compounds on a 4bt?

[cumminspatrol]

thanks for all the information on this forum.ive been a silent reader for about a month.good stuff. im working on a project with a cummins 4bt engine.you all probably know its the 4 cylinder version of our 6bt's.im interested in building a compound turbo set up and swank told me you guys are darn smart an could help me out.the 4bt is all stock right now.im looking for power sugestions(up to 250hp) as well as turbo sugestions. thanks,andy

[BobS]

You may also want to swing by http://4btswaps.com and take a look around. Some of the folks on here are also over there.

[cumminspatrol]

thanks,thats a good site. they have some threads about turbos and talk about compounds but no one seems to have tried it yet. is there any reason to go the compound route if a person is only looking for say 35 to 45 psi? from what i understand compounds can help with egt's some. i dont want to be pushing the egt's way up. i guess i could try the hy-35w and see if that has the power i want.any ideas for me would be apriciated. im near this point in my project and need to buy a turbo(or two) thanks for the help

[wannadiesel]

I don't think you need twins at that power level. I think a decent sized hybrid turbo would do fine. PDR-35 and HTT Stage III are good examples. I'd stay on the small end for the turbine housing, a 12 cm wastegated with some porting will flow plenty for your 4BT and still spool well. If your 4BT has an H1C on it currently you can use a compressor kit from HTT to make it a hybrid.

[cumminspatrol]

so would there be ANY benefit at all to a compound turbo set up at 35 to 40psi boost levels? im just looking for a reason to do it. if there is no benifit at all then i will go single. like the hy35w or somthing else with off the line spoolup.

[CAJUN 93]

it seems to me if your temps are well under control with a bigger single (hybrid) there would be no need for twins, other than the eye-pop factor when you raise the hood. i have no experience with twins, but it seems they would be kinda laggy for in town driving. considering you have 2/3 the engine as the rest of us,i would think spool up would be worse.

my opinion, save the money and complication and put a good single on it.

daryl

[cumminspatrol]

i agree that if i did the common hx35/bht3b setup it wouldnt work at all...but if a person put a compound setup built for a semi truck on his 6bt it wouldnt work either.yes, all things equal the 4bt produces 2/3 less exhaust so the turbos would need to be matched acordingly.the 'eye pop' factor and the fabrication challenge both peak my interest.thanks for the suggestions

[swank]

i think if built right, it would be a blast to drive. i don't have any lag issues (or boost threshold issues) with my set up. it's actually quite responsive. i've seen hx30's on ebay before. idaho speedcenter on fairview has a good selection of used (small) gasser turbos. they seem to think they are made of gold though. i don't think it would be a bad idea to start with an hy and see how that drives. if it is quick enough, then adding an hx55 under it or something might work well??? maybe kta has some ideas.

[bgilbert]

www.haisleymachine.com built a set of twins for a guy that has a Jeep and 4BT. They were small IIRC. I don't want to try to guess, but I think the big charger wasn't any bigger than a hx40. Heck it might've been a hx35 hybrid.

As far as being a blast to drive.. I don't think so. Unless you spent the money on head studs and got the head and or block fire-ringed. If not, then it would be a blast to drive maybe a time or two, then it would be sitting because of other issues associated with twins. Headgaskets, oil in this, water in that etc..

You probly could have just as much fun with a single. But if you really wanted to be different, which I understand, you might give Haisley a call and see what they have to say.

[cumminspatrol]

would it be necessary to do studs,o rings,etc; if i only wanted to run 35 to 45 psi?those boost issues that create problems start showing up around 55psi dont they? thanks for the input,and the website. dave nice pictures.at first glance i thought your truck was really hooked up to that big load.

[Begle1]

~40 PSI is about all the stock head gasket can be trusted for.

A stud kit for the 6 cylinder costs $400 and coupled with a thicker-than-stock headgasket should hold around 55 PSI. Above that and O-rings are necessary.
Just don't hold me on that.

[cumminspatrol]

is there a good site to figure out how to calculate my engines flow and how to match that to a turbo map? if i could figure out how all that math works it might open my eyes to other turbo options. im just trying to learn.thanks for the paitience.