8v71 straight pipe

[HB of CJ]

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)

[bevans6]

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

[usbusin]

What RPM is it tuned for?

GaryD

[bevans6]

6800 rpm, it's a stock specification Ford Pinto engine, makes about 150 hp.

Brian

[OneLapper]

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.

[luvrbus]

That collector does choke the 8v71 down IMO

[bevans6]

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

[Purplewillie]

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

[luvrbus]

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

[Purplewillie]

Or maybe a turbo...
More room for one with no muffler.
Wanna come fishing in BC
Clifford?
Lol

[Purplewillie]

[baker4106]

I had a 5" resonator and pipes on my 4106 at one time and got stopped in Ohio.   Too loud.

[Purplewillie]

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.

[Purplewillie]

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.

[lvmci]

Hi Mark, 300 HP is a lot out of an 8V71, should take your bus up a hhill real good, lvmci...