Seems like a read somewhere that a guy can buy a larger exhaust housing for the hx35? Mine is 12cm.If I can I think it might be better to have the larger 16 cm housing for helping with the egt's while towing?

Thanks for youre knowledge and help,Mike.

 

dont wast your money going bigger- stick with the 12. ive tested bigger ones- no real advantage. once the turbo is out of its map it doesnt matter if you have a 21. i run an he-351 with a 9 cm housing and it cools extremely well. i tow in the mountains alot.

 

If you have stock injectors and a 5 speed, it's hard to beat the 12 cm housing on an intercooled truck.

Where is your EGT problem, high RPM or low RPM? It might be a pump tuning or a driving style issue and can be cured by adjusting one of those factors...

 

Im new to these trucks,I dont know that I have a actual problem.Seems like these trucks prefer to run around 2200 2400 rpm's? So far I havnt actualy had to get out of it on any hills,been real close to having to get out of it.
The egt gauge has tickled 1,000* post turbo a couple times,when The engine cant pull much more and rpms start droping is when I see the egt's start to take off on me.On these hills rpms get down to 1,900 2,000 when im close to cresting the hill Ill see the high reading of the 1,000* If the hills where any bigger I would have to shift down and run 4th.Fwiw: on these hills im hitting them WFO @ 33 lbs of boost when I reach the top and im getting nervous about my egt's in sitting at 25 lbs of boost.

I dunno? im not complaining,im really impressed how the rig pulls( I only know my big block chevy,learning my CTD)Somone was telling me if I swapped out that lil 12cm housing to a 16cm unit I could drop my egt's about 150*??? so I figured It would be wise to come here and ask the question before I go spending my hard earned money.

Also I havnt had the time to get out there and install my m&H timing spacer yet! Ive turned in the fuel screw almost 1.5 turns...im sure some more timing should allow me to burn that extra fuel a bit better and maybe help with egt's????

Appreciate you folks helpin a brother out.

 

When towing, RPM is your friend. It keeps more air moving through the engine and lowers EGT. What will help you more than timing is a 3200 RPM spring, that way you can drop to 4th on those hills to keep RPM up without having to slow down. That's also going to be better for the trans, those things get hot pulling really hard in 5th. It's fine on the flats, but on a hill or against a stiff headwind dropping to 4th will help in all kinds of ways.

The boost is nothing to worry about, it sounds healthy. A bigger housing in your situation is going to lower boost and raise EGT, and that will be worse the lower the RPM goes.

 

Thanks for the great! informative post.Much appreciated!Ill keep the hx35 just how it is and focus on pump adjustments and get that 3200 rpms spring in it...just dreading that chore looks like a real PIA with that pump on the engine...

 

It is a piece of cake, just do it!!

 

yes sir!

Well I got after it last night,was able to get all the allen head bolts out of the top of the pump.The back idle adjustment screw was a nightmare,modified some tools to get the job done.I have so many wrenches cut and welded back together in weird shapes and skinny looooong screw drivers etc,etc, since Ive got this truck lol there kinda of PIA to work on with normal tools...need a set of crows foot sockets!

The toughest screw was that pesky backside allen head.Took me about an 1 1/2 hours just to get these 4 screws out.



The custom tools a ground on to get at that locknut and turn that idle screw out with.


Tonight or sunday morning Ill pull the cap off and swap the gov. spring

While im getting dirty Ill install the M&H dynamic timing spacer in there also.

These 2 items should make her buck a bit

 

PIA indeed lol But I got it done,took me about 5 hours with a couple of (I better walk away before I get ****** off breaks)

The truck now has the 3200 rpm spring and the dynamic timing spacer,I ws going to grind the fuel pin also but I figure 2 mods at once is plenty(how could I know what the fuel pin did?)

Anyway WOW!!!! what a differance that spring and spacer made SKOCKED! I cant wait to pull a load now!

Thanks for the great advice and the boot in the *** to get after that spring mod!

 

I just noticed you are reading EGT's post turbo!!!
You better know what it is pre-turbo!!!
For example, post turbo might be 1100, but you could see 300 dropped at the turbo!!! In this case you have 1400 in the manifold!!!

My opinion on it is that post turbo is useless.

 

I havnt actually allowed the gauge to hit 1,000* yet and dont plan on it.I was told to add 200* to 250* to the guages reading.YOu say add 300*?

When I installed the hx 35 I had intentions of drilling the hole in the manifold.But man the manifold bolts are so rusted in there,couldnt take a chance of busting studs off in the block,I only had so much time to work on it.The preveous owner of the hx35 had already drilled and tapped the cast elbow for the probe to be there.

I supose a guy could drill the manifold with out removing it? just grease the **** out of the drill and tap and hope it catches the rest of the chips...just hate to take a chance of getting ANY metal in my cylinders.Previous owner just told me dont let it get past 1000* and youl be fine...Idunno ...so far so good.

All I know for certain is the truck is a freaking BEAST now! lol and im so STOKED that everything Ive done to the truck has been a positive mod.

 

950 deg. post turbo will keep you out of trouble.

 

I have drilled the manifold without removing it or the turbo. Just use grease and after drilling and tapping run a magnet down in there. Any chips left in there will get blown through the turbo. After a brief starting of the engine shut it down and make sure the turbo still spins, if it does than its fine.

Also you could use a shop vac to suck the chips away while drilling and tapping.

 

I've done a couple of trucks the same way apwatson50 describes. The grease seems to catch almost everything.

Another option, especially considering we're talking about a 12 valve here, is that the exhaust manifold tends to shrink over time, sometimes bad enough to crack the head at the front or rear. If I had kept my '92, I would have bought an ATS 3 piece manifold. I think BD also has one. Anyhow, these are already drilled and tapped for a probe, so if you installed it you'd kill 2 birds with one stone.