On a seperate post I mentioned that Jaguar and Mercedes had a fuel cooler intergrated with the A/C as an OEM part. This is designed to stop fuel vapourisation.
Does petroleum have a specific heat range were it is more efficient ect, or does it behave the same way through a temperature range, right up until it vaporises.
As modern vehicles have EFI, which generally heats up the fuel, due to the cycle of the surplus fuel in the hot fuel rails returning to the fuel tank, I was wondering why even Jaguar and Mercedes to my knowledge no longer bother with A/C fuel coolers.
I have come across an aftermarket A/C fuel cooler and was looking to establish what benefits there would be (if any) if my fuel never vapourised anyway.
Are there any benefits to simply having cold fuel?
Regards
AGM
Fuel Coolers
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The chemical mixture called gasoline varies in density and viscosity during the year as the refineries ATTEMPT to match the maximum Ried Vapor Pressure for the 100 different EPA areas in US........to minimize evaporative emissions [when you fill the tank and have the sealed system open].
Years ago [and even today] the ecu were not smart enough to calculate mixture on the fly so knowing the fuel temperature has replaced trying to keep the fuel temperature cool in summer.Almost all OBD2 [96+] monitor the fuel temperature to fine tune the injector opening time [+-3%] as colder gasoline is thicker and starts the flow slower.
Nissan has designs in the past with fans blowing on injector rails.
The Q/J never seem to suffer from fuel rail vapor lock because the rail flow is 10-20 times the idle consumption and ramps up [why the variable speed pump] always maintaining at least 2 times the maximum required flow at WOT even at redline [big pump].
The 60 gallon per hour pump greatly exceeds the 25 gallons per hour that the Q could consume when making 320 HP.
Obviously if you only have 4 gallons in the tank even at 5 gallons per hour recirculation [idle speed].....the tank gasoline has a long time to cool from its brief exposure to 200-220F under the plenum.
Even in heavy stopped 100F traffic the AC heated, radiator heated air rarely exceeds 180F and the heads rarely exceed 230F.http://www.ftimeters.com/pages/uvc.htmlThere is probably a little HP to be gained from cooling the gasoline because the pre OBD2 ecuare probably optimized for 68F ambient but the WOT summer mixture are already so super rich to suppress detonation that if anything less fuel is desirable rather than more!
Guess a bad fuel pump might slow the exchange down enough to cause problems in Death Valley traffic jams.
Years ago [and even today] the ecu were not smart enough to calculate mixture on the fly so knowing the fuel temperature has replaced trying to keep the fuel temperature cool in summer.Almost all OBD2 [96+] monitor the fuel temperature to fine tune the injector opening time [+-3%] as colder gasoline is thicker and starts the flow slower.
Nissan has designs in the past with fans blowing on injector rails.
The Q/J never seem to suffer from fuel rail vapor lock because the rail flow is 10-20 times the idle consumption and ramps up [why the variable speed pump] always maintaining at least 2 times the maximum required flow at WOT even at redline [big pump].
The 60 gallon per hour pump greatly exceeds the 25 gallons per hour that the Q could consume when making 320 HP.
Obviously if you only have 4 gallons in the tank even at 5 gallons per hour recirculation [idle speed].....the tank gasoline has a long time to cool from its brief exposure to 200-220F under the plenum.
Even in heavy stopped 100F traffic the AC heated, radiator heated air rarely exceeds 180F and the heads rarely exceed 230F.http://www.ftimeters.com/pages/uvc.htmlThere is probably a little HP to be gained from cooling the gasoline because the pre OBD2 ecuare probably optimized for 68F ambient but the WOT summer mixture are already so super rich to suppress detonation that if anything less fuel is desirable rather than more!
Guess a bad fuel pump might slow the exchange down enough to cause problems in Death Valley traffic jams.
Vapor lock was a huge problem for the '73 and '74 Zcars. They recalled the cars and fitted insulations around the fuel rails. The switch to FI in '75 solved the problem untill the turbo came along.
The L series Z engine was not a cross flow head so the fuel rail was on the same side of the engine as the exhaust header and the turbo. While running there was no problem due to the continuous fuel flow of the Bosch LH injection system. But park the car after a good run and the heat would vaoprize EVERYTHING (Brake fluid included). A small fan was added that blew cooler air from the off side of the engine to the hot side. It kinda sorta worked, kinda sorta. I now use that setup on any Zcar with tripple Webbers.
I would think the Q would benifit from insulating the fuel lines and fuel rails in the engine compartment. I'm due for the pull the plenum, replace the hoses, replace the harnesses, redue the cam covers evolution soon so I will try it.
Thermal insulators between the head and intake plenum may be an idea. what do you think?
The L series Z engine was not a cross flow head so the fuel rail was on the same side of the engine as the exhaust header and the turbo. While running there was no problem due to the continuous fuel flow of the Bosch LH injection system. But park the car after a good run and the heat would vaoprize EVERYTHING (Brake fluid included). A small fan was added that blew cooler air from the off side of the engine to the hot side. It kinda sorta worked, kinda sorta. I now use that setup on any Zcar with tripple Webbers.
I would think the Q would benifit from insulating the fuel lines and fuel rails in the engine compartment. I'm due for the pull the plenum, replace the hoses, replace the harnesses, redue the cam covers evolution soon so I will try it.
Thermal insulators between the head and intake plenum may be an idea. what do you think?