496 & Raylar questions
 

What is the best way to tap a mechanical gauge into the fuel system on an 03 496? I picked up a FAST AF ratio gauge and can now measure both manifolds at the same time, but I'd like to measure the fuel pressure also. Speaking of AF ratio, my engine shop suggested that I didn't go over 12.4:1 anywhere in the rpm range, but I know it makes the most power @ 13:1. What do some of you guys run? I'm going to take some data and send the ECU back to Dustin for some fine tuning and I'd like to nail down an appropriate ratio somewhere in range first. Any help would be greatly appreciated!

Also, what is the sweet spot for this set up? I'm currently turning almost 5,000 rpms @ WOT with my 28's. I know if I change back to my 26's, I'll be up to 5,300 rpm, but don't want to burn more fuel for the same speed.

There is a schraeder valve fitting on the right side of the facotry fuel rail on a stock 496 right at the rear of the white coolant bottle. Make your fuel pressure guage connection there for a testing location only. I would never recommend running a fuel line from a pressure fuel system to a boats guage location, TOO LONG, TOO DANGEROUS. As for a snding unit on the motor with wiring to an electrical fuel guage on the dash, to unreliable from a calibration standpoint. Why are you monitoring fuel pressure on your 496?

Regards,
Ray At Raylar

Earlier this summer, I didn't monitor anything and fried #3 because of it. I figure if I can monitor my manifold pressure, fuel pressure and AF ratio, I should reduce the chance of a repeat. My high pressure braided fuel line will run along the side and the gauge will mount on my windshield (not in the dash or close to other gauges). Another thing, do you offer a larger throttle body?

Sorry to hear about your fuel pressure problem. Was it a problem with the adjustable fuel pressure regulator not staying at the new set pressure or did you have a delivery, fuel filter, screen problem which lowered fuel pressure? Its very unusual to have a fuel pressure problem on the 496 and most times the motor starts knocking quite a bit and sets of the "guardian" system in the ECM. You might want to make sure also you don't have a problem with the actual injector that was in #3 hole.
Yes we do offer a polished billet Raylar 80mm throttlebody to replace the stock 75mm unit. The cost is $486 each plus shipping. Hope everything is ok with your engine now.

Best Regards,

Ray @ Raylar

Mercury advised c/o Dustin Whipple that the PCM555 does not go into Guardian Mode when there is a detonation event. The PCM555 will only retard the ignition timing (8* max) when a detonation event is detected. Hence there is also no detonation / knock event fault recorded in the PCM555 either.

Thanks guys. I concur with the no detonation warning. I already have the mechanical fuel gauge and braided fuel line (which cost more than the gauge) and can't find the valve. Does anyone have a picture that I could look at to see where the valve is? Ray, is it relocated with your intake?

I was able to hook up a matching Gaffig monster electrical fuel pressure gauge up to my ´06 525EFi can bus 14 pin harness. The signal wire is already included in the installation kit for the motor, together with one for oil temperature (and for all other electrical gauges).

On a 496, the ECU has the fuel pressure parameter as part of its metering basis. It must be possible to tap off that info somewhere on a 10 pin 496 harness, as well.

The schrader valve is inboard and below the coolant res. The res. is notched out around it.

Okay, I've got all the gauges working properly. Thanks for the help! With a 496 bored 30 over, a Raylar 103K and Whipple Stage I upgrade, I set the fuel pressure @ 50 lbs and the AF ranges from 12.6 to 13.5 with the highest readings between 3,000 and 4,000 rpm. I also had to unplug the vacuum regulator (it's much more even without it being plugged in). My question: Is it a bad idea to run more than 50 psi with the stock injectors? In order to be in the mid 12's (on the high side), I have to run 55lbs. If I have to turn these up close to 60psi to be in the low 12's, I may give my engine builder some credit, as he told my my injectors were too small last month. Any thoughts?

