[Caleb from dallas]

I have a 2015 428I convertible with Dinan stage 1 tuner and dinan free flow exhaust. My car runs 0-60 in 6.3 and 5.4 if I use launch control. I have a 1.2 second lag between 1100 to 2500 rpm. These times are hardly official as my kids used their cellphone stopwatch to help me come up with these times. I have roughly 25k miles so anything that i am going to do to the car must keep the car in warranty status. Lastly I live in Dallas TX so it is freaking hot.
I am looking for ideas to cut the low rpm lag time in half. I have thought about adding a Dinan intercooler to add more oxygen and cooler dense air to help spool the turbo faster but not sure if that would help. I don't think adding a higher Dinan tuner will help as the tuner is more for higher RPMs and I need to improve low torque. I think the Dinan larger Turbo might increase the lag but would provide higher RPM Performance still going to have low torque issue. I've also thought about adding a Dinan fuel pump. One final note I know that Dinan doesn't offer intercooler for convertible due to the different chassis but my local BMW mechanic has added a intercooler on a convertible before by making modifications to the front bumper. Looking forward to hearing your ideas.

[jnecr]

I don't think an intercooler is going to help much in this case. Especially if the Dinan IC is larger. That will just increase the volume between the turbo and the intake.

I'm surprised that the Dinan tune doesn't help with the low end lag, but, this is a gas engine you're talking about. Torque doesn't usually come on that low in gas engines. You just need to launch the car with higher RPM.. If you want low end torque you should've gotten the 328d.

[German Straight-6]

Originally Posted by Caleb from dallas

I have a 2015 428I convertible with Dinan stage 1 tuner and dinan free flow exhaust. My car runs 0-60 in 6.3 and 5.4 if I use launch control. I have a 1.2 second lag between 1100 to 2500 rpm. These times are hardly official as my kids used their cellphone stopwatch to help me come up with these times. I have roughly 25k miles so anything that i am going to do to the car must keep the car in warranty status. Lastly I live in Dallas TX so it is freaking hot.
I am looking for ideas to cut the low rpm lag time in half. I have thought about adding a Dinan intercooler to add more oxygen and cooler dense air to help spool the turbo faster but not sure if that would help. I don't think adding a higher Dinan tuner will help as the tuner is more for higher RPMs and I need to improve low torque. I think the Dinan larger Turbo might increase the lag but would provide higher RPM Performance still going to have low torque issue. I've also thought about adding a Dinan fuel pump. One final note I know that Dinan doesn't offer intercooler for convertible due to the different chassis but my local BMW mechanic has added a intercooler on a convertible before by making modifications to the front bumper. Looking forward to hearing your ideas.

The lag you are feeling is the turbo trying to build boost and also the torque converter lagging slightly.

I suggest doing a rolling pull in first or second gear at 2500RPM while feathering the throttle and then ROLL into the pedal linearly. DO NOT just drop the pedal to the floor right away, you will feel the Turbo stumble as it tries to build boost.

Also, I strongly suggest to refrain from brake boosting and save it for very occasional races, because it’s very damaging to your torque converter. Your transmission is not designed to be constantly subjected to abuse like that.

Also, try to shift before redline at 6000RPM maybe 6500 max if you want to try that as well. I suggest playing around with all these factors and see what will improve your time.

Regardless, rolling into the throttle with a turbo engine will make the boost come on crazy hard and very quickly if done properly.

[RoundelM3]

Strange...my 2016 228i convertible has zero "lag" any time I nail the throttle, especially in Sport mode. My 2013 335i with MPPK and MPE in Sport Mode has zero lag as well. I bought the 335i when I lived near San Antonio, which is hotter than Dallas, and never had any heat-soak problems or perceived "lag". Must be something wrong with throttle adaptation.

[HighlandPete]

A second is a long time, something is not right with that sort of delay.

[Bimmer 808]

OMG this fool is back under another name. Please block ASAP.

[BMWtight2me]

Don't be gassing it like that at 1000 rpms. These engines don' pick up and engage the boost until about 2500 rpms. You should start using the steptronic shifting more and start to feel out the exact sweet spot where the boost first surges and try to ride that through the gear box.

Get a more aggressive tune, downpipe and intercooler and kiss any lag goodbye. Dinans stage 1 is a snooze -- traded it in for the jb4. Go that route or a proper ecu tune. Your tune right now is pretty weak, so get your boost up, and make sure you have a catless downpipe if you don't want lag (open up that poop shoot and let it breath). Then if you want your power to hold after a few hard pulls you better have that intercooler to keep your temps in check. Your car is probably getting heat stroke as it is. If you want to push it. Ditch dinan and do a jb4 so you can datalog and eventually stack that on top a proper ecu tune to get the most possible low end torque.

I have a boosted 320 with all the supporting bolt on to open up the flow with the turbo. Zero lag time. Can easily do 0-60 in 5 seconds or less. And like Germain straight six said. Roll your foot into it, just plowing the pedal shuddered the turbo surge and you lose all sense of the pedal feeling connected to the swelling rpms.

