Fuel economy: 1999 Tahoe

[Tempted]

Well, I've always wanted to see a 4BT in an OBS Tahoe. Couple it to a 6 speed Allison auto and I'll be impressed.

 

[DRAGGIN95]

Well, I've always wanted to see a 4BT in an OBS Tahoe. Couple it to a 6 speed Allison auto and I'll be impressed.

That combo would bring some amazing MPG's!

 

[Chris]

Except the Allison would never work.

Although the Cummins swap works well. > http://www.fullsizechevy.com/forum/...ax-forum/363370-93-k1500-blazer-4bt-swap.html

 

[Edahall]

The tank won't fit.
A 700R4 either has a mechanical or electronic speed sensor. If it's mechanical, you're SOL. If it's electronic you'd need to find some way to make the signal work with your gauge cluster. It probably won't in the end because of the pulse rate.

Listen to what you're saying. You're going to wind up with an unreliable jalopy that I wouldn't trust to drive 5 miles for a gallon of milk. Either do it right or don't even attempt it. With a fresh 5.7L in that Tahoe and a tune, 20mpg on the highway is perfectly reasonable. If my 5.7L rcsb can pull 23+, it can be done with a heavier SUV. It all boils down to the fact you aren't going to get even CLOSE to your mileage number in the end.

Other option: scrap both vehicles and buy a fuel efficient car. They'll still pull an apartment worth of stuff if you're concerned about moving. People in Europe do it all the time.

That's excellent fuel economy you're getting. That's a lot better than the horrible 16 mpg highway that is claimed by the EPA. Honestly, I would be interested in staying with the gas engine if it'll pull 20 mpg or better driving at a constant 60 mph on the freeway. My main concern about putting this engine back in is being stuck with 16 mpg when I could have put the 6.2 diesel engine from my 1982 Suburban in and be getting considerably better fuel economy. The only reason I've given up on the Suburban is because the body is rotting away. Other than that, it has been an excellent vehicle.

What inexpensive mods should I look into to bring the fuel economy up on a Vortec engine? You mentioned tune? How much does that cost? Is there a cam that increases fuel economy. I would gladly trade upper rpm power for better fuel economy.

 

[Edahall]

Well, I've always wanted to see a 4BT in an OBS Tahoe. Couple it to a 6 speed Allison auto and I'll be impressed.

Not exactly a 4BT and Allison auto but something similar. Here's the engine compartment on my 1996 Tahoe, 2 door, 4x4. The engine is a VE pump 6BT which puts more power than the 4BT and is much quieter and balanced. It's coupled to a NV4500 5 speed manual transmission.

You must be registered for see images attach

 

[Tempted]

Ever get the synchros in 3rd replaced? Who did the swap? Still have 9" of lift?

 

[Blue95]

DO you asked for people's opinion's but have already made up your mind? Why did you bother to ask.

 

[Edahall]

DO you asked for people's opinion's but have already made up your mind? Why did you bother to ask.

If you're wondering, I'm leaning back towards putting the gas engine back in since I've learned 20-23 mpg is not out of question on these engines. The 16 mpg EPA rating really scared me. As I said earlier, the plan for this vehicle is to put a lot of miles on it so fuel economy is extremely important.

 

[Edahall]

Ever get the synchros in 3rd replaced? Who did the swap? Still have 9" of lift?

I've learned to double shift it into 3rd gear. It's a little bit annoying but it does the trick.

I bought the truck this way.

Yes, it still has the insane lift. I'm amazed that it still pulls mid 20's as far as gas mileage is concerned.

 

[Tempted]

If you're wondering, I'm leaning back towards putting the gas engine back in since I've learned 20-23 mpg is not out of question on these engines. The 16 mpg EPA rating really scared me. As I said earlier, the plan for this vehicle is to put a lot of miles on it so fuel economy is extremely important.

It's out of the question on any gen 1 small block truck motor I've ever owned.

I've learned to double shift it into 3rd gear. It's a little bit annoying but it does the trick.

I bought the truck this way.

Yes, it still has the insane lift. I'm amazed that it still pulls mid 20's as far as gas mileage is concerned.

An inline diesel is nearly unbelievably frugal, even in big trucks. There is no wasted throw in the rods/crank that all V style engines have and the power output of diesel fuel means much less can be used to make more power than gasoline. No ignition means less chance of electrical failure and no distributor to foul. I've been ******* after 4HK1 powered OBS for years. If I had the pocket book to build it I promise you I would.