why the 2.4 has a rev limiter of 6750 while the other cobalts have 6500? (I could be mistaken)
 

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Different engine.
 

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Discussion Starter #3
No shit Sherlock! The 2.4 has a longer stroke and a very slightly bigger piston, so why would more rotating mass have a higher rev limiter? Come on guys, someone has to know something.
 

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Umm, more horsepower at higher RPMS. VVT. Different bottom end. More sporting nature of the car. What kind of explanation are you looking for??
 

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Discussion Starter #5
Why would designers give the 2.0 a lower rev limiter than that in the ss n/a? That is my question.
 

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it might be because it is boosted,
or maybe the internals are denser so that it actually has more mass.

thats my best guess
thats a good point though
 

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Boost. More stress on the internals even at 300 less rpms. though, now, the stage kits allow the 2.0 to hit 7000. Which is too much fun, i just drove it yesterday. It pulls like crazy.
 

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NM06ss said:
Does anyone know why the 2.4 has a rev limiter of 6750 while the other cobalts have 6500? (I could be mistaken)
so that one of the selling factors of the stage kits is that it'll raise the rev limiter 500 rpms ;)
 

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After driving one with the stage kit, im hooked. It feels like my car hits redline way too fast now.
 

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Well, correct me if I'm wrong.. ( it happens.. at least once a day )

Wasn't it discussed a while back here that the Supercharger's limit was around 14000 rpms?? Since the system bascially has it doubling the revs of the motor, they kept it at 6500 so there would be a safety factor built into the car so we wouldn't damage the SC??

Maybe I've misread something, or just have NO clue what I'm saying.
 

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well there is some discrepancy as to what the ACTUAL redline of the blower is. it has been widely accepted that for the gen iv m62 blowers the redline is 14,000 continuous rpms. however, some people will argue that we have the gen v blowers and the redline for the gen v's is 16,000 continuous rpms, so it is possible that it's really 16,000 rpms, not 14,000.
 

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you are pretty much right, the belt drive is slightly less than 2:1, the crank drive pulley is 6", factory blower is 3.25" i think, so there is plenty of safety margin. With the 3" pulley in the stage kits and the 7000 rpm redline, you are still within the allowable range for the blower. People with the 2.8 or smaller pulley are exceeding the limit on the blower, but i havent heard of anyone having problems yet.
 

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WOW... I actually had some info correct... I better mark this on my calendar.

It's sooooo nice here, and my SS is sitting on a rack at teh dealer ( or at least it BETTER be ) getting god knows what done with it.
Brakes
ALignment
Shifting
Wheel paint chipping
Exhuast rattle
Brakes
Brakes
BRAKES!!!
BRAKES!!!


oh wait... I forgot BRAKES!


:mad:

Can't wait to get it back.
 

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ItalianJoe1 said:
you are pretty much right, the belt drive is slightly less than 2:1, the crank drive pulley is 6", factory blower is 3.25" i think, so there is plenty of safety margin. With the 3" pulley in the stage kits and the 7000 rpm redline, you are still within the allowable range for the blower. People with the 2.8 or smaller pulley are exceeding the limit on the blower, but i havent heard of anyone having problems yet.
that's if any only if the redline is 14k rpms and not 16k. according to eaton the redline for the gen V m62 is 16,000 continuous rpms. so even a 2.8 pulley isn't passed that at 7k rpms.
 

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I'm sure that the difference in rev limits is really just the useable range of power for the car. With VVT, the range that the car can make power in is wider. Not compared to boosted motors, but just in general. Most cars can rev higher than their limiters, it's just making less power than if you shifted.

Also, what's the gearing like in the car, and where does it really pick up speed? With the LSJ, anything from 3,000 RPMS up is basically full torque and power. The LSJ makes alot of power, in a wide part of the RPM band, which means it can be geared longer, to keep the car in the power band longer. If you have a smaller powerband, which I would assume you do, since it's very uncommon to get a perfectally flat tq line in a N/A application. Generally they make better power up high, gear it a little shorter so it drops less in between shifts, and keeps it making more power than it could if it dropped like the shifts in the LSJ with the MU3 gearbox.

Since the stage kit LSJ's have a 7k limiter now, it sorta explains part of your question.

From what I understand, the long term durability testing was done around 6500 rpms. Then they released the RedLine and let us break them over and over again for you guys. Your welcome! ;) The stage kits were then released once enough data was obtained to know that they wouldn'd start floating valves like a dead whale.

As far as the supercharger's top end, that's adjustable with the pulley. Leaving the stock 3.35" pulley on, and bumping the limiter up to 7500 wouldn't overspin the blower at all. Also, the new Eatons in the Redline and SS/SC are good to 16,000 continuous RPMS, not 14,000 peak RPMS, as alot of people assume.
 

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Here's the genV Eaton data:

 

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Discussion Starter #17
You guys have a lot of interesting points but this theory is my favorite.

iso said:
so that one of the selling factors of the stage kits is that it'll raise the rev limiter 500 rpms ;)
Thanks for the interest.
 

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iso said:
lol, i loves me some conspiracy theories :D
Well, did you hear that the government planned the 9/11 attacks??
 
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