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Discussion Starter · #1 · (Edited)
Went of my first wheeling trip after regearing from 3.58's to 4.56's, running 32" AT tires, 5spd manual tranny with the 4 ponnies under the hood.

We drove 4+ hours each way, and I just couldn't keep up with the other guys in the highways at all. My engine was screaming like crazy:eek: , and it felt like asking for a 6th gear on the tranny. Unfortunately, i have the older-style dash board with no gauge for the RPM's. By ear, they were definetely super high. I knew that RPM's would be higher, but man, this was crazy. According to the charts, at 60mph I'm about 3200(fixed) RPM's. I'm wondering what the numbers are at 75mph, for example.

Now, on the trails, this tire/gear combo shined. Low-end torque was more than excellent.

My question is: would this combo kill my engine because of the higher RPM's?:confused:

Thanks
 

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At about 75 you're gonna be running a tad over 3200, not 32000 LOL. From what I've read, the 2.7 is more effecient between 2500-3500RPM's. On my 96 2.7 5spd, I had the same combo 3.58's up to 4.56's w/ the 32's, I had no problems on the HWY. It was a hell of a lot better than stock and 3.58's. I could stay in 5th and pull past ppl easy. Every now and then I might have to down shift if someone was being a real jerk when I went to pass them. Otherwise, it was an awesome combo.
 

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Discussion Starter · #3 ·
thanks for responding. i also fixed the numbers:D

that's interesting. maybe i got used to the lack of power when running with 3.58's, that now everything seems too much.

However, at one point i was driving side-to-side with one of the other trucks. Well, my spedo read 90mph and my buddy's GPS read 68mph. I guess I'm a little off there.

I hope you're right about those numbers. Seems a little high not to hurt the engine in the long run, but lets see.
 

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4.56's came stock on some 2.7 trucks equipped w/ the larger tires. I had an 00 2.7 5 speed 4wd 4Runner w/ the 265/70/16, as you say it was very high RPM's on the highway, 70 was close to 3k and it moved up quick from there, 80 was well over 3500. I put almost 100k trouble free miles on that truck before I wrecked it. A friend has the same set up except a 98 and he has over 180k and the motor still runs great. I wouldn't worry about revving it, these motors can handle it fine.
 

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Discussion Starter · #5 ·
well, if high revs won't hurt it, then i won't care much. Good to know other people's experiences.

thanks for responding.
 

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I made a day trip yesterday that was the equalivant of driving from San Antonio to Houston and back.

On the way down I was doing 70-75mph @ right around 3K rpms, the whole way.

On the way back with a 500lb + load, I was doing a little slower 65-70 mph and my Rpms were right at 2800.

Of coarse this was all with 5.29's and 37" tires. But the point is I have been running this combo for over a year and half with this trip as well as a trip from Indiana to Arkansas and back and have not one issue with the motor.

granted my motor is a 3.4 with supercharger but I do have over 180K miles on it. I think you will be okay
 

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Discussion Starter · #7 ·
Thanks Bear for your response. Hey, i got one of your quotes in my sig!

Our trip was from Houston to Gilmer, so it gave me a good grip of how the engine will respond during different highway conditions.

Another thing, believe it or not, i believe my mpg are better now with the high RPM's. I just can't understand how the engine deal better with gas at high rpm's.
 

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yup I have seen that quote a time or two.LOL!

I knew you went to Gilmer before you said anything, physic I guess. (or just physco)

It is not hard to believe you got better gas miliage with the new ratio. you are closer to being "balanced" than you were before. I can't remember what you had on before the change, but I am guessing larger tires/stock gears? If so, the 3.73's were always good on sucking down gas. I had a couple of friends back home that had the 3.73's and changed soon after moving up in tire size because no power and bad gas miliage.
 

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Discussion Starter · #9 ·
specifically, i had 3.58's spinning 28" factory tires. then, out of ignorance, put 32" tires with those gears. Needless to say, that was a bad idea. then, i put 4.56 gears. i wanted 4.30's but couldn't find them anywhere.

I guess i just have to get used to the way the engine works now. But as stated above, dude, on the trails this combo is perfect for my needs.
 

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You might want to consider adding a tach. Its really simple to do and there are some cheaper one's out there and they come in many sizes. Anyone of them is better than none at all. You probably don't need all the bling bling shift lights and what not so buy accordingly.

I got one for something like $25 as I recall. A little Sunpro, link below, that lives under the hood and its just as accurate as the factory tach that's on my dash.

http://www.sunpro.com/product_detail.php?pid=16330
 

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Discussion Starter · #11 ·
You might want to consider adding a tach. Its really simple to do and there are some cheaper one's out there and they come in many sizes. Anyone of them is better than none at all. You probably don't need all the bling bling shift lights and what not so buy accordingly.

I got one for something like $25 as I recall. A little Sunpro, link below, that lives under the hood and its just as accurate as the factory tach that's on my dash.

http://www.sunpro.com/product_detail.php?pid=16330
Hey Dick:

good idea.

Out of curiosity, wouldn't the tach be off the same way the spedo is off:confused:
 

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No. A tach only reads engine RPMs so if properly installed with always be correct.
 

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Discussion Starter · #13 ·
thanks for the clarification. i was just looking at the link you sent. that one looks good, pretty simple which is what i want.

So it is not a myth that toyota engines work better at high rpms. is that your experience as well?
 

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You were running the same tires before & after the gear swap -
So 3.58 >> 4.56 is a DRAMATIC change -
That's about a 27% lower gear.

If you don't have a tach and it is concerning you, look into one of these
http://www.scangauge.com/
It will also double as a OBD scan tool.
Although your speedo will stull be off- You should be able to replace the speedo gear to get you back on track.

If not other's have recommended the Dakota digital unit.
 

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Discussion Starter · #15 ·
it is a concern in the sense that at least i would like to know how the engine does at higher speeds.

You see, around town in Houston, everything seemed normal after the gear swap. It wasn't 'til the trip to Gilmer that I experienced the "dramatic" change as you said.

Then, when I finally went through the trails, that's when I clearly noticed how all that translated into low-end torque.

thanks for sending the link.
 

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I don't know about the myth or working better parts. Regardless of brand, a smaller engine will have to be run at higher RPMs to make the same amount of power that a larger engine can make.
This is how a small thing like a router can have something like a 3 horse power rating when compared to a standard 3 HP electric induction motor size wise. They do it with high RPMs. Standard induction motors like a pool pump run at typically 1800 or 3600 RPM while routers run at 20,000 RPM.
Remember house power is a measure of work done over time so the higher the RPM or redline, the higher the horse power rating will be.

However, if built to the same standards of tolerance and with the same materials the higher reving smaller engine will wear out faster in service than a lower RPM larger engine will if doing the same work. That stands to reason and is common sense since the smaller engine is asked to do the same amount quantity of work at the same overall rate as the larger engine. It just has to worker harder and faster and there is no free lunch. If I have to turn a shaft on a bearing twice as many times over a given period, its going to wear out twice as fast. And that's without taking into consideration things like increased vibration, heat etc. Otherwise we'd all be running around with 2 cycle weed whacker and chain saw engines under the hood, enviro whakcos not withstanding.
 

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Discussion Starter · #17 ·
nobody could have said that better than you dick!
 
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