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Discussion Starter · #1 ·
Well I’m building a 4bt to be in the 250-300hp range. I have my p pump flowed at 200cc set at 17* btdc running contagious 5x.012 injectors. I have 4 turbos sitting in my shop a hx25 hx30 hx35 and he351. Everything I have read so far has made me want to stay away from the he351. I know the he351 and hx35 pretty close to each other and seems like people are having better luck with the hx35. What are the recommendations lol

Thankyou Jake
 

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For that power level and to get those injectors to run clean you'll need the hx-30 and HX-35 as compounds That is what I'm running and as long as I'm easy on the throttle off the line and do not lug the engine the 5x.012's run clean and it runs real strong............$.02
 

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Discussion Starter · #3 ·
Thankyou. What manifold are you using. Looks pretty tight to fit compounds on the side of a 4bt but like the idea.

Would a he341 be an option or would that also have a hard time spooling up.
 

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I'm using the center dump with turbo on top,I don't have any real good pics as my drive crashed that held them but.....here is what I have.
 

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The the HP turbo is a 42mm 30 on top and my LP turbo is actually a wh1c down low,the wh1c 's gate is wired shut and the 30's is set to open at 36. At WOT under a good load I see 42 max at the manifold at 5,000' above sea level.
 

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Discussion Starter · #7 ·
Correct me if I’m wrong because I’m not familiar with turbo sizes. But the low pressure turbo is the smaller turbo right? And the high pressure turbo is the larger turbo.

If I understand what your doing correctly your keeping the waste gate shut on the smaller turbo so not to loose exhaust pressure and heat and using the waste gate on larger turbo as the main control. Couldn’t you over spool/spin the smaller turbo this way?
 

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Its the other way the big turbo has the gate disabled and feeds the little turbo that has the gate functioning the 30's gate is set to open at the point I want boost to stabilize, which bypasses more exhaust energy to the big turbo that is why I still see a bit of boost creep under high load. The big turbo at WOT is feeding the little turbo ~ 18 psi the little one then compresses it to ~ 40 psi so the actual "work" that each turbo is doing is about evenly split between the two.
 

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Discussion Starter · #9 ·
So when the gate opens it sends that exhaust to the big turbo instead of just dumping it off? Would there be a way to make it work so it stops at say roughly 35psi?
 

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Yes, it would be easiest/best to have a functioning gate on both turbos set up like that you should have positive control over total boost. When i did mine I used the tapped holes in the wh1c's exhaust housing to mount it so i can not easily mount a actuator on it,and now wish I had done it differently.I need to rework the inner fender on that side to fit a bigger air box and plan to see what options I have to mount one at that time.
 

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Jake, Steve has pretty well covered what you'll need. If you have an HX30W and an HX35W in you pile they should work well together. Do you know which size inducer your HX30W has? There were 4 sizes and any of them can work. The 40mm was stock on the P pump 4bt, the 42mm which Steve has was an odd ball that came on a 6bt and had a 12cm turbine housing, the 44mm which is the ideal unit is an import, and the 46mm Super HX30W is also an import that came on a Deutz diesel. As for exhaust manifolds, a lot depends on the vehicle and hood clearance. Ideally, it would be nice to get the small turbo as far forward as possible to make room for the larger primary. Some guys chop a 6bt Dodge manifold and use that. Cummins has a possible unit that may also work. It has several part numbers and is an import. It has part # 4932577 or 4984697. See photo below. It puts the small turbo all the way up front and tilts it away from the head so it clears the #1 injector and lines. There can be other mods involved with twins. One is changing the oil pump to a higher flow model. Not required but doesn't hurt. You'll also have to figure out the drain lines and the oil lines. Seems like the oil filter plate has a spare port but may require an adapter to get the correct threads. You aren't really pushing the power range to the limits so a larger 6bt oil cooler wouldn't be warranted. Might consider dual boost gauges to help tune the creature. A boost elbow on the small turbo can definitely be a benefit in adjusting the boost level there.
 

