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Real world, what would a 1/2 ton suburban 2wd, with a lockup OD transmission, 3.42 or so rear, highway tread tires, get city, highway? Would I gain by regearing numerically lower?

I bought a bread truck tonight, with a non intercooled 4bt, VE pump, allegedly 77k miles (it does look fresh). It has a GM adaptor and a 4spd behind it. I could go 700r4, or dodge auto, with a low stall converter.

Basically, I intend to build a suburban for my wife, who drives like 30k a year, mostly open roads. Towing, 4wheeling not important, I have other trucks for that.

This isnt really tow rig tech, but with the CTD mileage police always watching here, figured it would be a good place for it.
 

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Paging DRM :flipoff2:


Don't worry , he will be here shortly to call anyone with decent mileage claims a liar. Remember just because the other guys can't get decent mileage from from their diesels means you can't either. :shaking:

Especially from a 240 ish cubic inch motor...

You been warned :) (not sure on a burb, but saw a few in some half ton pickups that were impresive mileage wise)
 

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Real world, what would a 1/2 ton suburban 2wd, with a lockup OD transmission, 3.42 or so rear, highway tread tires, get city, highway? Would I gain by regearing numerically lower?

They have a sweet spot for mileage and power. Some of the Ranger guys get away with way low gearing to run it around 1600 RPM, but a Suburban needs a lot more power to shove it down the road, I would not gear it much lower than 1800 rpm at 70, whatever that math runs out to. Some of the 4BT Wagoneer guys have tried to go lower, like the 2.72s and 3.07, but the OD ends up being essentially useless. A lot of them have switched back to 3.42s or 3.73s. I would think 3.43s and 245/75/16s would be fine with a 48RE, and put you right around 1800 at 70.

I bought a bread truck tonight, with a non intercooled 4bt, VE pump, allegedly 77k miles (it does look fresh). It has a GM adaptor and a 4spd behind it. I could go 700r4, or dodge auto, with a low stall converter.

We tried and tried to get the 700r4 to work well with the 4BT and ended up with a 47RH. We had a "built" 700r4 from a reputable builder, a proper torque converter, a diesel governor with extra weight added to it to get it shift remotely correctly, and still got real frustrated with it. The low first is great for gassers, but with the 4BT it rips through it so quick it is almost useless, then it falls on its face until it builds boost in second. This makes it very slow to accelerate, and jerky. Overdrive comes in fine, and it is a good cruiser, but it is frustrating driving it around town. This was in a FJ80, so almost similar to a Suburban. We ripped the whole thing out and went with a 47RH from a parts truck and everything worked out much better. The longer first gear let it pull against the turbo sooner and made the whole acceleration process quicker and easier. Second is closer so it no longer falls on its face when it shifts. We did the potentiometer mod to the TPS, so the OD always locks in at 50 MPH. Over all it is much better to drive. If we did not have a 47RH, the other thing we were looking into was a 4L80E, which should have similar performance and strength, but would have required much more computer tweaking.

Basically, I intend to build a suburban for my wife, who drives like 30k a year, mostly open roads. Towing, 4wheeling not important, I have other trucks for that.

This isnt really tow rig tech, but with the CTD mileage police always watching here, figured it would be a good place for it.
The guys on 4BT that are getting the best mileage have low 2wd trucks and lighter duty manual transmissions like the M5OD. Makes sense, less air resistance and less mechanical losses.

Guys with "bigger" trucks seem to be getting 19-21 in 4wds with heavy feet, up to 25-26 with 2wds and not driving it like a 16 y/o.

I have been though a couple 4BT builds now, and I can suggest a couple things:

1. The little suckers vibrate like a son of a bitch. They make a 6BT look like a smooth running beast. If your box truck came with the Lord style fluid filled motor mounts, I would suggest using them. if they did not, I would use some 80s Ford 300 inline 6 motor mounts, they are fluid filled as well, and cheap.

