Why do diesel trucks spool so loud? I have an hx35...

[gripandslide]

Was just curious why diesel trucks spooled so much louder. I have a hx35 turbo on my car with the silencer ring removed and I still can't hear any spool. My previous car (b5 s4) you could hear the spool clearly out the exhaust.

[nujabe]

heh its dependent on your manifold set up and type of intake system also your motor to as well as exhaust.

[Bmxer300zx]

Idk I have an Rb stock turbo and exhaust manifold. Running a stainless downpipe and a alloy intake pipe my car spools loud as fuck lol. Do you have a rubber intake tube?

[PoorMans180SX]

Was just curious why diesel trucks spooled so much louder. I have a hx35 turbo on my car with the silencer ring removed and I still can't hear any spool. My previous car (b5 s4) you could hear the spool clearly out the exhaust.

This is because the tiny little turbos on the S4 spool practically at idle, when your exhaust is quiet. An HX35 won't spool till a few thousand rpms, where the exhaust is already loud and you can't hear it over the sound.

[gripandslide]

I see, but this same turbo spools so loud on trucks haha.

[shiftdrift]

Because it spools at low rpm on them.

[greatwhitebuffalo]

Seven liters and a 18:1 compression ratio will yield a bit more exhaust pressure than a SR/KA/RB.

[Thedriftbadger]

Just think how much air a 5.9 liter engine with a 16:1 compression ratio moves. Now compare that to your little 2 liter 4 banger.
Diesel turbo's have an mwe (map width enhancement) slot to prevent surging while towing. That's what makes them so loud. I had a first gen cummins with the h1c and no mwe slot and it wasn't very loud, but the second gen trucks are crazy loud cause they have the slot. When it's pushing 20+ psi into a huge diesel there's a ton of air rushing past that slot and it's making all kinds of whistle. When you're boosting like 12psi into a tiny engine it's not even close to the same amount of air and the mwe slot is doing almost nothing so not as much whistle.

[anti tyler]

basically what they're telling you is;

big truck puts out big exhaust=louder turbo.

you would have to restrict your exhaust ports/manifold to like 1/8th inch to get the same result.

(nerds calm down, I know those aren't acurate calculations)

[greatwhitebuffalo]

More exhaust = faster spool
Low RPM = less engine/exhaust noise
spool is more audible.

And probably all that fancy stuff Thedriftbadger was talking about.

[jtthebigguy]

They've got some big ol' turbos on them. My buddies who have big diesels take the "silencer" off their turbos, something in the airbox. Not sure exactly what that is.

[EsChassisLove]

My GTX3076 sounds like a semi truck turbo lol

[jr_ss]

My GTX3076 sounds like a semi truck turbo lol

Good, I'm looking forward to hear sweet turbo cacophony...

[EsChassisLove]

My stainless steel air filter helps with that noise though. It isnt as restrictive as a normal filter.

[gripandslide]

Yeah that makes sense. Took my silencer ring off too thinking I'd hear some kind of spool haha. Oh well.

[fliprayzin240sx]

Plus, do you have any idea how much boost most diesel trucks spool at stock? A Dodge Cummings truck spools at 36-38 psi stock...