454 to Cummins

[choctawmel]

Thanks for the insight, Dan.
I did install the EGT probe down stream for the turban. That was pre the instructions w/the gauge.
I have a turban blanket (for noise) and I think I saw an exhaust manifold blanket was available. Depending on the noise level, will also look at a blanket for the valve cover, IP and oil pan.
I usually set the cruise and go. My body does not like to push on the accelerator pedal from fill up to fill up.
Does your unit have the Holley electric pump in front of the tank like the gassers? Don't thing diesel would have the vapor locking problem that gas systems have. I'm concerned that the lift pump wouldn't be able to pull all the way from the tank.
Maybe I'll remember to get another oil (fuel) pressure gauge to replace that GlowShift. The reason I have for the to fuel pressure gauges is to make sure I have pressure to the lift pump and pressure to the injector pump.
Was going to work on it today, but got to go to the other side of Oklahoma City today and get some brace work done. Every time I go to the city, I'm gone all day.

[choctawmel]

Originally Posted by Kota

I've had decent luck with Glowshift gauges.

The lift pump should put out about 20-30 psi with about 15 at idle.

EGT on mine will hit 1200 on a hard pull. Normal cruising at 65mph is about 800 degrees and 7 lbs boost. On acceleration the boost will hit about 30 psi and the EGT will hit about 1100 degrees. Fuel pressure at cruise runs about 25 psi.

The star wheel in the fuel pump adjusts the fuel delivery and can be set to keep EGT down at the expense of power.

My governing speed is about 2800 rpms.

Thanks.
Was reading EGT X1000, it's really X100. So at 2400rpm, no load, was 400 degrees and 7psi boost. Hopping under load boost will increase w/more fuel and higher EGT.

[bkahler]

Originally Posted by choctawmel

Thanks.
Was reading EGT X1000, it's really X100. So at 2400rpm, no load, was 400 degrees and 7psi boost. Hopping under load boost will increase w/more fuel and higher EGT.

Whew!!!

[GCinSC2]

Mel,

Where is the EGT probe, before turbo or after turbo? Makes a difference IIRC.

I've run a Westac combo EGT BOOST gage on my dodge and the probe was before turbo. Really picked up temp nicely.

[Kota]

Everyone I've seen is before the turbo. The turbo extracts energy from the exhaust gas therefore heat. 400 degrees would probably be about right on that side. Probably about twice that on the upstream gasses.

[GCinSC2]

Kota,

Proof is where somebody installed it. Before offers a real look at this critical temp.

But if you have an OE installation, all functions working correctly should be able to just about floorboard it and hang on. But Mel is writing his own manual and warranty documents.

[Smartstream]

Originally Posted by choctawmel

Thanks for the insight, Dan.
I did install the EGT probe down stream for the turban. That was pre the instructions w/the gauge.
I have a turban blanket (for noise) and I think I saw an exhaust manifold blanket was available. Depending on the noise level, will also look at a blanket for the valve cover, IP and oil pan.
I usually set the cruise and go. My body does not like to push on the accelerator pedal from fill up to fill up.
Does your unit have the Holley electric pump in front of the tank like the gassers? Don't thing diesel would have the vapor locking problem that gas systems have. I'm concerned that the lift pump wouldn't be able to pull all the way from the tank.
Maybe I'll remember to get another oil (fuel) pressure gauge to replace that GlowShift. The reason I have for the to fuel pressure gauges is to make sure I have pressure to the lift pump and pressure to the injector pump.
Was going to work on it today, but got to go to the other side of Oklahoma City today and get some brace work done. Every time I go to the city, I'm gone all day.

In order to read the true exhaust temp the thermocouple needs to be in the manifold before the turbo. There is a line of thought that the thermocouple should be after the turbo because if before the turbo and the brass tip in the exhaust stream should fail and break off it could damage
the turbo. It is possible but as stated the turbo does remove energy and heat so the temp after the turbo is not as useful as the temp entering the turbo.

A blanket on the turbo is more for heat control then noise. If you are concerned about noise insulate your engine compartment and dog house cover rather then the engine itself.

