How much power can you get from a 4bt?

[Don in Missouri]

I've seen 105-125 hp stock.



What would it take to get 160, 180, or even 200 hp? When does it stop being practical?



I'm considering a swap into a fullsize Wagoneer for a daily driver. I have a 6bt that I could make fit, but I'm interested in the lighter, smaller, motor if it is more efficient. I want to cruise at 75 mph, amd maximize fuel ecomony.

 

[JLEONARD]

Well they ake a 250 hp P pumped version for marine apps.

But I would think that 180 would be doable... maybe 200 with a VE version.

Heck... . we go from 160 to 300 with the VE 6BTAs

Jay

 

[Don in Missouri]

Which do you think would get better gas mileage, a stock 160hp 12V or 4 cylinder hopped up to 160 hp? I'm looking at 3. 54 gears, but could go as high as 2. 73 with a 3 speed or 4 speed automatic.

 

[moparguy]

Don, I applaud your project. I've had a deep burning need (as yet unmet) to do a 4bt repower for the past few years. I've gone from; Dakota, mid 80s D150, late Ramcharger, to now a Grand Wagoneer as the perfect transplant candidate.



One thought I've had with the Wagon, hood clearance, have you checked on whether the tall 4 will fit without a hood massage?



On the fuel mileage, the 4 should beat the 6 everytime. Even if you bump it to 250 plus hp, just crusing down the highway, you would only be using what 30/40 hp. The BT4 would have 33% less internal friction to overcome so to my way of thinking, better fuel mileage.



Good luck, RJR

 

[michigandon]

Hey Don! What are you planning to use for transmission/transfer case? Or haven't you even gotten that far yet? I also have that "deep burning as yet unmet need", and I've got my candidates pretty much narrowed down to: K-Blazer, Ramcharger, or Wagoneer. I see a lot of Waggys around for reasonable prices, but I perosnally would want: 44s front and rear, ditch the Select-TRASH in favor of a REAL transfer case, and of course all that vacuum operated crapola on the front axle would have to go too!

 

[Don in Missouri]

I haven't checked the hood clearance. I should do that right away. It shouldn't be hard since I've got a Wagoneer and a 6bt in the garage. I have seen it fit in a Kaiser M715 with spring under supsension, so I am hopeful.



As a trail rig Wagoneers beat Bronco's (except earlies), Blazers, and Ramchargers because of their narrow track. At least I have found that advantageous on the trails I run. Of course if you've got an early Big-Three SUV with a removable top, that's a nice feature, and the Jeeps rust.



Not all the Wagoneers have the vacuum actuated front axle. I think that was only a few years in the early eighties. I might agree about the NP229 Selectrac. My 1986 was the only year they used the NP228 selectrac. It has a gear-driven differential for 4-Hi instead of that viscous coupler. I love it! It is great for wet or icy roads. You can drive in 4Hi on dry pavement all day if you want. It lock in low for uncompromised traction offroad. You do have to replace the chain as it gets stretched out.



For transmissions I want an automatic with overdrive. I don't know yet whether to go with GM or Chrysler. I'm trying to figure out which would be cheaper/easier. I know the Frito Lay motors come set up for TH400s and I have '92 Dodge auto in the garage. It's broken, but it might yeild something usable.



I also have the NP205 mated to that Dodge transmission. I like the solid, gear-driven unit, but I'd rather use a t-case with an open diff for 4-Hi even if it means dealing with a chain. I need to look into the adaptability of my NP228. Can someone teach me about NP241 or other cases?



I currently have Dana 44s with 3. 54s and ARBs front and rear. My front diff is on the driver side, but I have a Dana 44 with driver side diff I could use if necessary. I'd just have to swap my ARB. I still have my 2. 73 gears, but I'm guessing that's too high, unless I didnt' have overdrive.

 

[michigandon]

I'd use the 205 myself. But hey, it's your build!



The 3. 54s would probably be fine if used with an OD trans. I would highly recommend the Dodge 618/47re myself. The 2. 73 gears would probably work well with a 1:1 transmission such as the TH400. I wouldn't use a 700R4 to save my life!



I would go to Advance Adapters or Novak to see what they have available for mating up the transmission/transfer case combo of your choice.

 

[vssman]

I don't think hood clearance is too much of a problem. Jleonard's son has a 6BTA in a S-10. Stock hood closes too.

 

[Don in Missouri]

If I buy a 4bt that is not aftercooled, how expensive does it get to add the aftercooler?

 

[bgilbert]

A air to water aftercooler for the 6bt runs about $325 new, so I imagine it'd be close to that. Plus you will need new injections lines to route around the cooler. Plumbing, but no biggie. A air to air cooler wouldn't be any cheaper. If you're wanting power, some form of cooler will be needed.

 

[Don in Missouri]

I think I need an education on the different types of after coolers.



How hot is non-aftercooled air?



Do higher EGTs make the air passing through the boost side of the turbo hotter?



How much does an air-to air aftercooler lower the air temp? Does ambient air temp make a difference?



Which (air to air or air to water) is more effective? Which is easier to fit into a conversion?



Air to Air is what is standard on a '92-'93 Dodge right?



Is an air to water what I am more likely to see on a 4bta? Feel free to point me to some pictures.



Does an air to water aftercooler also mount out by the radiator, or is water piped about the air intake on the engine?



Learning is fun! Thanks for teaching!

 

[bgilbert]

I think I need an education on the different types of after coolers.



