figuring out RPM's

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, Nov 8, 2001.

1. 90K51/2 ton status

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figuring out RPM\'s

what equation do I do to figure out what RPM's I'm running at at a certain speed? Truck seems to rev kinda high when going about 80 on the speedometer...which is closer to 75 I think. I have 33's and 4.11's, which was supposed to bring it close to stock, but it seems to be trying really hard at higher speeds...yeah I know a K5 is about as aerodynamic as a barn though....

90K5

2. HarryH31 ton statusAuthor

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Re: figuring out RPM\'s

Check out the calculators at <a target="_blank" href=http://www.4lo.com>www.4lo.com</a> I think there's one there that will do the math for you.

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3. gokartergo3/4 ton statusStaff MemberModerator

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Re: figuring out RPM\'s

Also KLICK

4. DMK1/2 ton status

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Re: figuring out RPM\'s

I guess with 4:11's it will kinda rev high. This is what low gears will do. At 80 I would guess you are turning in drive close to 2800 rpm. Get A tach. Remember lower gears are not highway freindly. Use od may still be close to 2500 though.

5. tRustyK5Big meanieStaff MemberSuper ModeratorGMOTM WinnerAuthor

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Re: figuring out RPM\'s

Well at 75 mph true road speed with 4.11's and no OD you be turning well over 3000 rpm with 33's. If you have OD it would be more like 2250 rpm.

Rene

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