[Pampered-Z]

Here’s another of my novels!

There is allot to talk about, and I’m going to make some assumptions,
You are missing a bunch of factors and things you need to consider if just trying to go fast ( as opposed to trying to bracket race), Your on the right track, but it is not that simple. As already said, you have to take in the air temp barometric pressure. Major factor in your ET. And it will change as the day progresses.

Engine / trans temp can affect your ET. When you’re testing, you want to not hot lap the car, but being slightly warm may not be bad. But a hot trans can affect how it shifts. (I would suggest you add at least engine temp to your logs). If the track will allow it, ask if you can make 2-3 60’ hits in a row:

Launch - backup, launch - backup, launch, and on the last launch just go easy down the track ( because the trans/convertor will be really hot). But this could let you know if/how temp effects your launch / 60’.

Looking at you logs the first set you made 6 passes at night, so I assume they were pretty close together, I would guess that either the trans was getting hot or the track was starting to go away based on the earlier runs and launch PRMs or both. I would assume the starting line was just getting bad more than the car / your changes.
So pay attention to the starting line and try to find the best groove and stay away from bald spots. Also some tires like being in the glue, others like the groove, or the track being dragged. Play with this as well.

Track conditions and prep is going to be a factor, not only wheel spin but how much grip the entire track has. This could be a big factor when testing on different days and tracks. And what others are running. Street tires do tend to kill a track surface more than slicks will. A good sticky starting line will help your 60’, even launching at the same RPM and even if you are not spinning, the car will react faster. But if the track is real sticky down track, it can affect how the suspension unloads and/or ET as the tires have to pull out of the glue/ sticky track surface. This is going to change the performance of the car allot. Say the track is prep’d for Promods your car would not run as fast. In cars without allot of HP they think they are spinning or rattling their tires, but it’s the track having so much grip the car is struggling to pull out of the glue. I’ve even seen this happen to 10 second/big tire cars. Track grip is more than just the starting line and will affect your ET. Look at the track surface, the sides of the groove may not be glued as much as the center, move off to the side a bit once you get into 3rd gear, either towards the center or towards the wall. Don’t try to hug them! Just get the tires to where the track isn’t so sticky, could get you a few thousands.

So take all this into you logging. You need that in your data so you can connect it to each run record. Also car weight, every 100lbs you take out of a car is generally good for a 10th. So having a ¼ tank of gas as opposed to a full tank will help a little. ( the added weight might help the tire hook off the line?) But for ET, take as much weight out of the car as you can. Basic rule is that for every .10 you drop your 60' will drop .20 off the top end. So 10 off the start is 20 off the finish line / ET. (If your N/A - power adders can take .30 off the top ).

You logged rear tire pressure – what about front tires. I assume you aren’t running skinnies/ front drags. If so, put your front tires to 45PSI, lower the rolling resistance a bit – could get you a 10th or more.

Somewhat unrelated? One other thought is fuel. I assume you are running high octane pump gas? Are you using any octane booster? Canned octane seems to vary allot. Even with my street tune my car will pick up 40 and 3-4 MPH if I’m running on race fuel (100 oc unleaded) as opposed to pump gas. Do you have knock sensors, have you checked your not getting any knock that is pulling timing?

It is a bit odd your car does seem to like launching that low. How old are the tires? How many passes? Big burnout can overheat the tire and make them “greasy” and over time that heat can effect the sidewalls and how well the car is hooking, even if the tires don’t show allot of wear. But it does seem like the suspension isn’t working? Have you tried changing pinion angle? I would think you should be able to hook at higher RPMs, unless it’s all about the condition of the starting line itself. If there are allot of street tires during T~n~T they are going to destroy the starting block. AND DO you have a front sway bar? If you do remove it so the car rocks back to help plant the tires better. And you’ll find that you then need to go stiffer in the rear?

AS far as the pass itself:
You need to start with staging the car. You have to make sure you are staged in the same place. Either shallow (You want to just flicker the stage beam ) or Deep ( turning off the pre-stage beam ) There is 6-7" of rollout that will effect everything. Shallow (Think of it as a getting a running start out of the stage beam. ) Deep – gets you closer to the finish line. Try both leaving the same RPM and see which gives you the best 60’/ Most likely shallow staging. But be consistent. If you staged shallow one pass, and deeper the next, your data is not valid. Since you are just looking to get your best ET, I would guess that shallow staging is what you want.

Once you have determined which staging works best for you, then focus on RPM launch to 60’. Once you know what creates the best 60’, then you can start working on shift points. One point here, you said when you try to footbrake your brakes don’t hold? Are you sure it’s your brakes? If the starting line is bald from front wheel drive cars your front tires could be sliding on the bare starting line. And trying to use the line lock is just going to make it worse.

Once you get the 60’s to be low then look at the 330. I assume you are in 2nd by the 330. So start making passes short shifting ( maybe 5400 RPMs ) then move up until you get the best 330’. As you noted shift points and RPM drop. Do this because you want to shift based on torque as well as RPM. Torque gets the car moving by twisting the drive shaft, HPs get the MPH by spinning faster. You want to stay near/above your torque peak. Spinning too high could actually hurt you as shifting to low does dropping out of you torque curve. Looking at your dyno your torque drops over 6,000. So for your 1-2 shift - short shifting might help? Your 2-3 shift will be less effected as your have the weight of the car already accelerated and moving forward. Remember your acceleration between the 1/8 and ¼ is minimal. You’ll make up the most time in the 1st half of the track.

Few other comments: All cars move around ( I mean ET wise ), the basic rule is as much as .08. So a slower car can pick-up/fall off more than a faster car. You could make 2 identical runs ( starting line position, RPMs, shift etc ) and still end up with different ETs.

So again, Don’t always change things after just one run unless the change throws things way off ( like spinning the tires, or large change in ET ), and if that happens go back to the prior run and test again. If you make a pass and you get good results, make the same pass again to make sure you replicate the results. The car has to repeat before you make changes.

I would suggest making or buying a data logging book that you can make all these entries in. If you have a smart phone, there is probably a good weather App that can be a cheap weather station to get barometric pressure and determine your elevation. A Few hundred feet difference can be a factor. As an example, even with good track prep, and fairly similar weather temps my car runs different at various tracks. Numidia (slower – high elevation), Island ( I call this in the middle ), Acto ( lower elevation) Between the 3 there can be up to 1,000’ elevation difference and my car will be .40 and 6-7 MPH off. So if the air isn’t good the car is just not going to make power.

Good luck.