View Full Version : Aftermarket Fuel Infection for your older MasterCraft

01-12-2005, 09:52 PM
I know several people on this site are looking at ways to increase horsepower in their older mastercrafts or are having problems with their carburetor. Anyone ever consider replacing the carburetor with Holley's Pro-Jection Fuel Injection system? I first became aware of this system from an old Holley overhaul manual and thought I would see if anyone here has experience with it.

As near as I can tell this is a bolt on replacement for a traditional carburetor and can increase power by as much as 25% while improving fuel efficiency (numbers come from various sources so don't quote me). In addition to replacing the carburetor you have to have to add a fuel pump, a return line, and other related stuff. Once installed you there is a computer controller that can be adjusted to meet the performance needs of the application.

Here is a link to a system on ebay:


I looked quickly on the Holley site and didn't find the site too useful and didn't explore too much since I won't likely do this mod myself.

01-12-2005, 10:38 PM
I'm trying to find a way for injection to increase power by 25%. If it's 25% more than a badly adjusted carb, OK. If the carb is set up right and is the right one for the motor, just going to injection shouldn't be that much on an increase. Increased reliability and easier startups, yes.

Hotter spark, tweaked timing, hotter cam, valve job/roller lifters/rockers shaved heads and better intake manifold would definitely give you more power. On the other hand, if you did all of these other things and spent the $200 for a good carb rebuild, you would be money ahead compared with injection, although I really like injection for its dependability.

east tx skier
01-13-2005, 10:55 AM
When I mulled doing this on my old jeep, the consensus was that there would not be a noticeable power increase over a properly tuned carb, as JimN has said.

Jim, in all our previous discussions, a hotter ignition system never came up. I've got the electronic ignition already (OEM 93). Is there a hotter one that I could go to that would give me better performance. What else would have to be changed if I did this mod.

/I've been watching to much "Full Throttle" on the History Channel.

01-13-2005, 11:03 AM
Generally, a hotter ignition is for when a lot of gas is being delivered and it all needs to burn, usually high HP motors. A boat from '85 isn't going to have the most up-to-date technology on it, so if any major work will be done on the motor, I think a slightly hotter coil could help.

01-13-2005, 02:02 PM
I would be interested in stories of aftermarket injections systems also. I agree with Jim in questioning the HP gain information. My interest would be strictly in cold and warm-up driveability improvements.

east tx skier
01-13-2005, 02:11 PM
So Jim, in my situation, if I read you right, you're saying that an HEI ignition or the like isn't going to make much difference over the Petronix or whatever that is stock on my boat.

01-13-2005, 02:57 PM
Doug-if I remember correctly, you have the electronic ignition, which only replaces the points, right? You might call Skidim and see if they have a slightly hotter coil and if the module you have will handle it. If necessary, the distributor can be replaced with one that will. Whenever I watch the gearhead shows on TNN or whatever, they're usually replacing the stock coil with higher output. Yours probably puts out around 25KV and the MSD, Accell and others put out around 50KV. Then they open the plug gap and have a bigger spark to burn the fuel/air charge with.

east tx skier
01-13-2005, 03:37 PM
Cool. Other than the gap, nothing else you can thing of that would need to be tweeked?

01-13-2005, 03:52 PM
Just make sure the timing and fuel/air mixture are correct. If a cam is installed, the valve timing/lift/duration need to be right, too.

east tx skier
01-13-2005, 03:59 PM
no camshaft replacement at this point.

01-13-2005, 04:31 PM
C'mon! "Go big or go home!" (Donald Trump, in a Pizza Hut ad)

east tx skier
01-13-2005, 05:21 PM
I like to do one thing at a time so I can guage the results.

/patience grasshopper.

01-13-2005, 07:00 PM
JimN and Ericb are right, and I'll say it a little more frankly; 25% power increase is total BS. Not accusing the original poster of misinformation, because it was made clear that the info may not have been correct. Sonce the question was asked, however about power increase, no way are you going to get more power (everything else being equal) by switching to EFI. If you are loooking for power, and ESSPECIALLY if you are looking at power/$, EFI is the worst place to be looking.

Cam, heads, and intake is where it's at if you want more power.

As for drivability, cold start, and warm up, you can't beat EFI w/a carb, ever.

Having said that, the Holley Projection EFI is a piece of crap. Please don't buy one. The injectors are unreliable, the "ECM" is extremely crude, and out dated. It's like the absolute bare-minimum to make EFI work. Don't get it. The BEST way to get EFI economically is to adapt an automotive EFI system, ECM and all, onto your motor and then make it work. This is beyond the abilities of most on this forum, but it will result in the best drivability and refinement for the money.

01-13-2005, 07:14 PM
In my opinion,the best thing to do if you want EFI is selling your carb boat and get one with it...Factory build!

01-13-2005, 08:12 PM
Better than using a car/truck ECM is to use the same marine version as Indmar. It's made to go in an environment like this, it does everything needed and it does it well. If someone were to find a boat that has been badly damaged or the motor blew up but the owner doesn't want to fix it, they could get a reman and have a nice EFI or TBI motor. This ECM is also supplied with the injected GM Performance Parts crate motors.