Lowered the boost on the HX40... Questions

Cummins Driver

Cummins Driver

THE Cummins Driver
Joined
May 16, 2007
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I bought a cheap ball and spring boost controller off of ebay the other day and it came today. I have been running with the wastegate unhooked for as long as it has been on the truck and it makes right on 40psi at WOT. I tried hooking up the gate with no elbow before and it was awful. The gate started opening about 15 psi and it didnt come on hard like it does with it unhooked. Took it forever to get to 30psi. So i thought i would try a boost controller. I put it on and took it out for a drive today. I only got on it once, and it spools good and pulls hard still. It doesent start opening the gate early like it was, and is making between 32 and 34psi.

Now for my question... Why does my truck sound like its missing/popping when the gate opens? I noticed it sounded like that before when I had the gate hooked up and it is still doing it with the boost controller on it. Its not smooth sounding. It still has good power, it just doesent sound like it should IMO. When i have the wastegate unhooked it is smooth as glass all the way up and sounds good.

I was hoping to pull the boost down to 36psi or so, but I dont know if i can handle it the way the truck sounds. It seems i have heard other trucks with HX40's that sound the same.

Any ideas?

Eric
 
Could it just be the wastegate opening up and your hearing a different sound that your not used to? Cause that's the only thing I could think of because there's no other reason that a functional wastegate would cause any issues.
 
Yeah, I know it shouldnt make any difference. It sounded fine with the HX35 and the wastegate working.

It just isnt smooth sounding like it is with the gate shut? Im gonna drive it a little more and see what i think about it, but it seems to me it should be as smooth as normal with the gate open.

Eric
 
you're probably making more power now... larger hole... and three cylinders banging out with no muffling from the turbine.

I'd enjoy deafening people next to you in traffic :)
 
I guess the 3 cylinders that are bypassing are what is making it sound different, thats all i can figure, I just dont like the way it sounds as good.:poke: Its pretty noticeable under hard throttle. And i dont understand why my hx35 didnt do it? Im going to drive it some more and see what i think about it. Ill be driving about 60 miles tomorrow, so ill have some time to see how it acts. Thanks for the help

Eric
 
This is pretty much what it sounds like:

YouTube - cummins power

It sounds a lot like that truck up top once the boost gets high enough to open the gate. I cant say im a fan of it.

Here is what it sounded like with the hx35:

YouTube - My 94 Cummins on the Dyno

And it sounded the same as that with the 40's gate unhooked.

Looks like im either going to have to live with it, or unhook it again...

Eric
 
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