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holset cummins turbo on a 4.0L

turbojeeper

NAXJA Forum User
Location
whitehall, ohio
ok here is what i am thinking.

i had a 90 cherokee with an aw4 and a t4 turbo with 1.15a/r on the exhaust.
its would hit the 5psi at about 3200rpm from a stop and with an auto thats ok. but now i have an 89 comanche with the ax-15 in it and so not i nee da turbo that is going to spool faster. i was thinking a holset hx35 from a 5.9 cummins diesel. they are used to spooling 40psi. so i would be running a 1/4 of the boost, twice the rpm, but with only 2/3 of the displacement. think it would work? all input is welcome. once i get the turbo figured out this will turn into the build thread.
 
Damn, thats a lot of turbo for a 4.0! What is the size difference. I know the Holset is much bigger than the T4.
 
thats the things, i have looked and looked and can't find specs on the holset. the exhaust is way smaller, i just don't want to put the holset on it and find out its to small for what i need.
 
thats the things, i have looked and looked and can't find specs on the holset. the exhaust is way smaller, i just don't want to put the holset on it and find out its to small for what i need.

There is no way that is going to be too small!! My buddy was putting out 400hp from his cummins with that turbo, he just got a hx55 to replace it. Im sure you can make plenty of power with that turbo.
 
try the Cummins site. They own Holset.
 
i didn't think it would be to small especially when i wont be running any more than 10psi i just want to make the right choice the first time since money is very tight.
 
You need a smaller turbo than an HX35. I think the spool would be terrible. The hx35 IIRC has a 9cm exhaust housing and a 57 or 59?? mm inducer. With diesel thats enough air for 300-375 hp. I would say its gonna be a bit too much for a 4 liter.

IMHO
 
ok here is what i am thinking.

i had a 90 cherokee with an aw4 and a t4 turbo with 1.15a/r on the exhaust.
its would hit the 5psi at about 3200rpm from a stop and with an auto thats ok. but now i have an 89 comanche with the ax-15 in it and so not i nee da turbo that is going to spool faster. i was thinking a holset hx35 from a 5.9 cummins diesel. they are used to spooling 40psi. so i would be running a 1/4 of the boost, twice the rpm, but with only 2/3 of the displacement. think it would work? all input is welcome. once i get the turbo figured out this will turn into the build thread.

Ok I can't follow your reasoning, but found a compressor map here:

http://www.dsmtuners.com/forums/att...8378d1197242946-holset-turbos-part-3-hx35.jpg

10 psi is a pressure ratio of about 1.7. The surge line is 12 lb/m and you run off the map just after 40 lb/m, or a range of about 120 to 400 hp. You didn't say how much power you expect to make at that psi, but it looks good to me.

Now when it spools up is a different matter and I can't help much there. But you already have a turbo that makes good power but spools up late why don't you just change the turbine housing? Oh I know, it's 'cause those t4s are junk. Just to help you out I'll take it off you hands for ya :D
 
i figures it should be ok, if it can spool to 35+psi from a 5.9L with only 3200 rpm i think the 4.0L could spool it with no problem and pretty quickly to. thanks for the input srimes. ill have to take your word on it. im looking somewhere around 300hp. how good do you think it will spool?
 
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im looking somewhere around 300hp...
on 5 psi with the t4 it put down 212hp and 280tq to the wheels

Good, more info! Ok, let's assume that pressure ratio = power ratio, just to get ballpark numbers. We'll also assume that the aw4 eats up 30% of the horsepower:

212 Wheel hp = 303 Crank hp @5psi. 5psi = 1.34 Pressure Ratio
if PR=1 (no boost) then whp=158 and chp=226. Any other mods besides the turbo?
if PR = 1.7 (10psi) then whp=269 and chp=384.

If PR=1 and chp=190 (stock rating) then whp = 133 and
at PR=1.7 chp= 323 and whp= 226

The more the boost pressure changes the less linear the change in power may be, but these numbers should be in the (large) ballpark. At 380hp (and 10psi) you'll be on the back slope of the efficiency island (62-64%), still good but if that's where you want to run you may want a larger compressor. 300hp at 10psi is almost at the peak of the hill at 72% so that'd be perfect, but it looks like you made about 300 at 5 psi. Which is off the bottom of the compressor map.


i figures it should be ok, if it can spool to 35+psi from a 5.9L with only 3200 rpm i think the 4.0L could spool it with no problem and pretty quickly to. thanks for the input srimes. ill have to take your word on it. im looking somewhere around 300hp. how good do you think it will spool?

Once a turbo starts building boost it ramps up very quickly so you can't figure too much from that. I don't know much about the 5.9s but if they hit 35psi at say 2200 they probably start building boost about 1800. Turbos don't see engine size and rpm, they see airflow, which equates to horsepower.
That said, diesel spools slower than gas and holsets have a rep for quick spool, so it's probably a good match. Just looking at the compressor I'd say it's an excellent choice for boosting a stock 4.0 to 300-350hp.:cheers:
 
so from reading all that, and i think i am starting to understand it. the holset would be a good choice? stock is a 9cm exhaust housing, should i look for something a little bigger that 11 or 12cm. no other mods at the time, just the free flow 3 inch down pipe to a 4 inch exhaust, larger injectors, and piggyback fuel management. i am think about a 4.5L stroker but not anytime soon. umm
 
Going to a bigger exhaust housing will slow down your spool, the advantage is lower EGT's (at least on a diesel).
 
ok new dilema. buddy of mine has 2 hx40's for $50. would an hx40 still be ok?

working? How much for 1 shipped to 72023? :D

Looks like there are different models of the hx40:
http://www.dsmtuners.com/forums/1712027-post148.html

Looking at these maps I'd say they're a better fit than the hx35. Notice how compressor maps slope to the right. That means any one compressor is good for more power at higher pressures. An engine that will produce 300hp at 5 psi needs a larger compressor than an engine that produces 300hp at 30 psi. You're running relatively low pressure, so you need a relatively large compressor.

For $50 you can't go too wrong, and the compressor is perfect. If it spools up too slow you can set up a 40/35 hybrid.

For those of you saying that the hx35 and 40 is too big, how do you figure?
 
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