Exhaust ideas? 250 I6 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jfw432 · 12-11-2014, 09:58 AM

I realize the 6 cylinders won't sound like a big V8. However, the exhaust on my 79 C10 looks like a total hack job and the pipes have been crushed from being lowered previously so it needs to replaced.

I'd like it to sound a little more meaty or at least like an older truck. All i really hear now is transmission whine. I was thinking of a Flowmaster 50 or a thrush muffler.

The main question is will a high flow cat help with sound? If not, would deleting the cat help (no emissions here and I rarely drive the truck)? One last question if deleting the cat, would it help to cut the stock headers before the flange and run duals with a H or X crossover?

jfw432 · 12-12-2014, 07:55 PM

No one?

Oregoon · 12-12-2014, 08:55 PM

Probably what you're hearing is gear-whine from your timing set. It resounds throughout the drivetrain, and it's music!

I hope you have an early-style non-integral head, wherein your exhaust manifold is NOT a cast in part of your head?

If so, there's a variety of split-headers that you can run with or without a balance tube or cross-over, and with the discharge and muffler considerations tuned to your particular liking.

If you do have an integral head, there's no reason why you can't still run a new pipe with a less-restrictive muffler, though you should look into the emissions requirements in your area.

Let us know what you're working with, and I'm sure there will be suggestions galore!

Best of luck.

jfw432 · 12-12-2014, 10:05 PM

It's really hard for me to see but one guy on here was thinking I had the integral head. I do think the gear whine is a cool sound but need to redo the exhaust regardless and it seems silly to put stock back on.

slotard · 12-12-2014, 10:14 PM

The cat muffles the exhaust quite a bit.

I have a pretty generic full exhaust on my C20 (with a 350), a pair of these:

Amazon.com: Thrush 17713 Turbo Muffler: Automotive and it sounds nice. Be aware that what cam you have makes a lot of difference in sound as well, a bigger cam will sound a lot meaner. Mine's a Comp Cams 252H grind and it's very mild, no lope, lots of torque. You could go with something like what I have or a 260H if you wanted a bit of a lope.

Oregoon · 12-13-2014, 03:41 AM

If you have a stock '79, then you do have an integral head.

If you want headers and your state's emissions requirements will allow it, then you'll need to swap on a '74 or earlier head.

If you don't want to go that route, I'd suggest nothing more than a stock diameter pipe and a less restrictive muffler.

lilpoindexter · 12-13-2014, 03:35 PM

I have the integrated head on my '78...I hoped it doesn't ever crack

I kept the exahust in front of the cat, and it has a universal replacement cat (California) with a single 50 series flowmaster with 2.5" pipe. It sounds killer. When I'm under a bridge or other enclosed area, I goose the exhaust and I can drown out everybodys stereo.

jfw432 · 12-13-2014, 05:34 PM

Quote:

Originally Posted by lilpoindexter

I have the integrated head on my '78...I hoped it doesn't ever crack

I kept the exahust in front of the cat, and it has a universal replacement cat (California) with a single 50 series flowmaster with 2.5" pipe. It sounds killer. When I'm under a bridge or other enclosed area, I goose the exhaust and I can drown out everybodys stereo.

Awesome! Thanks for this information. I'll probably go this route.

Oregoon · 12-13-2014, 09:20 PM

Wise to keep things stock near the head... While the integrated set-up gets a bad rap, it is a well known weak-link in an otherwise bulletproof engine.

If you do wind up with head-troubles, the early switcheroo is a relatively painless task. My buddy had a '78 250-6 in his '63 Willys Wagon, and we axed the cracked head for an earlier model. Took a few days of dicking around, but it ran like a champ.

Oregoon · 12-13-2014, 09:22 PM

Wise to keep things stock near the head... While the integrated set-up gets a bad rap, it is a well known weak-link in an otherwise bulletproof engine.

If you do wind up with head-troubles, the early switcheroo is a relatively painless task. My buddy had a '78 250-6 in his '63 Willys Wagon, and we axed the cracked head for an earlier model. Took a few days of dicking around, but it ran like a champ.

franken · 12-14-2014, 12:06 AM

Just a WAG, but try running with the cat and no muffler for a bit and see how loud it is? If the cat isn't bothering you, why not have it and reduce emissions?
I've had (dating myself) vehicles w/ full length exhaust using glasspacks and they were quiet in the car, but had a nice rumble outside.
As an aside, the GM straight six is a great engine, as are most since they were used for about 50 years.

Oregoon · 12-14-2014, 01:26 AM

Apologies for the double-post... It seems I'm having some PC troubles.

