Just finished a fun couple of weeks out in the bus. 800 miles with one little incident . The collector ,if that is the right name,
blew the bottom out. The piece I'm referring to is where the exhaust from both banks comes together and the muffler mounts on top. Is this collector obsolete? I'm sure I could repair it if need be or have one fabricated. Just wondering what my options are?
Thanks Mark
8v71 GMC 4905a
Sent from my iPad using Tapatalk
Try Luke or Wildbob they may have a used one I haven't found a new one in a long,long time
I have an extra one in my garage and might be willing to sell it. I am in Michigan, just email me at larrydbaker@aim.com.
I got a new one from Luke a few years ago. Dog dish with outlets/inlets.
Now is a good time to flip the manifolds over and go to dual pipes out the passengers side a sweet sound the GM's with dual pipes 'I love the sound of a 4104 with the 6-71 inline with duals a sound all of it's own
Quote from: luvrbus on August 18, 2014, 07:04:22 AM
Now is a good time to flip the manifolds over and go to dual pipes out the passengers side a sweet sound the GM's with dual pipes 'I love the sound of a 4104 with the 6-71 inline with duals a sound all of it's own
Is that something that is doable on my MC9 with 8V71? I saw an Eagle with dual, a muffler for each side and thought that could be neat. Just flip the manifolds over and figure out how to plumb the exhaust to two mufflers????
Eagles with the 8v71 came from the factory with duals don't they sound sweet ;D
It's weird with exhaust sound. The 6-71 sounds totally different if the exhaust is in the middle of the manifold, compared to at the very end. Just like the Eagles with dual exhaust. The 8V-71 sounds like two 4-71's running (unremarkable sound). Yet if you combine them together, you get the nice V-8 sound the 8V-71's are known for. Course the best sound is a 12V-71TTA with twin turbos and straight exhaust. No other engine sounds like a 12V-71. Good luck, TomC
Not hard to on a MCI just flip the manifolds so they exhaust from the rear then that gives enough room for the 9 inch mufflers cut the cross over pipe to get your 2- bends the rest is uphill with a stick of 3 in pipe
I had duals on my 5301 with "shorty" mufflers. You could really hear it in the "cattle chutes" and the concrete sidewalls of bridges. ;D Thinking about putting them on my 4905--with more than "shorties" though! ;)
Steve Toomey
PAbusnut
(currently suffering from PTBWD syndrome)
When I installed my 8V71T in my MCI I fired it up without the turbo or the exhaust installed, to see if it would fire and if it had oil pressure. Two manifolds firing straight back while I stood in between them and manually worked the governor. Sweetest sound in the world would be a brand new 8V71 firing with just manifolds on two feet from your head! Talk about stereo!
Brian
We ran about 400 miles open and it sounds good. I asked my wife if we needed a mufler and she said it never bothered her open. We were in a closed in canyon for half of out trip so the echo was sweet.
My mufler is short and not much in it, so not much louder open.(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F14%2F08%2F18%2Ff1b3fe525384ddee0ccdd0f58bf05d91.jpg&hash=92db947a02766ed8d541dd4e83b3115961feaebd)
Quote from: bevans6 on August 18, 2014, 12:23:14 PM
When I installed my 8V71T in my MCI I fired it up without the turbo or the exhaust installed, to see if it would fire and if it had oil pressure. Two manifolds firing straight back while I stood in between them and manually worked the governor. Sweetest sound in the world would be a brand new 8V71 firing with just manifolds on two feet from your head! Talk about stereo!
Brian
And even better, the frisson continued for hours after the engine was shut down
Is a 4106 collector the same as my 4905a?(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F14%2F08%2F18%2F4fe743853740df2c213f4f29a2a93484.jpg&hash=2a22aac04d463114d5377a84711d20e5e127baf2)
Im more tolerant of open exhaust than most...
Dodge Ram Rummble Bee with Magnaflow duals
Rinker sport cuddy with small block chev Corsa Captains Choice exhaust
66 Vette LS7 Big Block 2 1/8 Hooker Comp. Headers into 4" sidepipes.
So loud to some, is fine to me.
