fuel system needs for 470-500hp setups
 

so i need some help on what people are using for fuel systems on around 500hp motors.

i have a new fuel pump 130gph which is more than enough fuel pump and my concern has become the lines going to it. i have a holley 850 on it and bought holleys chrome fuel line for that specific carb and it surprised me that the ID of the hard line is only .250dia going to each bowl and only .250 dia ID where the inlet feed from the hard line is, and if you look at my pic all of the things i have yellow lines going to are only .250dia ID. the hose nipple on my water separater is .312 dia ID.

i really dont want to replace every single thing in the fuel system, IE fuel separator, all the lines from the tank, the tank pickup ETC if i dont need to. did merc's 500HP engines all have bigger line for all this stuff????

unfortunately when they ran this motor on the dyno they fed my carb with there electric pump and -8 fuel lines to each float bowl. i wanted to run it afterwards with my fuel components afterwards to see if it became fuel starved or not but they didnt have any way to feed my fuel separator or check BSFC using my fuel system components so i dont have any good way to verify my stuff is sufficient until this boat hits water and honestly one of the reasons i dynoed it was so i didnt have to "tune" this on the water...

thanks!

http://i246.photobucket.com/albums/g...aja/fuel_1.jpg

Those lines will be fine. It looks to me like you dont have a fuel pressure gauge ? I would get rid of that cheap chrome line (it flakes off after awhile) and order the line from summit. It fits perfect...looks good...and has a port for a gauge. Then just make sure you have around 7 psi going into the carb, and your done !!! See how they look on my motors ?

http://www.summitracing.com/parts/SUM-220105/

http://www.summitracing.com/parts/SUM-800115/

no port for a gauge on the fuel line... i bought the holley "marine" line for the carb and once i got it and read the instructions it says "marine model has no 1/8" port" ..... so now that its all unpackaged so i could get to the instruction i really cant return it....

I'm figuring i when i make the new line for the new 130gph pump i will get the guage in there somewhere since i now need to add a pressure regulator to the system since the 130gph holley requires a regulator... $50 here, $50 there, pretty much doubled my cost for this project with all the surprise $50 and $100 items that pop up along the way!

what were your/are your motors now?? are you using the OEM fuel separators?

502's...and yes, they are OEM. Look at the lower right corner of the pic...you can see one of the water seperators. :drink:

ok, after looking at my fuel filter closer it seems that the holes feeding into the filter area are pretty darn small also??

are you guys making 500hp able to feed your motor through this stock OEM fuel filter setup??? heck i did some looking today and it seems like these filters only flow 70gph max..

i need to get all this fuel stuff sorted out in 3 days before this motor ends up back in the hull!!!


thanks!

When I was planning my engines I asked my engine builder if the stock setup was fine and he said up to 650 hp the stock set up is no problem. So with that said, your fine with what you have.

well after looking at the part microfiche for all year 525SC motors they used the exact same filter head and filter that my motor calls for OEM so i guess these parts will do the job after all!

now to the joy of making all new lines.....:(

Hmmm - if those fuel filters only flow 70 GPH, what is the point in running a pump that supplies 100+ GPH? I was considering upgrading my pump to a model that puts out 110 GPH, but now I wonder if that is worth doing?

bud,
i hear ya, that filter looks restrictive, and some of the specs i saw on fuel filters didnt look to flow real great, but after finding that the 525sc uses the same components for filter head and filter as mine did OEM then i guess it will work for my application. i can tell you the 525sc did NOT use the same fuel pump as the OEM 454 MAG so you might be borderline there with the OEM one


as for upgrading the pump, man what a cluster $%^&* that is turning into... trying to get fittings to go from the 3/8 npt to the flare needed for the hard line has been VERY problematic. i called about 4 different hyd places after striking out at my engine builders place. closet spot i found is michigan to get the fititng i need... just like eveytihng else, takes a week to solve a problem... maybe by 4th of july the motor might actually be inside the hull, instead of partying i will be laying inside my boat plumbing/wiring everything back together

GSXR, as Bill Clinton used to say, "I feel your pain". :) I finally got mine to light off last night, and ran it on the hose briefly, only to be greeted by clattering lifters and no water coming out the headers. Shut it down and drank several beers. I'll hit it again tonight.

Have you considered just running the stainless braided fuel lines or even the push-lock hoses? I believe the push-lock hoses are actually NHRA approved. I am running the braided lines on mine. You can generally find them in #6 for around $4 / foot, and fittings shouldn't run much more than $5 each. Now those damn #10 lines I had to run for the oil cooler cost a king's ransom! :eek:

i actually have all the pushlok stuff to do it, but its not USCG approved so i most likely wont use it. also, i need a fairly tight bend that i cant do easliy in pushlock without adding more 90's, and the 90's kill fuel flow. the adapters i got to go from the pump to the 6an in 90 degree are not "full flow" type 90's.. so those reasons have led me back to going with hard line plus CG cant balk about it either..

what lifters are you running? how much preload? i got lucky on mine and they didnt even have to touch them on the dyno. are you sure it ran long enough to fill the whole motor, when shes bone dry it takes a lot to fill all them hoses and block up!!!

good luck man!

They are stock GM roller lifters - i gave them maybe 5/8 turn preload, which is what the engine builder recommended. They apparently don't take as much preload as some of the aftermarket ones. I'm going to run it through a couple of heat cycles to see if they quiet down a little.

I ran it for close to a minute on the hose, so it should have had time to start sending some water out the exhaust. Headers started to get hot, so I cut it off. I'm going to pull some hoses tonight, weather permitting, to make sure the pump is putting out flow.

did you prime the engine long enough to get oil coming out of all your pushrods?? i know on mine it took forever with the drill and my mechanical guage showing 70psi of oil pressure to get all the pushrods full and flowing oil after i had turned the motor over doezens of times setting the valve lash? you might just have a bunch of collapsed lifter that arent full yet??

water issue, run your hose with the motor off providing your water dumps enough back that it will drain out the exhasut and not pour back into the motor and see if you get water flow? a bad impeller shouldnt stop water flow when on the hose unless something got clogged somehow?