Quote:
Originally Posted by NastyBuzzard
Ahh I see. I am just trying to figure out how I will have to do it or what I will need. I am supposed to be picking up my NV4500 today. It has the bellhousing on it for the 6.5 which from my research should bolt up to any standard SBC bolt pattern. I think the hydraulic clutch setup is on the passenger side though or something. I see you used the AA bellhousing.
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Correct, the 6.5L bell is no different than any other SBC or BBC. You didn’t mention if your ’88 crew cab already has a manual trans or not. If so, you already have the hydro pedals but the master cylinder for the square bodies is not compatible with the slave that would be on the passenger’s side on a factory NV4500 bellhousing. That is the exact reason why I use the AA bells on my K10 and Burb….so I can use the square body specific driver’s side mount slave cylinder and off the shelf factory GM square body hydro hose. AA has two bell housings as well, one for the 1 gen NV4500 and another for the second gen (trans to bell mounting holes are different). If you go the route of the AA bell you’ll need to determine what year your NV4500 is. Pretty much it comes down to if the NV4500 has the deep granny gear and the shift lever that push and twists on you have the 1st gen. If the shift tower is held on by 4 bolts and the lever itself screws on to the tower then you have the second, which would be the same that I have in both of mine. Personally, I would not use a factory GMT400 bellhousing on a square body due to the slave location and the way the hydro hose is connected (square bodies have screw in fittings and GMT400 have push in). Outside of creating a custom hose, there is no a hydro hose with a screw in fitting on the m/c side and push in on the slave side.
Quote:
Originally Posted by 83GMCK2500
Hi Larry, I've read through this thread, the NV4500 swap thread, and the 8.1 install thread for the K10 and I have some questions for you. I'm looking for big block exhaust recommendations/advice and your threads were the first that came to mind. I am past due for exhaust on my '96 and after reading through your threads I recognize you've got a lot of big block experience. If you have the time or inclination to impart any exhaust wisdom upon me, I would appreciate it. If you would like to reply back to me in my thread on my '96 instead of cluttering your thread that works for me.
I've got just under 290k miles on my truck and for the last 20k or so I've had something rattling in the muffler, I assume a weld has broken internally. It's obnoxious and I find it embarrassing.
Ultimately, when this is no longer my daily driver, I'd like to freshen up the engine, rebuild the heads, and put a more aggressive cam in it, injectors, 0411 ECM swap and tune. I would like to replace everything from the manifolds back and I'm considering a dual in/out muffler (unless otherwise recommended), at this time I'm looking at the oval 5x11 Magnaflow mufflers. Unless absolutely recommended I wasn't going to do headers at this time. When the time comes for those, this shop is local to me. I'm open to not replacing the cats, I'm prepared to have it tuned for that (now) or dummy O2 sensors.
The questions I haven't been able to find the answers for: what size exhaust to run on a big block, what kind of backpressure/velocity/flow characteristics are ideal? Do I use two separate mufflers but incorporate an x-/h-pipe before them or is the Mf 5x11 with internal x sufficient? I'm shooting for "not obnoxious at highway speeds" but sounds good if I get on it. I would think that my wheelbase (will take exhaust to behind duals with stock appearance) will help quiet it. With my gearing I'm running ~2,500RPM +/- 100-150 on the highway, depending on speed limit. The muffler is available in/out: 2.5/2.5, 3/2.5, or 3/3. What size do you think is appropriate? In my research to try and find what size exhaust you used on your vehicles I came across your L18 swap resource thread on CK5 and I read about the redesigned cat. converters on the '06+ vehicles. Should I try and source a pair of the new ones? Lastly, I'll be using mandrel bent tubing for the bends. |
Hey Devin,
Cool! Sounds like a fun project. Yeah, the guts probably came loose on your muffler. I had a 2005 Silverado HD that did the same thing…..very annoying. Regarding the cats, if you can get away with replacing the cats with a “test” pipe like I have on my Suburban (wink, wink) you could have whoever is doing the ECM tuning just tune out the rear sensors instead of dummy sensors.
Regarding exhaust pipe size for a BBC, it seems the preferred size is 2.5” where claims of 3” or bigger takes too much back pressure way equaling loss of low end torque and anything smaller is too restrictive. I couldn’t really tell you on velocity/flow characteristics as that seems to be what appeals to each person’s ear but I can tell you that an older BBC, like the Vortec 454 you’re working on, requires a completely different muffler/exhaust configuration than an LS engine or even an 8.1L due to the different firing orders of the newer engines (1-8-7-2-6-5-4-3) compared to the older engines (1-8-4-3-6-5-7-2). The newer firing order engines absoluty need an H, X or x-muffler to sound right, otherwise they wound sounding like two poorly running 4 bangers having a shootout while the older engines like yours sound darn good with true duals, with two individual mufflers. I personally have never had an H or X pipe in an older firing order engine as I always thought they sounded good just plumbed the old school way (twice pipes with two mufflers).
My K10 has true duals, H-pipe and two individual Thrush mufflers (Cheap $30 Flowmaster knock offs). This same exhaust was on the truck when it had a 454 and sounded great but once I swapped in the 8.1L with the different firing order it sounded horrible. Added the H-pipe and now it sounds like a mix between a 60’s muscle car at WOT, cackle of a medium duty truck at low RPM and a Ferrari at cruise. Very weird, but it sounds awesome to my ear. Meanwhile, the Burb’s 8.1L is running a dual inlet/dual outlet Magnaflow X-muffler (can’t remember the exact name and I’m not home to look up the part number) but it sounds great with zero drone found with the typical dual inlet/outlet mufflers. Really quiet idle and cruise but it has a set of LUNGS at WOT almost like there is an exhaust cut out welded in somewhere. The videos posted of my Suburban are not the new Magnaflow exhaust but the old out 2” Flowmaster that sounded great with a 350 but a 50 caliber machine gun spinning at 50,000 RPM’s with an 8.1L. It was horrible. If it were me with an L29 454, I would go with cat “test” pipes and 2 individual Flowmasters or Thrush Flowmaster knock-offs (not a dual inlet/dual outlet muffler). Dual inlet/dual outlet on a 1-8-4-3-6-5-7-2 engine makes way too much interior drone for my liking. Dealt with that on my old ’98 Z71. Not sure if that helps you or adds more to the confusion but that I my offering to your question. I’m sure the heck no exhaust expert. My wife says I'm deaf anyway so my trucks may sound like crap to other people but they sound good to me now
Oh, I almost forgot....I have a Flowmaster dual in/out Big Block Muffler on a
'93 C1500 with a 454 and it drones like mad. Sounds good, but the drone at throttle tip in is pretty sucktastic. It sound great on the outside though