EGT & Boost Gauge Questions

[jumpjg]

Happy New Year all,

I'm thinking of adding EGT & boost gauges to my 1994 HR Navigator DP. It's equipped with a Cummins 8.3 mechanical injected engine (read as no OBD II). I've owned Dodge Diesel PUs in the past and installed gauges on both, but in those cases the engines were just on the other side of the firewall so the wire/hose runs were short. I estimate the runs from the engine to the dash on my Navigator will be in the 40 ft range.

Question #1: if using a K-type thermocouple, can I just install extension wires to the thermocouple leads to run up to the EGT gauge on the dash? Would the gage of the extension wires make any difference?

Question #2: I prefer a direct reading gauge for boost pressure, and in most installations they use the plastic 1/8" line to supply manifold pressure to the gauge. Would an 1/8" plastic line be sufficient for a 40 ft run?

Thanks for your input,

[nehog]

Originally Posted by jumpjg

Question #1: if using a K-type thermocouple, can I just install extension wires to the thermocouple leads to run up to the EGT gauge on the dash? Would the gage of the extension wires make any difference?

Any thermocouple will require a special harness. They can't be extended with regular wire. Some (a few) have a sender on/near the engine that then sends data to the remote gauge, and those can be more easily remoted. I'd suggest looking perhaps at aircraft gauges as well, as they may allow configurations more to what we have in our coaches.

This may be extendable with standard wires... You should message them and ask however. This is a aviation gauge that may work too... Again you will have to check with the maker on cabling.

Originally Posted by jumpjg

Question #2: I prefer a direct reading gauge for boost pressure, and in most installations they use the plastic 1/8" line to supply manifold pressure to the gauge. Would an 1/8" plastic line be sufficient for a 40 ft run?

Personally I'd use an electronic boost gauge (such as this, or this) over a mechanical. Were I to use mechanical I'd probably want to run copper tubing, but probably the nylon tubing would work OK.

Originally Posted by jumpjg

Thanks for your input,

[tom chelbana]

We had a 95 Newmar London Aire with the 300HP C series which should be the same as yours. Installed a Banks Power Pack system with EGT and Boost gauge along with turbo up grade. What a difference. Went from 20 psi turbo boost to 30 and pickup 5 to 7 mph on 6% grades. Must have been close to 400HP. The Banks boost gauge most have been at least 45 feet and i ran rubber hose. The EGT was also at least 45 feet and had no trouble run the line to dash. London Aire 40 feet on a Spartan chassis. Would encourage you to go a head with the upgrade. Keep fuel tune for about 1250 degree exhaust temp with pickup before turbo which usually means 300 degrees hot then after turbo.

[GraySeal65]

I didn't have any problem running wire from the sender to gauge (36') EGT reads spot on.
Finding the tubing for the boost gauge was tough. Copper was to thick for the fittings. This is what I used but it looks like it's not available.https://www.amazon.com/ATP-Value-Tub...00+feet+Length

[ladagobago]

It is much simpler to contact glow shift and get everything in one guage display and electric connection with wire.

[Bob_C]

Originally Posted by ladagobago

It is much simpler to contact glow shift and get everything in one guage display and electric connection with wire.

X2........

[Piker]

I installed these:

Auber Instruments

These are digital gages. Nice thing about them is that they are programmable and have relays in them that you can use to trigger a buzzer or alarm to alert you to high egt or boost conditions. They have all of the thermocouple extensions you would need right on their website.

I have been using these in this configuration for about 4 years now with good results. It's nice to be able to keep your eyes on the scenery and not have to watch the gages constantly. Our engine is fueled to the point where it WILL exceed safe EGT in certain conditions... ie at high altitudes... and the buzzer keeps my foot in check.

