Good morning guys,

Question, I finally got my rebuilt 509 back from the machinist and prepping it to drop back in the boat. I am replacing the stock MPI fuel injection with a Holley HP system and want to upgrade the fuel system. I am running a Holley marine rated fuel pump but it will be all -AN line so I want to replace the factory cool fuel with a new aftermarket exchanger. I found the one in the link, wonder if ti is a good choice or is their a better route to go? Engine will be in the 550hp N/A range so nothing crazy.

https://azspeed.com/product/high-flow-fuel-coolers/

why not lose the fuel cooler and just run a return line to the tank.

I went with a new higher flow external fuel pump and an external fuel pressure regulator. I heard a lot of people say these cool fuel units fail as well. I have to hard proof of that but I figured I would just go all new and stay away from that unit.

If you run the fuel back the tank, the tank acts as the cooler. It’s much simpler.

I am 100% running it back to the tank, if I can eliminate the cooler all together Im good with that. I mean its a 100 gal tank I don't see that heat soaking and especially when my boat is running for maybe a 1/2hr to an hour at a clip before being anchored for hours.

Yep, you’ll be fine that way.

That`s how I did mine. Got it from Mr. Cool . It`s on the return line.

I don`t see how a gas tank would be cool in the summer heat under a floor.
Cool fuel makes more power and is better for fuel pumps, regulators, injectors etc etc.

I don't see how it will heat 100gal under the floor I mean in a car there is no fuel cooler but yes it has air flow across it under the car. I would guess if your running for hours at a time at low speed where it is returning most of the fuel back to the tank it possibly could heat soak the fuel or if you get low on fuel but for the most part I dont see no cooler being an issue but I have no real world proof. I may just install one to take the "what if": out of the equation.

I used a cooler as shown above, and it works fine. I would have preferred a return to the fuel tank, but with three separate tanks, it just wasn't practical.

Steve