What is our redline?

[ElAviator72]

Just curious, I punched the pedal to the floor getting on I-5 today with our toddler son (who took a nasty hit to the head on concrete at the playground-kid is fine now). We were on our way to the E.R. I saw the engine reach a Quad-4 like 6500 RPM before shifting. Oh, and my son giggled and said "go momma's car!" P.S. Love the sounds the big 6 makes at high power.

 

[gmcman]

I'm fairly certain the limit is set at 6200, if you're needle is reaching 6500, have you ever removed the dials to access the inside of the cluster?

 

[gmac310]

According to Wikipedia: Engine redline is 6300 rpm.

 

[limequat]

According to Wikipedia: Engine redline is 6300 rpm.

Correct, it's programmed to shift earlier.
Dash tachs are notoriously inaccurate

 

[ElAviator72]

I'm fairly certain the limit is set at 6200, if you're needle is reaching 6500, have you ever removed the dials to access the inside of the cluster?

I've never had the dash apart. We bought the truck used, with 23,000 miles on the clock (3 years ago). Up to 62,000 now...

 

[ElAviator72]

According to Wikipedia: Engine redline is 6300 rpm.

Always my first reference...

 

[seanpooh]

Hmm, my 2002 shifts at 6000rpm at WOT. Does the redline differ due to the years of our Trailblazer?

 

[ItsOnVoy]

Hmm, my 2002 shifts at 6000rpm at WOT. Does the redline differ due to the years of our Trailblazer?

My guess yes, it prob changes at 07 when they changed the engine a bit with more hp.

 

[AV8ER]

I see my tach go just past 6000 when it shifts though i would say at the rate the needle is moving it is probably inaccurate.

 

[kardain]

According to Wikipedia: Engine redline is 6300 rpm.

Hptuners concurs.

Hmm, my 2002 shifts at 6000rpm at WOT. Does the redline differ due to the years of our Trailblazer?

For 2002, 6300 when moving, 5100 when not moving.

 

[seanpooh]

Hmm... 6300K, I should of had PCM4Less remove my REV limiter then

 

[limequat]

Hmm... 6300K, I should of had PCM4Less remove my REV limiter then

Unfortunately, not much to be gained up there. I ran my 4200 powered Supra up to 7000 RPM for a while. Logs show that power does in fact drop off at about 6000. Depending on your gear ratios, it might help to shift later, so that you don't fall out of the power band.

Now...once we get some ported heads and thumper cams on the market, 7000 RPM is gonna be a sweet thing

 

[ScarabEpic22]

The I6s that run the P10 (02-05s) all have the factory limiter set at 6300. That said, factory shift points are set to 6100 so unless something happens (trans doesnt shift, slips too much, etc), you'll never see above 6100. I imagine GM left them the same for the other years as well, no reason to change it. The factory cams run out of steam around 6k like limequat mentioned plus the engine has a weird harmonic that is introduced around 6300-6500rpms (according to the guys that run them standalone). I would love to see a late head with a full port/polish job, custom cams, and proper tuning spin to 7k in a TrailBlazer. :wootwoot: Then maybe add some boost...

That said, my 02 shifts at 6500rpms now (logs say like 6450-6475), I like it because the engine revs stay a little higher for the next gear. Takes a bit to wind it out completely though, Ive got my friends GoPro for a few weeks, I should get a video of it. Spins the 265/70R16 Kumhos in my sig from 45-50mph from 1st to 2nd.

 

[ElAviator72]

Dash tachs are notoriously inaccurate

Took my Sunfire GT up to the rev limiter this morning getting on the Freeway (I've done it before...). My Quad 4 banged the rev limiter at th expected 6500 RPM indicated (which is the stock PCM programming), in a 13 year old GM vehicle with 227,000 miles. Don't worry, the car is maintained well, and the Quad 4 loves to rev I've been told by GM engineers on the J-body forum that the only reason for the 6500 RPM limit in the second generation Quad 4 (the 2.4L version) is so that the balance shafts spinning in the oil pan don't self destruct... older Quad 4 variants had higher redlines. Of course, having a stick helps

So, is it the GMT dash tachs that are innacurate? I know that in most vehicles made now (and since about the early 1990's), the tach is reading pulses from the hall effect crankshaft position sensor to count revolutions per minute...

 

[kardain]

Took my Sunfire GT up to the rev limiter this morning getting on the Freeway (I've done it before...). My Quad 4 banged the rev limiter at th expected 6500 RPM indicated (which is the stock PCM programming), in a 13 year old GM vehicle with 227,000 miles. Don't worry, the car is maintained well, and the Quad 4 loves to rev I've been told by GM engineers on the J-body forum that the only reason for the 6500 RPM limit in the second generation Quad 4 (the 2.4L version) is so that the balance shafts spinning in the oil pan don't self destruct... older Quad 4 variants had higher redlines. Of course, having a stick helps

So, is it the GMT dash tachs that are innacurate? I know that in most vehicles made now (and since about the early 1990's), the tach is reading pulses from the hall effect crankshaft position sensor to count revolutions per minute...

That and the torque curve doesn't require much more than 6500...

All OEM gauges controlled by the PCM will have a +/- variance due to smoothing of the output signal by the cluster electronics. If smoothing is not present, the needles would jump or twitch.