Yellow Bullet Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
452 Posts
Discussion Starter #1
I run Outlaw 8.5 (two rules,--weight and 26x8.5" tires) in my '73 Nova. I'm trying to get a handle on the launch curve feature of my MSD 7530 box. Anyone that runs on small tires/radials care to share some experience with the launch curve?

When using the launch retard to ramp the timing in, a .1 sec delay has worked well up to a certain power level. Any more nitrous than what I'm spraying right now results in it blowing the tires off about 15-20 ft. off the line.

So far my best 60ft. on the M/T 8.5" slicks is 1.35. Best ET so far is [email protected] I need to step up the nitrous and pick up a couple tenths in order to run with the top dogs in the class.

Any tips on a good starting point for the launch curve would be greatly appreciated.

Thanks.
 

·
Registered
Joined
·
613 Posts
Craig,
If I understand you correct, I assuming you’re using the Launch Retard in the Data Editor?
I would recommend that you use the Launch Curve. You will have more flexibility with the Launch Curve over the Launch Retard. The down side to using the Launch Retard is that it is active while you’re on the Trans Brake, for example, if you program 6 degrees to be retarded in the Launch Retard, you’re pulling 6 degrees while on the Trans Brake too. This will make it harder for the engine to get up on the brake.

When you create a curve in the Launch Retard Curve, you can design the curve to retard timing once you let go of the Trans Brake. For example if your Launch RPM is 4800 RPM, you would plot your curve to start retarding timing at 4900RPM.
Depending how stout your Nitrous tune up is, will dictate how much additional timing you would need to retard to keep from kicking the tires off the car, obviously, the more power you put to the car, the more additional timing you’re going to need to retard. You can keep this timing out until the car is up on the tires and then begin to gradually ramp timing back in, this curve will also depend on track conditions too.

I hope this helps
Sparky
 

·
Registered
Joined
·
452 Posts
Discussion Starter #3
I've been using the launch retard with decent results as long as the nitrous shot is not over about 175 hp. I'm wanting to start using the launch curve instead for greater tuning flexibility like you said. I'm just looking for general information or experiences from those using the launch curve.

For instance, does it seem best to keep most of the timing out until the front end has come back down and the front end settled or is it best to bring in the timing when its still up on the rear tires? Also, how much power does a given amount of retard seem to kill off? I don't want to pull out too much power and make it a dog, but need to get it hooking up with a bigger shot too.

So I guess I'm just hoping to find someone that'll share what they find works well for a curve.

Thanks for the input. I appreciate it.
 

·
Registered
Joined
·
4,949 Posts
craig w. said:
For instance, does it seem best to keep most of the timing out until the front end has come back down and the front end settled or is it best to bring in the timing when its still up on the rear tires? Also, how much power does a given amount of retard seem to kill off? I don't want to pull out too much power and make it a dog, but need to get it hooking up with a bigger shot too.

So I guess I'm just hoping to find someone that'll share what they find works well for a curve.

Thanks for the input. I appreciate it.
you'll want to start putting timing back slowly as soon as you can. i don't use the 7531 yet but between the fast timing controllers and timing map i'm able to get the timing back in 2 degree increments usually within the 2 seconds that your launch curve allows for. by the way, leaving like a dog is still quicker than smokin at the hit. :D
 
1 - 4 of 4 Posts
Top