[DaveN]

I know it's here but "redline" is a popular search word. I believe you removed the redline on the stage 3 chip?

Just confirming as I have gone <acronym title='wide open throttle'>WOT</acronym> a few times and lost traction; the needle goes past 7K real quick <img src="/forum/images/smilies/968/ohmy.png" class="smilie" alt="" />

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[flash]

nope - it's the same 6700. it should not go past 7k. that would not be good.

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[DaveN]

Well it does! <img src="/forum/images/smilies/968/ohmy.png" class="smilie" alt="" /> Maybe my tach is lying to me up there? Maybe there is some much needle momentum that it really isn't as high as it looks?

I have also noticed there is no rev limiter cut-out sound up there, engine sounds likes it's happy and getting fuel.

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[flash]

i'm going to go back and double check again, but it should cut out at 6700.



it is very possible your tach is off. check your tach reading at 80mph

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[Rap]

Flash I'm confused. I thought 6000 was the limit we should run the sc. Or I'm I confusing just a stage 3 chip?

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[AJG]

No Rap you're just confused, too many cars, not enough hours for track time, so much to do. It all adds up. Go back to knitting, you know where you are with that! Ha ha.

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[Rap]

Knitting? Hmmm. Haven't tried that one yet! Yes confusion reigns supreme. I suspect it's from engaging in activities and making decisions about that which I know nothing about, such as purchasing a truck and trailer. Blinder city man. Thank god for the Internet!

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[tamathumper]

6000 RPM with the SC is about where the air starts to shriek and you don't get any more performance gain out of it. I don't think it has anything to do with redline.

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[flash]

redline is 6700



useable power increase stops at about 6200 (where the squeal begins). this is the highest point you should go, and it is telling you to "shift dummy"



arrrgh - where were you when i was selling my fully loaded 18' enclosed trailer?

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[Rap]

I was right here of course!

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[flash]

lol - well, it was listed here for quite a while. you just hadn't yet come to the conclusion that track cars should be towed. everybody gets there eventually though.



back to the redline "issue". i'll check the maps today. in the meantime, i'd like to hear a reference check on dave's car (80mph in 6th gear is what rpm?). that will tell me if it is the tach, or something else.



to be clear though, running revs up over 6.5k on a boosted engine is BAD. the 968 valve train is not designed to do that. the valves float at about 6500 on boost. all you get at that point is blow by. this can cause all sorts of problems if you do that much. i left the redline at 6700 for the purpose of overrun on downshift, not so as to keep revving on throttle.



we have to keep in mind that a boosted engine is not at all like a naturally aspirated one when it comes to intake flow and exhaust flow.

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[DaveN]

Sorry about the rev check, can't do. Car is off the road as of last week and firmly on jack stands for 6 months <img src="/forum/images/smilies/968/sad.png" class="smilie" alt="" />

I will have to find a tach gun somewhere and compare it to my instrument cluster at various RPM. I don't think it's that far out as I do get the squeal up there but the engine just keeps on revving.

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[DaveN]

Finished the oil change and fired her up today. As Martin Luther would say of redlines - "Free at last, free at last". I have no redline.

I also don't get the squeal at 5K+ but I presume that is because it is not under load?

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[flash]

the squeal does not begin until over 6k. there should definitely be a redline.



i am going to look at the maps tomorrow. i was slammed and couldn't look yet.

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[DaveN]

No worries - plenty of winter left <img src="/forum/images/smilies/968/sad.png" class="smilie" alt="" /> I do miss that definitive squeal though. Pretty sure there's no belt slip. Tried to listen for the inrush of air but at 6K in the garage there is a LOT of engine noise.

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[flash]

ok - i went back over my notes. i am truly getting old.



i bumped the redline of stage 3 up to 7200. this was NOT so as to make more power, nor to indicate that you should run up that high. this was to provide some headroom for downshift for the track guys. under no circumstances should you stay on the throttle past 6700. the valve train is not designed for it. in fact, the valves float at about 6500 on boost in the best of scenarios. it happens even earlier on a valve train with mileage on it. really bad things can happen if you do that very much. you really should not take it up past 6200 or so. basically, the squeal will tell you to SHIFT!!!



the benefit of having the redline up that high, is so that fuel cutout is never engaged. fuel cutout at high rpm is a sure fire way to blow your motor. when the rev limiter is hit on a boosted engine, there is no fuel. no fuel on boost means LEAN. lean at high rpm, under any sort of load (read anything other than off throttle) means detonation. DO NOT DO THIS.



so, dave, you're not nuts. i'm just losing it.



it is possible that it will not squeal without a load on it. it's a velocity and volume thing. the pressures have to be right for it to happen. sitting in the garage you probably won't get the pressure needed. similarly, you won't see max boost sitting in the garage either.

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[Lear35A]

I would be the last guy to promote bouncing off the rev limiter. However, one thing in the explanation puzzles me. If the rev limiter in our cars is a fuel cut off, how can there be detonation? Sure certain lean mixtures could lead to detonation, but I don't see how zero fuel could detonate.

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[DaveN]

Thanks for checking. I don't ever intend to go there but with slippery wet roads and SC it's easy to get there. Maybe one day I'll get <acronym title='Limited Slip Differential'>LSD</acronym> and get a little more traction.

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[flash]

there is a delay between cutoff and running out of fuel, and a subsequent delay before the rail fills up again. during that time, the mixture goes wonky. during the entire process, things are under pressure. it's not like normally aspirated, where things just come to a stop. with the added pressure, you can easily have ignition with less fuel.

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