Bog and Launch

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

May 12, 2005

#1

• May 12, 2005

• #1

Ok im sure many of you who have been at a track to race know about this. I am wondering how to get around it. I tried a 4500rpm launch with slicks and ran a 13.07 1/4 mile time with a 1.8 sixty foot time. but the car bogged of the launch. i had a slew of 1.9 and 2.0 sixty foot times with various bogs. I finally twisted a axle shaft apart. how do i get rid of the bog? i realize if i want to launch much higher in the rpm range im going to need a built 8.8. however i dont have the cash for that right now. i dont bog with nos and run 1.6 sixty foot times

 

cleanLX

Founding Member

Jan 17, 2001

976

537

144

May 12, 2005

#2

• May 12, 2005

• #2

You run 1.6 60's on N2O but you are afraid to up the launch rpm when N/A?
That does not make sense to me.

At any rate, up your tire pressure so you can roll the slicks over, or up the rpm to achieve the same thing.
Bog comes from dead hooking... you want to roll the tires over, or, slip the clutch on the way out.

Good luck.

 

25thmustang

Mustang Master

Sep 5, 2003

2,021

85

99

Montgomery, NY

May 12, 2005

#3

• May 12, 2005

• #3

cleanLX said:

You run 1.6 60's on N2O but you are afraid to up the launch rpm when N/A?
That does not make sense to me.

At any rate, up your tire pressure so you can roll the slicks over, or up the rpm to achieve the same thing.
Bog comes from dead hooking... you want to roll the tires over, or, slip the clutch on the way out.

Good luck.

Click to expand...

I agree with everything he said!

 

silverstripes

Member

Apr 25, 2005

81

1

8

monroe, LA

May 12, 2005

#4

• May 12, 2005

• #4

Bog mainly comes from launching to high rpm. Sounds wrong but its true. Usually the best launch without bog will be around 500rpm (can range due to flywheel weight) above peak torque which on a mild cam on a 5.0 will usually be from 2800 to 4000. If you choose to launch too high the engine will pull down way below peak torque and bog. Whereas if you launch just slightly above peak torque it will pull down to peak torque and try to turn the tires as hard as possible. Hope this helps.

 

silverstripes

Member

Apr 25, 2005

81

1

8

monroe, LA

May 12, 2005

#5

• May 12, 2005

• #5

Oh yeah bog can also be a from a series of other problems that are related to proper tuning of the car. (fuel press., injector size, fuel volume, ect.)

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

May 12, 2005

#6

• May 12, 2005

• #6

thx guys didnt think of upping my air pressue on my slicks i was running 12 psi. its not that i am scared of launching at a higher rpm i tried launching at 2500 rpm and went up in 500 rpm intervals to 4500 rpm. it just didn't seem to help. i wondered if there was something i was missing. I'm not a hard core drag racer i only race 2 or 3 times a year. what psi would you recomend trying when i am N/A

 

T

tom2001gt

Founding Member

May 20, 2002

292

0

16

Delran N.J.

May 12, 2005

#7

• May 12, 2005

• #7

I would put the tire pressure at 13 psi and leave at 5500 I did that with a stock rear and axles with no problem. 302's don't have tourque like a 351 you need to leave hard.

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

May 12, 2005

#8

• May 12, 2005

• #8

thx ill try 13 psi!

 

silverstripes

Member

Apr 25, 2005

81

1

8

monroe, LA

May 15, 2005

#9

• May 15, 2005

• #9

tom2001gt said:

I would put the tire pressure at 13 psi and leave at 5500 I did that with a stock rear and axles with no problem. 302's don't have tourque like a 351 you need to leave hard.

Click to expand...

It doesn't matter if a 302 has less torque. It will still have a peak torque and it is not at 5500 unless you are blown or have a hell of a built engine that turns ungodly rpm. Once again the best launch is generally around 500rpm above peak torque and if you are still bogging then you have another problem probabaly fuel related. As for the tire pressure that will not cause a bog. The last thing i would want to do is spin the tires or slip the clutch we aren't talking top fuel here. Check out the NMRA and see how many guys want to slip the clutch or tires. Thats a joke.
Once again peak torque for any engine is where the tires will be trying to turn as hard as possible this is where you want to be during a launch regardless of what engine you are running.