[ticaohaha]

Dear Xi friends.

I have some question with the 1/4 time. My N55 is FBO + KW v1 , does not have meth. Run 13.9 @ 99 mph with run flat tires, no launch. Is this normal or it is really slow for FBO.

My current wheel and tire set up : FRONT 225/40/18x8 . REAR 255/35/18x8.5
Is this set up cause the car to have less traction and problem with the transfer case ?

I did search around but no luck for the solution

[ticaohaha]

Update ! I also have Alpina B3 Flash for transmission as well.

[mojobmw_e90]

Your cars broken.start with boost leak test.trapping less than stock is a problem

[blown07]

It sounds like you car is Full Bolt Off.

[DUI Elite]

Really slow. Something sounds wrong for sure. N52's are able to put down 14.2-14.4's consistently.

You should be in the 12's and trapping 115+ if you're FBO N55

[ticaohaha]

Thanks for all the reply guys. But beside possible boost leak. What about my wheel and tire set up. Is it slow the car down ?

[mike5809]

OP, what tune are you using?

Originally Posted by blown07

It sounds like you car is Full Bolt Off.

[Nonecure]

Originally Posted by ticaohaha

Thanks for all the reply guys. But beside possible boost leak. What about my wheel and tire set up. Is it slow the car down ?

Your wheel and tire setup is fine, it is well below the 1% difference front to back. If your not getting a good launch or traction, it can hurt your time, but you should see a higher trap speed. Your time and trap are way low, indicating that you are not producing the whp that you should be.

[ticaohaha]

Originally Posted by mike5809

OP, what tune are you using?

Im using JB4 now with map 5. With my current set up of FBO + meth 50/50 mix. Can i run map 7 all the time ?

[mike5809]

Ah - I am not sure, as I have a COBB. Would be best to ask a JB4 user - sorry!

But 13.9, FBO with Tune does sound like something is off. Should definitely be in the 12s.

Do you have a boost gauge - how much are you holding? Perhaps a boost leak - do a smoke test.

[ticaohaha]

Originally Posted by Nonecure

Your wheel and tire setup is fine, it is well below the 1% difference front to back. If your not getting a good launch or traction, it can hurt your time, but you should see a higher trap speed. Your time and trap are way low, indicating that you are not producing the whp that you should be.

Thanks for the reply. But i check around the xi forum here, some say launch is not good for xi transmission. Isnt it ?
I did try couple time to launch the car. Hold the brake, rep RPM around 2k5 to 3k then release the brake, and then pedal to the metal. Dont know if this is good for xi though

[ticaohaha]

Originally Posted by mike5809

Ah - I am not sure, as I have a COBB. Would be best to ask a JB4 user - sorry!

But 13.9, FBO with Tune does sound like something is off. Should definitely be in the 12s.

Do you have a boost gauge - how much are you holding? Perhaps a boost leak - do a smoke test.

Smoke test done with no leak. According to the log from jb4 software ( done by my friend ), he said i got 13 psi max

[Nonecure]

Originally Posted by ticaohaha

Thanks for the reply. But i check around the xi forum here, some say launch is not good for xi transmission. Isnt it ?
I did try couple time to launch the car. Hold the brake, rep RPM around 2k5 to 3k then release the brake, and then pedal to the metal. Dont know if this is good for xi though

Probably not good to do it everyday, but I have never heard it being an issue at your power level. I have only ran once and got 12.5 @ 110 with a strong headwind. I plan on running again this spring. I am not FBO and just running a tune.

To get a good launch power brake around 2-3k rpm when both cars are staged. My understanding is most tracks will start the light tree just a few seconds after staging. Then floor it as you let off the brake. Don't hit kickdown! You can search on that topic, but I used toilet washers under my pedal to prevent it. Let your car do the 1-2 shift, then shift around 6k after that. When you run stock turbos with a higher whp tune, you run out of torque at redline. This method will help your 1/4 mile time, but trap speed is mostly a result of whp.

[blown07]

Originally Posted by Nonecure

Probably not good to do it everyday, but I have never heard it being an issue at your power level. I have only ran once and got 12.5 @ 110 with a strong headwind. I plan on running again this spring. I am not FBO and just running a tune.

To get a good launch power brake around 2-3k rpm when both cars are staged. My understanding is most tracks will start the light tree just a few seconds after staging. Then floor it as you let off the brake. Don't hit kickdown! You can search on that topic, but I used toilet washers under my pedal to prevent it. Let your car do the 1-2 shift, then shift around 6k after that. When you run stock turbos with a higher whp tune, you run out of torque at redline. This method will help your 1/4 mile time, but trap speed is mostly a result of whp.

Not sure I understand your comment on not hitting the kick down. As you indicate you should be starting in 1st in the XI so the kickdown doesn't matter. I agree for RWD to block the kickdown and start in second.

[Nonecure]

Kickdown will prevent you from shifting 2-3 and 3-4th gears. It will only shift on its own when at redline. You are correct that XI is good to start in 1st, but stock turbos can't handle high boost at high rpms. Look at some dyno's from people with similar mods and you will see the loss of torque after 6k or so.

I let the car shift 1-2, but after that I shift at 6k. Of course the car really shifts closer to 6.5k, but that keeps it in the power band.

With more whp, you should do the Alpina flash if you haven't already.

[danniexi]

was traction control off?

either that or your car has some other underlying problem.

[Jacblack]

My very first pass ever in my n55 was a 13.0 @ 104 and all I have is a downpipe and tune. Wrapping the stall is fine on our cars, again just with anything the more use the more wear you place on an item, but you are fine to do it. I have the ebrake up, right foot on gas, left on brake, to about 3k Max, car builds around 10psi

[Needbmwpartzz]

Check your air filter and spark plugs.....your car is running like Shyte.....something is definitely slowing you down!

[blown07]

There may be something that I'm missing here. I only drive my car in "manual mode" but are you saying that if you are in DS mode and have the car on the kick down (gas fully depressed) then you are unable to manually shift and the car will only shift at redline? I know on my car when the gas is fully depressed I can still shift it at any RPM I choose....agree about the Alpina flash...a must have.

[Nonecure]

Originally Posted by blown07

There may be something that I'm missing here. I only drive my car in "manual mode" but are you saying that if you are in DS mode and have the car on the kick down (gas fully depressed) then you are unable to manually shift and the car will only shift at redline? I know on my car when the gas is fully depressed I can still shift it at any RPM I choose....agree about the Alpina flash...a must have.

Unless my car is different you should not be able to shift sooner in kickdown.

The last 1/8" or so is kickdown. It feels like your pressing on a switch, but kickdown is handled by software. Anyways I was able to full depress the gas pedal around town without going into kickdown, but when I went to the track, I kept getting into kickdown. When I did get into kickdown, I could not shift sooner. So I put a rubber washer under the pedal to fix that problem.

[beetle6986]

13.99 at less than 100 mph is slow. The 13.99 could be related to how well you drive the car. However, 100 mph trap tells me that your car is not making the power it should. Can you post the jb4 logs in an excel format so that we can look at them?

[peterparker]

I ran a 12.9 @ 108. JB4 Map5 with only a PE exhaust. So something is def wrong.

https://scontent-a-lga.xx.fbcdn.net/...85&oe=5523D1F5