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Charles I am running the 24 valve oil pump that is supposed to pump 33% more oil I also went with the higher flow piston cooling nozzles as well as the 6BT cooler.
My reasoning for the larger nozzles and cooler was the added heat load from cooling two turbos as well as more heat from the pistons due to the higher overall boost/fueling, the 24 valve pump brought the oil pressure back to where it should be with the added volume required by the second turbo and larger cooling nozzles................I don't know if that all was needed or not but the added cost was very little with it being a new build ;)
 

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Discussion Starter · #13 ·
Charles Thankyou. Not sure what size my hx30 is. My 4bt originally came out of an ingersoll rand asphalt roller that had a ve rotary pump on it with the hx30. 125hp rating on tag. I have since changed the front cover lift pump etc to convert it to a p pump. I have a top center mount exhaust manifold just like Steve’s in his picture. Think the other turbo might be an hy35. Came off a 2000 dodge. How much does that change things?
 

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An HY35W would not be a great choice for your primary. It has the same compressor as an HX35W but the turbine is only 9cm. Probably wouldn't spool the way you want twins to work. An HX35W or WH1C (basically the same turbo) is not terribly expensive. Might pick up a good used one an put a rebuild kit in it. The top center manifold is a good unit and can be used in the twin setup. Main thing is seeing where the primary is going to sit. Have to keep the position of the oil filter in mind. That manifold was very common on industrial engines. Often the turbo was in a reversed position with the exhaust facing forward. Not sure what size inducer your HX30W is. Does it have the compressor outlet with a clamp on elbow or just the slip fit? Also, is it the 6cm turbine housing? If you look inside the exhaust inlet you should see a number stamped there. 6=6cm. If you have a good caliper you can measure the inducer on the intake. Here's a couple photos of the 2 styles of compressor housings.
 

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Discussion Starter · #15 ·
Mine looks like the turbo on the right it has the elbow that clamps on so you can clamp a hose to the elbow. I will check to see which turbos I have exactly so I can ask if any of my combos will work or not.

How would a he351 pair with the hx30?
 

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The HE351 probably isn't going to work well either. If it's the cw model with the electronic boost controller, it is an HX40W compressor with a 9cm turbine housing. That small turbine housing just isn't what you want with twins. That is a great single for a 6bt. The ideal match up for a 4bt is the HX30W with the 44mm inducer and an HX35W with the 14cm turbine housing. That HX35W isn't very common and the turbine housing tends to be an expensive replacement part. That's why most use the HX35W 12cm which is a common as dirt. Not perfect but it works well. The other possible turbo is a Super HX40W which has a 16cm turbine housing. You usually wouldn't go there unless you're heading for big power in the 400 HP area. The HX30W's with smaller inducers can work well and have been used. Takes a little time to get the tuning just right. The end result is usually very quick boost extending all the way to the set limit and very low EGT's. Usually the HX30W will be pretty much on its own up to about 18 PSI boost which is when the bigger turbo really kicks in. Sort of like turning on the after burner on a jet engine. Just have to be careful not to have too much boost as you'll blow the head gasket. 40 PSI is about the limit without having the head O ring'd. I'd say head studs would be considered a must.
 

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Discussion Starter · #17 ·
Yes Thankyou that’s why I want to try and keep it 35psi. Do you know what the hx35 with larger compressor housing are found on?
 

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The WH1C you hear mentioned was only used 1 year on the 1994 Dodge. It is essentially the same turbo as HX35W that came on the 1995-1998 Dodge. The both have the same 8 blade compressor wheel with a 56mm inducer. 1999-2002 Dodges with manual transmission had a 7 blade compressor. A bit better but has one drawback. The waste gate actuator is attached to the compressor housing which makes reclocking difficult if necessary. The HX35W also came on tons of buses like Freightliner or Ford school buses with the 5.9 Cummins as well as medium duty trucks in the same lineup. There are just tons of those turbos that have been used. You'll also find zillions of aftermarket clones. Best advice on those is buyer beware. Most used ones you find may need some degree of rebuild. Bearing and seal kits are inexpensive. May need a new compressor wheel. Those often look like they've been chewed on by a bear. People who don't keep the air filters changed cause that. With that wheel spinning at tens of thousands RPM, a particle of dirt is like hitting it with a boulder. New compressor wheel can run $30 for aftermarket units to maybe $100 more or less for a genuine Holset. With a used turbo you never really know what it is until you tear into it.
 

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On the HX35W, I believe that is correct. Look at the compressor wheel and it should be 8 blades. I believe it was only the manuals that got the 7 blade. Is the waste gate actuator separate from the compressor housing or attached? If you have those 2 turbos, they can easily be matched for a good compound set. We have several member who have done it. Have to figure out which manifold to use, get the turbos mounted, and figure out the plumbing. You can darn near do 35 PSI with a single Super HX30W but twins do a better job and it's less stressful on the turbos.
 
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