Bogging off the launch
11-22-2010, 06:54 PM
#1
Bogging off the launch I am seriously thinking that my issues might be coming from the lack of jet extensions, anyone else launch hard as hell without them and get a good bite, front end up and the just bog down? I am wanting to get a set of jet extensions and go back and hopefully really be able to nail some better 60 foots, i only get 1.7x slipping the clutch out pretty good, but 5500-6000 clutch dump, it bogs, i am just thinking the fuel slosh is just the issue, 4 holes open and only the front two delivering fuel and the rears empty from the G force of the fuel getting sloshed tot he rear of the bowl.
11-22-2010, 07:22 PM
#4
Do you have clear sights on your carb to check float level? My brother was having the same problem with his old school Pontiac,untill i raised the level up.He could not see them(dual quads) and they were on the low side.Problem went away after adjustment.Set them on the high side,3/4 of the glass.
11-22-2010, 08:08 PM
#6
Zone, welcome to Stick shift drag racing lol.
It is NOT because you dont have jet extensions. The reason you are bogging, is because something in the transfer of power HAS to slip at least a little, and in your case nothing is.
I cant remember what kind of tires your running, but I'll assume you are dead hooking. Your clutch is designed NOT to slip, so it grabs hard and fast, and brings engine rpm down in line with wheel rpm. In order to get the car to leave cleanly you need to introduce some slippage.
If you dont really have a good idea where to start with rpm I suggest 45-4800rpm, and try to maintain this as close as possible - a 2 step is really the only way.
If your running bias tires, you need to air 'em up to around 20ish psi and make sure they spin on the launch. Then carefully lower psi each run, until you find the bog again, then go back up to the psi where it didnt bog, and you got just enough wheel spin to let it all work.
There is another way to do this, use a slipper clutch. It is what I run. It takes some more maintenance than a regular clutch, and it also requires adjustment between street and track, but it is the ONLY way I have acheived 1.60 60ft on drag radials with a stick shift. If I put slicks, or bias et street's I could leave WAY harder than I do now, and not bog OR BREAK ANYTHING, because the slipper clutch takes out the violent hit to the driveline and tires.
Barrett
It is NOT because you dont have jet extensions. The reason you are bogging, is because something in the transfer of power HAS to slip at least a little, and in your case nothing is.
I cant remember what kind of tires your running, but I'll assume you are dead hooking. Your clutch is designed NOT to slip, so it grabs hard and fast, and brings engine rpm down in line with wheel rpm. In order to get the car to leave cleanly you need to introduce some slippage.
If you dont really have a good idea where to start with rpm I suggest 45-4800rpm, and try to maintain this as close as possible - a 2 step is really the only way.
If your running bias tires, you need to air 'em up to around 20ish psi and make sure they spin on the launch. Then carefully lower psi each run, until you find the bog again, then go back up to the psi where it didnt bog, and you got just enough wheel spin to let it all work.
There is another way to do this, use a slipper clutch. It is what I run. It takes some more maintenance than a regular clutch, and it also requires adjustment between street and track, but it is the ONLY way I have acheived 1.60 60ft on drag radials with a stick shift. If I put slicks, or bias et street's I could leave WAY harder than I do now, and not bog OR BREAK ANYTHING, because the slipper clutch takes out the violent hit to the driveline and tires.
Barrett
11-23-2010, 06:53 AM
#7
I am running the ET streets, when i spun with too much pressure it hurt the 60 as you can suspect, with it lowered, it dead hooks, i could find no happy medium. I will however go with jet extensions anyway and install the slear site plugs while i am at it.
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11-23-2010, 07:14 AM
#8
The jet extensions arent going to hurt you, so go for it.
Do you have a 2 step? it will beREALLY hard to find the sweet spot where it will spin "just enough" without one, the difference between spin and bog can be 200rpm(where the cam gets happy). raise your launch rpm if you cant find the happy medium, that will give the engine an advantage over the tires. And then again sneak up on the tire pressure where it hooks.
Have you done all the front suspension tricks to this car to get it to weight transfer?
I been through all of this, and I frickin hated how touchy it could be, thats why I went to the slipper clutch, it really solves this problem. You may have a hard time using 1 with your t-56, as it is so wide where it matches the belhousing, you may not be able to drill a hole in the right spot on the bell to adjust it.
Dont give up on drag racing the stick shift!
Do you have a 2 step? it will beREALLY hard to find the sweet spot where it will spin "just enough" without one, the difference between spin and bog can be 200rpm(where the cam gets happy). raise your launch rpm if you cant find the happy medium, that will give the engine an advantage over the tires. And then again sneak up on the tire pressure where it hooks.
Have you done all the front suspension tricks to this car to get it to weight transfer?
