sounds good.


enough for it to not bog but not too much, we dan't want him to flip over backwards......

 

that would be bad

 

yeah, i dont have a wheelie bar yet....i dont want to have to beat my roof back out with a hammer.

 

ss#1230 I think I was in your shoes a couple months ago, take the sportline springs out and put the stock ones back in. my car with 3 years of launching and launching 3 sets of rear tires, so on it just would not get any traction, first gear was like ice, second was like wet cold pavement. after i put the stock springs back in you'd think it had slicks on it compared to when it was lowered.

 

well i wish i would have picked different lowering springs, but that ship has sailed. and putting the stockers back in isnt an option, i tossed em.

in another thread i saw that injuneer had some air bag helpers in his rear coil springs. i use these in my tahoe when i tow our trailer and they work great. im thinking about using them in the rear to get the rear springs a little stiffer...

 

There is a way around that. Some have ground just enough off from the gear face to get the stock paddle/pin in. The material comes of an area of the gear that doesn't do any work so it has no effect on longevity.

 

Hey all.
I went to the track on Friday and made four runs.

Three runs were consistant 13.1 and one was a dog from missing a gear. Of course 13.1 is a dog too (considering 410RWHP) but you have to see the rest of the picture. The 60 foot times were 2.1 each time.

I had the MT DR's on the salad shooters and they were biting extremely well on prepped track. I dumped the clutch at 4500 RPM and the tires barely broke loose then the motor would bog down to 1800 RPM then have to rev back up on through first gear. I had my Datamaster data logger going during the run and saw some interesting things. I dumped the clutch at ~500RPM and that was not much better.

Again I dumped the clutch at 4500-5000 RPM and it took ~2.5 seconds for the motor to go from the lowest bog down point of 1800 RPM back up to 4500-5000 RPM with no tires spinning on through first gear. Makes me only wonder what would happen on a good or even excellent launch when the motor stays in the power band.

Another interesting thing.
If you count the point were I was ready to launch at 4500 RPM to the point were the bog down bottomed out, that was 1 full second. If I had easy launched the car out at 1800 RPM I think I would have negated most of that full second since the motor would not have bog down from a 4500 RPM launch like had been ocurring. There is no doubt in my mind this would have been in the 12's.

According to my data logger, I have launched faster on street tires on the street than I did with DR's at the strip. I think if I had my street tires on at the strip, I would have easily made it into the mid to high 12's.

All this being said, its mostly my lack of ability and experience driving the car that caused the **** poor 13.1 ET runs. I am going to have to launch the thing much higher than 4500 RPM to ensure that I don't get any major bog down off the line in order to get the mid to low 12 second ET's that the motor is clearly able to provide.

Also instead of running 18# of air in the DR tires, I would have been better off leaving them at 30# or so in order to reduce the traction and allow them to spin more. Bottom line it ran 13.1 @107 while being bogged down like a big dog every time off the line.

 

There are other issues not limited to your launching, 107 MPH is LOW but you are also a heavy vehicle. You need the RPM and gear to get you going. If you are sticking with 3.90 then you need to launch it at 6500, and DRs will probably need to be in the 15psi range to make it all work.

I also wonder what kind of suspension parts you have, non listed in sig...

 

I am in the process of pulling the 3.90's and putting 4.10's back in like I had with the 10 bolt. That will help some.

I have a Midwest 9" with tunnel mount arm, relocation brackets and all tubular rear components. Springs and shocks are stock.
Car weighs in at nearly 4K pounds in full street trim. I did not take anything out of it.

I am in favor of skipping the burnout next time too. I think some tire slippage would be a good thing compared to last Friday night. Kind of learly of 6K launches. Too risky for MY street car.

 

Gonna need RPM then and the tune needs to be reviewed IMO....

 

Tune was dead nuts on on the old cam. The new cam is very similar (less lift). But you are right, it will be checked as soon as Bluecat starts tuning again.

Shon,
How big an effect does air pressure have on the tires traction? Why would I be wrong by airing them up to make them spin more?

Again with a 4500 clutch dump on Friday, the tires turned a couple time, grabbed hold and brought the motor down to its knees at 1800 RPM. Traction is certainly not a problem.

How can I get better launches without having to launch at 5K+ RPM?

 

Tire pressure is huge. But agree, the more air you can run and hook the better and if you are bogging down the motor when it still spins some then you need more RPM.
And to get better launches without going past 5+....get MORE HP in a different car. What is the issue with launching it at 6k?? You are spinning it to 6500+ right?

With the bolt on car at 3150#s and 4.33s on ET Streets or Drags, it had to be launched at 6000+ or else it would bog the motor, so I would guess you are in the same boat, MORE Weight But MORE HP by alot!! but you are seeing the same issue, bogging the motor, be interesting to see what would happen if you just blew the tires off and rowed it thru the top end, MPH should go up and ET 'might' be better....

 

Thats may next plan of attack. Get the 4.10's installed, air the DR's up to 30# and skip the waterbox. Dump it at 5-5.5K RPM and let it fly.

Even the DR's on the street dumped at 4.5K will spin a considerable bit.
Here is my datalog chart: