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#1 |
Nobody rides free
![]() Join Date: May 2005
Location: PA
Posts: 1,076
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Hey all, I've got a question for you. My '71 c10 is due for inspection end of Aug. & I need new headers & mufflers. I think I've decided on Hedman ceramic coated headers, & Flowmaster delta 40's. My dilemma is, I already have all stainless pipe that is still good but it's 2 1/4" dual & the headers are 3" out & I only see the flowmasters in 2 1/2" or 3" in the stainless ones. So I don't know if I should just scrap my good pipe & get dual 3" (my buddy's suggestion) or have the guys @ the ehaust shop use my pipe where they can & scab it all together in 2 1/4". I've been reading old threads tryin' to come up with something but just can't decide, I read somewhere 3" duals would be too much for a mild 350.... but this is a pretty stout 400sb so would it be ok? Any help would be appreciated.
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'71 C10 LWB 400SB/350TH ![]() '86 K2O LWB 350SB/400TH-6" tuff country lift, Shackle flip - plow truck '06 HHR - wifes wheels '01 Blazer - daily driver "It's better to burn out than it is to rust." -Neil Young |
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#2 |
Registered User
Join Date: Jul 2005
Location: DFW
Posts: 463
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Unless you're running a ton of power, I would not recommend 3 inch. I would say at LEAST 500 whp. If you're not there, you'll probably lose quite a bit of bottom end power.
Here's what I'd do: Have the shop expand your 2.25" pipe out where it mates to the nw 2.5" muffler. If you have dumps, replace them with 2.5", otherwise they can expand the pipe on the exit as well. When I upgraded from 2.25" to 3" on my Civic, it made a tremendous difference, but I was putting out a little over 300 whp on 4 cylinders. I guess that'd be about equivalent to about 600 whp on a V8 ![]() |
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#3 |
Registered User
Join Date: Jun 2005
Location: Sacramento CA
Posts: 1,255
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If you splice your 2.5" headers to a 2 2.5" tailpipe you effectivevly have a 2.25" exhaust system. If you want to do it once and do it right then build a new 2.5" system. If you want you can go to 3" after the mufflers. If you want performance you should consider an 'X' pipe, not an 'H' pipe. An 'H' pipe is manily for balance and tone. An 'X' pipe will add a little bit better performance if you like to challenge your engine plus it looks killer.
Summit online catalog 2.5" X pipe http://store.summitracing.com/defaul...=egnsearch.asp 3.0" X pipe http://store.summitracing.com/defaul...=egnsearch.asp H pipe http://store.summitracing.com/defaul...=egnsearch.asp
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Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck. |
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#4 |
Nobody rides free
![]() Join Date: May 2005
Location: PA
Posts: 1,076
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Is anyone with a 400 sb running a 3" system?
I just don't want to pay more for the 3" and then have it bog my low end. Will I notice a difference? Will it harm the engine in any way? I guess I just don't really understand what the advantages & disadvantages are. I'm thinking @ this point I'd be best to get the 2.5" headers & muffler & have the shop adapt them to my 2.25" pipe I have now.??? Feed back please.
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'71 C10 LWB 400SB/350TH ![]() '86 K2O LWB 350SB/400TH-6" tuff country lift, Shackle flip - plow truck '06 HHR - wifes wheels '01 Blazer - daily driver "It's better to burn out than it is to rust." -Neil Young |
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#5 |
Tot Roddin'
Join Date: Apr 2005
Location: Mid-MO
Posts: 24,461
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I'm in the same situation, except, my engine is not built yet...
I also have a sb400, and am considering exhaust. I'm considering 3" as well, but I've read on the board that 3" might be to much. So now I'm leaning to 2.25" or 2.5" exhaust pipe. I'm considering an X pipe, but I'm not sure how to it since I am also planning on running electric cutouts, and possibly turn downs or go an ahead and run it out the back. It will be kind of a confusing exhaust system to build, if it's even possible. Good luck bowtier.
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-Nate ![]() 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package) |
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#6 |
Nobody rides free
![]() Join Date: May 2005
Location: PA
Posts: 1,076
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Good luck to you too 72B.B......
So, anyone else able to offer some advice?????????????
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'71 C10 LWB 400SB/350TH ![]() '86 K2O LWB 350SB/400TH-6" tuff country lift, Shackle flip - plow truck '06 HHR - wifes wheels '01 Blazer - daily driver "It's better to burn out than it is to rust." -Neil Young |
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#7 |
The LuvShack Garage
Join Date: Jan 2004
Location: Maple Grove, TN (West Side)
Posts: 30,477
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Some advice to go by, look at this HP chart (Flowmaster's chart from their Dealer book)
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Owner/Op: "TN Classic Transport Carriers" The Toy: "Square Vette" 72 Hybrid Blazer Toy Barn: "LuvShack" 40 x 60 x 20 Shop Tow Piggy:"Maddy" 88 Silverado 3500 Hauler: "Feathers" 14 Aluma 8218T |
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#8 |
Tot Roddin'
Join Date: Apr 2005
Location: Mid-MO
Posts: 24,461
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So GQ, if I'm running a SB400, and I want to run in the future at least 400HP, should I go with 2.5" or 3"?
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-Nate ![]() 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package) |
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#9 | |
The LuvShack Garage
Join Date: Jan 2004
Location: Maple Grove, TN (West Side)
Posts: 30,477
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Quote:
Your right on the edge, you could go either way, 3" sounds mean, but it cost more than 2.5" if it is a P/U I say go 3", 2.5" if it is a BLAZER, only because a Blazer has alot less room to run tail pipes out the back in 3" it can be done, I have seen it, but it just looks 2 cramed to me, JMHO
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Owner/Op: "TN Classic Transport Carriers" The Toy: "Square Vette" 72 Hybrid Blazer Toy Barn: "LuvShack" 40 x 60 x 20 Shop Tow Piggy:"Maddy" 88 Silverado 3500 Hauler: "Feathers" 14 Aluma 8218T |
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#10 |
Nobody rides free
![]() Join Date: May 2005
Location: PA
Posts: 1,076
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Thanks a lot LUV2XCLR8. It's much easier to make a decision when I can see it in black & white. I don't think I'm makin' enough power right now to justify a 3", maybe I will in the future though..... Guess I'll just check out the price diff. & then maybe flip a coin.
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'71 C10 LWB 400SB/350TH ![]() '86 K2O LWB 350SB/400TH-6" tuff country lift, Shackle flip - plow truck '06 HHR - wifes wheels '01 Blazer - daily driver "It's better to burn out than it is to rust." -Neil Young |
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