SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: dm2bfree on January 21, 2009, 05:47:57 PM
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Hey Guys,
This is probably a stupid question. I was wondering what the benefit of using a control box is (msd 6a, etc). I have a '81 Sleekcraft 18 foot jet, new 460 w/ a JC pump.. It's a cruiser about 410hp.. I have a MSD coil and MSD distributor and the boat runs great. Does it just help with a more powerful spark at higher RPM's?
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Hey Guys,
This is probably a stupid question. I was wondering what the benefit of using a control box is (msd 6a, etc). I have a '81 Sleekcraft 18 foot jet, new 460 w/ a JC pump.. It's a cruiser about 410hp.. I have a MSD coil and MSD distributor and the boat runs great. Does it just help with a more powerful spark at higher RPM's?
No, not really, an ignition control box basically lessens coil saturation and gives several small spark discharges rather than one high dwell spark (dwell = time in degrees), the biggest performance gain from a, say MSD6AL is accelleration, starting and the "L" has a built in rev limiter, properly tuned an electronic pick up and high quality coil will kick ass, the CD boxes really don't do much for WOT running. In other words, I don't think there would be a difference in speed or horsepower once WOT is reached...
Just my opinion and subject to some oposition (hows that for politically correct?)
GT
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X2 GT, good answer. And an amazing description of how they work. I even learned something. Didn't know the technicals of it, but it makes sense.
We used MSD and Mallory in street/strip cars for the same reason. Acceleration. However, there are hidden benefits that affect mileage and engine wear and tear tho in everyday "Cruising". Far less chance of a misfire, leaving unburnt fuel from a cylinder or two being then blown into the exhaust. When that happens, that fuel is more likely to explode in the exhaust manifold from much hotter gasses and sparks from another cylinder that DID fire correctly. What this does is put a reverse pressure on all the exhuast valves on that bank. Not a good thing. Let alone what you've done to the exhuast. There is thought and theory that when you run these you can run a tad higher compression without the fear of detonation, which also makes sense.
Second advantage is that since you just put fuel into a cylinder and did not get the power from it, mileage suffers. That is common physics.
All in all, put a CD unit in, saves a lot of headaches and is as reliable as the sun.
Ray
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MSD means, multiple spark discharge. The box sparks for 20* crankshft rotation up to about 3500 RPMs. I run Magnitos, I just changed from a Mallory Sprint Mag to a MSD ProMag (sparks for 26*), difference in the new mag was dramatic, I had to go up 5 sizes on jets to eight number 99 jets w/ four 50cc squirters. Where timing stayed the same, for now, the burn marks on the headers moved and was more defined. This is just one way I keep an eye on a tune up, good way to tell how cylinders are running compared to each other as well as overall temp and timing. Like one dude I know built a wazzoo motor started it up and blued the headers on one side all the way out to the collector and only less than half way on the other side. Obviously something wrong here........ :o