New best

[dthompson]

I didn't light the world on fire last night, but I did manage to rattle off a decent pass last night at the local 1/8 mile track.



That pass was my best 60 foot so far, so I was pretty happy about that. It was a tenth better than my best 1/8 mile time at the shoot out when I ran a 13.08, but I was on the brakes that pass too. I'm guessing that would have been somewhere around 12.9?

Mph was down a little last night, but it was 85 degrees and 85% humidity. And other than eating a jack shaft belt, the car ran great.

 

[neverfastenough]

Practice practice practice! Get aggressive with it. Got a ways to go to back up those dyno numbers.

What was the tire pressure?

 

[dthompson]

tire pressure was somewhere between 16 and 18psi before the burnout depending on the pass. I found it a little difficult to make sure i dont roll out of the beams, watch the tach, and watch the tree. I understand the value of those launch control devices now.

 

[neverfastenough]

16 should be your max IMO, I've never had luck above that.

The launch is really all going to come down to clutch control more than rpm, unless you were bracket racing, dead on consistent launch rpm really isn't needed.

If you let the clutch out right, your chances of breaking an axle really doesnt change much by rpm.

 

[Ira R.]

Well done! Keep practicing.

 

[dthompson]

video of pass

Here is a video that my cousin put together of the pass.

 

[Jacob_Royer]

That should be good for a high 12 all day long. I pulled off a couple 7.90 passes @89.6mph last year but never could seem to get it together at the shootout. This year RWHP increased by 47 since i ran 12.70s and my 1/8th went to crap at 8.20 but mph was 90??? 2nd gear crapped the bed on power tour so i think i may have been slipping for awhile. Hopefully back in the 12s again this year.

BTW you need more burnout lol

 

[dthompson]

I wonder if the jack shaft belt was slipping the whole time. I noticed it starting to squeak after the third pass (the best pass) and then the squeak went away after the forth pass. The fifth pass the belt broke. The MPH was similar all night, so I may have been slipping all night and I was loosing some power there.

 

[DrFishbone]

Are you using the MP 10% OD Crank pulley and a 7-rib JS pulley, Derek?

I've wondered about belt alignment...since the MP crank pulley is 8-rib....it's hard to imagine that small of a distance causing problems though.

I broke 2 JS belts at the 2015 Shootout...didn't think anything was slipping at the time though. I'm still not certain that it was. I did change out my steel Dayco idler pulleys though. My belts looked almost like there was an abrupt stop that snapped them, so I tried the idlers first. Didn't snap any after that, but it's hard to say if an idler was really locking up (from the heat) and causing the problem.

Anyways, just curious.

 

[dthompson]

Are you using the MP 10% OD Crank pulley and a 7-rib JS pulley, Derek?

I've wondered about belt alignment...since the MP crank pulley is 8-rib....it's hard to imagine that small of a distance causing problems though.

I broke 2 JS belts at the 2015 Shootout...didn't think anything was slipping at the time though. I'm still not certain that it was. I did change out my steel Dayco idler pulleys though. My belts looked almost like there was an abrupt stop that snapped them, so I tried the idlers first. Didn't snap any after that, but it's hard to say if an idler was really locking up (from the heat) and causing the problem.

Anyways, just curious.

Its the MP 10% crank and the MP 10% jack shaft and the 5% sc pulleys. I was using the gates green stripe micro v belt... k080435

The idlers are all plastic... the belt that broke looked like it split into two smaller belts about 2-4 ribs each and the rest shredded.

On another note...
I drove the car to work today and it was doing the weird tach dip when it was sitting at a stop light. Like it was loosing the tach signal briefly (but the engine was running normal). On the way home, it started to idle incorrectly at one stop light and the check engine light flashed on for a second, then went back off. It ran fine other than those few seconds. I'm wondering if the belt coming apart may have damaged the crank sensor. I took the belts back off and I didnt see any damage to the harness, but everything was too hot to get down to the crank sensor, so it will have to wait until another night. Last time the tach signal was messing up, it was a problem with the DIS. But it seems awfully coincidental to have this happen after the belt broke. There are only four things it can be... crank sensor, cam sensor, DIS, or a bad harness... so shouldnt be to difficult to figure out.

 

[DrFishbone]

The idlers are all plastic... the belt that broke looked like it split into two smaller belts about 2-4 ribs each and the rest shredded.

That's right....yours didn't snap...may be different issues then, NM.

On another note...
I drove the car to work today and it was doing the weird tach dip when it was sitting at a stop light. Like it was loosing the tach signal briefly (but the engine was running normal). On the way home, it started to idle incorrectly at one stop light and the check engine light flashed on for a second, then went back off. It ran fine other than those few seconds. I'm wondering if the belt coming apart may have damaged the crank sensor. I took the belts back off and I didnt see any damage to the harness, but everything was too hot to get down to the crank sensor, so it will have to wait until another night. Last time the tach signal was messing up, it was a problem with the DIS. But it seems awfully coincidental to have this happen after the belt broke. There are only four things it can be... crank sensor, cam sensor, DIS, or a bad harness... so shouldnt be to difficult to figure out.

You're on the right track. I've had numerous DIS's fail in several SC's since my ownership began....symptoms can be any variety of tach-dipping, running bad etc.

BUT...the one cam sensor I had fail did just like you describe for months (small drop / twitch in the tach...maybe once a day. sometimes I would feel the engine miss once, sometimes not)...then one day it completely pooped out and felt like the car was runnning on four or less cylinders. After messing with all kinds of stuff (no CEL btw) in the parking lot, I unplugged the cam sensor, had the typical hard time starting, then it ran good all the way home (and the next day...).

 

[DrFishbone]

By the way, your cousin did a great job on the video!