I thought 5600 RPMs was the redline? Much over that and the engine will blow won't it? Will the computer even let me go higher than that if I wanted to?

 

I'm not sure what the maximum PCM allowable rpm is for the 4.3L... I'd have to do some searching to find that out. At worst, it would cut out the spark to limit the rpm and you'd feel it right before it would shift.

The max pcm allowable rpm is not the rpm at which the engine will blow. These bottom ends can handle probably upwards of 6000rpm given the proper valvetrain components, but I wouldn't do it on a daily basis or sustained. One problem that would also arise is that since you are falling back to a lower rpm (but still higher hp than the stock shift point), you may run into trouble with the internal components inside the transmission (much like Hanr3 is going through now although his blazer is stock).

I would increase the line pressure in the transmission before messing around with shift points, but I don't know if your hypertech can do this. This will make the shifts quicker and less traumatic on the transmission, but more harsh to you. The clutches will slip less during a shift, reducing the wear on them as well as the amount of heat generated.

 

http://www.hypertech.com/shiftpoints.html

"With the Power Programmer III, you can electronically increase automatic transmission line pressure for firmer shifts while reducing clutch slippage and transmission oil temperatures. That means longer transmission life!

You can also adjust automatic transmission shift points for maximum performance for quicker acceleration and better 1/4 mile times, as well as adjust the part-throttle shifting to work properly with non-stock tire sizes and/or non-stock rearend gear ratios."

 

So do you think it would be ok then to have the car redline at WOT as long as the shift firmness was upped???

 

Will it work, yeah. Can I guarantee that nothing will break, no. You have to realize that modding and breaking go hand in hand. Now, nothing that you are going to be doing should stress the transmission or engine too much, and it's not like you are going to be pushing WOT all the time. You have to show restraint in using WOT, this is true for stock applications, but even more so modified. You should always try to roll into and out of the throttle, never stab it or let off suddenly. By doing so, you will not lose any time, but you will save the life of your vehicle tremendously.