| Author | Message | ||
| John Rigby (65.112.227.94)
Rating: N/A |
I understand that early in the morning on a long trip with a full tank of fuel, the fuel runs cool though the head to my injectors, and back to the tank.The engine performs well.As the day goes by the ambient temp gets hotter the fuel tank gets lower, and the fuel gets warmer.This rise in the fuel temp Im told has a negative effect on the engines performance, as the cooler you keep the injectors the better they perform/the longer they last.while on long trips I have definetly felt a lack of power later in the day. I was told to consider routing the return fuel line through a small transmissin cooler mounted in front of the radiator. Does anyone have any input? John | ||
| JImmci9 (209.240.205.68) Rating: N/A |
caterpillar uses a cooler on its injectors on certain engines, not all.. ive seen them on 3412 HUEI genset engines...and some 3500 stuff.....by the time fuel would be cooled, filtered, and brought back into the engine again, it'll probaly be nearly as warm as it was in the tank....unless you realy shield those fuel lines, filters.etc..... | ||
| Ron Leiferman (Ron_In_Sd) (12.111.217.5)
Rating: N/A |
It is a know fact that colder air mixture returns more power. A cold fuel mix in that air will help. One reason why water injections helps. In the semi trucks, we run we have fuel heaters for the winter months. I know that during the spring months if I close down the heater my milage improves. This is running the same number/mix of fuel. When the heater is turned on you can see heat coming off the fuel. I also know that in the racing area people use fuel cool can that run the fuel from the tank into this can with ice packed around the fuel line. This is used mainly in drag racing. I have heard of people putting a 25 lb bag of on the intake manifold of a 5.0 mustage and turning faster quarter mile times. | ||
| Jimmci9 (209.240.205.68) Rating: N/A |
by detroits design, and i'm not a mechanical engineer, they didn't put a fuel cooler anywhere... and neither did mci....i'm not advocating that either is wrong, but why second guess engineers... unless you do a superb job of plumbing it in, its just something else that has the possibility of leaking or failure.... the way the fuel is introduced into the engine, will have it righ back to operating temp in about 1/2" of travel..remeber, this is MY opinion, not fact... | ||
| TWO DOGS (65.177.145.86) Rating: N/A |
I will have to agree...think it's a waste of time & a place for fuel leaks | ||
| Henry R. Bergman, Jr. (Henryofcj) (209.210.116.234)
Rating: N/A |
Somewheres a long time ago I read that with Detroits, a small but definite power loss occurs when the fuel gets above 120 degrees F. The hotter the fuel gets above this temp, the less power the mill will put out. I do NOT know if there is an upper limit on fuel temps. | ||
| Jimmci9 (209.240.205.68) Rating: N/A |
condsidering the heads (where the fuel rails are, theyre internal passages) are at whatever the operating temp of the engine is..(hopefully held even by a thermostat).. then the fuel in those fuel rails is the same temp....like 180.... | ||
| Nick Morris (Nick3751) (69.68.39.128)
Rating: N/A |
I would think that the improved performance in the early morning your talking about has more to do with the cool heavy air than fuel temps. I no expert on racing but don't most race setups have external lines to the injectors that are not run through the head as in diesels? If there not fuel injected they're carborated and those lines don't run through the engine. The ice in the 5.0 I would think have more to do with cooling air not fuel. My opinion based on what I've heard in the past. | ||
| Sam Sperbeck (204.248.119.254) Rating: N/A |
Hi Jim, This is an interesting topic. I don't have any information to add, but if someone who has a digital thermometer would check the fuel temperature as it returns to the tank I think we would have a better idea as to whether fuel temperature is a significant factor in the amount of power an engine produces. Another, and possibly bigger, factor is the air temperature, at least in a naturally asperated engine. In our area of the country the air temperature in the morning is quite a bit cooler in the early morning than in the afternoon, and it makes a noticeable differance in a farm tractor under heavy load. Thanks, Sam Sperbeck La Crescent, MN | ||
| John Rigby (66.25.227.151)
Rating: N/A |
Sam My info comes from SandW and was concerning the 671N in my 4104 that is a little underpowerd for the hills/moutains/100deg summer days. The guy has been with Sand W for many years, and I really believe he has the experience. Amoung lots of bus and other projects he supervised the maintainance and repair of Houstons fleet of 130 eagles with 6v92Ta,s and 8v71Ta,s for many years. One of the problems they found was the temp of the fuel raising during the day.eventhough the thermostate would keep the engine in the correct temp. the fuel temp would still raise. John | ||
| Jimmci9 (209.240.205.68) Rating: N/A |
on our shop dyno... and we can run an engine over 2000 hp....the temp of the diesel doesnt seem to change the horsepower output... we've got a 500 galon tank.... inside the bay next to the dyno... and the fuel gets to nearly the same temp as the engine.... the 3512 cat deisels pull 1200 hp at 1200 rpm for 1 hr under a continuous load...and horsepower stays the same... horsepower will fall off as the room heats up and ambient air temp goes up....especially on a non-aftercooled engine....but on a seperate circuit aftercooled (scac) it will really pull the hp... as the aftercooler is on a different cooling tower than the engine cooling... | ||