My shenanigans aside, as the above poster noted, the GM inliner is proven platform, and as the OP noted, it's not a big V8, which is why it's so much fun to work on: Tons of applications and mods, great torque, and best of all, so much room under the hood!

Post up some photos, please.

ChevDog1 · 12-19-2014, 12:54 AM

Check out my build thread. I'm running true duals on my 250.

ChevDog1 · 12-19-2014, 11:32 AM

https://www.youtube.com/watch?v=Q7ZLvxnwSl4

This is how mine sounds right now. It may be a bit loud in the cab for daily driving. I'm thinking about running the tailpipes out the back.

ECU PIRATE · 12-21-2014, 11:10 AM

Quote:

Originally Posted by ChevDog1

https://www.youtube.com/watch?v=Q7ZLvxnwSl4

This is how mine sounds right now. It may be a bit loud in the cab for daily driving. I'm thinking about running the tailpipes out the back.

I like the sound. I have been saving (2) Flowmaster Super 44's from my last project. Thinking about putting them in the 73' behind some Hedman inline 6 headers

Oregoon · 12-21-2014, 01:28 PM

Quote:

Originally Posted by ChevDog1

https://www.youtube.com/watch?v=Q7ZLvxnwSl4

This is how mine sounds right now. It may be a bit loud in the cab for daily driving. I'm thinking about running the tailpipes out the back.

That sounds awesome!

ChevDog1 · 12-21-2014, 07:56 PM

Quote:

Originally Posted by Oregoon

That sounds awesome!

Thanks - it's a bit loud with the windows down - and just tolerable with them up. I'll decide after driving it for a bit if I want to run it out the back. I like the sound, it's just a little to close to my ears.

jfw432 · 12-22-2014, 10:12 PM

I'm really impressed with the Flowmaster 50 Delta Flow so far! This one is the 2.5" version hooked straight to the header. I had to remove the catalytic converter for now because it was literally falling apart when I was cutting the pipes behind it. Haven't driven it yet because it started raining and I still need to finish securing the muffler and removing the old tailpipe. Either way, it sounds way more meaty than I was expecting.

I really didn't rev it much because it was a cold start and it really doesn't like revving in the first 30-45 seconds.

http://youtu.be/qRHVhnuZnLw

12-11-2014, 09:58 AM	#1
jfw432 Registered User Join Date: Nov 2014 Location: Lizella Posts: 41	Exhaust ideas? 250 I6 I realize the 6 cylinders won't sound like a big V8. However, the exhaust on my 79 C10 looks like a total hack job and the pipes have been crushed from being lowered previously so it needs to replaced. I'd like it to sound a little more meaty or at least like an older truck. All i really hear now is transmission whine. I was thinking of a Flowmaster 50 or a thrush muffler. The main question is will a high flow cat help with sound? If not, would deleting the cat help (no emissions here and I rarely drive the truck)? One last question if deleting the cat, would it help to cut the stock headers before the flange and run duals with a H or X crossover?

12-12-2014, 07:55 PM	#2
jfw432 Registered User Join Date: Nov 2014 Location: Lizella Posts: 41	Re: Exhaust ideas? 250 I6 No one?

12-12-2014, 08:55 PM	#3
Oregoon Roadside Rebuilder Join Date: Oct 2008 Location: Southeast Portland, OR Posts: 421	Re: Exhaust ideas? 250 I6 Probably what you're hearing is gear-whine from your timing set. It resounds throughout the drivetrain, and it's music! I hope you have an early-style non-integral head, wherein your exhaust manifold is NOT a cast in part of your head? If so, there's a variety of split-headers that you can run with or without a balance tube or cross-over, and with the discharge and muffler considerations tuned to your particular liking. If you do have an integral head, there's no reason why you can't still run a new pipe with a less-restrictive muffler, though you should look into the emissions requirements in your area. Let us know what you're working with, and I'm sure there will be suggestions galore! Best of luck. Last edited by Oregoon; 12-12-2014 at 09:01 PM.

12-12-2014, 10:05 PM	#4
jfw432 Registered User Join Date: Nov 2014 Location: Lizella Posts: 41	Re: Exhaust ideas? 250 I6 It's really hard for me to see but one guy on here was thinking I had the integral head. I do think the gear whine is a cool sound but need to redo the exhaust regardless and it seems silly to put stock back on.