Mark
How about a 1968 American LaFrance narrow cab Century Series triple combination fire engine with a Fuller T905M 5 speed manual tranny. Detroit 8V71N with N90 injectors. About 2500 rpm through the gears. About 60 mph at 2100. Practically no mufflers. Twin pipes exiting on the passenger side just behind the fire pump panel. Nothing sounded so cool as a good crisp 8V71N rowing through the gears. When pumping off a fire hydrant at a fire, the ground shook!
Flashing forward, up here in SW OR USA, we still have at least one logging truck with a very nice 600hp twin turbo 12V71TI Detroit Diesel. Some mufflers, but not too much. Yep...a very distinctive sound for sure. When that truck passes through our small mountain valley town carrying logs rowing through the 18 speed, us old coots all turn, watch and listen. A blast from the past for sure. I wonder what his fuel mileage is? But no visible smoke! HB of CJ (old coot) :)
This is what I built for the current race car - Lola T492 sports racer. four into one, stainless steel, and that's not a muffler - it's a megaphone! It blows big balls of flame every time he shifts...
Brian
What RPM is it tuned for?
GaryD
6800 rpm, it's a stock specification Ford Pinto engine, makes about 150 hp.
Brian
I have a 5" straight pipe setup for my 4106 that I'll use if I'm heading somewhere without the kids. There's a noticable hp increase with the straight pipe vs. the OEM 3.5" outlet muffler, plus it gets 1+ mpg better. But it's LOUD in the back of the bus, too loud for passengers.
One LOL moment was on Rt 80 in PA. I was climbing a pretty steep grade, towing my 26' car trailer. I was on the governor in third, an old 70's vintage Ford Estate Wagon passed me... the kids in the back had their hands over their ears and the mother gave me the finger! After that I figured it was a bit too loud and switched to the 5" Donaldson that TomC was using. The exhaust sound is still snappy, but the sharp "bite" is gone. I don't have a turbo, but it's amazing how much one will quiet down the exhaust.
That collector does choke the 8v71 down IMO
If that was in fact a picture of the collector, I bet it robs 20hp compared to duals with straight through mufflers. When I replaced the stock MCI muffler with the Donaldson, the engine breathed noticeably better, a definite reduction in smoke tells me it was flowing a fair bit more air.
Brian
That is the collector.
I am getting one from Larry Baker, but I'm still tempted to run dual straight pipes. No louder than 4 Harleys and my 8v71 leaks less too!
(Ducks from incoming flames!)
Mark
The little exhaust resonators take the bite out, still let the engine breathe and fit in small spaces plus fairly reasonably in price like 50 bucks each
Or maybe a turbo...
More room for one with no muffler.
Wanna come fishing in BC
Clifford?
Lol
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F14%2F08%2F19%2F5676046b422052b50c3a939ca7120233.jpg&hash=0eede499d4ac6696983e5e9b5bf5e160a50bc3b0)(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F14%2F08%2F19%2Fa63107c3b2d814c7006fe49f172c1be0.jpg&hash=cbf26968173bbe7a27e3c3274f93ea1656d5f4fd)
I had a 5" resonator and pipes on my 4106 at one time and got stopped in Ohio. Too loud.
As much as I dont mind the straight pipes, I think I will put the muffler back on. Larry (Baker4106) has a collector boxed up and ready to ship to me.
This engine runs so well,no leaks, cant get it to smoke on a hill. Just under 150,000 miles,
Just don't have a real reason to spend more than our bus is worth to build a turbo 8v71.
So back to a muffled 300 horse 8v71. Its probably the smart thing to do.
The collector from Larry should be here next week, but since we never went to Castlegar today I got busy repairing my old one.
All welded up, painted, stainless muffler back on and new tailpipe. (https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Ftapatalk.imageshack.com%2Fv2%2F14%2F09%2F06%2Fa988658fc9b5e9d42b70c5c2c9be2b52.jpg&hash=d14f15f7eaf1efe766601f796e0f34a6cce3c41e)
Hi Mark, 300 HP is a lot out of an 8V71, should take your bus up a hhill real good, lvmci...
quite a few slow climbs for the old girl here in BC, I can't help lusting over TomCs 8v71T when we are crawling over a mountain pass.
Just more time to take in the view.