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Vortec 350 - 454 fuel economy

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  #11  
Old 11-14-2011, 10:13 AM
SuburbanStevie's Avatar
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I've got a '90 Suburban, 454, 3.73 gears and tow a 26 ft travel trailer (probably about 7,500 lbs). Even installed a GearVendor overdrive.

Pretty much use it only for towing now days, and get about 9 miles/gallon. Solo get about 13 mpg. Everything except the transmission overdrive and Aluminum radiator is stock.
 
  #12  
Old 11-15-2011, 04:01 PM
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Originally Posted by SuburbanStevie
I've got a '90 Suburban, 454, 3.73 gears and tow a 26 ft travel trailer (probably about 7,500 lbs). Even installed a GearVendor overdrive.

Pretty much use it only for towing now days, and get about 9 miles/gallon. Solo get about 13 mpg. Everything except the transmission overdrive and Aluminum radiator is stock.
Hey Stevie, how is the GV overdrive working out? I have been looking at those. What is your RPM at 60 mph with the overdrive on. Is the overdrive automatic or do you switch it on. Thanks
 
  #13  
Old 11-16-2011, 10:16 AM
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Gregory,

Honestly, for me it’s been great. But there are several factors that you must consider before you buy: Cost, age of vehicle, cost, your type of driving, how many speeds the vehicle already has, cost, and what type of vehicle you have. Oh, and cost.
I don’t know what the highway speed RPM is. But it definitely lowers it, and makes the vehicle a little quieter.
Let me explain a few other things. This is not your everyday add-on, it is expensive. I would only suggest it for a vehicle that doesn’t have an existing over-drive. My Suburban only had the 3-speed automatic. I’ll repeat that, if you have an overdrive, don’t buy this product. Give your money to a worthy charity instead. Because having it installed can also create other problems (additional maintenance to worry about, and a possible drive-train issue I’ll discuss later).
Does it get me up a hill faster? Maybe 1 out of 10 hills I may find a “split” gear to be better than the stock gears. Faster? No. But I do like the overdrive feature, as it lowers rpm and noise. And I am a mechanical engineer, and enjoy being able to control an automatic transmission a little more. Does it go into overdrive automatically? Yes. You can also do it manually with a foot switch…very cool. But is it worth $2700 for having a cool switch on the floor? Only if you have a 3 speed transmission.
Cons.. and these are important. My Suburban came with a two-piece drive shaft, and when the GV was installed they replaced it with a one piece drive shaft that is pretty long. I now get a nasty vibration at speeds above 70mph, which is because the shaft is hitting a natural frequency (“critical speed”). It bugs me, but not much I can do about it, nor do I want to bother. As I only use the truck to tow a trailer, so rarely am I over 65mph anyway. I still have the original shafts, but the center bearing would need to be moved aft about a foot to balance everything out. Not worth it to me. Also, one more thing to maintain, although relatively easy. Downshifting takes a bit of practice as you need to press on the accelerator to rev-up the engine a bit (if you don’t you will feel a heck of a jolt). Final “con”… I think the cost is too much.
Pros.. It is cool, and a little fun. And it does work flawlessly. I’ve had mine for about 10 years, maybe 70,000 miles, and it still works great.
Any other questions?
Steve
 
  #14  
Old 11-16-2011, 12:02 PM
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Ya know Stevie, your post makes me really glad that I have a stock overdrive tranny
 
  #15  
Old 11-16-2011, 07:19 PM
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Gents... my dream truck is a Duramax with the 6 speed tranny. ...Someday.
 
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