question for coffee

bwenny247 · Post by **bwenny247** » Fri Jul 22, 2005 8:03 am

regarding gear ratios and tires:

is your blaze a daily driver and are you still running 4.10's and 33's (you're the only other one on here with 33's)
if so, about how many RPM's are you turning at 60 MPH?

I'm just wondering what the difference is from 3.42 to 4.10. at 60 MPH I'm turning 1500 RPMs with the hypertech set to 33" tires. I'm curious to see what the jump is and how much more 4.10's bring you into the mid-range of power.

thanks
Ben

coffeedrnkr · Post by **coffeedrnkr** » Sat Jul 23, 2005 10:15 pm

Hey, sorry it took me a while to get back to you I was in AZ on vacation.

Yes, the blazer is still my daily driver.

the 4.10's will DEFINATELY help your truck be up in the rpm's on the freeway and such. I can't really tell you for sure but I think at 70-75 it turns 2.5k rpm's.

I will try to get you some numbers tomorrow and get back to you.

Post by **HenryJ** » Sun Jul 24, 2005 6:58 am

bwenny247 wrote:regarding gear ratios and tires:

is your blaze a daily driver and are you still running 4.10's and 33's (you're the only other one on here with 33's)
if so, about how many RPM's are you turning at 60 MPH?

I'm just wondering what the difference is from 3.42 to 4.10. at 60 MPH I'm turning 1500 RPMs with the hypertech set to 33" tires. I'm curious to see what the jump is and how much more 4.10's bring you into the mid-range of power.

Sorry to stick my nose in here when the question was clearly addressed to another, but we do have calculators on the website for this.

Use .70 for the transmission in OD, 1 for the transfercase in 2HI, input your gear ratio, tire size, MPH and it will show that with 3.42 gears at 60 mph you will be running 1462.5163636363634 rpm. Change to 4.10 gears and you will be running 1753.3090909090906rpm at 60 mph.

At 70-75 mph running 4.10's you should be turning 2045-2191 rpm.

The Detailed specifications on the stock information page has all the transmission ratios, so that you can calculate the rpm for any chosen gear. For instance if you wondered what dropping to 3rd gear would do when pulling a hill on the highway. At 60 mph with the 4.10 gears in 3rd you will be twisting 2500 rpm.

Enjoy! Those calculators are lots of fun!

bwenny247 · Post by **bwenny247** » Sun Jul 24, 2005 12:26 pm

no apology neccessary HJ, man this is your show!

i was just curious, because with 33's, 3.42s at 75 MPH i'm running just under 2000 RPM's....and the calculators say (based on your example) running 33's, 4.10s at 75 will only generate 2050-2200 RPMs
coffee says his blaze runs around 2500 RPM's at this speed.
if the jump from 3.42 to 4.10 only gets me another 200 RPMs i don't think it's worth it.

RocK · Post by **RocK** » Sun Jul 24, 2005 4:00 pm

hey hj did you write that calc prog. You could use [math.round] to get rid of the extra decimal places...

I know how you like stuff lookin perfect.

Its what I did with my speed calc for RC cars on my website.

My Site Speed Calc

Post by **HenryJ** » Sun Jul 24, 2005 4:03 pm

bwenny247 wrote:no apology neccessary HJ, man this is your show!

Rrrrright. NOT, I am merely the man behind the curtain. Pay no attention to me

RocK wrote:hey hj did you write that calc prog...

Nope

calculators created by Mark Medina - www.4Lo.com

I'm not much of a "computer guru"...I just play one here

RocK · Post by **RocK** » Sun Jul 24, 2005 7:21 pm

Ahhh I see LOL.

coffeedrnkr · Post by **coffeedrnkr** » Mon Jul 25, 2005 6:42 pm

I finally got my truck fixed and running, and now I have a tranny cooler and a freshly cleaned k&n too so I will go get you some numbers here soon.

coffeedrnkr · Post by **coffeedrnkr** » Fri Jul 29, 2005 12:44 pm

Ok, I finally got you numbers

dang HJ that gear calc is pretty accurate.
at 70-75 I run about 2200 rpm
at 80 I run about 2500
at 40-50 I run about 1300

bwenny247 · Post by **bwenny247** » Fri Jul 29, 2005 1:16 pm

how does your blaze hold overdrive while going 75ish (freeway speeds)?

for the most part my 3.42's do fine to hang on to overdrive at 1900-2000 RPMs. the only time it downshifts is when it is very windy out, or you're climbing large hills. when it does, even in 3rd gear at 75 MPH, i am turning 2900 RPMs and that's plenty of power to accelerate going up hill once i peak the hill it's back into overdrive.

coffeedrnkr · Post by **coffeedrnkr** » Fri Jul 29, 2005 2:42 pm

Mine is about the same as yours on the highway, I only run about 200 more rpm than you do at 70-75ish

I think if you were looking for a reason to regear the reason would be for acceleration around town and going from a stop.

Another reason I say that is b/c I do a lot of offroading and when I am trying to climb rock and ledges and stuff sometimes it just doesn't have the guts to get up, I know the last time I was climbing the ledges I got in a spot where I even floored it and the engine just revved up and it didn't go anywhere.

Just my opinion but I have 4.10's and I still don't think it is low enough sometimes, if I ever get bigger tires like I want to I plan on going to 4.88's

bwenny247 · Post by **bwenny247** » Fri Jul 29, 2005 5:57 pm

thanks coffee

i appretiate you helping me out with the info, and i respect your opinion.
i don't think i'll be doing any rock climbing like you

and the truck throws the mud around pretty good as is. so, doesn't sound like regearing is too appealing right now.

happy wheelin'

Ben

coffeedrnkr · Post by **coffeedrnkr** » Sat Jul 30, 2005 12:19 am

hey, if you don't use it for that purpose then you don't need it.

with some of the performance mods you have done esp. the hypertech I would think that your truck would be alright on the road, the only thing I would watch would maybe be tranny temps b/c it has to work a little harder since you might have to push it harder to go. maybe get a tranny cooler, but that is just an idea. I am not even sure how much different it would drive on the higher gears b/c we did everything at the same time when we put on the bigger tires.

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