I am building a 1978 F250 with a 1996 12v Cummins..

I want to be in the 500 hp range..

the p-pump will be great for my fuel supply but I don't want a bunch of black smoke..

last time I built a Cummins is was a vp 24v with computer to limit fuel until boost lit..


I want to run parallel hx30 to make the boost and cfm keep the egt low and still have quick spool...


what are your thoughts?

I would split the exhaust manifold..

if anyone has ran parallel I would love to hear the pros and cons...

Thanks,

Scott Morgan

 

I think there's very few people who have actually run parellel set ups. I've been curious about the idea tho. For a cheap quick spooling 500hp 2 hx35's would work. As long has you have to fab skills to make 2 equal length header sections and can fit it under the hood should be golden.

 

This may be a stupid question. Would splitting the manifold and running two turbo's accomplish anything? Each turbo would be relying on half an engine to boost...wouldn't that affect the boost from each turbo? Isn't the goal to reduce the restriction to the exhaust while maximizing the boost? Wouldn't one properly sized turbo powered by all 6 cylinders be less restrictive and generate the desired boost. I understand larger turbos spool slower. To exaggerate the topic...would 6 small turbos...one bolted to each exhaust port be better than one properly sized big turbo? This post isn't anything other than me learning a bit more

 

It has been done on some pulling motors that turn high rpm's and have a few more cubes. Also has been done on many gas motors that also like to turn some rpms. For what your wanting to do its not the best option, the turbos you listed would not come up on boost until way too late in your power band killing all your bottom end. To make this work you will need much smaller turbos, than the issue you will run into will be limited compressor flow and compressor wheels that don't like high PR's.

A good set of compounds like a he351 over a s471 or gt42 would be a way better option.

Two HX35's would be way too big. Look at guys in the TDI world that run hx35's the turbo doesn't come to life till extremely high in the power band. Would be about the same on a 3cyl Cummins possibly even later.

One properly sized turbo would be the best option. while you could get the same or more flow from 6 small turbos they would only be fed by 1 piston each ... meaning 1 time every 720* the small turbine would receive energy. This results in very little energy transferred to the turbine and little drive for the compressor wheel.

 

"A good set of compounds like a he351 over a s471 or gt42 would be a way better option."

how much boost does this setup make?
how does the exhaust flow once the large turbo lights?

and just to clarify I was talking about putting two small turbo on not two hx35..
I was also going to keep the exhaust separate and merge the intake just before the inner cooler..

oh and I'm pretty sure I can fab anything..

 

A he351 s400 series compound kit is capable of a lot with crazy fast spooling. They have kits out there to put them in and come with turbo drains, feed lines etc. Although you are putting it in a fod but still not that bad to do. I'm about to do a 351 over a s475 and we are shooting for about 650 horse and over 1300 foot pounds. The he351 are torque monsters due to their incredible spool up. I believe most compounds like this are 70 psi or so. Depending on the fuel avalible to spin them. And the exhaust just exits the s400 and goes into the exhaust system

 

Overall boost depends on the rest of your set up. Once the large turbo lights the exhaust is pushed out the exhaust pipe.

http://s388.photobucket.com/user/94_12valve/media/twins.jpg.html
I understand what you were saying about how to fab up the two chargers in your original post its still not the best option.

 

I looked at your pictures in your album and I find it a great idea to run smaller turbos for quicker spool especially on a tow rig or general work truck. It is interesting that the new Ford V6 SHO gasser does just that one little turbo on each exhaust manifold outlet flange.

 

That is a piece of art nice compound set up. hate to even see it get dusty.

 

Here is a dyno sheet of the eco boost. Take a look at where peak torque and peak power are made. Unless you plan on turning that kind of rpm than you will not like this set up.



For the record I did not make that set up.