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Hi all. I am currently in the process of upgrading from the supposedly unsafe and shaft snapping hx40 to a larger charger. It is currently set at 45psi and I’m making somewhere in the 420-470hp range. I want to be around 600+. I have found a guy with a bunch of turbos that is going to build one for me to whatever specs I desire. So I am trying to figure out the single best turbo specs for my exact modifications to get me around that hp mark and still be somewhat driveable. All my previous mods should be listed below. Thanks for your responses. 

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A single turbo in the 600 hp range won't be very drivable on a vp truck.   

 

If it is anything other than a hot rod twins should be in your future

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@Me78569 yes this is true. It’s very easy to drive right now however so I can’t see another 150hp making it impossible to drive. I can turn it down and drive like a stock truck at this power level. But, would an hx40 make a decent low pressure turbo in a compound setup? 

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The turbo to flow an extra 150 hp won't be easy to spin on a vp truck.  

 

A hx40 isn't a preferred turbo from my point of view.

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What would you recommend? And how so? I know a guy personally with a SO pump and the same 7x0.012 injectors that runs a single hx55 making 70-80psi of boost. 

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People define drivable differently.  I wouldn't consider that setup drivable for my needs.

 

 

I would suggest a 62 over 75 setup.  It is well tested and works well on a vp truck for 600+ hp

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3 hours ago, BlkCummins01 said:

What would you recommend? And how so? I know a guy personally with a SO pump and the same 7x0.012 injectors that runs a single hx55 making 70-80psi of boost. 

An hx55 is doable but it would spool like a pig and be smoky.  I think it's somewhere around 70-71mm.  Some drivability will surely be lost and egt's will be warmer.  Not to mention unhealthy drive pressures and warmer charge air since the efficiency range on a turbo map is much smaller for a big single charger compared to the map of compounds.

 

You can upgrade your single to a 62 or 63 and get a little more hp than you got now with same spool up as you have now...since your hx40 is only 60mm.  But any single bigger than 63 will start introducing turbo lag at rapidly growing rates. 

 

3 hours ago, Me78569 said:

People define drivable differently.  I wouldn't consider that setup drivable for my needs.

 

 

I would suggest a 62 over 75 setup.  It is well tested and works well on a vp truck for 600+ hp

I run the same twin setup mentioned by me78569 above and he's right on with his comments on that setup.  Super reliable and a very drivable 600hp+. 

 

I was not satisfied with the bigger single charger.  The twins drive and spool exactly like stock.  You don't even know they are in there if you don't mash the skinny pedal.  It costs a little more for twins but it's worth it overall.  It's hard to find anybody complaining about their twins setup.  Complaints are much more abundant on big single setups. 

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@Bullet where did you get the piping for your compound setup? And do you think the hx40 would be decent as a low pressure turbo? I may be mistaken but I’m almost positive my compressor wheel is a 62mm. 

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40 minutes ago, BlkCummins01 said:

@Bullet where did you get the piping for your compound setup? And do you think the hx40 would be decent as a low pressure turbo? I may be mistaken but I’m almost positive my compressor wheel is a 62mm. 

My current compound setup is the full DPS twin kit 62/75 and it came with all the piping that was pre-engineered to fit perfectly...and it all does with the exception of the heat exchanger on the auto trans.  No problem with manual. 

 

If the hx40 spools like stock than yes.  But I think it's a t4 flange which means that it wouldn't.  An hx40/35 hybrid (t3) would be better than the hx40 as a smaller turbo...but there are other turbos out there that can spool like stock and pump more air than the hx40 or hx40/35 hybrid.  I thought hx40 was 60mm...but not 100% sure.  Like @Me78569 said the 62/75 is a tried and true setup on the VP trucks...and I concur. 

 

If I were crazy I could let my girlfriend daily drive my truck with no problem...but I'm still sane. Driving manors like a stock truck...regardless of the power available.👍

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Posted (edited)

Most gated HX40's out there are T3.  The non gated ones are usually the T4 variety, but those are very loose guidelines because Holset has so many submodels out.

 

I'm also 95% certain the Super Hx40 is the largest size offered at a 6 blade 60mm compressor wheel, and a 9mm shaft to alleviate the breakage issue of the 7 mm HX35 shaft.

 

The HX40 is old technology anymore.  Even a S300G (same 60 mm compressor) way outperforms an HX40.  In a mild compound setup, an HX40 should do just fine, but for a 600 horse goal, a 62/68 secondary is a wiser choice.

 

For piping kits, mine came from Crazy Carl, and is all metal construction, as opposed to the silicon found in DPS kits, but costs significantly more.  Slicone shouldn't give you any issues, as you'll only be running a primary at 25-30 psi. 

Edited by trreed
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@trreed after some searching holeset indeed made a 62mm hx40. Even though there are other turbos that spool better and flow more, this turbo is very drivable at 45psi and will spool up around 1700rpms so I would probably use it on my compound kit. Just need to get a atmospheric turbo and the piping. Anyone know where you can get piping, hot and cold? Also for the atmospheric charger what would y’all recommend? Still a 72? What about turbine size and compressor housing size? Also A.R? @Bullet @Me78569

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Honestly in my opinion if you are going to go to twins you might as well do it right.  The hx40 is not a good choice in my opinion for a 600 hp build.  

 

you would be better off with a he351cw and a 75 or 72.    

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Posted (edited)

Both Crazy Carl and DPS have been mentioned for piping.  

 

For turbo selection, that's all on the end goal.  Is it going to be just a race truck? or are you wanting to tow with it?  Me personally, I sized my turbos and injectors for maximum torque by using tighter exhaust housings.  my 75/96/1.15 will start making noise at 1400 rpm, and be fully spooled by 2000.  It's harder on the driveline than most setups, but when I put it together I had smaller injectors. Still tows well, but is capable of ~650 hp at 6500 ft of elevation.

 

Knowing the specifications of your HX40 will help in your determination of what primary, or if it will be a good secondary.  It's possible it just won't work well.

Edited by trreed

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Posted (edited)
33 minutes ago, Me78569 said:

Honestly in my opinion if you are going to go to twins you might as well do it right.  The hx40 is not a good choice in my opinion for a 600 hp build.  

 

you would be better off with a he351cw and a 75 or 72.    

It's a lot of work to put in the twins...especially if you are fabbing yourself.  So I would have the same opinion as above. 

 

37 minutes ago, BlkCummins01 said:

@trreed after some searching holeset indeed made a 62mm hx40. Even though there are other turbos that spool better and flow more, this turbo is very drivable at 45psi and will spool up around 1700rpms so I would probably use it on my compound kit. Just need to get a atmospheric turbo and the piping. Anyone know where you can get piping, hot and cold? Also for the atmospheric charger what would y’all recommend? Still a 72? What about turbine size and compressor housing size? Also A.R? @Bullet @Me78569

Regarding piping you can order a universal kit with various bends to fab your own (lots of work) or talk to some companies that sell twin kits for a pre-engineered pipe set for your application.

 

If your budget is tight and you don't mind all the work and your Hx40 spools that well and is a t3 wastgated 62mm and is your only option then go for it.  Either a 72 or a 75 will work.  72 a slightly better towing setup and 75 for a little more fun on the street.  I'm pretty sure my S475 is t4 96mm turbine on a 1.32 housing. 

Edited by Bullet
Corrected info

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