[char1355]

Well, the ideal setup is generally the HX30W 44mm with the HX35W with the 14cm turbine housing. The Super 30 should do OK with the HX35W. Any twin system is a mater of fine tuning to get the balance just where you want it. An HX40W is not too large but is normally more for guys going all out in the performance area. The preferred unit is the Super HX40W which has a billet 7 blade compressor wheel and a special turbine wheel and a 16cm housing. There are lots of Super 40 turbos out there but few if any are the true super model. I would recommend having twin boost gauges to monitor what the 2 turbos are doing. Another gauge to consider would be a back pressure gauge. How much power are you planning on? A P pump 4bt with a Super 30 can do around 225 HP with stock 5x.010 injectors. You'd want a #10 torque plate in the injection pump and set the pump timing advance to around 16 deg. With twins, you will need to change injectors to 5x.012 which can take you past 300 HP. The factory 250 HP 4bt used those. Are you running a manual or automatic transmission? A stock manual transmission clutch will not hold the torque of a 300 HP 4b Member Eggman can advise you on that one. He's on his 3rd transmission to get to the right size clutch. Also, any boost above 40 PSI will likely need the head O ringed. Stock gasket can only hold so much. Hope you have a good intercooler. Some cheaper units won't hold 40 PSI or more.

 

[char1355]

OK. The Super HX40W has a 60x86 billet compressor wheel with 7 blades. Wheels came in 8, 7, and 6 blades but the Super is a 7. There are also 7 blade models with cast wheels. On the turbine side it has a 76x64 10 blade turbine wheel in a 16cm2 housing. The 10 blade is unique to the Super. Standard models are the same size but 12 blades. I believe the part number for that turbo is 4033666H or maybe 4044662D. The genuine item is not cheap. Around $1500-1800. Not positive on the turbine housing flange, but it may have come in T3 or T4. Another thing is the HX40W is not small and requires a 4" exhaust. It's a big puppy. On the compressor outlet elbows, they come in sizes of 3"-4". The 4" would be ideal since the intake on the Super 30 is 4". That same elbow will also fit the HX35W. It is part 3884977. Sounds like your other equipment is in proper order. You'll have to figure out which exhaust manifold to use. Space on a 4bt is kind of cramped. If hood clearance isn't a problem, one of the top mounted manifolds would be better. Will have to work out bracing to support the primary turbo. Oh, and don't forget you'll need a big air filter.

 

[char1355]

The HX30W standard models came in 40mm, 42mm, and 44mm inducer. The Super is a 46mm. All came with a 6cm2 turbine housing with the one exception being the 42mm which also came in a 12cm2 version. That one was used on an industrial 6bt and is not a good match for the 4bt. The 40mm was used on industrial engines and we rarely see it used. The 42mm came on the P pump 4bt as well as some industrial engines. The 44mm is an import only item which is probably on some of the later built 4bt's. The 46mm Super came on a Deutz 6 cylinder and is also an import only item. Most guys tend to use the 44mm mainly due to availability and cost. Same goes for the 46mm Super. The 40mm and 42mm units can be had but since they were mainly built in the USA or UK they tend to be more expensive. On the primary side, most have used the HX35W with the 12cm2 turbine simply because its easy to find and used ones are cheap. The 14cm2 version is kind of scarce and buying that turbine housing to change one is kind of pricey. That housing can be had in both gated and non gated. Not sure that a gated housing is necessary on a 4bt primary. Unless you're running some extreme power level I doubt the primary would ever reach 20 PSI. By the time the exhaust gases have gone through the smaller secondary they have lost some of their energy. That's one of the reasons for having good insulation on the exhaust manifold and turbine housings. That heat is the energy that spools the turbos.

 

[char1355]

Dougal, If 250 HP only needs 30 PSI then the 42mm and 44mm can readily do that. May be a little less stressful on the 46mm Super. To do 250 HP will need one size up in injectors. The 250 HP 4bt used 5x.012. You can get that size for both VE or P pumps. 36 PSI for 300 HP ain't going to happen on a single. Above 250 HP you need twins.

Jeep, not all Cummins 6bts came with the Dana 60 4.10. They also came with a 3.55 and the early automatics had a Dana 61 with a 3.07 ratio. You ask about the size of the HX40 vs the HX35. Holset shows the dimensions for the HX35 as L224mm x W250mm x H169mm. Weight 9-11 Kg. The HX40 dimensions are L231mm x W250mm x H169mm. Weight 11-14 Kg. Main issue would be the exhaust. The HX35W will generally use a 3" where the HX40W requires a 4". Both turbos have 4" air intake and both use the same compressor outlet elbows ranging in size from 3" to 4". What exhaust manifold are you working with. If you have adequate hood clearance, you can put the small turbo up top and the big one down low. There are 2 top manifolds that can work. One is 3901635 which puts the top turbo in the center and the other is 4934697 which puts the small turbo to the front. See photos below. Also, have to keep an eye on the oil filter in relation to the big turbo intake. You can get a cobra head intake that can help some on clearance issues. And, on the HX40W there is a cobra head exhaust Cummins part 3927862.

 

[char1355]

Johnny, what is the size of the upgraded turbine housing. They are using the Super 40 turbine but I'd think that may not work in a 9cm2 housing that was standard on that HE.