odin1954

I went to a hx40 turbo over the hx35 that was in the truck now now its slower at low rpm's but its got more power at higher WHAT can I do?

RowJ

Not much... bigger turbos lag more due to greater mass ... takes longer to spool up. Any change in turbo size is a compromise. The lag is particularly irritating on an Automatic. Couple Of possibilities....
-Ck turbine housing size on HX-40... smaller may be available.
-Go back to the HX-35 and put a 14 cm2 turbine housing on it. Will not be as much additional lag.
-Add fueling so the HX-40 spins sooner... may also smoke more.

Note: Only way to get more air and fast spoolup is with compound twin turbos.

RJ

odin1954

thanks RJ I'll check it out What about a BD super B turbo?

signature600

If you have a 16cm or 18cm housing that will hurt the spool...but remember an HX40 has bigger wheels on both ends than a HX35!

Chris

odin1954

Chris it has 18 cm housing, now what can i do this truck has 410 gears it runs higher rpm's highway 1,800 rpm's at 60 mph

dieselrob

Get a smaller exhaust housing for it. 14 or 12 cm would be alot better. Then you can move your fuel plate forward and get some more power to.

signature600

Did you get my PM?

Chris

Forrest Nearing

yikes, definately get a 16cm housing for it... you can't go smaller without going to an hx35 turbine wheel or having the housing custom machined to fit the 40 wheel (which will probably result in a broken shaft)

if I had a truck w/ 4.10's, I'd do a 4.5" lift and 37" tires

signature600

I've got a custom built Diesel Dynamics 14cm housing for a HX40

That should be exactly what he's looking for!
Chris

Forrest Nearing

just don't fuel it too hard or you'll snap the shaft...

signature600

12v's don't fuel hard...what are you talking about Forrest??

I can't see him fueling it that hard with what he has in his sig. Now if he's wanting to upgrade to more fuel, he bought the wrong charger anyway!
Chris

fiveology

Just curious, how would the exhuast housing make the shaft more likely to break? I was considering a HX40 for my truck, and have heard about the weak shaft, but I have also been told if they are wastegated to about 38 psi they will live a good long time.

signature600

Spool it too fast (hard) and it can snap the shaft because it's not heavy enough for the size wheels on it! HX35 and HX40 have the same shaft, but the HX40 has bigger wheels on both ends, and usually bigger housings to make it spool and run slower!

Chris

fiveology

Ahh, makes sense, with the smaller housing it would spool faster there by increasing the chance of shaft snappage. Maybe my cheap butt should just buy TJ's B1.

Forrest Nearing

yup, basicly you have to think about the turbine housing as a nozzle and the turbine wheel as a lever... the tighter the nozzle, the more leverage you have don the turbine wheel... IE, it's going to accelerate quicker. problem is you've got a big ol' compressor wheel on the other end of the shaft, and if you try to accelerate it too quickly, the inertia of the compressor wheel can cause the shaft to twist, and it doesn't twist much before it snaps!

I beat the snot out of my 40/16 for a long time... I ran it at 42psi and I sneezed it quite often. when I ground the plate it would do 45psi, so I turned it down to 38psi and it's still going strong. it was a stock rebuild, but I had Majestic balance the wheels. I'd estimate that turbo has about 65k on it now