Heres a good question

[Aleromaster]

I was racing tonight (yes leagly). I have the 3400. Going throught the first gear it reved up to 6500rpm and during the shift the tires chirped. Then trough second gear same thing happened again. What the heck happened. I was unable to recreate the events though. What do you guys think happened. By the way I spanked the accord

[Aleromaster]

What nobody has anything to say? Ops I also noticed its in the wrong section

[dopey]

u sure it was the tires chirping??? u may be mistaking that for the motor hitting the rev limiter......

[Aleromaster]

No it was tires cause it happens after the shift and I know what my tires sound like. And anyway souldn't the rev limiter kick in before that. I was not shifting it manually

[dopey]

well then i would jsut guess that ur tires for whatever reason really hooked up an the tranny jerked extra hard to get them to chrip that one particular time.

[Aleromaster]

Actually I was more concerend about the 6500RPM thing as I have never seen It go that high before and believe me I've tried to recreate it. The Tire chirps was just kind of cool. Made people think I had some mad power under the hood but all I have is a WAI

[brsexton]

Your right, that is a good question on how an automatic can do that. If I were you though, I would not rev it up to 6500 very often to do it again unless you want to end up like SilverKnight :eek: .

[Aleromaster]

Originally posted by brsexton@Mar 2 2004, 09:52 PM
Your right, that is a good question on how an automatic can do that. If I were you though, I would not rev it up to 6500 very often to do it again unless you want to end up like SilverKnight :eek: .
Well its not exactly like I wanted it to happen. I always relied on the car shifting its self when it needed to. And me warrenty would acctually cover my engine casue I have no major mods done. Just WAI fore now

[brsexton]

I know what you mean. I don't think mine has ever hit 6500 but if I floor it from a stop, it revs really high before it decides to shift. My mom's malibu (3.1L) was the exact same way. Other cars I have driven don't rev like that. I think GM's just like to rev.

[Fast Eddie]

I've get a 2.4 manny with C/H/E and can only chirp third when I try very hard, and my gearing is alot more likely to transfer that kinda power to the wheels, so I'm calling BS on chirping third in an auto.

As for revving high I think the rev limiter, at least on the 2.4, is like 66-6700, so 6500 is just before the limiter, but I wonder how many autos, not manual shifting, have hit the rev limiter.

[smokinAMD]

That is a bit high, I believe the highest mines ever shifted at is around 5700.

[quitlahok]

i've seen mine take it up to ~6100-6200 but it's never chirped the tires after the shift

[Crazy_Canuck]

http://www.gm.com/automotive/gmpowertrain/...s/4t45_main.htm (http://www.gm.com/automotive/gmpowertrain/transmissions/4t45_main.htm)

Maximum shift is at 5800rpm.... check the link out for more info on the 3400 tranny.

[Redog]

I "chirped" mine once but it was under normal acceraton on a rainy night right after I have the manifold done.

Mine usually shifts around 57 or 5800, but I have pushed it above redline but only until about 6400


Maximum shift is at 5800rpm.... check the link out for more info on the 3400 tranny

This is only for the tranny, the motor usually can handle about 6500 RPMs. They put the redline lower for a safety. (at least they used to) :unsure:

[Crazy_Canuck]

Originally posted by Redog@Mar 3 2004, 06:29 PM
This is only for the tranny, the motor usually can handle about 6500 RPMs. They put the redline lower for a safety. (at least they used to) :unsure:


Not debating that, just posting the information for technical debate. ;)

I've seen auto tranny's once in a while shift out of a gear only once you've let your foot off the gas so it can get back to lower RPM's.

[haulmarc]

more than likely the engine rpms never got that high. the stock tach isnt that accurate or responsive.

[Crazy_Canuck]

Originally posted by haulmarc@Mar 3 2004, 07:12 PM
more than likely the engine rpms never got that high. the stock tach isnt that accurate or responsive.
I don't know about that. My mother had an Olds 98 a long time ago. I took it out for a ride once and stomped the gas pedal to the floor. It screamed in first gear until it ran to the end of the power band and peaked out. It didn't shift until I took my foot off the pedal.

As for the stock tach, it's not THAT out to lunch either.

[Final-Reality]

There's a fuel cut off somewhere around the 6500rpm mark so don't worry about it... the fuel cut of is there for a reason, so unless you somehow go past that I wouldnt worry.

It's odd how nobody seems to know exactly where the 3400 is supposed to shift under WOT... my 2.4/4-speed auto shifts at 6500RPM under WOT every time, and fuel cut off is at like 6700rpm, I've only hit it like once when the shifter was left in D1 (have to move it back to get change out of my ash tray)

[overdrive75]

Originally posted by Crazy_Canuck+Mar 3 2004, 02:44 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Crazy_Canuck @ Mar 3 2004, 02:44 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-Redog@Mar 3 2004, 06:29 PM
This is only for the tranny, the motor usually can handle about 6500 RPMs. They put the redline lower for a safety. (at least they used to) :unsure:


Not debating that, just posting the information for technical debate. ;)

I've seen auto tranny's once in a while shift out of a gear only once you've let your foot off the gas so it can get back to lower RPM's. [/b][/quote]
You are partially right, the reason the 4 bangers can get up the 6500 rpms is they have a lower speed going into the transmission. The sprockets on the 4 bangers are under driven, also they have a looser torque converter. The 3400 have a considerably tighter torque convert, and straight sprokets. 1:1. So to keep the speeds down doing into the baral of the trans, they have to shift lower. There are some things that can be done to the trans to raise WOT shift speed though.