-cheers

[jumpjg]

Thanks for all the replies. I'm pretty interested in a Hewitt Gauge combo set...

https://www.amazon.com/Hewitt-010TM5.../dp/B01MTEJUM2

2 ea 2" round gauges, one boost, the other EGT. I was able to speak with engineering at Hewitt about extending the EGT wires. Told me that all they were concerned about was resistance over the length of the run, recommended 18 AWG at a minimum, looking for a nominal value of 4 ohms (+/- 2 ohms) through extension lead and thermocouple. So for at least this mfg's EGT gauge, no special wire is needed, just a heavy enough gage copper wire to avoid high resistance/voltage drop.

They also told me that 4mm (od) tubing is adequate for the boost gauge. Plenty of alternatives there.

I was snooping around on my engine (8.3 mech) for locations to install the TC & boost line. Looks like there is a 1/2" pipe plug installed on the top of the intake manifold cover adjacent to #4 or #5 injector - simple adapter should do. The turbo is mounted on top of the exhaust manifold - looks like the best place to drill & tap the manifold for the TC would be below the turbo on the outboard side just below the turbo mounting flange. Pretty tough access to that area on my coach without first removing the turbo. Not wanting to open up a can of worms. Don't want to cause a crack to propagate in the manifold. Trying not to remove the exhaust manifold because I know most of the bolts would snap. Open to suggestions/lessons learned here.

Thanks for your time.

[Bob_C]

On this old truck, the boost take off point is a hollow exhaust manifold bolt....

[SlowJoe]

I am completing an installation of these gauges on the same engine. I know the manifold has never been removed before and like you, I had heard of bolt breakage being a problem, as well as cracked manifolds. I decided to go ahead and take it all apart. I figured if they were going to beak I would rather have it happen at home where I can do something about it at my leisure and not be obligated to pay an expensive shop bill. Often times these bolts are broken in the first place because the monkey turning the wrench does not have enough care and finesse to get them out. I sprayed the bolts that were accessible with PB blaster and let them sit a few days. I was able to get all of them out without breaking any. Three or four of them were a bit difficult and I had to carefully exercise them with more penetrant oil to get them out. Someone who didn't care would almost certainly have snapped them with an air wrench. I chased all threads with a tap once I got it off and after rinsing the holes with brake cleaner, I applied a liberal amount of anti-seize. I am pretty sure those bolts will not ever give a problem again in the event of a cracked manifold or other reason to remove it.

[jumpjg]

SlowJoe,

Thanks for your reply. I haven't progressed on gauge installation but I figured I would do the same as you when I do, i.e., address the exhaust manifold bolts at the same time. Good info you provided.

With respect to the gauge installation, I'd like to know where you tapped into the intake for the boost gauge and where you installed the thermocouple.

Also, did you have any challenges removing the turbo? Looking at my engine, there isn't very good access to the turbo-to-manifold mounting bolts. How was the condition of your turbo? The waste gate on mine seems to be frozen shut so I planned on sending mine out to get refurbished at the same time. Any pics you could provide would be appreciated.

Thanks again for your reply!

[SlowJoe]

I have been working on things and progressed with the gauges a bit. I drilled the manifold in the area between the #5 cylinder and the turbo. The boost gauge is connected in a port in the intake between #5 and #6. There was a 1/2 pipe plug installed, so it made a convenient point to connect it. I will post a photo of both connections for reference. I sprayed the turbo nuts and they really did not give much of a fight coming off. Spraying a few days in advance helps as well as patience when removing it all. The oil line for the turbo put up more of a fight than the nuts did. Often times a few smacks with a hammer to break the rust bonds helps before trying to use a wrench too. I smack it straight down on the head and then at 90 degrees from the bolt head if there is room to get at it. In case it is helpful, the gasket numbers for my set up are:
Manifold to engine: 3929012
Manifold to Turbo: 3911941
Turbo oil drain gasket: 3519807

While I had it off, I bench tested the wastegate actuator. It was starting to open with only 12psi and was fully open by 16-18 psi. I replaced it with a banks big head actuator #24329 and set it to begin to open at 30psi.