Cummins 4BT & Diesel Conversions Forums banner
1 - 10 of 10 Posts

·
Registered
Joined
·
35 Posts
Discussion Starter · #1 · (Edited)
Hi, I have a 4bt I am overhauling and planning to produce 400 or more hp with it. I will list all the scopes of my engine below and what I currently have. I am needing help on deciding on a few things on the best way to achieve the power I am wanting. I have a few main areas to look at.

1. Turbo and Air Intake set up. I have an hx30, not sure what size exhaust housing but I am planning on checking on that asap. Running a cut down 6bt manifold, and compressing the air thru a 1994 ram 12 valve intercooler. The hx30 I have is castigated but have had that disconnected for a while, was making 25-30 psi max before I tore it back out.

2. Camshaft. I am considering a aftermarket camshaft, but what would an aftermarket gain me vs OEM cam. The only info I've heard is it would help lower my EGTs, but performance wise won't see much different than OEM. that's what I've researched a bit but could be wrong, that's why I'm here asking for input.

3. Overhaul Kit, as stated about my CPL is 730. What is the best CPL for an overhaul kit for a Turbocharged and Intercooled/aftercooled engine. My engine is a VE pump, but don't think it had one on it from the factory. Pretty sure mine was an industrial Application, not aftercooled or intercooled. some CPLs I've found are 857 or 986 being aftercooled and intercooled respectively. So what is the best CPL for the setup I'm trying to run?
As far as brand, Mahle Clevite, Maxiforce, or PAI? Have used Mahle Clevite and Maxiforce, but never had an experience with PAI before.

4. Fuel delivery. Going to be running a fast pump to supply fuel. Keeping the on road VE rotary pump, and am going to send it off for tuning and repair to make sure the pump is top notch. My question is what brand fuel pin and what stage should it be? I have heard of Denny T's fuel pins but that's about it. What would be a recommendation for the fuel pin? Already has a 3200 gov spring in it but should I upgrade that too.

Injectors. The ones I have are stock units, have had them tested multiple times and are good, were put oil new when I bout the engine and don't have much use on them. Should I upgrade injectors, or will the stock ones handle the amount of fuel I am needing to push out of them. Either debating going with nw injectors or having the diesel shop redo these ones if they need larger tips or such.

Fuel Timing. Not sure what I was running on timing before, but I know Ill have to run advanced and play with it a bit, but just questioning where people that have similar 4bt engine run their timing at.

5. Head gasket. Will a stock head gasket work with studs, or should I upgrade to a MLS gasket? Doubt I would need fire rings but I've never built a 4bt before so I don't have a clue.

6. Finally my use of the engine. Its going to be kept as a farm pickup, but want something kinda fun. Have had it running for a year and my headgasket kept blowing due to a warped block, so that's why I'm tearing it down completely. shooting for 400 probably and just looking for some advice from people who've done this already for help.

Let me know what y'all think for some of my concerns, I've done plenty of engine overhauls, but never tried to push power like I want with this build. Thanks, Christian.
 

·
Super Moderator
Joined
·
8,979 Posts
There isn't 400hp of fuel in a VE pump or 400hp worth of air in an HX30.

400hp in a 4BT is basically a tempermental race engine. Not something for a farm pickup. If you were to drop your sights to 300hp it is acheivable. Compound turbos are going to be way more drivable and your VE pump has enough fuel for that.

Read here: Calculating 300hp using cc/ 1000 shots and turbo sizing

This 250hp one will be easy for you: 250hp 4BT Recipie
 

·
Registered
Joined
·
35 Posts
Discussion Starter · #3 · (Edited)
There isn't 400hp of fuel in a VE pump or 400hp worth of air in an HX30.

400hp in a 4BT is basically a tempermental race engine. Not something for a farm pickup. If you were to drop your sights to 300hp it is acheivable. Compound turbos are going to be way more drivable and your VE pump has enough fuel for that.

Read here: Calculating 300hp using cc/ 1000 shots and turbo sizing

This 250hp one will be easy for you: 250hp 4BT Recipie
Call it 300 then, I want something hot, but not something I can't drive. What extra components do I need to reach that. As far as compounds, I'm open to the idea, and I have a wh1c out of a 94 5.9 as well as a hx35 out of a 5.9 I believe too, but I'm not sure the specs on either of those. Would either of these suit the needs for a compound setup with my hx30?

I am not very technical on the science behind fuel delivery, but I will give my injection pump guy a call today to see if he is good with that. I believe of I send him the injectors and pump and a bit of info (what info he needs idk), he should be able to tune the pump and match the injectors to flow enough fuel for the hp and torque I'm looking for. Am I thinking correctly?
 

·
Registered
Joined
·
450 Posts
400hp 4bt is akin to a 600hp 6bt. Not something that's going to be reliable or easy to daily drive. These aren't LS motors where 600hp can be a comfy DD or 400 on a 4bt. To make that kind of hp, first off you won't do it with a VE pump. Guys have, but it's BIG money to get that kind of fuel to flow through a VE pump, and you'll be sending it to one or two specialty shops in the country. Not "your pump guy". So plan on a P-pump swap, or a completely different motor with a P-pump, period. Second, now that you've got a P-pump, you'll need so much timing to make that kind of hp that it won't start worth a darn if the temp gets down into the 40*F or lower range. Get used to lots of ether. It'll need big enough turbos that it'll be a smokey turd in the low rpm range, and they'll be slow to spool due to their size. You'll need really big injectors, so it'll probably have a nasty fuel haze at idle. Stock injectors won't even come close to that kind of supply. Don't put nozzles on. You need completely new injectors. You'll want an automatic trans with a pretty high stall converter to have much chance at spooling big turbos without hating life. And that auto will need a high dollar build, with billet shafts, and a triple disk converter. So you get that, ok well now that high stall converter lets your turbos spool, but once they do, now you're out of useable RPM in the blink of an eye. Beyond that, you'll need head studs and either fire ring or O ring heads, 4k governor springs in the pump, valve springs in the head, a lift pump, delivery valves in the pump, plan on upgrading every inch of fuel supply and return lines. The pickup in the tank, all the way to the inlet of the pump, the overflow valve in the pump, and the return line back to the tank. Plan on lots of fab work for a twin turbo kit, bigger intercooler. A cam swap will help for sure. But again, it can make it even more doggy in the low rpms, but better in high rpms. They typically will have more lift, and longer valve open duration to help get more air into the cylinders.

