• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

HX35W on 6.5 optimizer

B

Ba_051

Member
Messages
38
Reaction score
5
Location
Everett, WA
Well I have a line on an HX35W and manifolds and such but have a few questions. I want to run a 4" exhaust but am having issues figuring out the back of my HX35W. It is a weird ID/OD on the Vband flange. It measures 3.111" (3 1/8") OD. What size V-band do the stock HX35's use? Also, with ARP head studs, what is a safe boost pressure to run the 6.5 optimizer at? I have heard no more than 10 psi, some say 10-12 psi, and have heard some run 20-22 psi on stock, hi comp pistons...
 
I saw that kit, only thing I need is the v-band clamp size though. Everything else is ready to go.

Will the back of an hx40 bolt onto a 35 to use a 4" vband?
 
I see typical chrysler... Figured it was an oddball size... I may just make a 1/2" plate and weld a 3" vband flange to it... \

About the boost level now... Would a 6.5 optimizer with head studs handle 15-20 psi of boost?
 
that's a loaded ? if I've ever heard one. LOL better ? might be how many times can you hit those numbers and stay reliable. For the most part I think you should be fine but... if you combine that with high ECTs it might not stay reliable very long.
 
I don't see much reason to go much above 15. You want air volume, not just pressure. This where the att shines is it moves so much volume of air at low boost levels. And at 15 psi, you are effectively doubling the pressures inside the cylinder as you are doibling the volume of air going in to it.
 
22 pounds on 35w with stock pistons, right? Are you running +.010 gaskets? Your planning on pushing some air all right. Get you rings tight as you can, and don't be ginger with the torque wrench on the studs. Gapless rings?
What are you fueling with? Watch you egt/ect that will eat your rings getting too hot and running that pressure.
 
I am thinking of only running 15 lbs or so... Was curious on everyone's take on 20 lbs of boost... I know with 18:1 Pistons, you can run 20-25 just fine. My boost gauge only goes to 20 anyway. It has a db2, 831 and can't remember the last 4... I turned it up 1/4 turn already.

Looking at a 3" vband on the turbo going into a 4" downpipe and just running strait 4" from there... It's in a jeep so I have plenty of room for a 4" turndown...
 
Theres people out there doing it, but I dont reccomend it. My feeling is set the boost to as high as you need it to clear the sm9ke at wot, no higher. But also keep that boost number within reason. I run 28 on mine, but its a 18:1 direct injected diesel designed for 22 from the factory. Just dont see a reason to push a 6.5 that high.
 
Ba_051 said:
About the boost level now... Would a 6.5 optimizer with head studs handle 15-20 psi of boost?
Click to expand...

Granted we are talking about the HX, but seeing as the ATT was thrown into the mix for comparison . . .


As noted, higher psi comes at a cost of completely going through the motor and getting it ready. Or, just do as some do and boost it until it blows and share the tale :)


With the ATT, I do not see much above 12 psi and got ~245 hp / ~394 tq at the wheels. This is plenty for pulling my 6,500# RV although I'd personally like the torque to come up a bit ;)


On another forum I follow, it seems that the most important part of a turbo charged system is not the intake psi. But rather measuring the pressure difference between the intake and exhaust where lower differences are better (ex: intake psi - exhaust psi = near 0). We kind-of do that here by noting that the GM-X is a restriction which indicates that the pressure difference is high (on the exhaust side).


Back to the point, more pressure does not mean that you are getting a good deal. How well the beast breathes is the important part.
 
With 15 lbs of boost the CFM flow varies from size/design of various turbo compressors.....pressure ratio would still be 2.0 +- elevation.

Sea level we see 14.7 psi atmospheric + 15.0 psi boost (on your gauge) = 29.7 psi actual or 2.0+- pressure ratio.......knowing this you can now look at compressor maps and see the CFM output of almost any given turbo compressor @ 2.0 pressure ratio.
 
Jay's right, and it's "back pressure", also thought about in terms of "flow" or the lack of....

From the valve in the head out the exhaust pipe & everything in between has to do with it... it matters as much in getting the air through & out the motor, not just how much psi going in...
 
Well it's all up and running great. I turned the fuel screw up 1/8 of a turn when it was n/a with the dual 3" and intake mods and it smoked very little at wot...

I just turned it up another 3/8 of a turn, maybe slightly less, and the the boost has maxed out at about 15 psi. My wastegate is supposedly calibrated to open at 18-20 so I am not even using the wastegate. It smokes a little when starting from a stop at wot but clears up once it hits 10-12 lbs of boost. Cruising is around 2 psi at 65 on flat ground...

My EGT's stayed the same driving into town, but dropped nearly 250 degrees driving home after I added the turbo and 4" exhaust. N/a would hit 1100-1150 on the 6% grade and would slow from 65 to 60... Now it runs 850-900 and has a lot of power to spare... I drive from 7000ft (home) to 5000ft (work) every day... It is in a 6200lb jeep truck running 4.56's and 37"s...
 
At that altitude and load, I'm surprised it did much of anything without a turbo. Turbos do lower egt's when sized properly. Sounds pretty good from your numbers.
 
You must log in or register to reply here.
Back
Top