msd's got a box that allows for individual cylinder timing. anyone seen someone use it to alter the a/f ratio of a given cylinder?
Changing timing isn't going to alter AF mixture...that's already been determined way upstream. It'll alter cyl pressure, but you'll never be able to tell without some serious equipment. Are you thinking of trying to correct a fuel distribution problem?
nope. just curious.
it will alter egt and can affect the amount of fuel burned in each cylinder. i have heard of big nitrous motors responding well. Nitro engines will alter compression in cylinders to maximize output, so I've been told. What do you have in mind?
That box sounds a lot easier than bending the reluctor under the distributor cap to change individual cylinder igniton timing.MSD makes a bendable reluctor for that purpose.
But probaby not cheaper. :idea:
As stated above, adjusting timing per cylinder will only change burn rate and cylinder pressure of that cylinder. If you haven't done burn rate analisys for each cylinder of the type of engine you are working on, your best bet is to leave them straight up. We have done extensive burn rate analisys on the small block chev, and we move 2 cylinders 1 degree.
Now checking cylinder to cylinder is a very good idea, as all distributors will vary anywhere from 1-5 degrees between cylinders out of the box (and even the best distributor machines only get them close). That adjustable system would help to level them out cylinder to cylinder, or replace the reluctor with a "bendable" one as described above. If you are running a dist. with mechanical advance (terrible thing, makes this spark scatter even worse) make sure you do your timing adjustments at an rpm past this advance point. Same with setting total advance.
Better yet, eliminate the mechanical advance and set timing at max and forget it!
It is what happens to the individual cylinder timing throughout the rpm range that is flat scary. We are mandated to use a distributor and certain igntion boxes in our class of racing, and have found as much as a 6 degree swing (each cylinder advancing and retarding at different rates) from 6400-9500rpm's. We have whipped every type of conventional distributor to death to try and eleviate this problem, and after spending cubic dollars, have got them down to a couple of degree swing.
Now enter the crank trigger. With this set-up, timing varies less than 1 degree throughout the rpm range, and if you have no class rules against it (no rules in pleasure boating) it is the ONLY way to go for optimum performance, as well as longevity in anything other than a high end Alchohol or a Nitro application.
As mentioned above, you need a cylinder pressure data acquisition system to see what's going on. I use the one from http://www.tfxengine.com. It's not cheap, but if you have to know what's happening in there, it's the only way to fly.
As mentioned above, you need a cylinder pressure data acquisition system to see what's going on. I use the one from http://www.tfxengine.com. It's not cheap, but if you have to know what's happening in there, it's the only way to fly.
This stuff has come along way in the last 5 years or so. It is to the point most upper end engine shops can afford them. It takes a little while to understand how to apply the data, but can be VERY useful in understanding cylinder burn rates and pumping losses throughout the cycle.
I can also make you scratch the hair right off your head!!!!!:2purples:
Warp Speed
it will alter egt and can affect the amount of fuel burned in each cylinder. i have heard of big nitrous motors responding well. Nitro engines will alter compression in cylinders to maximize output, so I've been told. What do you have in mind?
i dont have any plans to buy the box or put it to use in the immediate future but i've talked to some people that believe you can alter the a/f ratio with timing adjustments. i've never tried it so i was curious if anyone else has. doesn't look like anyone here has used it yet.
Yea I'm sure it alters something.
But basic physics dictate that the ratio of air to fuel is not going to change once it enters the cylinder.
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