How hot is non-aftercooled air? - Usually around 300*f depending on your fueling level. Whatever the temp is at the exhaust manifold/turbo is what will be entering the intake.



Do higher EGTs make the air passing through the boost side of the turbo hotter? - Yes. Lots of hot air into the engine.



How much does an air-to air aftercooler lower the air temp? Does ambient air temp make a difference? - Temps entering the intake after being cooled by an air to air intercooler will be as low as 120*-150*f. So it would be 300* vs. 150*. More air more power. Cooler the air, the more power= less egt's. Not sure on ambient temps, I'm sure it has an effect.



Which (air to air or air to water) is more effective? Which is easier to fit into a conversion? - Air to air definately. An air to water cooler will only be as cool as your engine coolant temp. A2W cooler is like a heater core fitted ontop of the intake manifold. Coolant in, out. Charge air passes through/past the core. If you have a 160* thermostat, thats as cool as your air could possibly be. As far as fit, I'm sure the air to water will be the easiest. It just sits ontop of the intake manifold. A air to air will need to take up space in front of the radiator or some other place.



Air to Air is what is standard on a '92-'93 Dodge right? - Yes.



Is an air to water what I am more likely to see on a 4bta? Feel free to point me to some pictures. - I'm not the 4bta expert, so I couldn't tell you that.



Does an air to water aftercooler also mount out by the radiator, or is water piped about the air intake on the engine? - Air to water I'm sure only mounts ontop of the intake manifold. .



Now if these pics come out. They are of a 6bta air to water aftercooled. The aftercooler takes up the whole place of the intake manifold cover. Injection lines route around it. It has an in and out port for engine coolant. There is a 'core' inside it. If you looked closely on a 4bt or 6bt there are 1/2" pipe plugs in the head near the t-stat housing. That is where the coolant comes and goes. Hope some of this will help.

 

[bgilbert]

Don heres a 4bt on ebay that has a air to water aftercooler on it. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4537957599&category=34202

 

[Don in Missouri]

Thanks, that helps a lot. I'm going to my Cummins dealer today to learn some more.



I think I'm leaning toward and air-to-air aftercooler.



I still want to keep my NP228 so I have full-time 4WD in high range and I don't have to modify shifteers or driveshafts.



I found a 700R4 out of a Diesel Blazer for $150. I know they have a bad reputation, but I'm thinking it might bolt right up between my Np228 and a 4bt out of a bread van set up for a th400.

 

[mschoenheider]

o with a 700r4 and a np241c. Overdrive transmission, t-case can handle more torque than a 205 and has a better low range.

Mark

 

[Don in Missouri]

Is an NP241C a driver side or passenger side drop? I could do either, but prefer driver side. NP241 is part-time, right? I've never driven a part-time case on the highway. What's it like? I just know I really like my full-time 4Hi on the highway when it is just a little icy.



I learned today that a 4bt has higher compression pistons than a 4bta. My thought was "Good, so if I put an aftercooler on a 4bt-all the more power, right?" My local Cummins dealer is not as imaginative as I am. He thinks you might burn a hole in a piston by adding an aftercooler to a non-aftercooled motor.

 

[bgilbert]

I learned today that a 4bt has higher compression pistons than a 4bta.

Hmm maybe thats why KTA's 89 is top dog in HP race? I bet thats the same for 6bt's?

He thinks you might burn a hole in a piston by adding an aftercooler to a non-aftercooled motor.

Ah oh, I added a intercooler to my 89 6BT, talk about a power increase.

Don if I had the rig for a conversion, I wouldn't hesitate to get a 4BT, there's not that big of a difference as far as egt's. That is unless you plan on bombing it, POD's, hx40 etc...

 

[Don in Missouri]

What about a non-turbo 4b? I found one of those for sale. It would have higher compression still.



I think I'm comfortable adding an aftercooler to a non-aftercooled motor, but what about adding a turbo and and aftercooler? My un-scientific gut feeling tells me that's too much alteration.

 

[BJMarshall]

Definitely more complicated than just bolting on a turbo. Look for a 4bt from the beginning. The non turbo versions have no way of adding fuel as boost rises so you would definitely be looking for a new pump. Adding an aftercooler will in no way harm the engine. An air to water aftercooler is much more efficient that an air to air type, but you can only decrease the charge air temp down to the temp of the engine coolant. An air to water aftercooler with it's own captive coolant would work great especially if you had a container to add ice, but that is getting rather complex.

The 250hp version is a 4btaa I believe. I understand it has 2 aftercoolers on it. One is coolant, and the other is seawater. There are limitations on how long it can be operated at max power.

The 4bt I had in my Bronco responded well to the same pump tweaks for a first gen truck and a governor spring. I estimate it was making 120 to 130 hp and well over 300ftlbs of torque. I managed to get 19mpg with 4. 88 gears and 38" tall tires. In this configuration it had a top speed of 64mph with the stock governor spring. I'm not sure how fast it would go with the new spring.

I had a 400 in mine. Cummins sells all of the parts to put a Ford or Chevy transmission behind it, and any of the adapters from a 6bt will work. The 700 would be a good choice as it can be built to withstand what this engine can do, but I found it was going to require a custom converter. I was told by one of the larger transmission outfits common to this site that the 400 uses a wider 6 lug pattern than the 700.

Hope this helps.

Barry

 

[bgilbert]

I think I'd pass on a 4b, only get a 4bt or 4bta. Edit: for anyone that doesn't know or hasn't figured it out, 4 is for cylinders, B for B-series, T for turbocharged, A for aftercooled. 4BTA.