My coach does not have an electric fuel pump near the tank. I don't know if the 454 requires a higher fuel volume or pressure then the diesel or possibly the rubber diaphragm pump on the 454 cannot lift as well as the pump on the Isuzu. Another item is the Turbine Series Racor primary filters on our diesels are recommended to be installed in a vacuum rather then a pressure. A call to Cummins technical support might provide the best information. I wonder if the long school busses with the engine at one end and the tank at the other require an extra pump? My old Greyhound bus with tank up front and rear engine only had the engine mounted pump.

I fully agree with the use of cruise control however when you hit a grade and the coach slows down and starts to downshift that is when you need to keep an eye on EGT and boost. You are mounting your Cummins to a GM trans and being a non factory installation you do not have the benefit of many hours of factory engineering. Our Isuzu's coupled to the GM trans puts us in the same situation. Good luck.

[Kota]

Most big trucks have manual transmissions. You have to e aware and operate at an rpm an power (skinny pedal) range to keep the EGT in an acceptable range. You can burn up an engine in a second by lugging it. RPM are your friend. Speed becomes secondary to running in the sweet spot.

These 12 valve Cummins motorhomes with Allison offer no protection against over temping other than detuning them to an anemic 180 hp. They are capable of much more but something has to monitor the EGT. Since there isn't a computer controlling the engine, the driver has to be ware. The fuel controller can be deidiot proofed by cranking the star wheel and fuel schedule with the fuel plate to limit power and EGT. If you want to play with more power, you have to pay attention to EGT, rpms, boost, engine temp... Especially if you want climb all the passes in the Rockies.

[Isuzusweet]

Originally Posted by Kota

If you want to play with more power, you have to pay attention to EGT, rpms, boost, engine temp... Especially if you want climb all the passes in the Rockies.

I'm going into surgery to get more eyes. One for the EGT and boost gauge at the end of the dash; one for coolant and oil pressure in the upper centre; one for rpm and speed; one in the back of me head to see that eighteen wheeler storming along at 80+ coming fast towards the merge; one on the GPS trying to tell me I'm crossing someones corn field; one on the wife trying to read a map upside down; did I forget anything......oh yeah I guess a couple on the road ahead would be good.

A spider; I need to be a spider.
Cheers
Tony

[tjdonahoe]

Originally Posted by Kota

Most big trucks have manual transmissions. You have to e aware and operate at an rpm an power (skinny pedal) range to keep the EGT in an acceptable range. You can burn up an engine in a second by lugging it. RPM are your friend. Speed becomes secondary to running in the sweet spot.

These 12 valve Cummins motorhomes with Allison offer no protection against over temping other than detuning them to an anemic 180 hp. They are capable of much more but something has to monitor the EGT. Since there isn't a computer controlling the engine, the driver has to be ware. The fuel controller can be deidiot proofed by cranking the star wheel and fuel schedule with the fuel plate to limit power and EGT. If you want to play with more power, you have to pay attention to EGT, rpms, boost, engine temp... Especially if you want climb all the passes in the Rockies.

. My 07 dodge with 6 speed auto and 6.7 Cummings normally is at 1600 rpm, when going up a long grade ,if you hold your foot still it will pull down to 1000 rpm..now has 100,000 miles.. Same as my big truck with a 500 hp cat , pull down to 1200 rpm for short while near the crest of hill, has 1.4 million miles, head never been off..just saying

[Kota]

Originally Posted by tjdonahoe

. My 07 dodge with 6 speed auto and 6.7 Cummings normally is at 1600 rpm, when going up a long grade ,if you hold your foot still it will pull down to 1000 rpm..now has 100,000 miles.. Same as my big truck with a 500 hp cat , pull down to 1200 rpm for short while near the crest of hill, has 1.4 million miles, head never been off..just saying

My 08 dodge with a 6 speed auto 6.7 Cummins does the same but it has an ECM (same as yours) controlling the engine. Just saying...

My 360 runs at over 16000 lbs. About like my Ram pulling a heavy load.

Many of these motorhomes of this generation have burnt up their engines from poor technique. That's my opinion and I won't offer any more bad advise.

