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Fuel cooler

Blackmagic94

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I’m don’t think you’ll end up with much of a cooling effect once that fuel returns to saddle tanks. Do you have an idea of the temp increase from the pumps? I don’t see where the juice is worth the squeeze.
Not sure I’ll laser temp some alum fuel lines next time out. But regardless a liquid to liquid will still bleed some water heat
 

oldschool

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I guess adding cooler fuel back to the tanks is better than adding warmer fuel, but unless that fuel is significantly cooler than the 12 gallon tank is it going change the fuel temp the pump sees much? Now, if you put some cooling coils around the fuel tanks you might change that temp, a little.
 

Rajobigguy

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I guess adding cooler fuel back to the tanks is better than adding warmer fuel, but unless that fuel is significantly cooler than the 12 gallon tank is it going change the fuel temp the pump sees much? Now, if you put some cooling coils around the fuel tanks you might change that temp, a little.
You are right that returning it to the tank directly will have little affect on the temp because you are comingling it with a large amount of warm fuel. That's why I did mine the way I did. If you look at the pic in post #60 you will see a red bottle and that is what I call the comingler. Fuel returning from the the fuel rail goes in there after it has passed through the cooler and mixes with fuel from the lift pump. The fitting at the top of the bottle is the return to tank but that bottle also serves to maintain positive head over the injection pump . This way I'm only trying to cool a small amount of fuel that is available for the injection pump to feed off of.
 

oldschool

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You are right that returning it to the tank directly will have little affect on the temp because you are comingling it with a large amount of warm fuel. That's why I did mine the way I did. If you look at the pic in post #60 you will see a red bottle and that is what I call the comingler. Fuel returning from the the fuel rail goes in there after it has passed through the cooler and mixes with fuel from the lift pump. The fitting at the top of the bottle is the return to tank but that bottle also serves to maintain positive head over the injection pump . This way I'm only trying to cool a small amount of fuel that is available for the injection pump to feed off of.
Have you measured the temp change with that setup?
 

JUSTWANNARACE

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Blackmagic94

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All that race car shit doesn’t work on anything that’s driven more than 10 seconds at a time. In a marine application you have the ultimate coolant, the lake water. Why would you not use that media as your coolant.
 

JUSTWANNARACE

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All that race car shit doesn’t work on anything that’s driven more than 10 seconds at a time. In a marine application you have the ultimate coolant, the lake water. Why would you not use that media as your coolant.
Right, I get not running the co2 or nitrogen.

But if you think outside the box a minute, why could you not plumb it in to the fresh water feed from the pump? They are basically a canister in side I canister. Water flows through the outside can, fuel flows throw the inside can!

You will never find a "bolt on" "application specific" for you exact set up. They dont make them!
 

Looking Glass

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Right, I get not running the co2 or nitrogen.

But if you think outside the box a minute, why could you not plumb it in to the fresh water feed from the pump? They are basically a canister in side I canister. Water flows through the outside can, fuel flows throw the inside can!

You will never find a "bolt on" "application specific" for you exact set up. They dont make them!

You Will NEVER!!!!

o_O
 

white tortilla

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Ok looking for something out of the box and I had an idea. It’s complicated and not typical.

For both tanks, plumb a -8 line from jet pump gate valve to a AN “T” fitting, then reduce to two -4 lines from “T” each directly into gas tank. This will allow ample lake water into the gas tank to cool fuel. Then put high flow mechanical fuel water seperator on each of your fuel supply lines out of the tanks to the motor. The seperator will need a -6 return dump line out back of boat to keep consistent water flowing into and out of tanks.

just another option.
 

JUSTWANNARACE

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You Will NEVER!!!!

o_O
So you think there is a bolt on application for a 1979 Carrara bubble deck jet boat(or whatever) with a BBC, 6-71 blower, with aftermarket fuel injection? Type that in an see how it works out for you!

Custom boats mean custom parts. Parts that have to be made, modified, ect..

But whatever, You're an idiot, go troll someone else
 

Uncle Dave

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Seems to me a 2 stage sea pump and a dan olson cooler with fuel routed through one leg would do a pretty good job of cooling down your tank.
 

