Cummins 4BT & Diesel Conversions Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
788 Posts
Discussion Starter #1
Ok, so I know modern gas engines are designed to run hot. If you pull the thermostat and the weather is such that the engine runs cooler than the design temp, the result is poor mileage and proformance in general. I can't say I've ever experienced this, but it makes sense.

Is this true in a diesel?

Second question, if you were to lower the water temp by lets say 30 degrees, would that likely lower the egt's?
 

·
Registered
Joined
·
11,229 Posts
A diesel engine works on heat. Like any internal combustion engine you don't want it too hot or too cold. Generally, removing the thermostat will make it run too cool. Even with a thermostat in place, having an over sized radiator can have a similar effect. May not make the heater work well in cooler weather. The thermostat is there to keep everything in balance. Not sure about the EGT question. Don't know that changing the coolant temperature will have a significant effect on EGT. Things like cooling the air coming off the turbo and adjusting pump timing do affect that. Getting the air fuel ratio just right also has a big effect. That's why properly tuned twin turbo engines generally have much lower EGT. Most of their heat energy is being used to make power, not hot wasted exhaust.
 

·
Registered
Joined
·
788 Posts
Discussion Starter #4
Ok, so I made at a point in my project that I will be hooking up e-fans. I have two Spal fans and a very large radiator. My 4BT has the original thermostat installed. (Not sure what temp that is) At what temp should I set the fans to come on?
 

·
Registered
Joined
·
196 Posts
The use of electric or hydro fans on diesels came about when truckers started running higher operating temps to increase MPG by using higher temp stats and or waterless coolants and tweeking the cooling fans on/off points.

Knowing the stats temp and what temps your diesel can safely run is critical in deciding on/off fan settings.

I'm quessing you are using a water to air CAC that's why the question relating too cooler water temps & EGT.
 

·
Registered
Joined
·
11,229 Posts
If this is a 4bt, you may find that the electric fans may never turn on with a large radiator. Only if the engine is really stressed or in extremely hot weather might they turn on. The 4bt is very heat efficient. There have been guy running in 100 deg weather and not have the fan come on. Thermostats on these engines were normally either 160 or 180 deg.
 

·
Registered
Joined
·
2,204 Posts
If this is a 4bt, you may find that the electric fans may never turn on with a large radiator. Only if the engine is really stressed or in extremely hot weather might they turn on. The 4bt is very heat efficient. There have been guy running in 100 deg weather and not have the fan come on. Thermostats on these engines were normally either 160 or 180 deg.
Charles this is true up to ~200HP power level beyond that the 4BT does start to tax the cooling system, between the air temp coming out of the I/C the added heat from the oil cooler and the water jacket the total load on the cooling system begins to build quickly.
I have the same cooling system as I started with and it was more than sufficient @200hp but now it is JUST holding it's own, but I have high loading's and high ambient temps. so kinda a worst case for a cooling system.
But IF your gonna end up making and using big power I'd go as big as i could for both I/C and radiator..$.02
 

·
Registered
Joined
·
788 Posts
Discussion Starter #8
It is a 4BT and I assume it's making slightly less than 200 hp. (Differnt turbo) On my installation, the rad gets zero air blast from forward travel. So I expect at least one fan on most times. In testing I just wire one fan on and it doesn't get hot. But I've only driven it on short trips (7miles) because of no registration.
 
1 - 8 of 8 Posts
Top