Help ! What I'm I doing wrong here?

[Top Gon]

Ok so I went to the dragstrip a couple days ago and was somewhat disappointed with my times. My best out of 4 runs was a 13.609 @ 99.9 MPH. I was hoping for a little better times somewhere in the 13.3-13.4 area. My only mods are BMS DCI, muffler delete, and tires (Star Specs 265r/245f). I was also running with 1/2 tank of gas(91oct)

Temp: 90 degrees, low humidity (if any), headwind at about 10mph.

Driving technique: Small 1-2 second burnout to clean off the tires and get a little heat in 'em. At the line, I brake-torqued to about 2k rpm then let off the brake and hammer the gas at the 3rd yellow. There was no wheelspin each time I launched. Transmission was put into Manual mode with me doing the shifting at about 6700rpm.

So my question is, what went wrong here? or is this normal for these conditions?

Timeslip:

[Focusedintntions]

Well you may want to try raising your launch rpm. You're driving in a fairly high temps and you have the DCI which when at the line is very prone to heat soak. Especially after a burnout and reving the motor. You going to lose a lot of power there till you get moving.

[Lubo]

Originally Posted by Focusedintntions

Well you may want to try raising your launch rpm. You're driving in a fairly high temps and you have the DCI which when at the line is very prone to heat soak. Especially after a burnout and reving the motor. You going to lose a lot of power there till you get moving.

That is actually not bad, weren't magazines getting like 13.3 13.4 stock? Fill up with 93 and go there when the temperatures are in the 60s and you will do that much better.

[Top Gon]

Originally Posted by Focusedintntions

Well you may want to try raising your launch rpm. You're driving in a fairly high temps and you have the DCI which when at the line is very prone to heat soak. Especially after a burnout and reving the motor. You going to lose a lot of power there till you get moving.

I tried that and it resulted in massive wheelspin off the line. I don't think the launch is the problem. a 2.0 60' is normal, no?

[Top Gon]

Originally Posted by Lubo

That is actually not bad, weren't magazines getting like 13.3 13.4 stock? Fill up with 93 and go there when the temperatures are in the 60s and you will do that much better.

Yeah, I basically wanted to replicate magazine times. I guess it really is the heat. I'll throw in a couple gallons of 100oct too next time to bump up the octane rating.

on a side note; my 60' improved by 0.2 over the stock runflats. both were at the same psi (36). yet, my E.T was exactly the same as when I was stock. Only thing is, the weather was a lot cooler back then.

[Focusedintntions]

That psi for drag racing seems high...try maybe 30-32??

[Top Gon]

Originally Posted by Focusedintntions

That psi for drag racing seems high...try maybe 30-32??

If anything. It should've been higher. i wasn't getting any wheelspin off the line.

[135forthewin]

I guess you could try a 2nd gear launch with full powerbrake, but a stock car might bog.

And sorry to say, that DCI on a stock car is costing you some power, I'd ditch it unless you get a tune.

With 225/245 star specs, SSTT, and a helene drop-in filter, I ran 12.9@109, to put it into perspective. Unless you're going with a serious tune, that DCI will hurt power because the motor really doesn't need that extra air and the heatsoak is killing you.

[1fastbmw]

If you are rasing your rpms at launch and you get wheel spin, you obvisouly could use more traction to take advantage of the resulting additional power. I would also play with lower psi in the tires with no burnout for street tires.

[Top Gon]

Originally Posted by 135forthewin

I guess you could try a 2nd gear launch with full powerbrake, but a stock car might bog.

And sorry to say, that DCI on a stock car is costing you some power, I'd ditch it unless you get a tune.

With 225/245 star specs, SSTT, and a helene drop-in filter, I ran 12.9@109, to put it into perspective. Unless you're going with a serious tune, that DCI will hurt power because the motor really doesn't need that extra air and the heatsoak is killing you.

Yeah I probably should've put the stock airbox back on but was too lazy. I'm saving up for an AccessPort.

On one of the runs I accidentally clicked 2nd gear right at the launch. It resulted in a 2.3 60' and a 13.7 at 101mph. I think ill do 2nd gear launches after I'm tuned

[MarkRacerX]

I had to test mine out as I have only done a few Autocross events, Launch was Very Tricky!

I managed a couple 2.0X 60' early on. The track was very well prepped and as the day cont on and got warmer my 60's were 2.1-2.2. I seemed to have best luck around 2k rpms, any higher would spin.

I managed a 13.512 @ 104.01 mph w/ stock setup.
I do have BMS DCI (leftover fr prior 335Xi ) I might install and drag again this Friday. I didn notice when its Hot weather lowend loss on my 335, but high rpm seemed to pull harder.

Don't be too hard on yourself, def was a HOT day for your runs !

Good luck!

[Focusedintntions]

Originally Posted by 1fastbmw

If you are rasing your rpms at launch and you get wheel spin, you obvisouly could use more traction to take advantage of the resulting additional power. I would also play with lower psi in the tires with no burnout for street tires.

I agree with this....before you said if you rev'd any higher you were breaking loose, but now you have no wheelspin?? You contradict yourself here. Need to lower psi and raise rpms and you'll launch better

[Top Gon]

Originally Posted by Focusedintntions

I agree with this....before you said if you rev'd any higher you were breaking loose, but now you have no wheelspin?? You contradict yourself here. Need to lower psi and raise rpms and you'll launch better

I think the wheelspin was also due to not doing a small burnout before the run

[Focusedintntions]

On street tires a burnout really doesn't do anything for you...

[Top Gon]

Originally Posted by Focusedintntions

On street tires a burnout really doesn't do anything for you...

well from my experience, Star Specs like a little heat in them.

[Vectors2final]

Originally Posted by Focusedintntions

On street tires a burnout really doesn't do anything for you...

Agreed.

The compound in radials are designed to gum up and be sticky once heated-- street tires don't really perform well when heated up. Also, you can't really say that a certain tire likes to be heated up as there are many factors during each run.

[Focusedintntions]

Star specs are designed as an autocross tire. They perform equally when cold or hot. Car and driver did a tire comparison and showed that Not trying to bash ya here or anything so please don't take it wrong here. Just trying to give you as much information as we can to help get those results you want man.

http://www.caranddriver.com/reviews/...r_spec_page_11

[Top Gon]

Originally Posted by Focusedintntions

Star specs are designed as an autocross tire. They perform equally when cold or hot. Car and driver did a tire comparison and showed that Not trying to bash ya here or anything so please don't take it wrong here. Just trying to give you as much information as we can to help get those results you want man.

http://www.caranddriver.com/reviews/...r_spec_page_11

hmmm, interesting. I guess I'll need to go out there again and experiment some more to get my times down.