Engine RPMS @ 80MPH

[tahoeman21]

Wassup guys? I just want to know how are your RPMs like on your tahoe/yukon/escalades engines when you are traveling speeds of 80MPH.... Mine runs at 2500 RPM at 80MPH, isn't it too high? mine is a 4dr, 2wd, with a 3.73.... your feedback is appreciated..:cool2:

 

[sasquatch094]

mines a 95 tahoe 4 dr 2 wd, at 80 runs about 1500 to 1700. but my motor was rebuilt not to long ago.

 

[General Stalin]

...You have a 5.7L 350 TBI motor that cruises 80 at only 1500 RPMs? Are you serious? Did you rebuild it with different/performance parts, or is it a totally stock rebuild... or do you just have a different rear end gear?

I have a 1995 Tahoe 4-door and it runs about 2500 at 80 mph. What year Tahoe do you have, tahoeman? If you have a 5.7L Vortec, then I would imagine that the engine should be running a little lower than 2500 @ 80 mph. Like I said, I have a TBI 5.7 which is much more low end power than the Vortec, so it revs pretty high when getting up to high speeds like that. The Vortec engines are a bit more tailored for performance, and have much more top end power making for higher speeds with lower rpms, relative to the rear gear.

then again, I'm not sure if we have the same rear end gears or if you have a stock rear end etc. All that stuff plays a part.

 

[sasquatch094]

yes sir, 350 tbi 5.7 motor.. lol.. not the vortec. i have no idea about the gears. as far as im considered it still have the stock gears and such in it.. As for the rebuild, i couldnt tell ya what the hell went in it, i bought it from the guy all done.... yea my truck runs about 15 to 17 thous on the freeway at 80mph... its got the 4 speed auto trans, stock stuff.. so i guess theres really no way of me telling you why it runs like that.. my truck runs at idle like 500 to 700 rpms.. kinda high compared to my other 350tbi, that one runs 200 to 400 rpms.. kinda crazy stuff.

 

[96ProCompTahoe]

i run under 2K RPM at 80, mainly because it hasn't been regeared from the lift.

 

[tahoeman21]

rpms @80mph

mine is a 1999 with a vortec, even before i got the engine rebuilt, it still ran @ 2500 rpm at 80..... i have a 3.73rear end along with a 4 speed tranny... i think it has the stock 3.73... i checked my sticker inside the glove box and it has the GT4 code which stands for 3.73.

 

[sasquatch094]

hey and i lied.. lol. it runs about 2 or a little under.. i was thinking u said 70 for some reason, so then i decided to take it out today and for sure check.. lol.. but yea

 

[General Stalin]

That is a little better. Btw, since you mentioned it, something is wrong with your other 350, because 200 is WAYY too low of an idle. You want it to idle where you rebuilt one idles; right around 600 - 700 or so when in drive.

 

[sasquatch094]

im sure nothings wrong with the other 350, its only got 75,xxx miles on it and runs like u wouldnt believe.. its smooth and everything..

 

[Colabella7077]

2100-2200RPM's at 80. anyway to lower it?

 

[96ProCompTahoe]

regear it, or throw on some taller tires.

after my 4.88's and 35's im pushing 2300RPM at 70. (although i still need to have the computer adjusted so the shift points and speedo are back on track. (i'm pulling 65 the speedo says 79mph)

 

[GMCYukalade]

Im pushing around 2200 rpm at 80 - 3:42 4x4

 

[Colabella7077]

Im putting on a set of KMC Wheels but I'm stuck on whether I should go with 18 or 20 inch rims.

 

[Rollin Thunder]

im sure nothings wrong with the other 350, its only got 75,xxx miles on it and runs like u wouldnt believe.. its smooth and everything..

my 07 with 7000 miles idles in drive or about 400-500 rpm (but they dont loose that 0 for long:gy::smilielol

 

[95TwinTT]

Obviously, it is all about tire size and axle ratio’s and transmission ratios.

Here is a “do it yourself†kit for figuring out the rev’s

Tire diameter times “pi†(3.146)

Translate into feet

One mile equals 5280 feet

MPH = RPM’s times 60

4L60e transmission ratio’s 3.06 / 1.62 / 1.0 / .70 to one 1st, 2nd, 3rd and 4th

4L80e transmission ratio’s 2.48 / 1.48 / 1.0 / .75 to one



Stock tires are 30†in diameter

Circumference = 7.85 feet

That equals 672.71 wheel revs per mile.

Times 3.73 = drive shaft revs per mile. 2,509

Minus 30% if in overdrive = 1756 @ 60 mph

Times 25% for increased speed running at 80 mph = 2,195 rpm’s

 

[omar]

mine runs at 2500 RPM @80 mph, but I have the 4:30 gears & 26's... that sounds way off for stock

 

[Blue96Tahoe]

im at about 1700 at like 70 havent had it long enough to get to 80