Now if you want a driveable, fun, reliable engine? Set your sights between 200-250hp. You can keep the VE pump, put in some bigger injectors, do the ratchet strap trick on the pump for a little more timing, an hx35 turbo and call it a day.
 

·
Registered
Joined
·
93 Posts

A powerful 4bt is already proven, don't listen to stockers on here for any power advice. I have a daily driven 650hp 6bt and it performs perfectly fine in every situation.
 

·
Registered
Joined
·
450 Posts
A powerful 4bt is already proven, don't listen to stockers on here for any power advice. I have a daily driven 650hp 6bt and it performs perfectly fine in every situation.
This is very subjective. I know they CAN make great power. But you're not easily making 400hp out of a 4bt on a VE pump. And not with stock turbo, stock injectors, stock head bolts etc. And I'd bet it's a hell of a stretch to say a 650hp 6bt performs "fine" in every situation. "Fine" is again, very subjective. Are you able to make it do what you need? Likely. But I bet you have to watch gauges like a hawk, and be conscious of how you drive it in order to make it useable. My 400rwhp 6bt does "fine". But EGT's get hot if I tow and let the rpms get too low. It's a bit laggy with a single turbo, but yes, it's "fine". But compared to my 400rwhp LML duramax? There's no comparison. The duramax is better in EVERY way. Quieter, cleaner, smoother, spools faster, tows better, lower egts, smoother power curve, same or better mileage, starts better. Guys say they can tow campers "fine" with their stock 1980s half ton pickups, or they can park their crew cab long bed dually "fine". But that doesn't mean it's ideal.

I'll stand behind everything I said in my post above. I bet if you listed out the mods on that 650hp 6bt, my list is pretty damn accurate. Would be very simliar on a 400hp 4bt.
 

·
Registered
Joined
·
93 Posts
Don't have to watch gauges because it's built correctly. It's been driven in traffic, towing, hauling bed fulls of dirt, driven in rain, snow, hot climate. These engines have been proven for years maybe decades now to be reliable when pumped up. Many people daily drive their 12 valves with far more power than mine daily as well.
 

·
Registered
Joined
·
450 Posts
Don't have to watch gauges because it's built correctly. It's been driven in traffic, towing, hauling bed fulls of dirt, driven in rain, snow, hot climate. These engines have been proven for years maybe decades now to be reliable when pumped up. Many people daily drive their 12 valves with far more power than mine daily as well.
I'm not arguing the durability of the engine one bit. It's pretty common knowledge how well they can hold up. Heck mine had 220k miles when I swapped it in. I've put 60k on it. Most of it at north of 400rwhp, and it sees 4000rpm a lot just because its basically my beater truck and I like to have fun with it. And yeah, I know a guy with a 12 valve thats in that 650-700rwhp range, and he occasionally will DD it too. And yes, it does the job. But anyone that claims one drives as easily and care free as a stock truck isn't telling the whole truth. Thats my point.
 

·
Registered
Joined
·
12,433 Posts
Basically, if you go beyond 250 HP you are out of single turbo range on a 4bt. You can't use larger singles because the engine just won't spool it properly. The marine 250 HP engine used an HX35W turbo but that one is water cooled. That size turbo on a road vehicle just doesn't work very well. Stock injectors also tend to run out when you're heading for 300 HP. Stock 4x.012 injectors used on VE pumps or 5x.010 units on the P7100 normally get upgraded to 5x.012. If you're really going to push to the limits you may need 5x.014. A good turbo match has been an HX30W 44mm being fed by an WH1C or HX35W primary. Now it you're pushing on into the stratosphere, you'd probably use a Super HX30W 46mm being fed by a Super HX40W. Also, a stock P7100 does have limits and you may need to modify it at some point. That gets real expensive. The VE pump gets left in the dust around 300 HP. Once you enter that territory and above you'll have to decide on other mods for both engine and drive train. Just have to remember that a 400 HP engine will have in excess of 800 lb ft of torque. In stock form few automatics or manuals can handle that. The ZF S6-750 was probably the strongest manual used in a regular passenger vehicle with it's 750 lb ft rating. Very few if any automatics can handle that without some upgrades. You ask about pistons. If you are seeking big number you might consider true marine P7100 pistons. A normal 4bt had a compression ratio of around 17.0-17.5:1. The marine units were 14.7:1. They also have dual keystone rings and coated skirts instead of single and plain skirts on the regular engines. Those open bowl piston do make cold starting a bit of a chore but are good for higher boost pressure which you would need. When you start talking big power on a diesel the budget sort of goes out the window. You can only go so far for cheap. It's not hard to drop $10-20K in a diesel and some racers hit the $100K point.
 

Attachments

1 - 10 of 10 Posts
Top