12-12-2014, 10:14 PM	#5
slotard Registered User Join Date: Nov 2014 Location: Alameda, CA Posts: 877	Re: Exhaust ideas? 250 I6 The cat muffles the exhaust quite a bit. I have a pretty generic full exhaust on my C20 (with a 350), a pair of these: Amazon.com: Thrush 17713 Turbo Muffler: Automotive and it sounds nice. Be aware that what cam you have makes a lot of difference in sound as well, a bigger cam will sound a lot meaner. Mine's a Comp Cams 252H grind and it's very mild, no lope, lots of torque. You could go with something like what I have or a 260H if you wanted a bit of a lope. __________________ 1973 C20, 350/350

12-13-2014, 03:41 AM	#6
Oregoon Roadside Rebuilder Join Date: Oct 2008 Location: Southeast Portland, OR Posts: 421	Re: Exhaust ideas? 250 I6 If you have a stock '79, then you do have an integral head. If you want headers and your state's emissions requirements will allow it, then you'll need to swap on a '74 or earlier head. If you don't want to go that route, I'd suggest nothing more than a stock diameter pipe and a less restrictive muffler.

12-13-2014, 03:35 PM	#7
lilpoindexter Registered User Join Date: Sep 2010 Location: los angeles Posts: 1,136	Re: Exhaust ideas? 250 I6 I have the integrated head on my '78...I hoped it doesn't ever crack I kept the exahust in front of the cat, and it has a universal replacement cat (California) with a single 50 series flowmaster with 2.5" pipe. It sounds killer. When I'm under a bridge or other enclosed area, I goose the exhaust and I can drown out everybodys stereo.

12-13-2014, 09:20 PM	#9
Oregoon Roadside Rebuilder Join Date: Oct 2008 Location: Southeast Portland, OR Posts: 421	Re: Exhaust ideas? 250 I6 Wise to keep things stock near the head... While the integrated set-up gets a bad rap, it is a well known weak-link in an otherwise bulletproof engine. If you do wind up with head-troubles, the early switcheroo is a relatively painless task. My buddy had a '78 250-6 in his '63 Willys Wagon, and we axed the cracked head for an earlier model. Took a few days of dicking around, but it ran like a champ.

12-13-2014, 09:22 PM	#10
Oregoon Roadside Rebuilder Join Date: Oct 2008 Location: Southeast Portland, OR Posts: 421	Re: Exhaust ideas? 250 I6 Wise to keep things stock near the head... While the integrated set-up gets a bad rap, it is a well known weak-link in an otherwise bulletproof engine. If you do wind up with head-troubles, the early switcheroo is a relatively painless task. My buddy had a '78 250-6 in his '63 Willys Wagon, and we axed the cracked head for an earlier model. Took a few days of dicking around, but it ran like a champ.

12-14-2014, 12:06 AM	#11
franken Registered User Join Date: Jun 2013 Location: Somewhere Posts: 3,148	Re: Exhaust ideas? 250 I6 Just a WAG, but try running with the cat and no muffler for a bit and see how loud it is? If the cat isn't bothering you, why not have it and reduce emissions? I've had (dating myself) vehicles w/ full length exhaust using glasspacks and they were quiet in the car, but had a nice rumble outside. As an aside, the GM straight six is a great engine, as are most since they were used for about 50 years.

12-14-2014, 01:26 AM	#12
Oregoon Roadside Rebuilder Join Date: Oct 2008 Location: Southeast Portland, OR Posts: 421	Re: Exhaust ideas? 250 I6 Apologies for the double-post... It seems I'm having some PC troubles. My shenanigans aside, as the above poster noted, the GM inliner is proven platform, and as the OP noted, it's not a big V8, which is why it's so much fun to work on: Tons of applications and mods, great torque, and best of all, so much room under the hood! Post up some photos, please.

12-19-2014, 12:54 AM	#13
ChevDog1 Registered User Join Date: Aug 2013 Location: Banks, OR Posts: 497	Re: Exhaust ideas? 250 I6 Check out my build thread. I'm running true duals on my 250.

12-19-2014, 11:32 AM	#14
ChevDog1 Registered User Join Date: Aug 2013 Location: Banks, OR Posts: 497	Re: Exhaust ideas? 250 I6 https://www.youtube.com/watch?v=Q7ZLvxnwSl4 This is how mine sounds right now. It may be a bit loud in the cab for daily driving. I'm thinking about running the tailpipes out the back.

12-22-2014, 10:12 PM	#18
jfw432 Registered User Join Date: Nov 2014 Location: Lizella Posts: 41	Re: Exhaust ideas? 250 I6 I'm really impressed with the Flowmaster 50 Delta Flow so far! This one is the 2.5" version hooked straight to the header. I had to remove the catalytic converter for now because it was literally falling apart when I was cutting the pipes behind it. Haven't driven it yet because it started raining and I still need to finish securing the muffler and removing the old tailpipe. Either way, it sounds way more meaty than I was expecting. I really didn't rev it much because it was a cold start and it really doesn't like revving in the first 30-45 seconds. http://youtu.be/qRHVhnuZnLw

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