Fitting HX35 on Mid size Engine


Torque Junkie
Rexton 270xdi 2005
someone Recommended the Holset X35 Turbo for my Car after looking at the turbo graph but i have to wonder how well does a Turbo designed for 5 liter+ Engines work on smaller engines like my 2.7 liter engine (Keep in mind its a Diesel engine ) ... it will be Replacing a Garret GT2056s , Theoretically a bigger turbo will take longer to spool and will cause more lag , does that apply in this case aswell ?
In part it will depend on the AR of your turbine housing BUT as a general rule installing a larger turbo means that it will take longer to build boost pressure and be laggy
Make sure you find a small enough exhaust housing for these turbos or else you're in lag city.
Each model has several different compressors and exhaust housings that have spool characteristics and compressor maps, with different surge lines.

These have been used with RB25 so will work with a petrol engine . Not sure about deisels but they can run quite a lot of psi so Im not sure they would suit a 2.7 deisel
theres no real way to tell without testing it right ? numbers on papers cant decide this matter i guess
Flow rates on diesels are slower as they operate in lower RPM ranges so lag will pretty much kill any gains IMO.
hmmm you do have a point but there has to be some way people tune Diesel engines to produce power .. i mean look at those crazy trucks in the Us that produce over 1000hp .. its possible , question is how ... i need to do some research
Try some of the Cummins forums and Diesel Bombers....another I think was DSM Tuners?

I know a few who've had great success with Holsets, especially the VGT ones, but these were petrol Saab engines, made some BIG numbers. I looked into it myself but fancied the Super HX40 on the old car after seeing what it can do.

I had a mad idea to fit a he451vgt until I got the thing in my hands and sized it up to a gt30!!!! HUGE....and weighed 25kgs!!! But being a variable vane turbo should have spooled up ok if I could lock the veins in the right place (looked a world of pain trying to get the Vgt controler to work with the cars ecu so decided to leave it in the end)
They make 1000+hp because they have the cubic inches to spool the turbo (exhaust gas volume) and they will more than likely run more than one turbo but not as a twin turbo setup but compounded or in series, a massive turbo blowing into a not so massive turbo, and sometimes that will be blowing into a smaller turbo still, it's all about using multiple turbos to create massive amounts of boost pressure (sometimes into the hundreds of PSI) while still allowing each turbo to operate where it's most efficient,

Guys who tune old Mercedes diesels using the HX35 on there OM605 and OM606 engines and make 350-400hp on a stock block at high rpms... and some even use a HX40 to achieve 500hp...
is a video of a W202 C250TD with an om605 (2.5l 20v 5 cylinder turbo diesel) doing some roll on acceleration, pretty quick if you ask me,

as for your car, I know that your current turbo is wastegated rather than VNT so makes it easier to work with, your best bet is going compound with another turbo blowing into your existing turbo but I'd go smaller, something like a GT2560 would be enough I would think and you'll preserve your low down torque in the process
wow a twin turbo build ... i never imagined id go there , wont that give me way too much power over what the engine can handle ??? im limited to 480Nm and im already at 400 .. this does however sound like a great idea that i would really love to take into consideration , however i must ask what would happen if i just went straight for the GT2560 instead of my GT2056 ?
You can limit your torque output by limiting your fuelling at certain points in the rev range within your ECU, if you talked to your tuner I'm sure they'd be able to do it, on diesels increasing the amount of fuel injected into the engine is how you accelerate it,
as for going straight to the GT2560 on it's own, I wouldn't think that it would suit your engine when run on it's own, the GT2560 flows up 340~hp worth of air, but does so at a relatively low boost pressures, your standard turbo is the other way around, doesn't flow as much air but can run high boost pressures in order to force that air into the engine (if it needs to do so, all applications are different) a diesel engine like yours would need a fairly high amount of boost to run some decent power (again its a relevant thing, how much power is needed/wanted is up to you)
The reason for suggesting a compound turbo system (not twin turbos since the 2 turbos aren't the same) is that we can exploit the benefits of both turbos by running them in there optimal range, by that I mean that gt2056 makes lots of boost, and the gt2560 moves lots of air(and another reason for going compound is that you retain much better drivability than just "wacking a big turbo on it" ), the thing is with turbos is that they will compress any air that you give them, even if the air that's feed into the inlet of a turbo is already pressurise above atmospheric pressure, the output air pressure is multiplied though rather than just added together...
for example,
lets say both of those turbos are running 1 bar of positive pressure each, (now thats 2 bar of absolute pressure why? because atmospheric air pressure at sea level is 1 bar or 14.7psi so if we increase the pressure by 1 bar that gives us 2 bars of absolute pressure or 1 bar positive pressure, absolute pressure is what is displayed on a turbo compressor map)
so both turbos are running 1 bar each which is 2 bar absolute each, so we multiply them to together as 2x2 which equals 4 bar absolute pressure take away 1 to calculate positive pressure(inlet pressure) and you get 3 bar or 45~psi,
the point being is that neither one of the turbos mentioned would be able to do that without throwing out loads of hot air,
so compounds will make the boost while keeping both turbos working efficiently, you'll have lower exhaust gas temps since have lower exhaust back pressure and make as much power as a large single without sacrificing low down torque

hope that helps, I know it's a lot to read :S

i really enjoyed reading this , i learned new things to say the least .. if you are mentioning this combo then theres no reason for me to ask if its reliable and safe to try out cuz you wouldnt bring it up if it wasnt .
im very grateful , you redirected me to a new path and gave me hope when i was about to give up , i will discuss this combo with an Expert and see if he can make it happen , might take a while but ill try to update this thread when this project starts
So i never got the chance to walk down this path due to life getting in the way for a while , so heres the thing about a year ago i had a weird noise in my Car and everyone suspected the turbo so i ended up buying another one and in the end the turbo had nothing to do with the sound , so im left with two GT2056 turbos .. so that got me thinking Twin GT2065 since i already have both and theres no need to go hunting for Turbos on dead cars ... question is what to expect from such a combo ? currently my Car is estimated at 220HP and 460Nm with 1 GT2056 ... will this combo work well or will it cause more bad than good ?
previously your "twin turbo set up" would have been sequential , the larger turbo coming in when the smaller one runs out of steam.
This wont work with equal size turbos so you would have to be looking at running the two of them spooling up together . It is then theoretically it is possible to get somewhere near double the power.

However this is a completelt different ball game.

Unless your engine engine was spooling up one 2056 with absolute ease trying to spool two will be a complete waste of time . Indeed you might never even reach optimum boost and even if you do the lag will be pretty bad (at best)

You will also need a new custom exhaust manifold and a completely differnt fuel system as you will be needing close to double the fuel if it ever does reach full boost.

Or to put it another way I cant see it working
I got the same answer from other aswell , it seems two identical ones are a bad choice for my car .. guess that turbo will have to continue collecting dust in the garage ... they are however telling me to get the IHI RHF55V instead of the turbo i have and using a 3 inch Exhaust .. they believe it would be within safe range for the engine while adding power and torque ..

they mentioned that the issue with the GT2056 that i have is that it cant achieve 35Psi which is what ill need to get more power on a diesel .. dunno how much truth there is to that

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