671 dual exhaust - which manifold & where would it be best to place a EGT probe?

dtcerrato · February 24, 2016, 06:08:16 AM

Curious about where would be the best area & in which manifold to place a EGT probe on a dual exhaust 671 Detroit
Spec tells us that EGT for the 671 naturally aspirated engine is 900F.
What would be a cautious high temp?
I've added propane injection and am curious of any variations in EGT.

luvrbus · February 24, 2016, 06:34:39 AM

A probe in 1 manifold is not going to be much help,you should be 870 F with N65 injector's @ 2300 rpm 1100 F is toast at a long period of time.The propane injection I won't go there

TomC · February 24, 2016, 07:05:26 AM

2 stroke engines flow a lot of air and being 2 stroke, just don't have the big power jolt 4 stoke engines have. With a non turbo 6-71, if you stay at a N65, you don't have too much to worry about burning anything. 7G75 on turbos. I had a 8V-92TA with 9A90 and was told an pyrometer was not necessary. Don't waste your time, effort and money on a pyrometer for a 2 stroke engine. Good Luck, TomC

luvrbus · February 24, 2016, 05:19:38 PM

2 strokes have a higher EGT than a 12.7 series 60 by over 100 degrees.TomC I have never saw a V manifold that didn't have a boss to tap for a probe.Just reading from between the lines I think this guy wants to monitor his EGT using propane which is probably a wise choice on his part

dtcerrato · February 24, 2016, 06:54:43 PM

I appreciate the feedback guys. Want to keep the old girl ticking like a fine watch. Thanks

chessie4905 · February 25, 2016, 03:51:12 AM

Main thing, don't run it below 1500 at full fuel on the grades. If you turbo it, it'll run like an Na 8-71. Best thing we did to ours.

dtcerrato · February 27, 2016, 03:06:02 PM

Thanks for all the feedback, this beats the Encyclopedia Britannica! Remember them...LOL
I've decided to go with a dual gauge (info attached) and a probe in each manifold. Found a nice source for pyrometers & much more - Hewitt in Huntington Beach CA. They even had their Tech/Engineer on the phone walking through it with me. Sometimes the piece of mind portion of things is priceless.

TomC · February 28, 2016, 07:51:04 AM

On huge Diesels on ships and in generating stations, they use a pyrometer on each cylinder. Also they use a tachometer on the turbocharger. Both of which we don't use in trucks and buses. Good Luck, TomC

chessie4905 · February 28, 2016, 01:35:12 PM

Make sure they have the proper extensions to reach clear to the drivers area. The ones I've seen need special resistance wire.

luvrbus · February 28, 2016, 01:50:24 PM

I got ripped off for years buying the harness wire from pyrometer gauge manufacturers,then I found out you can buy it at about any pottery supply that sells kilns for around a dollar a ft

dtcerrato · March 11, 2016, 07:14:33 PM

A follow up on my pyrometer project
I ended up tapping both manifolds
I went with an "old school look" double read pyrometer
Looking forward to getting it on the road, feeding it some propane
And see what its doing?

dtcerrato · March 15, 2016, 09:30:00 PM

An update on 671 NA propane injection. Did a small dry run towing a 6000# toad for the 1st time since installing propane injection and pyrometer/thermocouples. The most substantial noticeable change (w&wo propane injection) is a slight increase in power and top end with propane. As far as EGT, couldn't get the temps to quite touch 900 degrees - probably due to Florida's flat terrain. Very noticeable increase in power when pulling overpasses and small upward inclines (holds speed in high gear). Propane pressure is set at 8-9 psi (when flow is off) with 1/8" entry into air flow just ahead of blower. Pressure drops approx. 3 psi when flow is turned on. Not a whole lot of difference in smoke out tail pipes with and without. I'd like to bump the pressure to ten psi (probably as a max). One term being used in propane injection dialog is "pinging". I know what it sounds like - but should the driver be able to hear it from the drivers seat or should taking a listen be closer to the engine? In general I'm pleased with the modification, especially with the added toad weight. Looking forward to some mountain driving...

gg04 · March 16, 2016, 07:30:58 AM

Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw

luvrbus · March 16, 2016, 07:37:08 AM

Quote from: gg04 on March 16, 2016, 07:30:58 AM
Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw

yep pole vaulting over piss ants

zubzub · March 16, 2016, 03:18:21 PM

Quote from: gg04 on March 16, 2016, 07:30:58 AM
Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw

rdw?