Question About De-Tuning CAT Standby Generators

Hugh R · 11-05-2010, 04:49 PM

Without going into it too much, an organization that I associate with has 4 standby emergency generators they are CAT and John Deere, I can get exact model numbers if needed all are in the 65-80 HP range. The local air pollution district wants them to spend about $10K each to install particulate traps on the exhaust. If they can be de-tuned to under 50 HP, they become exempt from the P-trap and air district permitting. These generators are diesel and all are less than five years old. I don't know generators very well, but I believe industrial generators like to run at a fixed RPM and as the load increases, they increase fuel flow and air mixture to increase HP to meet the load demand.

Can a modern fuel injected diesel generator like this be de-tuned from say 65 hp to just under 50 HP by putting some kind of fuel flow limiter in line, or some kind of stop on the how far the intake manifold is allowed to open?

Selling the generators out of the state of CA and buying new ones is not economically feasible.

Thanks for any input and suggestions.

rick-l · 11-05-2010, 04:53 PM

rated under 50 hp or produce under 50 hp? I can't imagine the later.

Hugh R · 11-05-2010, 05:01 PM

They need to be rated under 50 at the crank.

944Larry · 944Larry's Garage

As you realize this is what's wrong with the US today. These idiots regulate things that are not worth regulating. The key word here is 'stand-by". This, I assume, means it only runs during a power outage. Sorry for the rant. To answer your question, you wouldn't be able to cut the horsepower on a generator. As you said, a generator runs at a very precise RPM rating. Any change in horsepower would mean a drop in RPM's with a drop in voltage output and cycles.

Hugh R · 11-05-2010, 05:57 PM

Are you sure? I understand that it runs at a constant HP, but can't you use a governor to limit the HP so that you can only pull so many KVA?

944Larry · 944Larry's Garage

Quote:

Originally Posted by Hugh R

Are you sure? I understand that it runs at a constant HP, but can't you use a governor to limit the HP so that you can only pull so many KVA?

I still think output would suffer but if Hugh can get some model and serial number data I'll be at the Cat place sometime next week and I'll run it past them. It might be possible with some of the newer style engines as they are all computer controled now. If you have engine trouble nowadays, the first thing the Cat man does when he gets to the machine is hook up a laptop. I had a D6T quit recently. When the mechanic hooked up the laptop in just a minute he said the trouble was that the injection pump was "only" putting out 20,000 PSI, it was supposed to be putting out 30,000 PSI. I was stunned, it seems like the old pumps with the mechanical governors only put out about 1200 PSI or so. You can't even reuse injector lines anymore. If removed, replace them he told me. Different world nowadays.

Hugh R · 11-05-2010, 08:17 PM

That would be great. I'll get the model and serial numbers and send them to you.

James Brown · James Brown's Garage

I think the problem is certifying them as detuned or finding a state citified dyno willing to run them, if this even exists. Maybe Cat or John Deer sells a kit (most likely smaller injectors) to de-tune them.

red-beard · red-beard's Garage

The primary thing would be a smaller throttle assembly to limit airflow into them. I definitely would talk to CAT about this. I bet you'd be better off selling them and buying new ones.

Tobra · Tobra's Garage

CARB is the Devil

red-beard · red-beard's Garage

Hugh, what is the cost to install the particulate traps in the exhaust system?

lendaddy · 11-06-2010, 07:43 AM

I'm sure someone that knows the numbers could calculate an air intake restrictor or that would limit the HP to whatever you want.

red-beard · red-beard's Garage

Hugh, just to throw this in the Mix, the cost for a Particulate Trap for my Ford F250, 350 hp, 4.6l Diesel is $1500, list price. I cannot imagine an 80 hp unit would cost even $1000.

john walker's workshop · 11-06-2010, 08:33 AM

the state is going to check the specs for that model, which will say what it's hp is, and that's that.

Hugh R · 01:49 PM

The p traps are around $12,000 each.

I was wrong, they are Cummins and John Deere.

Someone at the organization (it's a very small elementary school district) who doesn't know anything about generators asked Cummins to do something, and they offered to sell them 4 $12,000 load banks and 4 p-traps, the load banks do nothing to reduce HP, and they were an additional $12,500 each.

Larry: here is the info from the descriptions on the Air Permits:

Cummins Model No. 4BTA3.9-G5, four cyl. 99 BHP, turbocharged, after cooled No. Serial No. at this time.

Cummins MModel 4BT3 3-G2 Serial No. 68011959 82 BHP

John Deere 4 cyl tubrocharged Model No. 4045TF150 110 BHP No Serial No.

Cummins Model No. 4Bt3.9-G4 Serial No. L00185069 4 cyl turbocharged 102 BHP

I will contact Cummins, but in looking at the permits I see three of them would have to have their BHP reduced by 50% or so. That may not be obtainable. Since I don't know generators, as Larry said some of them run 30,000 PSI on the injection which to me is amazing. I just want to be able to talk to Cummins intelligently about options.

My understanding is that any modifications to get under 50 BHP must be "real, quantifiable and permanent". John Walker, you are correct in that they look at the model and what the State and local agency will require and that is generally it, unless you can demonstrate a real, permanent drop in BHP.

red-beard · red-beard's Garage

Let me look into it...

yetibone · 11-06-2010, 01:52 PM

You would have to decrease fuel delivery from the injection pump to decrease power output. I've seen fuel delivery increased before to raise the output on road, and farm tractors, or when turbocharging is added, but not the other way around.

I would guess that the power units are certified for their respective outputs at the crankshaft by the manufacturer. Turning down the fuel rate would decrease the power, but the air quality police would likely still have to regulate based on the factory's standards for fuel rate on that power unit, and not on an altered, and non-certified fuel rate.

stomachmonkey · 11-06-2010, 02:12 PM

Quote:

Originally Posted by Hugh R

The p traps are around $12,000 each.....

Have you verified that 1st hand?

Seems you can buy the generator itself for not much more.

Cummins 4BTA3.9G5 Diesel Generator - Caterpillar Diesel Generator, Used Diesel Generator

GeneratorJoe Generators: Cummins, Industrial Generator, 50 kW, (50 kVA) 60 Hz,, diesel fueled, liquid cooled, single phase, Model DGCA

Would be really insulting and piss me off to no end if true.

Don't diesel big rigs have particulate traps?

Do you have to get it from Cummins or can you source and fab something yourself?

krystar · 11-06-2010, 02:12 PM

can't u just do like nascar? install a restrictor plate.

Hugh R · 02:57 PM

Quote from Cummins Cal Pacific LLC is $47,179.49 for four DCL International Mine-X Sootfilters.

It's a CA requirement for standby generators within 100 meters of a K-12 school (SCAQMD Rule 1470). Since these are schools, they have to comply with the rule.

My wife is the purchasing manager for the school district and I'm trying to help them out gratis

I've given them several suggestions including selling them outside of CA and buy gasoline ones under 50 HP (exempt from permitting).

Don't know about exhaust filters on diesel trucks other than that they are requiring older ones to be phased out in CA and replaced with much cleaner ones. Going the same way with cargo ships.