Just curious about this because the other day I did a full throttle pull on the way home and in drive (auto trans), the tach stops at 2500 RPM, and about 80 mph is top speed now.
This is with a lift pump from an auto parts store. The lp is about 1.5 years old.
With the previous lift pump, the truck would rev in drive to 2700-3000, and top speed was about 88-90.
So it made me curious about other people's trucks.
The automatic seems to defuel around 2.200 to 2,300 rpm. After that it may increase rpm's but lacks any extra power. It seems that the 5 speeds can defuel much later as GAmes shows.
I do not know how fast my truck will go. I know it sucks fuel driving at 70mph compared to 55 mph. I have no desire to burn a lot of fuel finding out the top speed.
I do not know how fast my truck will go. I know it sucks fuel driving at 70mph compared to 55 mph. I have no desire to burn a lot of fuel finding out the top speed.
Because of the low O/D ratio in the G56 my top speed is a little over 90. You can figure yours out by seeing what speed you are doing at 2000 rpm and do the math. I found out that duelly extensions break from centrifugal force at about 80mph the last time I was on a dyno. Scared the hell out of me, and most of the people who were there.
On occasion those who tighten the stock governor springs have broken their injection pump. Buying a genuine 4k GSK (even if you leave out one spring and use it as a 3k GSK) is the best way to do this.
First I've heard of people actually breaking something just by tightening the springs, but the issue I ran into with tightened springs is that I had to set the idle screw so low the truck wouldn't start normally. It cranked over and slowly wound up like a carbureted gas engine does if you don't pump the gas before cranking. I didn't like that.
No, the afc has nothing to do with governor speed. The springs hold tension on the governor fly weights and at different rpms the centrifugal force of the weights overcomes the spring tension and pulls the rack back to defuel the pump. Search how my truck works.
I doubt a truck will make full rpms with no rack travel past pre boost. I could be wrong on that though. I've made 120+ pulls but it gets way to scary going past that.
Not sure on rpms. I've had it on the 2nd 0 where the tach says x1000 . 110mph in 4th fastest I've taken it on the road. It gets real squirmy at them speeds.
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