Looking Glass

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So you think there is a bolt on application for a 1979 Carrara bubble deck jet boat(or whatever) with a BBC, 6-71 blower, with aftermarket fuel injection? Type that in an see how it works out for you!

Custom boats mean custom parts. Parts that have to be made, modified, ect..

But whatever, You're an idiot, go troll someone else

BUT!!, you're so "EASY"😊
 

rickdarling

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If you have a stock injected Mercruiser motor, it’s probably a cool fuel unit. It is cooled and maintains a certain pressure.

I’m told that it is almost impossible to change to some other system of fuel feed if it’s a late model Mercruiser motor. I was further told that it is necessary as there is no return line and, as a result, the unit is necessary to avoid vapor lock and other problems.

I don’t know if it’s absolutely true but, it forced me into having both of my units rebuilt because mine failed and there is a big back log of new units.

Teague Marine helped address the issue.

That said, based on your motor (just re-reading now), it looks like this might not apply..
 
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Orangegazm

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CP Performance makes a sea strainer with a cooling coil in it. P/N 620-913203
 

Rajobigguy

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What is the end application for this system.
383 SBC engine that I adapted a a M112 supercharger to and a Ford racing computer to drive the fuel injection and coil on plug ignition. A very detailed build thread for this project will start around Nov. of this year.

Teaser photo of the mock up.

1623260299946.png
 
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motormonkey

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I have all my fuel shipped in from Canada so it's already cooler.
The best cooler is the sea strainer style on a return system. No deadheading of regulator.
. Put phenolic spacers on fuel rails. Also cover your tanks with interior panels.
 

DaveH

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if
He’s going to be pushing around a shitload more fuel than a carbed engine, and that will heat up the fuel quite a bit so he’s starting at a disadvantage.

@Blackmagic94 I’d insulate the supply line from the surge tank to the engine for sure, and also where you place the regulator will probably be important, and running the return back to the main tank may be what you want to do.
you are circulating so much fuel that heating it is becoming a problem........someone didn't do their homework designing the fuel system.

highly vaporized (meaning incredibly volatile) fuel is introduced to a cylinder at temps far in excesses of what your fuel plumbing sees. yet it doesn't light then.

vapor lock occurs when there isn't fuel flow........so i wouldn't waste money on a fuel cooler.
 

LargeOrangeFont

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if

you are circulating so much fuel that heating it is becoming a problem........someone didn't do their homework designing the fuel system.

highly vaporized (meaning incredibly volatile) fuel is introduced to a cylinder at temps far in excesses of what your fuel plumbing sees. yet it doesn't light then.

vapor lock occurs when there isn't fuel flow........so i wouldn't waste money on a fuel cooler.
My point was that hotter fuel is more prone to vapor locking once you stop running your boat.

Merc equips their OE engines with a fuel cooler for this reason.
 

Blackmagic94

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if

you are circulating so much fuel that heating it is becoming a problem........someone didn't do their homework designing the fuel system.

highly vaporized (meaning incredibly volatile) fuel is introduced to a cylinder at temps far in excesses of what your fuel plumbing sees. yet it doesn't light then.



How do you pump enough fuel to support the bsfc of the engine then?

vapor lock occurs when there isn't fuel flow........so i wouldn't waste money on a fuel cooler.
 

Racey

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My point was that hotter fuel is more prone to vapor locking once you stop running your boat.

Merc equips their OE engines with a fuel cooler for this reason.
Merc dead heads the fuel rails. If you have a flow through rail this is never an issue. A flow through rail is far more robust, less prone to a multitude of problems.

Merc does this because they don't equip a return line for the installation of their motors, just a fuel inlet, the fuel is self returning back to the inlet of the high pressure pump on a merc setup, all part of the engine package. The merc fuel cooler won't do anything to prevent vapor lock in the rail, which is where it is most troublesome and common, as the fuel is already past the cooler at that point, you can't do anything to cool it once it's in the rail.
 

asa400ex

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Merc dead heads the fuel rails. If you have a flow through rail this is never an issue. A flow through rail is far more robust, less prone to a multitude of problems.

