Surfncowboy

Ok, What's the best size turbo for a 4.0 HO?

Japple650

Lol

Gee oh Dee

How much boost are you trying to make?

ericfx1984

there is more to it than 'making boost'

a t3 from an old Saab at 10 PSI, makes a whole lot less power than a GT35r at 10 PSI

it really comes down to the volume of air being moved

one example is my buddies 1993 MR2 turbo,

for a while he was running a stock turbo at around 15 psi

then he got that same turbo, but with lots of porting, still running 15 PSI, but he made more power

later he went to a much larger turbo and made more power on around 12 psi

it's more about air volume, less about PSI

if you are looking to do it on the cheap, I would look at getting a turbo from a cummins turbo diesel, Holset 35 or 40 should work well

I would look for a larger Holset 35, or even an HC1, either should offer a quick spool up on the 4.0 engine

they are also cheap, plentiful and damn near bullet proof...


now you need to address other things...

turbo manifold
BOV
waste gate
charge pipes
intercooler
better radiator (the one that you already have barely does it's job as it is)
tuning
larger injectors
maybe a bigger fuel pump...

and a bunch of misc stuff

Gee oh Dee

If you are only trying to make less than ten lbs a HX35 is overkill. So starting with the basic qualifying questions here is the way to go.

You can toss out tons of turbo info all day long, but if you don't k.ow the desired goals and intended use of the rig, its near impossible to accurately suggest the most ideal turbo and supporting setup.

All of this is of course ignoring the fact that the OP has one post on this forum, and of course he's asking about what turbo is best for a 4.0h.o. so i'm surei cas see how well this will turn out...

lolz_jeep

yea who guy dont get a hx35 thats waaaaaaaayy to big you wouldent get that to spool till 4 grand i would deffintly go with a 96 chevrolet 6.5l turbo diesel turbo, its a Borg Warner, for it that is the perfect size and will push some dang air in to those cylinders i think a GM 8 is also the same thing but a little bit better

ericfx1984

honestly you would think that the holset 35 is big but is really is not...

I had no issues on my old BMW 2.5 I6 rig... it made boost pretty quick and plenty of power... if my little 2.5 liter can spool it, then trust me, your 4.0 will have no problem

was it as quick to boost as my buddy's 3.0 with a gt35r? NOPE! but it worked and came on sooner than you would think...

just do some research, the Holset 35 and HC1 do great in the most 2.0 - 4.0 liter gasoline setups

but yeah they are not a good choice to run under 10 psi or so Gee Oh Dee is quite right about that for sure

no matter what you decide you need to under stand that there is WAY more that goes into it than just slapping on a turbo

Gee oh Dee

Its funny how we haven't heard anything more from the op.

ericfx1984

did we scare him away?

1996XJSport

I was thinking of doing a supercharger setup in my XJ so I'd have boost at lower RPMs for wheeling. Problem is all the money you'd have to spend on things to make it work lol

JeepingDan

rawwrrsss..

ericfx1984

honestly traditional super chargers really do not come on boost as soon as people think

the ones that make lots of boost down low run out of steam as you get higher up

a smaller turbo will make boost pretty fast

and when an engine is under load you make boost even sooner...

N20jeep

clearly a 100mm turbo is needed for your application

N20jeep

IMO a proper supercharger setup is more desirable in technical offroad situations(like crawling) than a turbo setup. in my experience the powerband of the turbo is not as predictable as a supercharger. the way the boost builds is the big difference, the turbo is not as progressive as a S/C.

ericfx1984

true, I will agree, a larger turbo tends to be somewhat on/off... but a smaller on is much more predictable...

I would rather have a super charger

but to be honest, when off road, just keep it simple, NA is the way to go