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Discussion Starter #41
Cool ! Thats what I wanted to hear. I've had no experience with these 4b's so I don't know what their capable of. I know they have a pretty healthy stroke for a smaller motor & the compression is up there so I'm excited to get mine running .
 

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Alessi knows what he's talking about. Stick with the guys who have had a lot of experience with the 4BT. I just unleashed the wheel spinning power in mine and don't think I have more than 150-175 H.P. and 2,400 RPM. If you are like the rest of the 4BT owners it's about doing a nice combination of loaded and unloaded running while getting more miles per gallon. Please stay away from the gasoline engine mentality unless you feel you need to be in the drag strip, farmer's fair load pulling group.
 

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Since the original question that started this thread seems to be relevant again, I'll throw in my .02 in case anyone is still reading. Whether or not the 4BT will be adequate for your intended purpose depends entirely upon your expectations. I have been driving a 4BT powered 1990 Chevy K1500 4x4 for 56K miles now, and here are some observations.

Acceleration is comparable to a TBI 350 in the same vehicle.

Lugging power, torque, or whatever the hell it's called these days far exceeds that of any engine GM ever put in a pickup.

Passing at or above highway speeds is not a problem.

Does just fine pulling a 5000# trailer, but if towing is your thing, you'll be happier with the 6BT.

With just a little tweaking, the 4BT will give a stock GM clutch all it can handle and then some. Is more than that really necessary in a daily driver?

26.4 mpg making my normal commute. Got over 28 mpg once on a long trip.

Bottom line: The goal for this conversion was to have a small, efficient, reliable turbodiesel in a fullsize truck for a daily driver, and it has exceeded all expectations concerning those criteria.
 

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Discussion Starter #45
Wow, that's what I was looking for ! I didn't know they could run as well as an injected 350. This was the info I was looking for , Thanx.
 

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Acceleration is comparable to a TBI 350 in the same vehicle.

Lugging power, torque, or whatever the hell it's called these days far exceeds that of any engine GM ever put in a pickup.

Passing at or above highway speeds is not a problem.



26.4 mpg making my normal commute. Got over 28 mpg once on a long trip.
.

If those things are all true, I'd love to put one in the Burb. So I'll think on that for a bit.
 

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26.4 mpg making my normal commute. Got over 28 mpg once on a long trip.

Bottom line: The goal for this conversion was to have a small, efficient, reliable turbodiesel in a fullsize truck for a daily driver, and it has exceeded all expectations concerning those criteria.[/QUOTE]

What trans and gears are you running? Thanks. Doing the same with a 1990 F150 4x4.
 

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MCINFANTRY -

0858 cpl/105 hp. The answer to the second question is both yes and no. I bottomed the starwheel in the AFC housing and rotated the diaphragm to the maximum fueling position. Advanced timing 2 degrees. These adjustments don't do so much for maximum power as they do for driveability, which is of far greater concern to me in this application. I did not move the fuel screw because, at that point, I felt that the power level was adequate for my purposes and making more power just for the sake of using more fuel or torching the clutch would be defeating the purpose. That said, I cannot stress enough the importance of making sure the engine is "right" before attempting to increase power. The vast majority of 4BT's that will fall into our hands are high milers, with no way for us to know how they have been (ab)used or (not) maintained. Making a few checks up front can save a ton of tail chasing later on. Explanantion follows:


Check lift pump pressure. If you don't have 6-8 psi, nothing else you do to the engine is going to make it run better.

Check throttle linkage - stretched cable, worn linkage, etc. Make sure you're getting WOT.

Set the valves. Most people, myself included, are not very good about checking this every 30,000 miles like we're supposed to, and they will tighten up over time.

Find true TDC and make a timing pointer. Do not trust that the timing pin is at exact TDC, because it's not.

Set timing to spec + adjust from there. Of the numerous B Cummins engines I have worked on, I have yet to check pump timing and find it to be correct. Advancing the timing a degree or two doesn't do much good if it's 5 degrees retarded to begin with, and the only way this can be verified is by checking it.

Check pin in AFC. Bosch VE pumps are notorious for having this pin stick. Stuck pin = no boost fueling = sick, sick, sick.

While the injectors are at the shop getting new tips (at the very least), perform a compression check. It will most likely be fine, but you will KNOW it's fine.

TACOMA -

Allow me to clarify my statement concerning acceleration. It is NOW comparable to a TBI 350 (1987-1995) thanks largely to the AFC adjustments mentioned above. Also, acceleration is NOT comparable to that of an L31 Vortec 350 (1996-1999). If you have driven both, you know what I'm talking about. Just didn't want anyone to get the wrong idea.

52WRENCH -

Trans is HM290 Getrag 5 sp manual, 3.42 gears, 265/75/16 tires
 

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Thank you. All 3 of my current vehicles are late 80's TBI motors, and their acceleration is fine, for the vehicle. Appreciate the info. ;)
 

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Flyin71H, thanks for all the good info!
 

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i ran a 105hp cpl858 in a 6300+ curb weight truck. it ran fine for me. i was satisfied with milage, acceleration and reliability. but what would i know.

here it is pulling out TWO stuck vehicles at once in second gear, low range(2:1) 4.56 gears and 39" tall tires. i guess if i had 200hp, or 400hp it should have done what better????

i think 150hp would be PLENTY
it probably was 7400+ in the video, passengers, gear etc.

http://homepage.mac.com/ltalessi/iMovieTheater124.html
mcinfantry your truck kicks a** that thing is awsome.
 

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My take

Okay. There are a number of replies so why not throw in my .02.

I am not sure if anyone has put quite like this: I have driven a number of trucks that would have about the same performance as a 4bt in the idle to 3200 range even though they are gassers and can rev to 5500 or so. It sounds like you have a few If I have the right person here. Just drive it below 3200 rpm. If you have one with a stick than see how fast you can accelerate but shift out before going over 3200. I know there are plenty of variables that could be different and by chance could be very close to the same, I do not have a 4bt yet but this is the way I am looking at it. You can get into all the number if you want but seat of the pants is what counts.
 

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Please think of the tone of Colonel Sanders from Waterboy when you read this:


Well, friends, Enzo is wroooooooooonnnngggggg again......
Well not entirely.
People always quote peak HP figures, which really mean jack in the real world.
If you've got a big fat torque curve, then you can have higher average power available to the wheels than someone with higher peak power but less area under the curve.

In general diesels have got a much bigger proportion of their peak power on tap than petrols do.
 

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I'm positive I've never witnessed a person wasting more words or more of other people's time solely for the sake of impressing themselves.

That said, thanks first to Mcinfantry & BobS for great posts, and to Andre, Carl, TnDonor, Dougal, flyin71h, 52Wrench, and all the rest who actually contributed useful information!

Don't think twice about the 4BT. I run mine bone stock through some very serious mountains and tight twisty roads in a roughly 5,400 lbs & 40 year old truck and only the very hottest rigs can begin to keep up with me, or even want to try! Far more power than I ever expected, exactly as described by owners here: strong bottom end and mid-range TORQUE and smooth power throughout the operating range. Been driving it since May this year and still thrilled every time I get in and turn the key, and deeply impressed again after every single ride! With the fabulous mileage thrown in the bonus is I can actually afford to drive it.

I do plan to turn mine up around 30%-40% and that will just be that much more fun. :)
 

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I'm positive I've never witnessed a person wasting more words or more of other people's time solely for the sake of impressing themselves.
Just carving deeper with the whip into that-> :deadhorse:
 

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