| Ron Leiferman (Ron_In_Sd) (24.220.237.100)
Rating: N/A |
I agree that a colder air charge will produce more power. But spraying cold fuel into a warm air charge will reduce the air temp by amount. How big of a reduction, I don't know. I don't know how large the temp delta has to be to show a increase in preformace (HP) or fuel mileage. Since the fuel spends so much time in the engine on a detroits the delta would have to be very large. I think I would spent my time on figureing out how to get a colder air charge to the engine. Maybe extending the air intake outside the engine bay and putting a "hood" scoup on the side of the coach to get a "ram" effect. Ron in SD Sioux Falls, SD | ||
| CoryDane RTSII (66.155.188.218) Rating: N/A |
Going back to my dayz in school and in the science class with "Good Ole Mr Nix", we had learned that the molecules of cool air are close together because cool air can't move around as much as hot air molecules do. The condensed cool air molecules get so tight that they won't hold moisture (good illustration is Winter time up North where you have to turn on humidifiers), in this case are a better (thick) gas to supply the burn. As the day warms up, the air will thin out as the air gets warmer. Fuel is in a liquid state and as far as we were shown, didnt make much of a difference. For instance, remember that item that came out some years back that was hooked to the water heater line on the car, was supposed to heat up the fuel and make the car get better gas mileage, but did'nt do anything? This is along the same lines as liquids don't change state all that easily. If you were noticing a difference, it would probably be the air/vs temp rather than fuel/vs temp making the difference. "Good Ole Mr Nix", my science teacher, had a pleathera of practical experience and this part of the class was particularly interesting. I wonder if he wanted a diesel motorhome too? "Imagine" cd | ||
| dhallmci8 (198.81.26.45)
Rating: N/A |
I have a friend who flys and he claims that on mornings when the air is cool and heavy his plane goes much better than on warm or hot days when the air gets hot and thin dick | ||
| FAST FRED (63.234.23.10) Rating: N/A |
Its a good idea to purchase fuel early in the AM as a gal will weigh more when cool , so your purchasing more energy. I doubt that you run full throttle enough that any tiny loss in fuel density from heat would not be made up just by throttle position. The bottom of most coach fuel tanks is air cooled and is only warm , not hot on shutdown adter a long run. FAST FRED | ||
| Phil (204.89.170.126) Rating: N/A |
There are a number of things that make an airplane fly better in the cold air, all related to the air density. The engine puts out more HP (more oxygen molecules per cubic foot of air ingested), the prop and wings work better (get a better "bite") in cool (dense) air. As any of the pilots on this board know, the worst things for getting a plane off the ground are "hieght, heat and humidity", all of which decrease the densaity of the air. While fuel density also changes with temperature, I doubt it has a noticable effect but how do you non-scientifcally seperate the effects of the fuel vs. the air? | ||
| Sam Sperbeck (204.248.119.254) Rating: N/A |
Hi Fred, Where do you come up with your theories? Even if you are getting your fuel from an above ground tank, how much variation in temperature is there in 24 hours in a 10,000 gallon tank of fuel? Most of the truck stop fuel tanks in this area are underground so the fuel temperature stays very uniform over a 24 hour period. Of course if you are getting your fuel from a 300 gallon above ground boat dock tank there may be a slight difference between morning and afternoon. Thanks, Sam Sperbeck La Crescent, MN | ||
| FAST FRED (65.154.177.182) Rating: N/A |
That colder liquid is more dense than a heated liquid measured by volume (gal) is not a thoery. Not all land based fuel tanks are burried anymore. IF the fuel is any cooler in the AM is open to debate. FAST FRED | ||
| TWO DOGS (67.30.17.184) Rating: N/A |
I'll try to make this short...A guy I knew years ago kept asking me to take him up in my plane...passenger & pilot to weigh no more than 250 pounds..as specified on the specks for the plane....one HOT day he said "NAAAA,YOURE TAKEING ME FLYING NOW"...I said o.k. & we got in the plane & started down the runway...when the storage builing on the next guys property kept getting biger & bigger...(THE GUY LOOKED AT ME WITH GREAT BIG EYES & SAID...."HOW WE DOIN"...bet you he will not argue with me now !!!...that was 25 years ago..(both of us weighed 350)  | ||
| TWO DOGS (65.179.209.248) Rating: N/A |
only us old guys would remember...back 'before' air conditioning...Ya' had this round thing that had mats in it & the evaperation of water cooled the air as long as you were moving..that's what you need on your air intake...I've had cold diesel...in the middle of Montana ...my engine died...no motor..no heat...middle of the road I wrapped my elec. blanket on the crossover..had run all the fuel out of one tank... | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
Having lived and worked in the pretty city of Bakersfield CA for many years, nearly everyone knew that if you filled your diesel tanks in the cool morning, by late afternoon when it got very hot the fuel would expand and run out the tank. |