single carb vs efi same horsepower... upside?? downside??
 

Looking at buying a single carb new motor set up making around 600hp... With some tweeking... My merc 500efi's could get close. I have a triple 500 set up in my 47 fountain. If i switch to single carb motors... Will i show any gas savings? Will it effect resale value up or down?? Any suggestions are greatly apreciated!!

Team: to get the HP 500's to 600 horse you would have to tweak them quite a bit. Probably stroke them, cam, head work. The EFI manifold will be a limiting factor also. The 500 efi's are pretty thrifty on gas so there will not be a savings.

Wannabe

Ok, understood.... What if we compare the stock 500 efi's to some pro built 572 700hp single carb motors? Will resale ramp up or down? Also thinking about reliability on the efi vs single carb....

that depends on who's looking at buying....some think EFI greatest thing since sliced bread...others see it more of a headache with much more to go wrong..harder to service...with little gains...so ???

if I recall, hotrod or some other mag did a test back to back with an efi and then a carb. after tuning there was very little difference between the two. not enough that you would notice when driving. the efi did use slightly less fuel but that is because you can tune every rpm point to be exact where the carb will always have a spot or two that are a little off. their opinion at the end was that it is personal preference due to the nearly identical power.

The majority of people I talke to would look more favorably on a set of fresh factory blue motors that are not too modified vs old school carbed engines, efi has became more accceptable these days and expected by many people. A triple engine boat is a hard sell already , if your keeping it long modify it the way you want though and enjoy it, Smitty

I'm surprised at the number of high end boats and engines (MTI, Skater, Nortech, Sterling, etc) who use carbs rather than EFI. I am converting to EFI, hoping I'm doing the right thing....keeping my carbs just in case though...

i have done allot of research on switching to efi in the past, after allot of reading i came to the cunclusion that there is little benifit to having efi. because of the high rpms we run consistantly you will not get much if any better gas milage from efi and they restrict you if you are doing high perfromance. in stock form i wouldnt mind a efi motor, if i am trying to gain power then i would be removing it. there is a reason why you see efi manifolds up for sale all over the place. now saying that, i have been looking at possibly pro charging, i wouldnt mind efi on a pro charged motor since it seems that there allot of guys that have the computer programing nailed on that setup. lack of efi would not push me from buying a boat

little benefit switching to efi. NO benefit switching back to carbs. especially on a really high dollar boat like that.

I would think the stock 500EFIs would be the most saleable motors in the boat. Had a buddy with a 2004 47 that came with 525s in it. Wanted to go faster so he built them to carbed 600s. Boat picked up like 3 mph. And then the drives started to blow. That boat is a tough sell, stock blue motors are probably your best bet.

heres my 2cents.i had efi in one of my boats for 5yrs.it ran flawlessly.at times i could get 3.4mpg @45mph.i started having problems with the efi.i have never worked on efi,let alone fuel injection,but i did mess around w/hotrods in my younger years,so i was comfortble w/a carb.after paying people to work on efi,i decided to go with what i could work on.i switched a carg.heres what i lossed.i lossed about a i/2 gal on my fuel consumption,from 3.5 to 3.0 miles per gallon.i loss the get in and turn the key idle on the boat.heres what i gained.a set up i could work on.i gained parts excess,i can walk into any auto store and buy carb parts and stuff fot the distributor.i can trouble shoot the carb.but the biggest thing i gained,,,,,,,pease of mind.knowing if it broke,i could fix it myself,and i wouldnt go broke paying someone to fix it.jus my 2cents.

I have given it a lot of thought guys and I agree with you. Stock blue motors are hard to beat. I have the factory build sheet from Fountain and all motors and drives are 100% factory. The center gimble was upgraded to an HP Gimble but other then that... everything is 100% original to the boat.

The more I think about it... finding one of these 47's bone stock and all original is like picking up a numbers matching 69 Camaro with the original build sheet. (well... kind of :whistle: )

Alright... the drives are in Clearwater right now getting a full bearing / seal rebuild... should have them back along with the rams in a week or so. I am going to go ahead and take the trip 500's out in about a week and begin the rebuild process. That way... when everything is put back together, I'll have a fully documented zero hour boat all the way around. Also performing general service to the generator and HVAC unit, etc...

New upholstery was installed last week on the engine hatches along with other parts and pieces. Should make for a good ride... I'll keep you guys posted and thank you for the help!!!!

Q

I have 2 boats one with EFI one without.


EFI on a boat does not provide the benefits that it does in an a car because there is no O2 sensor in the loop when running to continuously "retune".

Water wreaks havoc with the O2 sensors so Marine EFI operates in a closed loop environment. It gets tuned once then is "set". Sure you can apply a different a map

Yes you get instant starting, kitten like idling, and great part throttle economy.

You do NOT get altitude compensation without retuning.

Swapping jets is almost as easy (some would say easier) as dragging out a laptop, putting in an O2 sensor, and retuning.

I love my EFI rig, but there is a lot to be said for the dead on simplicity of a carb.

Uncle Dave

I would love to have a 47'. If and when I am lucky enough to move up I would want mine with stock motors. JMO