Had a bad night at the track last night

[d0n_3d]

I have a mid 11 second combo and I couldn't get out of the 13's last night. First of all I made the mistake of not draining my gas tank from pump gas when I got to the track. I accidently put about 3-4 gallons of 89 octane before I left for the track (don't ask why...I wasn't paying attention to the pumps and assumed the last one was 93). I had to mix it with about 3-4 gallons of my 118 I took with me. Well anyways my first run I put in my race chip and set the fuel pressure to 45 psi with the line off (50's) and boost was around 22-23 lbs just to be safe. I launched with only 5 lbs of boost because I was having trouble keeping the brakes steady and the car would jump. Once I got halfway down the track the knock meter lit up all the way to red and I let off slowly cruising to a 13.4 @ 104 mph.

Soooooo...I said no way to the race chip and put in my street chip again. I never got a chance to record any runs with turbolink so I have no idea what my o2s were or anything. I had a bad night. My second run I didn't knock too much...the guy beside me didn't know how to stage properly and threw me off...I could only launch with about 5 lbs again and this time I ran a 13.2 @ 106 mph not going full throttle until about halfway down the track to make sure I didn't knock. My car has so much more in it its not even funny.

I decided to open the exhaust up last night for the first time. I am used to running through full exhaust. I am sure that makes a major difference in tuning. Also I had put on a new ds header this week and I am sure that had something to do with it too. My car was COMPLETELY out of tune last night. Any suggestions as to what I should do next time? I always have to guess at my boost and fuel pressure and I am never sure if either are where they should be.

 

[azgn]

you will never be able to tune your car if you are mixing fuels....drain your tank and put at least 10 gallons of race fuel in everytime

if you don't know where your boost is set, you need to waste a run at the track just to reference your boost......don't know what kind of boost control you have, but usually 1 full turn on the wastegate rod = 1 lb boost

106 mph indicates a high 12 et normally......your speeds will be fairly constant regardless of et if you go thru the traps at wot....and speed is HP...you can tune based on speed, not et

opening a dump can affect your boost (+2 lbs on my car)

practice, practice, practice!

 

[d0n_3d]

you're right about the mixing of fuels...also that is a good idea that i need to use a couple of runs just to see what the boost is set at and stuff...i need an entire day of just test and tune i think...maybe i will do that soon...

 

[Turbojorge]

Dude! I was thinking you were coming back with an 11 sec pass for sure.

You definatly need to drain all the pump gas at the track and fill it back up with nothing but race fuel like AZGN said. 10 gallons at least! I know that may be around $80 for 10 gallons of 118, but you don't need to go that high in octane. I ran the times in my sig. using C-12 (at $5.75 a gallon), 30* of timming, and 009's and had 0 knock and was still .790-.800 on the 02's.

Now I know you went faster than me with your stock set up, but keep in mind that my motor has almost double the amount of miles as yours. With a better 60', I could start tickling the 12.0 range with my mph.

I would think that, with 50lbers, 28-30* of timming, 23-25psi of boost from a TE-44, your never going to use up all the octane that 118 leaded has to offer......so your going to be rich.

Just my .02

 

[DonnieShort]

I had to mix fuel a few weeks ago, about 4 gallons of 92 with 5.5 gallons of 115. Had no knock at all at 23 psi and 25º timing that resulted in an 11.79 @ 113, but I won't be mixing next time out just got caught with my britches down. But those times I had was on an 8-9 psi launch, but anyway. What tires were you using? And 60' times? Even with a 5 psi launch your combo should help make some of that up on top end.



Donnie

 

[UNGN]

I always go to the track with atleast two 5 gallon fuel cans. one for the out and one for the in.

Its embarassing to admit, but I only run with 5 "known" gallons in the tank (around 8 total). I know I probably should run with more, but under accelleration, I've never had a fuel problem. Turning a corner is another story as the car will run out of gas and die with 3 gallons in the tank (unknown gas, before I put in the five) as I idle around the exit off the highway to the track, then start back up when I straighten out. oops. Well anyway, thats the way I've run it for 7 years and no blown headgaskets ever. Your results may vary

 

[Turbojorge]

I'll admit that it's a PITA to drain the fuel threw the rail sometimes, specially when your dying to get on the staging lanes. Thats why I've leaned exactly how much gas my car needs to get to the track (or close to it). It's a 106 mile drive for me and last time up, for the first time, I was able to run out while idleing in the pits after 5 minutes. First time that I've ever been happy about running out of gas. I just dumped in 10 gallons of C-12, mounted the slicks, changed chips, and I was done in record time.

Hope I have the same luck next time.