Rage, what is your current fuel pressure vs AF @ 3,500?

The injectors were tested and came back "good". see post above about the injectors...

Is the diameter of your intake already sized to accept an 80MM, or do I need to hone it out some? Do you feel 80 is all you need for maximum performance? Do you, or does anyone else offer a 90MM?

The intake will not benefit from a larger throttle body on a stock block motor with the 525HP 103 kit. we've tested them many times. this larger throttlebody is required only when we build a HO600 engine where the larger cam and breathing requirements require the larger throttlebody. You are correct as we instruct. You always set fuel pressure with the vac. line disconnected. Your fuel pressure setting should be set a 50psi and you don't need any addtional pressure than that. Your fuel pressure at 3500 rpms under load will probably be around 47-48 psi. Your air fuel settings are just fine. In all the 103 kit equipped motors we measure about 12.8 to 13.2 in that 3000-4000rpm range which is right where Mercury sets them to run on a stock 496. You will see that the air fuel ratios will drop between 4000-5000rpms into the 12.4 to 12.8 range which is right where they should be for a balance between power and slightly safe side. The problem you seemed to have at #3 cylinder was not one of to lean a mixture in the engine overall, since cylinders 1, 7, 2,& 8 are the first ones to lean out under load when the fuel pressure is to low. We know this from our dyno testing where we have exhaust gas temperature sensors on each exhaust during dyno testing. Remember also the air fuel meter guage you are using is not a highly calibrated dyno type we use for our testing and we find they all tend to read a little on the lean side in actual testing. Your numbers on air fuel are just fine and there are hundreds of Raylar 103 kits out there running those same numbers for over three years now with not one engine damaged from a lean condtion. The injectors are just fine and these are the same injectors the factory F-1 race teams used in 2001-2003 for the 525HP engines. Also be advised I believe it is actually Coast Guard illegal to run a fuel line to your dashboard for fuel pressure. Use a claibrated electric guage and sensor for saftey and realize that a fuel pressure line that long from engine to dash would most likely have a pressure drop due to the volume and distance involved. If your stock boost pump, fuel water seperator and primary fuel pump and injectors are operating properly and the fuel delivery system is not impeded you should be having no problems. Also you might want to check the fuel line size from your fuel tank to the boost pump or fuel water seperator and make sure its at least 3/8" size as a restriction in line size here will affect the fuel systems flow at higher demands.
Hope this information helps with your examinations.

Best Regards,
Ray @ Raylar

Ray is being nice, running a line with 50psi fuel pressure to your dash or windshield is foolish. No sanctioning body would allow this and no doubt your insurance would void your coverage. The technology exists to do this safely. If the gauge or line fails or even loosens you will be instantly inundated with fuel looking for an ignition source, of which there are plenty in most boats.

Thanks guys, I appreciate the feedback. I ended up installing the fuel pressure gauge near the floor and on the far starboard side with the line tucked out of sight which would make it very difficult to tamper with. This location is not near the dash or windshield. However, you bring up interesting points and concerns about safety and legal issues. The line I'm using to measure the fuel pressure is much stronger than the factory lines and the thought of it failing didn't cross my mind. I'll look into an alternate this winter.

Ray, I will say she now runs smoother than I ever expected. I don't know if it's the 103 kit or the fact it's a true and balanced hand-built motor, or what...but she runs much better than before and the throttle response is great! :D

Ray,
RE: "Remember also the air fuel meter guage you are using is not a highly calibrated dyno type we use for our testing and we find they all tend to read a little on the lean side in actual testing. " Can you share the amount that the hand held A/F meter (Innovate Technology Model LM-1 or similar) reads leaner than the dynamometer unit? What is a make and model of a typical dynamometer A/F recording unit?

Its a wide band gas analizer unit which costs over $3000 and its calibrated to be about +- 1% on O2 readings which we take cylinder to cylinder on the dyno.

Regards,
Ray @ Raylar