[mayco]

I for one would be interested in more of your "bad advice" Kota in regards to technique in driving these old diesels. Im new to diesels, as most of you already know, and have logged between 5k and 6k on my Isuzu. I realize you fellas are speaking of the Cummins but surely there are techniques in driving these diesels that are common. Ive been through some areas where we have encountered some pretty steep and long grades. I pay close attention to my EGT and my RPMs when climbing, also the sound of the motor is a pretty good indicator of whats going on. Its my understanding that there is a direct correlation between the EGT and the RPMs and thats obvious when watching my gauges. EGT climbs as the RPMs drop and the engine starts to lug. Giving it more fuel (or even steady pressure on the pedal) is not the answer to maintaining momentum in my 310, I downshift on my Allison once I reach the RPM range where I think its safe to do so on the tranny. Im guessing in or about the 2000RPM range. Maybe a bit lower. Once I see the EGT approach 1200 degrees on a climb, and I see the RPMs dropping, Ill take my foot off the pedal and let the RPMs decrease until I thnk its safe to downshift.

Am I on the right track here for the health of the Isuzu and fuel consumption?

Mike

[Kota]

Even the computer on my Ram shifts down to keep the rpms up on acceleration and under load. Between 2500 and 3000 on hard acceleration. It only drops back to 1000 to 1200 under very light load. You can really feel the sweet spot on the cummins. Mine seems to really like 62 mph at around 1900 rpms to cruise flat.

[mayco]

I can definitely feel the sweet spot on the Isuzu but its sooo much higher rpm. 60-61 mph but running at about 2850 or so rpm. Thats WITH the Allison 4sp. But that seems normal compared to others Ive talked with. I would think the Allison would make a bigger difference over the chevy 3sp buy apparently not. Thats on flat roads. Oh well, it is what it is.....I doubt Ill ever go the Gearvendor route but who knows once we are able to travel more. I just make sure Im cruising under 3000rpm. It seems and sounds happy at 2850 to 2900.

[Kota]

Sounds a bit high. I've had a few gotta be there trips on the interstate where we've run 75-80. About 2200 rpms. Mileage drops off a little but it seems happy.

[SpiceStream]

I finally got my tach working, my axle situation totally ironed out, and got the 310 on the highway this morning before work. I have a 5.9 Cummins, Allison AT545 and a Gear Vendors, not sure on the Diff Gears. At 70MPH i am running exactly 2000RPM.

The previous owner installed a Gas Tach in the 310 so I chased the 3/4-16 threads in the top of the Allison and used the Dakota Digital DSL-2 Flywheel Tach Interface, it takes a few minutes to program, but it seems stable so far.

On the Road again

[Smartstream]

Originally Posted by SpiceStream

I finally got my tach working, my axle situation totally ironed out, and got the 310 on the highway this morning before work. I have a 5.9 Cummins, Allison AT545 and a Gear Vendors, not sure on the Diff Gears. At 70MPH i am running exactly 2000RPM.

The previous owner installed a Gas Tach in the 310 so I chased the 3/4-16 threads in the top of the Allison and used the Dakota Digital DSL-2 Flywheel Tach Interface, it takes a few minutes to program, but it seems stable so far.

On the Road again

You might want to recheck those numbers. With the factory 4:56 gears and a non overdrive trans with a Gearvendors 70 mph will be closer to 2800-2900 rpm depending on torque converter slip. The differential gears may have been changed and it would be interesting to know to what ratio.

My 280 with a Gearvendors and 4:56 gears is closer to 60 mph at 2000 rpm.

[SpiceStream]

The gears in my differential are 3:52

[Smartstream]

Originally Posted by SpiceStream

The gears in my differential are 3:52

That is indeed a big jump from stock and makes a big difference. How does it feel power wise in overdrive?

[SpiceStream]

I suspect the gears may actually be 3.54 since that is the tallest gears I can find for the Dana 70 HD. The Summit Racing Gear ratio calculator comes up with just under 2500 RPM without overdrive which seems about right since I have overdrive. The previous owner said the gears were 3.52? I will get a hand tach and double check the RPM's at the crank and make sure it all checks out.