Merc does this because they don't equip a return line for the installation of their motors, just a fuel inlet, the fuel is self returning back to the inlet of the high pressure pump on a merc setup, all part of the engine package. The merc fuel cooler won't do anything to prevent vapor lock in the rail, which is where it is most troublesome and common, as the fuel is already past the cooler at that point, you can't do anything to cool it once it's in the rail.
@ Racey Do you have any suggestions on how to stop vapor lock on a rail that dead heads? I have this same issue with my 1996 7.4 MPI. I was hoping a cooler would stop this from happening. Does Merc make a replacement rail with a return to the tank?
 

DaveH

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@ Racey Do you have any suggestions on how to stop vapor lock on a rail that dead heads? I have this same issue with my 1996 7.4 MPI. I was hoping a cooler would stop this from happening. Does Merc make a replacement rail with a return to the tank?
you ditch the mercury pressure regulator, replumb the rails adding an aftermarket regulator then add a return from the regulator to the tanks. set the pressure to the same PSI with the regulator merc runs. done.
 

DaveH

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you calculate the needed fuel flow. in some cases, you cant find a pump with the volume/pressure to match your requirments. . in this case......i would go with a SECOND pump, that comes on with boost. super easy to control with a good ecu.
 

Racey

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@ Racey Do you have any suggestions on how to stop vapor lock on a rail that dead heads? I have this same issue with my 1996 7.4 MPI. I was hoping a cooler would stop this from happening. Does Merc make a replacement rail with a return to the tank?
Yeah like DaveH said, you gotta change the regulator and rail plumbing.

Some of those merc motors like the 502 and 525s run a single rail in the valley, you gotta pull that rail out and machine the end with the schraeder valve to accept a fitting that can flow the fuel to an external regulator. Not the simplest job in the world.
 

Blackmagic94

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you calculate the needed fuel flow. in some cases, you cant find a pump with the volume/pressure to match your requirments. . in this case......i would go with a SECOND pump, that comes on with boost. super easy to control with a good ecu.


So what you are saying is you didn’t read my thread about the fuel system.


I have a low pressure lift pump to a fuel surge tank with two internal Bosch fuel pumps, one runs all the time and secondary fuel pump comes on with load.


Due to have the potential for 3 pumps at wot. I want a cooler.
 

DaveH

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So what you are saying is you didn’t read my thread about the fuel system.


I have a low pressure lift pump to a fuel surge tank with two internal Bosch fuel pumps, one runs all the time and secondary fuel pump comes on with load.


Due to have the potential for 3 pumps at wot. I want a cooler.
actually I did read your post.

your lift pump wont create any heat as it will make bare minimal pressure. if you are staging your pumps correctly and CONSUMING the fuel based on flow requirements, and not recirculating most if it, heat in the fuel is minimized.....

maybe you should not be a DB and think about what someone who is simply offering suggestions on your thread that may actually have merit.

besides you really think the temp delta across that merc cooler actually does anything? got any data? i have temp sensors in my fuel systems....you might be surprised.
 

Racey

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So what you are saying is you didn’t read my thread about the fuel system.


I have a low pressure lift pump to a fuel surge tank with two internal Bosch fuel pumps, one runs all the time and secondary fuel pump comes on with load.


Due to have the potential for 3 pumps at wot. I want a cooler.
You could run 5 pumps, you still don't need a cooler. I doubt you would see a 2 degree rise from the pumps in that boat, what does it hold? 30,40 gallons?

They are much more important in DI applications, like diesels, where you are pressurizing the fuel to 10's of thousands of psi. and you are creating 50 degree temp increases on your returns.

Merc runs the cooler to prevent vapor lock at the fuel pump, they run them on closed cooling motors that have operating temps of 180F, in closed engine bays. The thought behind their's is that if the fuel is sitting in a cooler right there attached to the pump which is flooded with lake water, it's much more difficult to vapor lock causing a lack of pump suction. That is why they do it. It also wicks heat away from a pump sitting right next to a hot exhaust manifold and engine block with no air circ, for a pump that is not submerged, or being cooled by fuel flow.

Let's do a little math.