2. Even if the engine is a "reman" or "low mileage", I would pull the pump and injectors and get the pump flowed and the seals replaced, and I would get the injectors popped and consider some tips for them. We had a friend that worked for Frito Lay back in the day when they ran a lot of 4BTs and, basically, you never know what you are going to get. Even if it is reman'd, you might have an older pump and injectors, and some of the drivers talked the mechanics into "turning up" the pump- basically you never know what you have. Plus, getting a pump flowed and getting a seal job now is much easier and cheaper than having it blow out something when driving and needing to get an entire rebuild done. Many builds on 4BT have put in a "good used motor" only to have the pump redone in a year or 2.

3. Injectors, pump tweaks, a HX35, and a 3k governor spring really wake this motor up, and help move the powerband from an "industrial" motor to a "automotive" motor, and they are cheap to do.

4. "Stock" GM auto adapters put the engine at an angle. It is fine to run it this way, but not everyone likes it. Plus the "wave ring" puts a lot of stress on the flywheel and a lot of them end up breaking the flywheel. Destroked has a nice non-tilted adapter and a much stronger flywheel.

My friend's wife really likes her 4BT FJ80, and it gets low 20s, they are very happy with it. Good luck.

If your wife would agree to driving manual, a 2wd NV4500 would be a pretty slick option for the Sub...
 

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several relevant threads on 4btswaps.com
Why not a 6.2? Mine has done 28 MPG highway.
Most people swap the 6.2 OUT to put in a 4BT:flipoff2:

My 4BT runs circles around any 6.2 I have driven. Just a completely different motor built with different things in mind.

Some good threads on 4BT swaps:

http://www.4btswaps.com/forum/showt...kage.-Out-with-the-tired-350-in-with-the-4bta.

Older suburban, pretty detailed.

http://www.4btswaps.com/forum/showthread.php?15772-2003-Ford-Expedition&highlight=expedition+4bt

Newer Expedition, but kept most of the electronics and the AC, has some good thoughts about work arounds for the newer electronics.

http://www.4btswaps.com/forum/showthread.php?14170-Help-with-2003-Tahoe-swap!&highlight=suburban

A little jumbled, but a 2003 Tahoe with a 4BD1T. Problems with the 700R4, switched back to the 4l60E. Mileages he posted looked like 19-22.
 

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several relevant threads on 4btswaps.com
Why not a 6.2? Mine has done 28 MPG highway.
Because no one wants those pieces of shit, and no you haven't.

You keep posting this 6.2 shit in every damn thread concerning diesels. I will clue you in to a little bit of info; The ONLY question that has the 6.2 as the answer is " What OEM diesel do I absolutely not want?"
 

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Because no one wants those pieces of shit, and no you haven't.

You keep posting this 6.2 shit in every damn thread concerning diesels. I will clue you in to a little bit of info; The ONLY question that has the 6.2 as the answer is " What OEM diesel do I absolutely not want?"
Or what's a good boat anchor...a 6.2 might get 28 mpg if you threw it out of an airplane.

I have talked to a few guys running 4bt's in 2wd pickups as it was a swap I was (and still am) considering. With a light 5 speed and normalish gears, 25-28 seems to be the norm. I would think that in a burb you would be looking around 23-24.
 

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Because no one wants those pieces of shit, and no you haven't.

You keep posting this 6.2 shit in every damn thread concerning diesels. I will clue you in to a little bit of info; The ONLY question that has the 6.2 as the answer is " What OEM diesel do I absolutely not want?"
Thank you !
 

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several relevant threads on 4btswaps.com
Why not a 6.2? Mine has done 28 MPG highway.
Sweet, I know what Im putting in my new prius.......i will be the envy of all the tree huggers, I will have sooo much power, and still be greeeeennnn. This will be epic......:shaking::homer:





Seriously swap in a 6.2......why did GM create the duramax?:laughing:
 
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