Hey guys, I have 1985 Corvette with a Miniram, 58mm throttle body, Flat tappet ZZ409 camshaft, 3.75:1 gears, 1 5/8" Hedman Longtube headers, Dynomax true dual 2 1/4" exhaust, AFR 195 Eliminator Heads, Nitto 315/35/17 NT555R drag radials, MSD 6AL2 ignition box, D.U.I. distributor, and all supporting mods and miscellaneous mods, 10:1 Compression.

So, I'm headed to the drag strip soon, either next week or the week after to see what she'll run.

I'm targeting 13:1 WOT AFR, with currently 35* total timing.

While I'm at the drag strip I want to try a few variables.

First, I want to get the launch down using the two step rev limiter in my MSD ignition box. What RPM should I launch at first so I can fine tune the launch RPM?

Secondly, what is the safest AFR I should target at WOT?

Thirdly, if you take a look at my timing table below, where are some places that I should add timing, and how much advance can I have?

Thanks!

 

Personally I'd shoot for 12.5 AFR to 12.8....

Timing will be whatever it will take under a load.... I would not expect it to want more than 34 total unless your over fueled.
Will

 

I would start out at 12.5 to be safe. You won't gain that much hp being close to the edge. Keep it cool and your motor will last a long time.

 

Your timing table shows 35 degrees at wot, so plus 6 base initial means you've got 41 total. I would start at 36, and go to 38 total if it were me.

 

have fun good luck and most importently be carefull

 

For goodness sakes, Daniel, be gentle...... a few easy revs just to let the engine know you mean business in a few minutes. After all the
work you have recently done, we don't need to hear you destroyed the engine. Nice smooth runs..... good luck!

 

I love the anticipation of taking a new combo to the track for the first time.

Be careful and have fun

 

I suggest you take 'er out onto the highway and do a few WOT runs up through the 1-2 shift point before the strip. This will allow you to gather enough data on A/F & timing before flailing on 'er at the strip.

If your strip has a scale let us know trap speed & launch weight so we can calculate CHP for you.

 

And pls Daniel, take it easy out there! If you are unsure whether or not your engine and tune are working 100% like they should, dont use two step! If these are your first passes on the strip with the new engine, there's no way you will need to launch with 2-step.

 

I don't think that you need a two step, period.

 

So I should basically shoot for 12.8:1, and when would I actually need to use the two step? Thanks!

 

When to use the two step is a personal choice; it's a "driver's aid", so I personally wouldn't ever use one -I want to drive my own car, myself.

Only time I can think that you'd even consider using one at your power level would be for bracket racing as it would help make you more consistent. But to ME, a two step w/an auto, you set the two step, you launch and the car shifts for you....what are you doing as a driver? Not much reward in that, IMO, but like I said, it's a personal choice.

For your first trip after mods, if I were you, My goals would be the following:
1. Get the car down the track w/conservative driving a few times to confirm soundness and safety -no leaks, good handling etc.
2. Ensure that it's running right; AF ratio, oil pressure, temps, etc.
3. Lastly, I'd want a good TRAP SPEED.

For a first trip, i wouldn't be concerned with launching, wicked 60' times, basement ET's...I'd just want to make sure it's all working right, and I'd want a good trap speed so I'd know horse power and how the engine is working.

 

When you start bracket racing is when the two step is beneficial. For your trial runs, you're not concentrating on killer reaction times. Just getting the car down the track safely and gathering information is what you should be after. Once you get things dialed in, then use the two step. Before you enter the staging lanes, find a safe place, put your car in drive, foot brake the car and slowly increase the rpms until the car starts to creep. Note the rpms and when you stage, duplicate what you did but keep the rpms 200 below when the car started to creep. If you have decent tires, you should be able to hammer the throttle on the third amber and hang on. If you start spinning, decrase your launch rpms each time until the car launches without spinning.

 

Okay. But my car is a 4+3 if that makes any difference.

I've never raced on the track before, so how long should I expect between each of my runs? I'm going on a test and tune night by the way.

Thanks

 

It depends which tuning file he has some show total timing with the base added in some do not. As long as he has the total timing displayed the base will be included and this will be his actual timing.

On the timing it looks Ok to me except the 208 load range in my opinion is too aggressive. I would leave the 22 degrees until 2000 RPM and then ramp from 22 degrees to 35 degrees by 3000 RPM.

 

If you have a 4+3, then the 2 step will eventually be helpful being able to duplicate your launch rpms. Again, when you go out next week, you will be using your runs as a test and tune session, not necessarily to win the plastic trophy. When the lights start coming down, pick a launch rpm (3000)? and slip the clutch and go. Practice outside of the track grounds before raceday. You won't want to dump the clutch, you will either spin, bog or break something. You will want a quick release and let the clutch work for you. After a few runs and when you get your launch rpm established, you can set your 2 step to replicate your desired rpm. You will also have to practice taking your finger off the button at the same time your right foot goes down and your left one engages the clutch. Good luck!

 

Oops my bad. I should have known/remembered that. So, again the two step is helpful...it is a driver's aid. But I've never had one, and all of my cars have been stick shift, and I run them as fast (generally faster) than any comparable car around, so the two step is definitely not necessary....especially at your power level. Use your FOOT to control the launch RPM. Just do similar to what 383vett suggested for the auto but w/the stick; bring it up to an RPM; I'd recommend ~2000 to start with. Then bring the clutch pedal up, until it just barely starts to slip, then push back down ~1"...just enough so it's not dragging and creating heat. Now, you're ready to launch. AFTER the light turns green, simultaneously roll off the clutch and at the same rate, roll onto the throttle. See how it goes. If it spins, less RPM/softer on the throttle/clutch. If it bogs, more RPM, heavier/faster on the throttle. Sometimes, you have to let the clutch slip some on street tires, for maz 60' times.

All ^that^ is pretty advanced driving technique, IMO. Again, I wouldn't recommend going to max effort runs here. I'd just roll out of the box like any semi aggressive street start, floor it, and run it though the gears to get baselines, car assessment, and trap speeds.



As for times between runs? As long as the car is "checking out O.K.", I'd cycle as fast as possible to get the most runs in w/the car. Cycle times TOTALLY depend on the track and how well it's run. Our track here in SLC is a **** show so sometimes it's 3 hours/run. At New England Dragway/Epping NH, though, I used to find some nights were I could comeback and drive right into the burn out box, make another run and repeat. More runs will prove durability, consistent running and get you some practice.

 

good example on how to leave with a stick as posted above

 

I opened a $1F HLH stock in both Tunerpro as the OP has shown, and in Tunercat, and both do not include initial. Therefore, as I originally posted he has 41 degrees all in shown in his original post. The HLH shows 30 degrees where he has 35 with the exception of the weird rounding Tunerpro does. Please feel free to correct me if I'm wrong, but both program modifiers view it the same.

 

Ha ha...that was sweet driving (in the right lane), but some how, I don't think Daniel's car is going to come out of the hole, like that one does.