I was looking at the HTT website. They offer a stage 3.5 upgrade to the HX35 good for up to 400hp for $325. Sounds good to me. Has anyone done this themselves? Apparently internal modifications are required... what sort of mods? Does this essentially create a Dodgezilla turbo? Would you typically do a basic rebuild at the same time? Any advice would be great.
Thanks
Alan

 

Call or email HTT, they are very helpful!

 

To do this, you'll have to have the compressor cover of your existing turbo machined to accept the larger compressor wheel they are selling you.

This DOES essentially create a DodgeZilla, albeit one with a 12cm turbine housing instead of the 14 on the DZ.

For high altitude or hot weather running, the 12CM housing can be good in helping you get up on the turbo, but it will runner hotter at full throttle, and you'll need to make sure you don't let boost get too high (keep in under 38psi or so max-- lower is better).


Generally, this HTT mod is done to the older H1C or WH1C turbos that came on the CTDs--- not so much done to the HX35s, but I'm not aware of any specific reason this is the case or even if there's a reason you can't do it to an HX35.


If you have an auto trans in high altitude, the 35/40 hybrid with the tight 12 housing works pretty well.

 

FYI they give you a new outer housing with the wheel, you have to get the center section/housing backing plate machined larger to accept the larger major outer diameter of the wheel. Something like .1" larger diameter, don't quote me on that measurement though, HTT will do this machining for 80 bucks if you send in your turbo. They will also rebuild, rebalance, and install the new bigger wheel for 600 bucks. To me, I'd rather save 250 more dollars to get an s300g or smallish variant.

 

I was so close to doing the same upgrade also. Research and read up on turbos before you do the upgrade. The cost really doesn't justify the benefits for this upgrade. Yes It sounds like a good deal but you really wont gain that much.
I think the best way to go is the s300g. Everyone seems to love these and they are not that expensive.

 

I just did this to my truck last week before I put down 455hp. It comes with the wheel and compressor housing. The reason it is done to the WH1C's more often is because the backing plate on it is removable with bolts. The HX35's backing plate is cast as one piece into the center section. I had to chuck the whole center section up in the lathe to machine it out for the larger exducer.

As for the wheel size it was quite bigger than one of the ones I did on a WH1C. I actually had to take almost .300 out of the center section for the exducer to fit.

Here what the exact sizes were on both my stock HX35 wheel and the HX40.

HX35
Inducer 2.130" = 54mm
Exducer 3.075" = 78.1mm

HX40
Ind. 2.364" = 60.045mm
Exd. 3.386" = 86.044mm

Some how even with the compressor wheel that much larger than stock the spool up is excactly the same except it hits much harder when it does spool.

 

Kxhonda, what did this do to your egt's? I'm very interested in doing this because I don't want to lose my exhaust brake if I was to go with a different turbo. Thanks, Eric

 

Thanks for the info! Still sounds like it may be a doable idea. kxhonda, did you rebuild the turbo while you were at it? I am a do it yourself kind of guy so I really don't want to send my turbo out for the machining. Sounds pretty simple. I only have a little 13" standard modern at work to use. This should be big enough shouldn't it? Did you clock it in on a 4 jaw? I am sure the upgrade turbo would be better if I decided to go for the twins project down the road.
Alan

 

It def lowered my egt's without my Tst on, highest I have had them was 1150. With my Tst on anything over level 3 I can still peg the gauge but it slowed it down. Keep in mind this is with 200hp sticks.

AlanF, I did rebuild it while I was at it. Hardest part was the tiny snap rings holding the journal bearings in. That lathe should be fine for it. I dialed it in on a 4 jaw, just used aluminum shims in between the center section and the jaws. Thats what I was thinking too. I heard the 35/40 does very well as the top turbo on twins. Only thing I would prob do is switch to a bigger exh housing.

 

They say a hybrid on top in twins works pretty well, but drive pressure can get crazy at elevated boost levels.