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4BT into a Chevette - Where to start?

3K views 16 replies 5 participants last post by  Fanman43 
#1 ·
Hey, Guys! Where the 4BT guru's at?

So I got a 1982 Chevy Chevette that hadn't run for almost 10 years for free a month or two ago. I just got it running and driving 2 weeks ago. It has the 1.8L Isuzu 4FB1 N/A Diesel engine with the B/W T5 transmission... Since I got this little car, I've been thinking on doing a 4BT swap. I have been driving it as a daily driver and I love the 45MPG but it struggles to keep above 60MPH on any incline on the freeway and can hardly move out of it's way. Yeah, I know, it's not supposed to be a FAST car - but I sure wish I could keep up with traffic on my way to work.

Here's what I need to know:
Will a 4BT even come close to fitting?
I have another 81 Chevette with the same engine and trans as a parts car that I got with the 82 (Also for free. Package Deal) so I don't care if I have to cut the hood, but Length wise, will it fit?

Will I need a stronger Transmission?
I know that the B/W T5 (AKA - Tremec T5) was also used in some jeeps and Camaro's (I think) But I don't know if it could hold the torque that a 4BT puts out.
If the trans can hold it, what Clutch am I going to need?

I don't know exactly what rear end is in it, but will I need to upgrade that or will it hold the power of a stock 4BT?

What kind of suspension upgrades should I look at?
Being that it's a RWD car - that makes it easier - but I don't even know where to look for a stronger spring and Shock for a chevette. Probably have to go custom? Maybe I could shorten some jeep springs?

I know next to nothing about the 4BT's other than they're basically a 6BT with-out 2 cylinders. meaning it's just about as heavy as a full 6BT.

What kind of radiator will be small enough to fit, but big enough to cool the 4BT?

This little car is a BLAST to drive just from the fact that every where I go people either think it's about to throw a rod or tell me about how they had a chevette or how their parents had a chevette and that's what they rode in all the time. I love this little turd and so far it's been the best investment I've made since buying my Ram.
To be honest, I got this car to have as a daily driver/Beater car. I just think it would be an even better beater with a 4BT. Plus parts for a 4BT are easier to find than this Isuzu. I've found a few dealers that deal with them for old fork-lifts and such, but finding parts for the automotive version is a gigantic PITA!
 

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#2 ·
Depending on which IP is on the 4BT the HP would be between 90 and 110 HP. Alot would depend on how you'd drive it if the drivetrain would hold up.

The 4 BT is 2 cyls shorter then the 6BT so you could get a close measurement from a 6BT on the length to see if it would fit. I think the weight of the 4BT would be the biggest issue for the front suspension.
 
#3 ·
The "IP?"
I was thinking the HP Rating for the 4BT was closer to 120HP. But I guess I was wrong! haha At that rate, I guess I won't really need to worry about the trans as much.
 
#5 ·
I've thought about that too, but According to the title this engine has 300,000 Miles on it. I do have a spare 4FB1 that could go into it, but... I also want a 4BT.
 
#6 ·
You could always put a narrowed 9" under the rear.
 
#8 ·
Most 9" are under the older Ford trucks and Bronco's. There are 8.8's out there and I think they were under the Bronco 2's and Explorers.
 
#10 ·
Jegs, Summit Racing, Moser have narrowed ones. They have to be done custom, then you just put your choice of pumpkin in.

A S10 rear axle maybe close to size, I think they are a 10 bolt GM.
 
#11 ·
Definitely some things to look into.
I think the Drive line stuff should hold up if the base power output of a 4BT is only 110 Ftlbs. I think the biggest concern for me now is the weight on the suspension and actually getting it to fit.
 
#12 ·
110 would be the horse power, the torque would be around 250 to 300 ftlbs.
 
#13 ·
The 4BT has been swapped into a lot of Jeeps so there's lot's of information on conversions on Jeep sites. Here's a link to one.

https://www.drivingline.com/articles/39l-cummins-engine-4bt-diesel-pros-cons/

I'n my area, the 4BT's have become kind of rare and expensive. They're also pretty challenging to swap due to weight, size and electronics on the later models. They're known for producing low end torque but not particularly good mileage. The weight and size make it more applicable to pickups and larger SUV's.
 
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