2 Walboro 255's @ 7.5 amps each is is 90 watts per pump, 180 watts total, 180 watt hours is 614 BTUs

1 BTU raises the temp of 1 pound of a liquid (water, but we'll say fuel here) 1 degree. in 40 gallons there is 250 lbs, so even if the pumps were fully inefficient acting as heaters (they aren't), and both were running for 1 hour straight (they won't), that would still only be enough to raise the temp of the circulated liquid 3 degrees F appx after a complete hour of operation. And this is without them shedding any of that heat back to the surroundings through the lines and tanks (they will).

Even if it was only 20 gallons, and we said they heated at double that rate , all of this added complication to drop fuel temps ~10 degrees?

🤔

On all of the installations i have done from 600hp NA to 1500hp turbo motor stuff, we have never, ever, not once, had fuel temp problems. Big electric pumps, waterman mechanical pumps, etc. Even in offroad cars that have way more heat issues than marine stuff due to radiators etc.
 

Blackmagic94

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actually I did read your post.

your lift pump wont create any heat as it will make bare minimal pressure. if you are staging your pumps correctly and CONSUMING the fuel based on flow requirements, and not recirculating most if it, heat in the fuel is minimized.....

maybe you should not be a DB and think about what someone who is simply offering suggestions on your thread that may actually have merit.

besides you really think the temp delta across that merc cooler actually does anything? got any data? i have temp sensors in my fuel systems....you might be surprised.

The pumps are 15% over the calculated lph consumption of the planned power output for the reason of min heat. I’m not suggesting the merc cooler but a better setup. Better yet is it gonna hurt me to run a cooler? Is it gonna offend you since you are calling me a douche bag in my thread?
 

Blackmagic94

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You could run 5 pumps, you still don't need a cooler. I doubt you would see a 2 degree rise from the pumps in that boat, what does it hold? 30,40 gallons?

They are much more important in DI applications, like diesels, where you are pressurizing the fuel to 10's of thousands of psi. and you are creating 50 degree temp increases on your returns.
Merc runs the cooler to prevent vapor lock at the fuel pump, they run them on closed cooling motors that have operating temps of 180F, in closed engine bays. The thought behind their's is that if the fuel is sitting in a cooler right there attached to the pump which is flooded with lake water, it's much more difficult to vapor lock causing a lack of pump suction. That is why they do it. It also wicks heat away from a pump sitting right next to a hot exhaust manifold and engine block with no air circ, for a pump that is not submerged, or being cooled by fuel flow.
Merc runs the cooler to prevent vapor lock at the fuel pump, they run them on closed cooling motors that have operating temps of 180F, in closed engine bays. The thought behind their's is that if the fuel is sitting in a cooler right there attached to the pump which is flooded with lake water, it's much more difficult to vapor lock causing a lack of pump suction. That is why they do it. It also wicks heat away from a pump sitting right next to a hot exhaust manifold and engine block with no air circ, for a pump that is not submerged, or being cooled by fuel flow.

Let's do a little math.

2 Walboro 255's @ 7.5 amps each is is 90 watts per pump, 180 watts total, 180 watt hours is 614 BTUs

1 BTU raises the temp of 1 pound of a liquid (water, but we'll say fuel here) 1 degree. in 40 gallons there is 250 lbs, so even if the pumps were fully inefficient acting as heaters (they aren't), and both were running for 1 hour straight (they won't), that would still only be enough to raise the temp of the circulated liquid 3 degrees F appx after a complete hour of operation. And this is without them shedding any of that heat back to the surroundings through the lines and tanks (they will).

Even if it was only 20 gallons, and we said they heated at double that rate , all of this added complication to drop fuel temps ~10 degrees?

🤔

On all of the installations i have done from 600hp NA to 1500hp turbo motor stuff, we have never, ever, not once, had fuel temp problems. Big electric pumps, waterman mechanical pumps, etc. Even in offroad cars that have way more heat issues than marine stuff due to radiators etc.

26 gallons on stock system plus 1.45 gallon increase for surge tank.

I can post instruction from pump manufacturers to not run continuous duty on a 90 deg plus day. That’s why I went surge tank with Walbro/Bosch style oem intank pumps as I know they will run cooler and more reliable. Back when I was doing fast cars no one had cool surge tanks like this for sale. I’ve seen A1000s fail on street duty turbo cars in az.

