Turbo Lag from Piggyback or Flash?

[mikeo]

Sounds like a 'must have' mod to me.

[Numb3rs]

Originally Posted by mikeo

Sounds like a 'must have' mod to me.

Correct me if I am wrong, but would that modification only be necessary if you were running your car with the PROcede? Since I have read of no instances of this happening in stock form.

If you forgo that path, then this particular upgrade is not needed. (:iono: ?)


Forgive my intrusion here (I am coming from the M3Post.com/E90Post.com), but the more I read about this car the more I like what it stands for. I just spent this whole weekend snuggled up with my computer and a cup of coffee reading these boards. (approx 20 hours). Aside from some inconsistency and inaccuracies I think I might be hanging around.


That said, I am wondering if the BMW DV is monitored by the ECU. Offcoarse I do not mean directly, but indirectly. The Bus System Overview in that newly released doc is not detailed enough. Or this is just a direct relation to the mechanical ability of the OEM DV to handle higher absolute pressure?

I will inquire over at the E90 boards.

[clived]

The DV itself does not contain any sensor, so can not be monitored directly. The boost pressure, controlled by the DV, is of course monitored

[angelr]

It does seem to be shaping up that way. So far all reviews have been pretty glowing and made mention of improvements in both response and boost curves. If there are any changes to be made to the 135i kit they will be minimal and easily accomplished.

Originally Posted by mikeo

Sounds like a 'must have' mod to me.

[Madjack]

If you look at the dyno graph, you can see the perceived lag. Notice at low RPMs that the power has shifted to the right. This is going to cause some delay in power delivery. Turbo spool time should not be affected, unless you are installing big turbos. I have noticed many tuners focus on top end instead of the entire powerband. This is fine for drag racing, but there are times in auto-x where I need the low-end grunt.

[JOe335i]

i am running the SSTT( split second turbo tuner) and there is no lag at all.
what many may think is lag, is the 300ft lb of tq rushing in at 1500rpm, which some may think is lag but is just the way of the motor and power curve. u want to see lag jump into my 07 sti. lol

the SSTT keeps the stock curve just more power everywhere.
the burst of 300 crank ftlb that usually kicks in is now somwhere around 380 crank hp with the SSTT which really kicks u into ur seat around 1500rpm
but there no lag i can notice anymore than stock for comparison. the SSTT runs at 11-12psi FYI

[john970]

How can a dyno show lag? lag is time from the pedal application (which isnt shown in the dyno) and power delivery (the only thing shown in a dyno).

I would like to see a graph of pedal or throttle position relative to torque output on the 135 w/ and w/o mods and perhaps against a NA car (m3?).

[clived]

Really pronounced lag, where the turbo is so big in comparison to the exhaust flow the engine creates at lower revs, shows up easily on a dyno - no torque, no torque, no torque, LOTS of torque....

Not the case with the 135i, remap or not, I'm sure though

[Evolved]

Originally Posted by john970

How can a dyno show lag? lag is time from the pedal application (which isnt shown in the dyno) and power delivery (the only thing shown in a dyno).

I would like to see a graph of pedal or throttle position relative to torque output on the 135 w/ and w/o mods and perhaps against a NA car (m3?).

Point was, it isn't actual "turbo lag". Maybe it could have been a shift in the power band and that would show up on a dyno graph.

[john970]

Maybe a better way to say it is if you move the throttle to 1/3 position, where the n54 generates 300ft/lbs, how long after the throttle is applied is the engine actually outputting that torque?

[rajuncajun]

I think the "lag" everyone is referring is actually the electronic thottle. There is a hesitation, not found in older throttle cable systems, that feels like turbo lag. It's really just the throttle taking a sec to figure out that you've just planted your foot to the floor.

[F0Bman]

Wow that looks serious

[An2ny]

Originally Posted by rajuncajun

I think the "lag" everyone is referring is actually the electronic thottle. There is a hesitation, not found in older throttle cable systems, that feels like turbo lag. It's really just the throttle taking a sec to figure out that you've just planted your foot to the floor.

I think "rajuncajun" is correct here.

[WhereItsAt]

Originally Posted by rajuncajun

I think the "lag" everyone is referring is actually the electronic thottle. There is a hesitation, not found in older throttle cable systems, that feels like turbo lag. It's really just the throttle taking a sec to figure out that you've just planted your foot to the floor.

Detailed answer as to what is the issue:
http://www.e90post.com/forums/showpo...8&postcount=33

A thread from E90 on the same topic with plenty of info (and tits for tats)
http://www.e90post.com/forums/showth...t=throttle+lag

[Crowley]

good info here ..

thanks
Crowley

[aus]

I've read the Forged valve was more useful for high boost cars, where the stock valve may not be up to the added pressure. Maybe if you're running PROceed 2.x or JB2HR, but SSTT should fine with the stock valve.