Problems with sequential drag launch
 

Two weeks after running my best time on 18" rims, I headed back to the track armed with my BFG drags mounted on stock rims. They're quite a bit stickier than Kumho's, LOL, and I was expecting to run a "best time ever" despite the high temps/humidity.

It's not my first time running on the BFG's, but I encountered a problem I hadn't before, mainly no or low boost in 1st and 2nd gear. Essentially I'd launch at about 4K, maybe 4500, and she'd hook. Then the car would fall flat on it's face, rev up, no boost, and continue that way until third when all hell would break loose (aka normal mode :-). I ran a consistent .8 slower than my average times. and .6 less than my best ever run on street tires.

I did manage one run where I had full boost in first and second. Thing is, it seems as though I cannot maintain boost off the line unless I slip the clutch. This of course, is a bad thing as I'm running an Extreme pressure plate with an OEM disk. It doesn't react very well to slip.

I do rev the engine to build up boost but it seems very hit or miss. Any suggestions? My thoughts are to upgrade the differential and clutch disk and just launch higher. Would I be better off going non-sequential? Any help greatly appreciate.

Re: Problems with sequential drag launch
 

Well dropping it at 4000 or 4500 will do you no good. Rev it up to redline let it fall to 6000 or so and punch it again and drop that bad boy and you are off like a prom dress. Are BFG's slicks or drag radials? You need slicks and do a real good burnout and she will get you into the 11's with no problem. Unless the SEQ system is giving you trouble. I myself had a problem like that. No boost in first gear none or very little in second gear. So I went non-seq and never worried about it again.


just my .02

-Rikki

Thanks for the feedback. Yeah it was strange...never actually happened before but I believe it was caused by the launch, not by a boost issue as I have no problems on regular street radials. The BFG's are drag radials and they hook very well. I don't do much of a burnout if any, just clean them off and go. I'm afraid to launch much higher as I may kill my differential. I'm going to upgrade the clutch and rear diff here in the not too distant future.
Michel

bfg drag radials are too sticky if you don't want to break rearend parts. they'll just slow you down if you don't launch high enough cause when they hook they'll take you out of boost and you'll bog. you basically defeat their purpose if you don't launch at a high enough rpm.

That's what I've found. If I slip the clutch a bit it works and I'm able to dip into the 7.7-7.8 range in the 8th with a 1.8 60ft. time, but it seems to be few and far between. I'm much more consistent on street tires. I'm updating my diff and clutch anyway, so we'll see where it goes from there.
Michel

get the chromoly axles too.

Think I need the chro-mo axles? I thought you had to be running into the 10 second range to really snap those?
Michel

I had the same problems at Cali Spdwy. Just went non-sequential and I'm fine now. I dont know if it's related to the setup, but I get boost all the time now when I'm supposed to.

Michel,
With the stock twins, you won't need to worry too much about breaking your diff or axles. You would be wiser to run ET streets instead of drag radials. With the drag radials, you have more of a chance to wheel hop which WILL break your diff. The ET streets will wrinkle and you'll slingshot out of the hole. Tach it to 7500rpms (don't be scared) and dump it. You'll spin just slightly and take off. BTW...you want to spin a little. If you totally hook up, you can break things just as easy that way too.
Good luck,
Ernie

haha... michel hasn't had twins for forever.... somone brought this thread back from TWO years ago!!! hahaha