[LeroyVT]

So I am new to the swap world and have a wild hair about putting a 4BT in my FJ40.
We tore the front end up in the FJ and it got me thinking about pulling the 305 in it and putting in a 4BT. I have a 01 2500 with a nv5600 sitting around and was thinking of pulling the axels trans and transfer case, bolting the 4BT up to it and go on.
Am I crazy? Is that going to be too much for my FJ to handle? I know we would have to beef up the suspension some bout other than that would the 4BT bolt up to 5600? I called some places about adapter plates and couldn’t find much out. Any advice would be greatly appreciated. Thanks.

 

[char1355]

The 4bt would be a direct bolt up to the NV5600. Of course you need the block adapter, flywheel and clutch assembly, and starter off the 6bt that came with the transmission. Now as far as putting it into an FJ40 you'd have to judge that. That drive train is probably much longer and the stock Dodge axles are probably a bit wider. Wouldn't be a simple bolt on swap but few are. Would the Dodge transfer case physically fit between the frame on the FJ40?

 

[LeroyVT]

Taking the truck to the shop to start disassembling it. I think the t case should fit and clearly I’ll need to get new drive shafts but knowing the motor will bolt to the trans is a great start. Thanks.

 

[char1355]

Yes, drive shafts will be a custom part. What level of performance for the 4bt do you plan? Anything above bone stock 105 HP needs an intercooler. 200 HP is a fairly popular power point and pretty easy to achieve. On a VE pump engine the main change is the turbo. On a P pump engine it would be mostly injection pump adjustment. Your stock radiator may do fine. 4bt's run cold.

 

[LeroyVT]

Well the motor I have will be interesting. It bored .20 over, marine pistons, helical cut DV’s, pump that flows 450cc, etc... I think it’s a little more than what I was looking for but go big or go home so glad I’m going with the dodge drivetrain. All that motor work will make my radiator and inter cooler set up more critical though. Thoughts on a coolant bypass for it?

 

[char1355]

Sounds like someone was planning a very extreme level of power. I assume this is a P pump engine. It's very rare that we see anyone change the delivery valves unless they're heading north of 300 HP. You say it has Marine pistons. Question would be are the true marine units which have 15.3:1 compression ratio and coated skirts or marine style combustion bowls which are around 17.5:1. Big difference in the 2 pistons. Below is a photo of a true marine P pump piston. Nothing wrong with the true marine units but again we've had few people use them. #1, they are expensive, and that lower compression makes them harder to start in colder weather. On the plus side, they have dual keystone rings and the lower CR works out good for engines running higher boost. What turbo or turbos does the engine have? Not sure what you're asking about a coolant bypass system.

 

[LeroyVT]

Sounds like someone was planning a very extreme level of power. I assume this is a P pump engine. It's very rare that we see anyone change the delivery valves unless they're heading north of 300 HP. You say it has Marine pistons. Question would be are the true marine units which have 15.3:1 compression ratio and coated skirts or marine style combustion bowls which are around 17.5:1. Big difference in the 2 pistons. Below is a photo of a true marine P pump piston. Nothing wrong with the true marine units but again we've had few people use them. #1, they are expensive, and that lower compression makes them harder to start in colder weather. On the plus side, they have dual keystone rings and the lower CR works out good for engines running higher boost. What turbo or turbos does the engine have? Not sure what you're asking about a coolant bypass system.

 

[LeroyVT]

Yes to the P pump. They are marine style 17.5:1. I have a hx30 on it and am trying to figure out the big charger. Could I run a S471 or something similar to the turbo off a 855 Cummins? I heard coolant bypasses help keep everything cooler and I’m a little worried about heat on this. Thanks for the input/advice.

 

[char1355]

On the primary turbo, the HX35W has been a popular choice. If you have the original P pump HX30W that one has the 40mm inducer. That one can do fine in a a twin set. The absolutely ideal HX30W is supposed to be the 44mm and the best primary is the HX35W with the 14cc turbine housing. However, most use the HX35W 12cc because the 14cc is kind of scarce. Now, if your power plans go into the stratosphere, You could run a Super HX30W 46mm fed by a Super HX40W. As for cooling, when properly set up, a good twin set often runs cooler than a single. More engine exhaust heat is being converted to energy. Also, the more heat you can keep in the exhaust system the better. Ceramic coating exhaust manifold and turbine housings is great idea but kind of pricey. Minimum would be turbine blankets and wrap the interconnecting down pipe. You'd probably want an upgraded oil pump and the 7 plate oil cooler from a 6bt. Head studs should be part of the picture and having the head O ringed a strong possibility. With boost levels going north of 40 PSI that would be a must.

 

[eggman918]

Yes to the P pump. They are marine style 17.5:1. I have a hx30 on it and am trying to figure out the big charger. Could I run a S471 or something similar to the turbo off a 855 Cummins? I heard coolant bypasses help keep everything cooler and I’m a little worried about heat on this. Thanks for the input/advice.

I would get as much engine cooling capacity as I could if you plan on really working your rig at this power level, when doing my build I thought I went with more capacity then I would need and at the 200 HP level I think that was the case.
However now at closer to the 300 HP point I wish I had about 50% more then I do, now I line in N. AZ. so high temps, high interstate speeds and lots of grades.
Over all regardless of the power level though engine coolant temps not EGT's have been at least for me what has limited just how hard I can work my rig.

 

[LeroyVT]

Well the motor is going in a FJ40 so it’s not like it will be towing or anything serious. Just want something fun to play with and do a little off roading when I want to. Any more thoughts on the secondary are appreciated. Also any ideas on intercooler locations or any other know how is appreciated. Thanks for all your input char....