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Oh boy, that turbo exhaust housing is going to be sloooow to spool. Just saying.
 

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Oh boy, that turbo exhaust housing is going to be sloooow to spool. Just saying.
I was wondering if anyone else noticed that too. Looks to be at least 18cm2 to 21cm2.
 

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My next major decision is exhaust size: 3 inch or 4 inch? What are the upsides and downsides for each? Thanks.
I recently installed a 4 inch diamond eye full exhaust made to mate up behind a hc1 with a flo pro twister resonator muffler 4inch in & 4inch out sounds pretty damn good!!! Came with plenty of pipe made for a long bed so i had where to choose from to make it work with my build. Drove it to have the down pipe modified a bit since i dont have any welding skills but once the whole exhaust was on and tighten. Drove back engine felt a whole lot better. Glad i went with 4 inch instead of 3 inch
Engine only has fuel pin and gov. Spring done to it.
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Welder, I believe he's referring to the current build. That turbo appears to be the large H1C that came on the Dodges. It has the large non gated housing. A better word to describe it is it will be an absolute dog on a 4bt. Its compressor is near the size of an HX35W which is hard enough to drive with a 12cc gated housing on a 4bt and on top of that it has that huge non gated housing. Power band on that combo will be kind of narrow.
 

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Char is correct. Large turbo & large exhaust housing = slow spool
 

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Discussion Starter #28
I am concerned...The last few posts are signs of a growing cancer that almost every forum discussion I have read and reviewed over the years has suffered from. The discussion has begun to derail from the original inquiries and, I am afraid, is turning into a typed battle that showcases the knowledge and competence of others, often at the expense of the inexperienced author [myself]. I firmly believe that there is a wealth of experience here. I am hoping to tap into it. I have been helped through this so far and I will continue to post progress and ask those that have traveled this road before for their advice. But please, let me enjoy a little warmth and glow before dousing the embers of my still growing campfire. I mean no offense here. Please understand.

I am sticking with the 3"exhaust system and am hoping to find out where I may pick up a downpipe that will attach directly to this H1C turbo. Preferably mild steel [not cast] so the other exhaust components can be welded to it. I am not afraid of junkyard hunting and that may be the most cost effective route to go. Are there years where a stock Dodge Cummins exhaust setup would have what I am looking for? Thanks very much.
 

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No one is trying to knock you down. There is concern that the turbo may be the wrong one for a 4bt. The H1C did come on the 4bt and 6bt, but the one on the 4bt has a much smaller compressor wheel. The exhaust housings were essentially the same. If you can measure the inlet on the compressor wheel it should be 45mm for a 4bt H1C. If it is 50mm or more it is a 6bt turbo. Those larger compressors are just too big for a 4bt to spool properly. The exhaust housings came in 18cc and 22cc depending on transmission. The result of a turbo that is too big will be a lot of smoke due to unburned fuel and higher than normal exhaust temperature (EGT). If the turbo you have is the smaller compressor, it will work OK. Now for the exhaust down pipe. The OEM connector was a cast iron part on the 1st Gen Dodges which is angled at about 45 deg. See photo below. I believe the turbo housing has a half Marmon flange which measures a fraction over 3". You can find weldable flanges for that and create your own down pipe. Most aftermarket down pipes are usually 4" since they were being created for a 6bt dodge.
 

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Discussion Starter #31
There is a cast number on the exhaust housing that is 16. Does that mean 16cc? I am assuming so. I pulled a downpipe off of a junkyard truck that clamps right on. It is 3” and I am going to run with that size all the way through. Picked up a very affordable Dynomax muffler. It is still quite a way off, but I am excited to hear what it will sound like.
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The main issue is not necessarily on the exhaust side but the compressor side. The size of the turbine exhaust housing is often stamped inside the throat where it bolts to the exhaust manifold. I don't remember any 16cc housings on the H1C but there may have been one. Can't read the part # on the housing where your circle is.There was one one the HX40W because I have one. Like I said, the main concern is on the other side. If that compressor inducer is larger than 45mm the 4bt will have a terrible time ever spooling it properly. The 45mm wasn't great and they usually top out around 18 PSI. Some guys get them a bit higher but it takes more fuel and generally produces more heat than power. Those turbos worked OK in the 105-120 HP range, but Cummins mostly discontinued them using the HX30W or other models.
 

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Discussion Starter #33
Intercoolers:

I am interested to know thoughts about intercoolers for this motor. I am setting this truck up to run as a cruiser in and out of my little town and then to take off-road. This motor is only rated for 105 hp and I am not going to turn that up at the pump, or at the injectors. What would the benefits be of running an intercooler? What are your recommendations? Thanks very much.

derek
 

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A bone stock engine with the H1C turbo and no mods probably won't benefit much from an intercooler but it wouldn't hurt, especially if more power is desired in the future. The next step up from the 105 HP was the 120 HP which came with a water/air aftercooler. The next step up was the 130 HP model that had an air/air intercooler. The problem you may encounter with the H1C in off road crawling around is a lack of boost depending on your gearing. The engine must sense stress to build boost. Cruising down the highway with no load the boost may only reach 6-8 PSI. Start climbing hills and the boost will start to rise significantly. Also, the power curve on these engine is kind of odd. The engine will have only 90 HP at 1800 RPM while the torque hits its peak at that point. Peak 105 HP comes at 2500 RPM while the torque has already dropped to 220 lb ft. This is why most guys try to operate in the 1700-2000 RPM range. I would think in an off road situation a turbo with quicker boost than the H1C would be an advantage. That's why I mentioned the HX30W. Another turbo that could be used is the HE221W which can boost even faster. You must also consider what altitude you are operating at. Higher altitude air has less oxygen than sea level. Member Eggman can tell you about how that works.
 

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I was hoping Char1355 would get in on the question of installing an ic on the basically stock 4b. I have pretty much the same engine ( I think it’s 110 hp) out of a Skytrac in my 58 Willys pickup. It’s got the ve pump minus the afc. Getting ready to pull the front clip off and start an ac install. While I’ve got the front end off to fab up a condenser it would be a good time to look at an ic. Like the man said it can’t hurt.
 

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Discussion Starter #36
Update with pictures:

The exhaust is in place now and the motor is in final position. I needed to move it back a bit further for the firewall to clear the downpipe. Firewall is being rebuilt as is the tunnel over the transmission. Hope to have the chassis taken for driveline measurements by the end of the week. Went to the local JY and pulled the middle seat out of a 1st generation Dodge Durango. This seat has a flat bottom mount and fits very nicely. It is a 40/20/40 bench and the center folds down as an armrest.
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That Dodge turbo elbow look very neat on there. As long as you stay with that style turbo it will be fine. Should you ever think on going to an HX30W, the same elbow will bolt right on, but the turbo is about 1.5" longer due to having a waste gated housing. Just something to keep in mind. Looks like you're making great progress.
 
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