How high can you safely rev an '04 4.8L?
05-05-2005, 10:55 AM
#11
I have a built tranny coming. Hopefully I will be able to shift as you say, I just e-mailed my builder and asked. What I was really wanting was for mine to be able to shift into overdrive at WOT. How can I make that happen? Right now, with the stock tranny, I have to get off the gas to get into overdrive, or maybe I just haven't left my foot in it long enough to see.....
05-05-2005, 01:26 PM
#13
Originally Posted by hirdlej
Are these motors really that tough? I was thinking with the goofy oil pumping system we have with that long *** pickup tube and the concentric oil pump on the crank that these are weaker than the old style chevy smallblocks (i'm used to that old technology) Or am I wrong? Not trying to dog on these motors, I own one myself 
I'm just wondering how tough these things are compared to the smallblocks of yesteryear that I am so familiar with.....
Thanks already for the great input.
Joe
I'm just wondering how tough these things are compared to the smallblocks of yesteryear that I am so familiar with.....Thanks already for the great input.
Joe
05-05-2005, 02:23 PM
#16
01Thunder on the dyno spun his up to 7200rpm thats with a stock bottom end and the valvetrain replaced with quality parts though. All the speed shop have said 6100 and under for stock internals and the bottom end is good till about 6800.
05-05-2005, 02:42 PM
#17
TECH Veteran
Originally Posted by Tiburon
Tell that to Randy.....
LOL, i don't think he's concerned about safely. if his lets go he'll just go bigger most likely. i wouldn't be nervous turning one 7200 or so if it were my own, but to say that some else's can go that high is a touchy area. the guys with the 5.7's and T-REX cam's are turning their bigger cube motors higher without much problem. after 6700 i'd personally say it's a let'r fling issue and don't cry if it breaks.
05-05-2005, 03:19 PM
#18
The 4.8's have a lot shorter stroke and longer rod then the 5.3-6.0. I believe its a 3.26 stroke, which makes for a high rev potential motor. Plus it has the 6 bolt mains like the rest of the gen3 motor's. Like the other members here have said I think you have more of a limiting factor in the valve train then the bottom end.
05-05-2005, 04:00 PM
#19
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The 4.8 has a ridiculously short stroke (for being a V8). Stock the valve springs are the limiting factor. Upgrade those and you can REV the lill' 4.8 high. Being that its still a push rod motor you can put a 'Rev Kit' on it (a rev kit is a second set of valve spring on the lifter valley) though I dont know of anyone making one for the gen3's yet. I dont see why a mildly upgraded on cant rev to the 8-9K range (No joke).
Stock I would keep it in the mid 6K range with out better springs.
Stock I would keep it in the mid 6K range with out better springs.
