MSD7531 and E85

MSD Digital Ignition Programming & Troubleshooting, Playing with Dots, Slew and other fun toys for traction challanged racers

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John_Heard
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Re: MSD7531 and E85

#1 Post by John_Heard » Mon May 21, 2018 8:46 am

I really doubt this is any big deal to take a bit of timing out at launch, you could use the Launch Retard feature on the 7531 to do it. Not sure how many degrees you're talking about but I don't really see it having any issues to take out a few degrees of timing out at launch.

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John_Heard
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Re: MSD7531 and E85

#2 Post by John_Heard » Mon May 21, 2018 11:04 am

There's a lot of questions as far as how much and how long to ramp the retard out.

If the car is hooking ideally use no retard at all.

If the car is just barely hazing the tires at launch, probably only a degree or two for say 1/2 second - just really depends on what it's needing. If it's totally nuking the tires at launch, quite a bit more.

Do remember the way the 7531 works, launch retard is also pulled while you're on the transbrake, so if you pull a lot out it can make the engine a bit hard to get up to launch rev limit. One of the good features they fixed on the new PowerGrid, it has the ability to not do that and only pull the timing after the brake is released.

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