pc12driver

I'm curious as to what you consider terribly high egt's to be. With my 100hp injectors and a Comp with my stock turbo (wastegated at 34psi) I could easily shoot past 1400* (pre turbo).

You can see a sharp rise in egt's once the boost passes 34 psi with the stock turbo (HX35/12). After that the extra boost hurts rather than helps (the air charge is super heated, and actually is less dense at 40+psi than it is at a much cooler 34psi). Not to mention that the turbo is overspeeding and can grenade at any time. The compressor section is the main factor in how high you can run your boost before it becomes superheated, thus useless. If you want higher (safe and productive) boost, you'll need a bigger compressor. Stepping up to a hybrid turbo will allow you to run higher boost numbers safely (like my Dodgezilla - it's good for a little over 40 psi).

The larger exhaust housing will lower your top end egts, lower your boost, and probably do nothing for your horsepower (fuel=power, air=cooling). It essentially will extract less energy from the exhaust so the compressor won't be driven as hard. But like Hohn said, it flows more on the top end because of the less restriction. A 14cm housing won't do much, and 16cm housings don't come wastegated. But you will be able to run your exhaust brake with any of the HX35 housings.

Any of the diesel shops that sell Holset turbos or hybrids can hook you up with different housings and compressors.

Adjustable wastegates can limit boost to a point, but sometimes the stock wastegate just can't keep up (Holset only wastegates the back 3 cylinders), and that's when you'll need a larger housing (or mod the wastegate to open on all 6).

And as far as headgaskets, mine let loose at 40 psi.

blackdiesel

so i either need a bigger compressor or i need to get the right waste gate?

Bobcat698

Again, I ask, can I adjust the wastegate on my HX35's wastegate so I don't hit 45PSI?
Thanks!

pc12driver

A bigger compressor will move more air at cooler temps. The tradeoff is lag.

The exhaust housing will "move" the compressor's efficiency range around the rpm band. Smaller housings will give quick spoolup but can choke earlier on the top end, and vice-versa. This is how you can "tune" your turbo to match your driving habits, etc.

A lot of fuel and rpms and a small housing can overrun the wastegate (built into the ex. housing), and the wastegate won't be able to control the boost anymore. At that point a larger housing is needed, or you can modify the wastegate to bleed air from all 6 cylinders (drill a hole through the divider). Or you can fabricate an external wastegate into the mix (not a bolt-on affair).

A larger compressor would be the way to go to get more cool boost. A hybrid would be needed if you want to keep the exhaust brake, so something like the PDR35, Dodgezilla, or one of HTT's hybirds would be the ticket. Then pick a housing to match what you want to do with the truck (14cm for top end, 12cm for better midrange and bottom).

Bobcat, you need an adjustable boost elbow. citydiesel.net has 'em, as do others. 45psi is useless from a HX35. 40psi from a HX35/12 has something like 70psi of drive pressure (exhaust backpressure).

blackdiesel

im not really looking for the high end horsepower but rather the low end torque. however, i want the lower egts. i do quite a bit of pulling with my truck and i do not hot rod it i wasnt really wanting to put on a whole new turbo. . . . .but rather change something out on mine if its absoutly necessary. thanks for the info

CTD NUT

A boost elbow isn't going to cut it for your application.....you are already moving more than enough fuel to overpower the wastegate......you will need to modify yor exhaust housing by drilling a hole in the wastegate that allows it to gate all 6 cylinders.....then you can use an adjustable boost elbow to tune the wastegate to meet your needs.

BIGHEAD

Just to be totally diiferent & at the risk of sounding stupid, I ran my last HX35 with waste gate welded shut for over 200k exceeding 40psi many times,running 45 psi often,& bumping 50 on several occasions. I finally changed it when I noticed my EGT's were climbing too quick. I bought a reman, welded the wastegate shut & have been strutting right along. These bigger housings may help with egt's but they will slow down your spoolup,thus you will have smoke clouds behind you until you build up some boost. I don't care if mine blows up today. The HX35 is a much better turbo than people give it credit for. That is just my opinion & comes from the Hell I have put mine through. I have not blown my head gasket or anything else for that matter.