I have a question. How long should a 6500 mah battery last running a 4700kv motor in s 4wd sc truck last before shutting the esc off due to voltage cutoff??
Is 7-8 min about right??

It will thermal off or melt down, before it hits LVC with that battery lol. I would expect 35-45 minutes on it.

I would also expect it to thermal before it hits lvc unless...
The lvc is set too high.
and/or
In spite of an impressive mah count on the battery, the battery itself can't put out anywhere near that so it starts to tease the lvc into triggering under load prematurely. That could be because the battery is old, was purchased from a website in English only so far as Google translate could get it that way from Chinese, etc., etc.

I know this doesn't help, but it depends. First I don't know what motor you have. Some motors like the Tenshock are absolute power hogs. It also largely depends on how your driving. If you stopping and accelerating a lot, that's going to use power more than simple cruising around on a flat track.

Just some rough math. First I don't know what 4700kv motor you have, but it probably has a max power rating of anywhere from 300w to 800w.

Let's just take something in the middle, 500w. Roughly, w = a * v (I'm ignoring power factor or efficiency here). Over the course of a discharge your battery would have an average of 7.6v, so w/v = a or 500w/7.6v = 65a

Your battery is 6.5a hours, so 6.5a/65a = .1 hours or 6 minutes.

Now that's assuming things like your motor using it's max power the whole 6 minutes which would be impossible.

But I also don't think you would get 30-40 minutes out of it. Especially since 4wd SC trucks are typically heavy and have lots of drivetrain resistance.

Plus depending on the C rating of the battery, you might be hitting LVC because of high voltage sag under a high load from motor in your truck.

WTF?? You two clearly have no idea of running a Pro4 SCT. I run a 4700 Hobbywing and get about 15 min out of a 6000 80c pack. Temps after I hit a LVC of 3.4 is about 130* running an 17t pinion.
7 to 8 is a bit short. You could try lowering your Punch or Current limit setting depending on your ESC. Also being smoother with the throttle will help a lot, not so much point and shoot.

Ran it for years with a pretty high win percentage before the class died by me so I can say, conversely, if you're hitting LVC with everything that cool, you're leaving something on the table. If you're getting 100% out of a maxed out 4wdSC that isn't spending a large part of it's run stationary on it's roof, you're not going to go to LVC comfortably on motor/esc temps in that class.

Best thing you can do is pick up a voltage tester
http://www3.towerhobbies.com/cgi-bin...&I=LXCVEU&P=ML
That will tell you exactly what the state of charge you have before and after running vehicle .