I been through all of this, and I frickin hated how touchy it could be, thats why I went to the slipper clutch, it really solves this problem. You may have a hard time using 1 with your t-56, as it is so wide where it matches the belhousing, you may not be able to drill a hole in the right spot on the bell to adjust it.
Dont give up on drag racing the stick shift!
11-23-2010, 07:38 AM
#9
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3pedals do you think it would be bogging that much with him leaving at that high of an rpm? I agree that it could be that but also think jet extensions wouldn't hurt anything. Also zone try to make sure when you are letting out on the clutch that you are going down with the gas pedal. Like 3pedals said, a 2 step will really help.
11-23-2010, 08:07 AM
#10
doesnt matter how much rpm, if the tires dead hook, and the clutch is not slipping, it will do 1 of 3 things: spin, bog, break - maybe you get lucky and it will move out perfect. I been there and am just relaying track experience.
I just noticed that 5500rpm is where he is leaving, if it is still dead hooking at that rpm, then add more rpm, but also air up the tires a couple pounds,
Something NEEDS to slip a bit.
I just noticed that 5500rpm is where he is leaving, if it is still dead hooking at that rpm, then add more rpm, but also air up the tires a couple pounds,
Something NEEDS to slip a bit.
11-23-2010, 02:54 PM
#11
You know i have a 2 step on the 6010. I have left at 6000 and it still bogged, wen it spun i was slipping the clutch hard, I need a drive shaft, the stock one will probably not take launching nay higher, so should have one soon . I also notice that i was launching so hard that my TQ arm tore a hole in the rear tunnel, so lower control arm relocation brackets are on the to do soon list:
11-23-2010, 04:10 PM
#12
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Wow dude, a hole from the torque arm lol, that's a hard launch! I keep stalking your threads hoping my build comes out half this strong. You are tempting me to do a 6 speed swap on mine.
11-23-2010, 05:38 PM
#14
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I agree dead hooking is definately hard on everything. And I also agree on adding a few punds of air to the rear tires. What rear end gear are you running on this car? Also is this a stock t56 with stock gear ratios?
11-23-2010, 06:23 PM
#15
Yea, it should be wanting to seperate the tire from the body when power is applied. I bet all the control arm bushings and the mount in front of the torque arm are beat? It definately should not be pounding a hole in the floorpan, lol. How is that happening anyway? Is it wheel hopping? Is the rear of the car squatting that hard? you want it to raise slightly, not squat.
Have you checked the pinion angle?
Have you checked the pinion angle?
11-23-2010, 06:36 PM
#16
I need lower control arm relocation brackets, set them down one hole so it is pushing the car forward more rather than making the rear dive.
I am running 4.30 gears on a 26x11.5x16 ET street, the pinion angle is at 3*, no wheel hop.
This happened the last track outing when i tried to slip the clutch at 6000 on the two step, but instinct made me dump the clutch because i have trained myself to do so on the two step for some reason. Kind of like shifting when the shift light comes on, you just shift by instinct, i told myself not to dump the clutch, but when the green was dropped, i went with what i have been doing for so long when the two step is activated.
I am running 4.30 gears on a 26x11.5x16 ET street, the pinion angle is at 3*, no wheel hop.
This happened the last track outing when i tried to slip the clutch at 6000 on the two step, but instinct made me dump the clutch because i have trained myself to do so on the two step for some reason. Kind of like shifting when the shift light comes on, you just shift by instinct, i told myself not to dump the clutch, but when the green was dropped, i went with what i have been doing for so long when the two step is activated.
11-23-2010, 07:02 PM
#17
I need lower control arm relocation brackets, set them down one hole so it is pushing the car forward more rather than making the rear dive.
I am running 4.30 gears on a 26x11.5x16 ET street, the pinion angle is at 3*, no wheel hop.
This happened the last track outing when i tried to slip the clutch at 6000 on the two step, but instinct made me dump the clutch because i have trained myself to do so on the two step for some reason. Kind of like shifting when the shift light comes on, you just shift by instinct, i told myself not to dump the clutch, but when the green was dropped, i went with what i have been doing for so long when the two step is activated.
I am running 4.30 gears on a 26x11.5x16 ET street, the pinion angle is at 3*, no wheel hop.
This happened the last track outing when i tried to slip the clutch at 6000 on the two step, but instinct made me dump the clutch because i have trained myself to do so on the two step for some reason. Kind of like shifting when the shift light comes on, you just shift by instinct, i told myself not to dump the clutch, but when the green was dropped, i went with what i have been doing for so long when the two step is activated.
If you can introduce tire spin on your launch, then you can dump the clutch just like you are used to, and creep up on the right tire pressure to get enough traction back, in order to get the car to 60ft without bogging.
Again, this is not easy. Thats why there are VERY few guys who run a stick at the track, guys are just too lazy to shift there own gears nowadays
PS have you ever checked out the UMTR? The forum is dedicated to Stick Shift racing
http://www.umtrnorth.com/forums/
