Riddle me this

[FordGuy100]

So, I went over to a friends house Saturday, and wrenched on it with him. Anyways long story short, we opened that thing up open headers (Crate 350, 330hp 370ft lbs of torque), and that thing was so fricking loud at idle, and insane going down the road.

Anyways, when we put the turbo on my truck, we fired it up open exhaust manifolds so I could move the truck and push out all the metal shavings from when we drilled and tapped the manifold for the pyro. It sounded like a big block with glass packs and wasnt all that loud at all. Granted I didnt rev it or anything, but it just seemed way quiter than my friends small block.......so whats the deal?

 

[85hauler]

Pipes and or mufflers will dampen sound a certain percantage at a certain flow rate. Lower the volume (flow) of exhaust gasses and it will dampen less. Raise the volume and it will dampen more. Think of it as pouring 90w thru a funnel compared to 30w. A larger motor puts out a larger volume of exh gasses compared to a smaller motor. So in your case you have a 420 c.i. motor pushing out of exhaust manifolds with a single small outlet compared to a 350 with with 1 7/8" pipes going into a large 3" collecter there will be a huge sound difference. If you were to bolt those same headers to a larger motor it would be somewhat quieter and if you were to bolt them to a smaller motor it would be even louder.

 

[92F350CC]

Which is why honda civics with fart cans are too F$$$$$ loud.

 

[poolguy]

Which is why honda civics with fart cans are too F$$$$$ loud.

I thought Civics were just wheel chocks at Wal-mart!

Chuck

 

[82F100SWB]

I had to move my truck while I had the DS exhaust manifold off to change the studs... It was barely louder than it is through the turbo and straight pipe at idle with no manifold at all, until I gave it a little fuel... Then that was a different story... .

 

[sootman73]

when i had my cross over pipe off for my pyro i started it up just to see how loud it was. mind this was with only one open manifold as the other side was still connected to the turbo. i started her and it had a nice rumble but wasn't real loud. at least until i revved it up! loud as hell! especially in the relatively small shop i was in. it roared and woke my friends dad up who was sleepin in the basement of the house! he came out to see what happened real quick.

 

[Agnem]

God help you if you put a load on that diesel and open it up.....

There is no comparison between a gas and diesel engine at idle.

 

[sle2115]

God help you if you put a load on that diesel and open it up.....

There is no comparison between a gas and diesel engine at idle.

I was going to say the same thing. When I put my 3 inch y pipe on, I had ordered a stainless flex joint that was 3 inch ID. When I got it, it was 3 inch od, so I had to send back/exchange, etc. Anyway, with just the y pipe on there, I moved my neighbors big tractor up to the club on my trailer. Was not bad at all until I started up the hill to the club. It is long and pretty steep. By the time we got to the top, I had to stop and let my ears stop ringing! I sounded AWESOME, well, at least as long as I could hear! But it was VERY loud! I ran both small and big blocks with stubbies, open headers and such and what the small engines gain at idle is quickly lost under duress to the big boys!

 

[FordGuy100]

Alright I see. I was thinking why the heck was his so much louder at idle over mine, but it makes sense now. I didnt try revving my truck open exhaust manifold because there were some other guys in Russ's shop, and I didnt want to **** them off in cause they were his boss or something. I really wish I would have then, but oh well. I suppose mine is pretty loud high up in the rpm's, when I pass somebody the echo off there rig and back into mine is pretty loud.

 

[tractorman86]

I suppose mine is pretty loud high up in the rpm's, when I pass somebody the echo off there rig and back into mine is pretty loud.

that is the coolest sound isn't it . ill lay into it just to make myself smile sometimes next to trucks and buildings.

 

[gamudslinger88]

Let me get this right. You want to know why a strait piped turboed diesel is quieter than a open header small block chevy, or any gasser for that mater. Its because a turbo will absorbe alot of the sound, A flowmaster uses the sound waves to cancel themselves out right, a turbo does the same thing in essence. Open headers are louder than strait pipes with no mufflers bacause the sound bounces around and deletes itself before exiting into the world. plus a 350 pushing them numbers is atleast 9.5 to one compression which is on the high side for a gasser with iron heads(and I mean high as in having to run premium gas). The higher the compression the louder the bang. I would imagin a 6.9 with open headers would ring your ears it would be so loud. Manifolds are quieter than headers also. hopes this helps, sorry so jumbled up Im in a hurry

 

[FordGuy100]

Let me get this right. You want to know why a strait piped turboed diesel is quieter than a open header small block chevy, or any gasser for that mater. Its because a turbo will absorbe alot of the sound, A flowmaster uses the sound waves to cancel themselves out right, a turbo does the same thing in essence. Open headers are louder than strait pipes with no mufflers bacause the sound bounces around and deletes itself before exiting into the world. plus a 350 pushing them numbers is atleast 9.5 to one compression which is on the high side for a gasser with iron heads(and I mean high as in having to run premium gas). The higher the compression the louder the bang. I would imagin a 6.9 with open headers would ring your ears it would be so loud. Manifolds are quieter than headers also. hopes this helps, sorry so jumbled up Im in a hurry

No I had it running open exhaust manifolds to move the truck and push all the metal shavings out because we drilled the exhaust manifold for the pyro. The turbo wasnt on it yet.

 

[gamudslinger88]

No I had it running open exhaust manifolds to move the truck and push all the metal shavings out because we drilled the exhaust manifold for the pyro. The turbo wasnt on it yet.

Ohh...........never mind;p