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77 K5 Just had to do it

Overview Gallery Discussion
ZooMad75 said:
Looking good! When are you getting the exhaust done?
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I am taking it to the exhaust shop Tuesday morning. I spoke with 2 different shops and they both said 2 1/2" should be fine considering I plan on running dual exhaust. I admit to not knowing much about the science of exhaust and have read a few of the threads here.
Opinions are welcome!
Sound is bit of a weird subject for me as I am legally deaf so performance means more to me.
This was a no emissions rig from the factory so cats are not required.
No mufflers with dual cats?
Turbo style mufflers with side exits?
Stacks thru the hood? (I joke of course)
2 1/2 or 3 inch?
At this point cost is secondary to performance.
"I would rather pay once cry once."
 
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Capt Ron said:
I am taking it to the exhaust shop Tuesday morning. I spoke with 2 different shops and they both said 2 1/2" should be fine considering I plan on running dual exhaust. I admit to not knowing much about the science of exhaust and have read a few of the threads here.
Opnions are welcome!
Sound is bit of a weird subject for me as I am legally deaf so performance means more to me.
This was a no emissions rig from the factory so cats are not required.
No mufflers with dual cats?
Turbo style mufflers with side exits?
Stacks thru the hood? (I joke of course)
2 1/2 or 3 inch?
At this point cost is secondary to performance.
"I would rather pay once cry once."
Click to expand...
I did all the calcs a few years back to find what I needed to run on a 475 horse 406.
Basically around 450hp is when you actually need to step up to a 3 inch pipe dual exhaust. So if your running a 250hp 350, 3 inch pipe is basically a waste of money. If you need to see the research I can redo the calcs for you.
 
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beags86 said:
I did all the calcs a few years back to find what I needed to run on 475 horse 406.
Basically around 400hp is when you actually need to step up to a 3 inch pipe dual exhaust. So if your running a 250hp 350, 3 inch pipe is basically a waste of money. If you need to see the research I can redo the calcs for you.
Click to expand...
I like math
 
2.5 is what Larry has on the K10 in true duals with an h-pipe. Ian went with 2.5 on his 8.1 Blazer too.

I think 2.5 in duals would be enough for the L29 to run fine. I think 2.25 would work as long as it is duals. Plus packaging is easier going past the t case on the pass side. I'm curious @beags86 run the number on 2.25 duals for his combo and see if it's choking it down too much or not?

The h-pipe that Larry and I have on ours is more for tone than power. The sound of a LS or 8.1 (same firing order, but not the same as the og sbc or BBC) have a different tone with true duals we found. With the h-pipe it sounded better to us. Your results may vary...even more so if you can't hear it!
 
Bent77 said:
Crabby patty
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No, not since I found that chart. Which I hadn't found before. It's pretty close. I remember a couple numbers from when I did my calcs longhand. I wish I would have stumbled on that before. It's close enough to give you an actual idea. Of course you kinda have to be honest with your of what kinda power you are making. Not everyone has a Dyno sheet for their engine at the ready.
 
beags86 said:
No, not since I found that chart. Which I hadn't found before. It's pretty close. I remember a couple numbers from when I did my calcs longhand. I wish I would have stumbled on that before. It's close enough to give you an actual idea. Of course you kinda have to be honest with your of what kinda power you are making. Not everyone has a Dyno sheet for their engine at the ready.
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Those numbers are consistent with what I've seen before. But yeah, butt dyno numbers are great
 
So correct me if I'm reading the chart right or wrong. A L29 is factory rated at 290hp/410lb/ft so he'd be good for 2.25" duals or step up to 2.5" for future gains.

Am I right?
 
I just spent about 1 hour really checking out the real estate or I should say the lack of real estate underneath. Fuel lines, front driveshaft, t- case brace etc....
I am now wondering maybe 3" single with a dual exit muffler might be best. If I am reading beags chart correctly one 3" pipe is good to 339hp.
 
Capt Ron said:
I just spent about 1 hour really checking out the real estate or I should say the lack of real estate underneath. Fuel lines, front driveshaft, t- case brace etc....
I am now wondering maybe 3" single with a dual exit muffler might be best. If I am reading beags chart correctly one 3" pipe is good to 339hp.
Click to expand...
Really analyze the path for that. I know @skunked and many others have mooshed the pipe with the driveshaft where it crosses over. After much debate I stayed dual
 
Capt Ron said:
I just spent about 1 hour really checking out the real estate or I should say the lack of real estate underneath. Fuel lines, front driveshaft, t- case brace etc....
I am now wondering maybe 3" single with a dual exit muffler might be best. If I am reading beags chart correctly one 3" pipe is good to 339hp.
Click to expand...
If I had mine to do over again, I'd stay duals but run them both down the left side like Larry did on the Suburban. I'll look at his flicker page to see if he has the routing on it.
Here's one of the Burb.
26252361254_4a24c6625c_b.jpg


Closer up to the engine.
24033454972_55b1f3cf3c_b.jpg


Running down the drivers side will save a lot of bs dealing with the heat near the fuel system. Plus as you found it gets darn scarce for real estate around the t-case.
 
One from mine during the guy putting mine together. It's way tight even with 2.25" pipe.
39182331282_cbbf2c38ca_b.jpg
 
Bent77 said:
Really analyze the path for that. I know @skunked and many others have mooshed the pipe with the driveshaft where it crosses over. After much debate I stayed dual
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I did wonder about that. If I run single the crossover would be pretty much directly under the bellhousing. The rain sent me inside for the night. I will get some measurements tomorrow.
 
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Capt Ron said:
I did wonder about that. If I run single the crossover would be pretty much directly under the bellhousing. The rain sent me inside for the night. i will get some measurements tomorrow.
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I have pictures in my thread of how I went over the t case

Long story short, you are going to compromise something
 
ZooMad75 said:
Running down the drivers side will save a lot of bs dealing with the heat near the fuel system.
Click to expand...
L29 fuel lines come off of the drivers side of the engine and like a total newb I ran my fuel lines along the drivers side frame rail.
At the time I had visions of running fenderwell headers [I know I know] but Maddog would not make me a custom set of headers that dumped back instead of down towards the ground. I was willing to pay whatever it took as I am a pretty big fan of fenderwell headers but they flat said no.
I am amazed Larry had enough room to run duals on the drivers side, that looks good. Maybe I could try that and if it gave me heat soak on the fuel lines I could install some shields or move the fuel lines.
 
Sleeve the fuel lines with some heat sleeve. Summit sells some that uses Velcro, used a bunch on my truck for fuel lines, trans lines and shifter cables.
 
I think if you've got the fuel lines running down the drivers side I wouldn't stack duals down that side. Maybe a two 2.5" pipes if you have both sides combined in a "Y" pipe by the trans to a single 3" pipe out to the muffler.

Or run true duals.

I'd do at least this. When you take it over to the exhaust guy have him get it up in the air and give him the layout you would like best and get his take on the idea. He should be able to tell you what will easier or harder to build with your packaging.
 
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