[XKxRome0ox]

Originally Posted by Bimmer 808

OMG this fool is back under another name. Please block ASAP.

lol who is it?



and yes, the n20 is great because peak torque is already achieved at 1500-1800 rpm
so if your car is lagging like that, something is wrong
was it like that before any bolt-on mods? or only after the mods?

[Caleb from dallas]

Hi everyone thank you for the feedback. to jncer 328 is nice but my hardtop conv is the best looking 4 seat hardtop conv on the market hands down. To german, I have been practicing the roll technique I don't want to lauch it as it is stressful on the car. TO BWMtight I am going to take your advice and get an aggressive tune add an intercooler. Will a catless downpipe pass inspection and keep car in warranty? What is the difference between JB4 and dinan and if I get jb4 will I remain under warranty?

[Caleb from dallas]

One more thing I was thinking about changing out the charge pipe and the downpipe. Thoughts?

[BMWtight2me]

Originally Posted by Caleb from dallas

One more thing I was thinking about changing out the charge pipe and the downpipe. Thoughts?

Yeah, ditch the plastic OEM charge pipe cause it will pop under higher psi.

Charge pipe is a must performance mod but depending on your relationship with your service provider it may need to be swapped off before coming in. I leave my tune and bolt ons on for maintenance appointments. But I would risk it if I was bringing it in to get something replaced under warranty. You just don't want anything in the car they could point to and blame for any failure. I've heard of people getting flagged for simply having mods, but I havnt had any issues. Mod it properly and they'll probably respect you and lay off.

[Wires]

Originally Posted by BMWtight2me

Yeah, ditch the plastic OEM charge pipe cause it will pop under higher psi.

Charge pipe is a must performance mod but depending on your relationship with your service provider it may need to be swapped off before coming in. I leave my tune and bolt ons on for maintenance appointments. But I would risk it if I was bringing it in to get something replaced under warranty. You just don't want anything in the car they could point to and blame for any failure. I've heard of people getting flagged for simply having mods, but I havnt had any issues. Mod it properly and they'll probably respect you and lay off.

I don't think you'll ever get enough PSI in a N20 to blow a charge pipe. Any N54/N55 charge pipe issues aren't about the pressure, it's the rocking of the engine to the fixed intercooler....

[BMWtight2me]

Originally Posted by Wires

I don't think you'll ever get enough PSI in a N20 to blow a charge pipe. Any N54/N55 charge pipe issues aren't about the pressure, it's the rocking of the engine to the fixed intercooler....

Supposedly it's been known to pop off with 20+psi. It can stretch under high pressure as well. A metal one will hold pressure much better. And I imagine any rocking too.

I recommend evolution racewerks intercooler, downpipe, and charge pipes for OP.

[eluded]

Originally Posted by Caleb from dallas

These times are hardly official as my kids used their cellphone stopwatch to help me come up with these times.

[Martin.328]

I have a 16 n26 and theres an unusual ammount of lag from a dead stop. I think it has more to do with throttle mapping than an actual tune.

[RM7]

Lol, a bigger intercooler would increase lag.

[BMWtight2me]

Originally Posted by JamesNoBrakes

Lol, a bigger intercooler would increase lag.

It's the catless DP he really needs. Depending on the temp where he lives, and how hard he pushes the car, the larger FMIC may be necessary as well. The stronger metal charge pipe should hold boost better and will help as well. After adding all three components I have little to no lag whatsoever.

[Caleb from dallas]

Could someone explain the science behind an intercooler increasing lag time. Is it because the intercooler has to fill up first filling a larger space thus creating more lag? If that is the case then can you get a same size IC that produces colder air or is that not possible? Or offset this with a larger air intake

[Caleb from dallas]

Could someone explain the science behind an intercooler increasing lag time. Is it because the intercooler has to fill up first filling a larger space thus creating more lag? If that is the case then can you get a same size IC that produces colder air or is that not possible? Or offset this with a larger air intake

[Caleb from dallas]

Also a catless DP is not an option I have a convertible the smell would be horrible and I am confident that would cause a check engine light. I have 20K miles on the car anything that i do must keep the car under warranty

[jnecr]

Originally Posted by Caleb from dallas

Could someone explain the science behind an intercooler increasing lag time. Is it because the intercooler has to fill up first filling a larger space thus creating more lag? If that is the case then can you get a same size IC that produces colder air or is that not possible? Or offset this with a larger air intake

Yes, this is the exact reason why a larger IC causes increased boost delay. However, I doubt you could really fit an IC that is significantly bigger to produce noticeable increased lag.

The stock IC is well designed, so finding an IC of the same size that is more efficient at cooling the charge is unlikely.

[MONSTAR]

Originally Posted by Caleb from dallas

Also a catless DP is not an option I have a convertible the smell would be horrible and I am confident that would cause a check engine light. I have 20K miles on the car anything that i do must keep the car under warranty

The smell is hardly noticeable. I actually enjoy it, however...