And I love the math. Thank you.
 
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Racey

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26 gallons on stock system plus 1.45 gallon increase for surge tank.

I can post instruction from pump manufacturers to not run continuous duty on a 90 deg plus day. That’s why I went surge tank with Walbro/Bosch style oem intank pumps as I know they will run cooler and more reliable. Back when I was doing fast cars no one had cool surge tanks like this for sale. I’ve seen A1000s fail on street duty turbo cars in az.

And I love the math. Thank you.
I've seen a1000s fail right out of the box 🤣

The surge tank is a 100% absolute must. I don't know how many times i've tried telling the hard headed how crucial they are.

The cooler, i wouldn't bother with.
 

DaveH

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The pumps are 15% over the calculated lph consumption of the planned power output for the reason of min heat. I’m not suggesting the merc cooler but a better setup. Better yet is it gonna hurt me to run a cooler? Is it gonna offend you since you are calling me a douche bag in my thread?
does it hurt? lets talk about the down sides.

1. more complicated plumbing
2. another potential fuel leak
3. potential to mix fuel and water
4. adds $$$$$

upside? still looking for that one.

as for aermotive pumps failing? that's like saying night wont come.
 

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Merc dead heads the fuel rails. If you have a flow through rail this is never an issue. A flow through rail is far more robust, less prone to a multitude of problems.

Merc does this because they don't equip a return line for the installation of their motors, just a fuel inlet, the fuel is self returning back to the inlet of the high pressure pump on a merc setup, all part of the engine package. The merc fuel cooler won't do anything to prevent vapor lock in the rail, which is where it is most troublesome and common, as the fuel is already past the cooler at that point, you can't do anything to cool it once it's in the rail.
Agreed, great points and I’d certainly trust your expertise.

From an automotive application perspective, I’ve seen the surge tanks setups create notable heat in the fuel, but cars don’t seem to vapor lock very often.

My race car has a deadhead fuel setup and does not even vapor lock, I was confused as to why it was even happening on fuel injected boats when I was new to boating.
 

Racey

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Agreed, great points.

From an automotive application perspective, I’ve seen the surge tanks setups create notable heat in the fuel, but cars don’t seem to vapor lock very often.
Never seen them create heat in any of the offroad cars we have put them in. Properly setup they circulate more than the HP requirement of the engine back to the main tank continually, the pump feeding them operates at a very low pressure so it adds basically no heat, esssentially they make no difference in fuel temp vs just a standard single pump setup.

Now if you mount the tank somewhere that it is absorbing engine/exhaust heat, well that is a problem not caused by the tank itself, but rather the installation. If the surge tank is going to be mounted in the engine compartment it should be heavily insulated with a glass/therm blanket. The tanks are usually aluminum so they act as a kind of radiator themselves, if you mount them somwhere cooler than the fuel, they will cool the fuel, if you mount them somehwere hotter than the fuel they will heat it.
 

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Never seen them create heat in any of the offroad cars we have put them in. Properly setup they circulate more than the HP requirement of the engine back to the main tank continually, the pump feeding them operates at a very low pressure so it adds basically no heat, esssentially they make no difference in fuel temp vs just a standard single pump setup.

Now if you mount the tank somewhere that it is absorbing engine/exhaust heat, well that is a problem not caused by the tank itself, but rather the installation. If the surge tank is going to be mounted in the engine compartment it should be heavily insulated with a glass/therm blanket. The tanks are usually aluminum so they act as a kind of radiator themselves, if you mount them somwhere cooler than the fuel, they will cool the fuel, if you mount them somehwere hotter than the fuel they will heat it.
That’s is true. We typically have them in the trunk area picking up some radiant heat, especially in a gutted car. When using PWM fuel pump drivers heat is way less of an issue. Again I’ve never really seen vapor lock issues from them in the car, just warm fuel from being endlessly circulated, and with the right return setup, it is a non issue. I have set them up with the return going all the way back to the tank. Some people return to the surge tank, which I don’t like as much.
 
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