[haulmarc]

[QUOTE]QUOTE (haulmarc @ Mar 3 2004, 07:12 PM)
more than likely the engine rpms never got that high. the stock tach isnt that accurate or responsive.


I don't know about that. My mother had an Olds 98 a long time ago. I took it out for a ride once and stomped the gas pedal to the floor. It screamed in first gear until it ran to the end of the power band and peaked out. It didn't shift until I took my foot off the pedal.

As for the stock tach, it's not THAT out to lunch either. [QUOTE]

canuck, if you looked at it on an auto xray diagnostic scanner in realtime you would clearly see that most if not all stock tachs respond slowly and overtach on acceleration. the scanner reads off the computer. the tach is analog and is inherently slow. aftermarket tachs otoh are more accurate.

[Fast Eddie]

Originally posted by haulmarc@Mar 3 2004, 09:35 PM
canuck, if you looked at it on an auto xray diagnostic scanner in realtime you would clearly see that most if not all stock tachs respond slowly and overtach on acceleration. the scanner reads off the computer. the tach is analog and is inherently slow. aftermarket tachs otoh are more accurate.
Just an observation, generally digital readings are slower than analog, since they have to undergo A/D conversion first, that may be why the computer says its slower. And most aftermarket guages typically use the same method of extracting data, IOW, it is no or less acurate than the stock one.

[haulmarc]

not to make an issue here so ill retract my statements and advise all racers to use alero tachs for racing. maybe autometer should close up shop to. j/k

all i said that the tach is not accurate and further ill say it may read 2-300 rpms out from true. ive burned enough chips and read enough runs on my laptop info for my camaro and others to know how bad tachs can be.

[Fast Eddie]

I'm not trying to start an argument but before you compare one vehicles flaws with another you should know there are some things to be taken into account before making a stament that equipment is junk.

I'm not saying that one guage is more accurate than another, but think about it if the method of gathering data is iffy then no matter how accurate the guage its only as good as the collection device, I would esp expect this from a CPS used for engine speed.

Before I go any further does the alero have a gear driven tach or an electric sensor on the crank? What about the camaro? and what yr? Ive done enough with A/D and D/A conversions to know that they take time and can cause discrepancies between devices. The thing to remember is that analog devices, like most tachs, are constantly moitoring a source. Whereas digital is just a sampling at constant timepoints, albeit rather small. In other words digital sources are more prone to error than analog sources. However if the tach in a vehicle is not gear driven analog style and is a secondary output from the PCM or ECU then it may very well be a few fractions of a second behind. I've seen this when looking at designs for building datalogging devices for FMUs as well as the resulting datalogs.

You said the tach climbs faster than the computer, which would lead me to believe, at least in the case of the alero, that it is a true engine speed, and the ECU is trailing, since if the tach was off it would trail not lead. Yet, both the ECU and the tach agree, at least on my car, as to when the fuel shut off adn rev limit is to occur and they agree on the hard code in the ECU and number on the dash. However w/o knowing how the alero or the camaro drives the tach and the ECU I'm not real sure which is more accurate, I can see the case for both. Its just kinda wrong to say that b/c you see disrepencies on one vehicle that does not mean its true on another, esp. w/o know all the specifics.

[Silverknight]

I've only ever seen an Alero with the 3400 rev up to aproxx 5900 MAX with manual shifting...after that the car just kicks around that RPM and doesn't move anyfaster...and prolly gets damaged doing it too...the 2.4L 5 Speed can rev up to 6500 MAX.

[jturkey69]

the sound you are hearing is the serpentine belt slipping...with the autotrans turned up a lil...i can get it to do it every time i go WOT...so that is most likely the sound your hearing

[nevr_enuf]

I've got the 2.4L and from a dead stop, throttle mashed to the floor mine shifts at 6700 rpm. I personally don't think that hurts the engine one bit.

[Silverknight]

^how the hell did u get it to do that? I got the manual tranny and my engine kicks back at me when it hits 6500 RPM....maybe u're tac is wrong....

[Aleromaster]

Originally posted by jturkey69@Mar 8 2004, 07:05 PM
the sound you are hearing is the serpentine belt slipping...with the autotrans turned up a lil...i can get it to do it every time i go WOT...so that is most likely the sound your hearing
Nah I know it was definatly the tires. My tires have a unique sound to them. I sepentine belt has slipped before and its a diffeant sound.