What can be done about turbo lag?

I have a stock 05 LGT AT. I've looked at all the mods. Haven't touched the engine. Stage 2 stuff looks easy enough. Every thing I see is all about more flow naturally. A 2.5 with a big turbo is going to have some lag. For all those that want even more power a bigger turbo is required.

 

The turbo hit is fun, but also annoying. I traded a manual for an auto because it is the wife's car, but I really regret that. Throw in the auto downshifting every 2 seconds and it's a drag. Sport shift is OK, but since it isn't a manual I forget a lot.

 

So are there any mods out there that improve turbo lag? There are upgrades for more power, but do any of them move the power band down, or do they actually make it worse. Any valving improvements to keep the turbos spooled up better? (besides going back to a manual:)) I'm just curious, or if turbo lag is just "the cost of doing business".

Are u talking about improving lag in the context of a bigger turbo? or on stock turbo?

stage 2 will be the least laggiest setup for our cars. Just get a UP/DP and AP

Yo! Yooz NAWS!!!

 

That or shift.

...

I'm just curious, or if turbo lag is just "the cost of doing business".

Are u talking about improving lag in the context of a bigger turbo? or on stock turbo?

 

No, stock turbo. Stage 2 is simple enough and worth it. At this time, I have no intention of doing anymore in the future. I was just thinking though if lag could be improved. Understanding of course that it will not be eliminated.

You need a supercharger bro......

You are at altitude...

 

All cars lag at altitude...

take the turbo out. Presto!

nitrous prespool

Engine swap w/ me?

You guys are funny.

 

I'm not asking to rewrite the laws of physics, I was just curious.

 

So Praedet, does altitude make it worse, or is it that at lower elevations with more power on tap you don't notice it as much? I went to sea level once in the LGT and it did drive nice.

Are we talking about lag or boost threshold?

 

You could run anti lag, if you into changing out you turbo on occasion:lol:

does altitude make it worse, or is it that at lower elevations with more power on tap you don't notice it as much? I went to sea level once in the LGT and it did drive nice.

 

I think a good way to describe it is that altitude makes the turbo lag more noticeable. Just like the "turbo lag" seem worst on a 5EAT than on a 5MT. In reality both turbos spool about the same, but 5EAT introduces an additional source of lag to the system so the whole system feels more sluggish. You can look at altitude as another source of lag to the system.

You have an 05. I believe you have a Cat in your up-pipe. Do stage 2 (downpipe, up-pipe, accessport) and you could always send your stock turbo to deadbolt to get it ported, polished and your wastegate enlarged. All of which will help with spool. Also, a nice high flow filter in your STOCK airbox will help a little.

 

If you want to go even further. Port your stock headers...coat or heat wrap them and the up-pipe. Then a custom tune on the accessport with these mods will help alot.

 

BUT....if you were to do ALL of the above...you might save 250rpms...max.

and you could always send your stock turbo to deadbolt to get it ported, polished and your wastegate enlarged. All of which will help with spool. .

 

This will not help spoolup, also if not done properly could actually hurt it.

Well, when your engine is not running boost (depending on where you are in CO) you are about 20% or so down from what you would be at sea level. Once it reaches the boost threshold, you are only about 9-10% or so down.

 

The problem is that the boost threshold (where the manifold pressure starts to become positive) is higher at altitude. This is because it takes a certain mass flow rate (combination of exhaust velocity, density, and area of the uppipe) to reach the boost threshold. Since density is lower at altitude ,(as is pressure) it takes a higher RPM (exhaust velocity) to reach the same mass flow rate. This means you reach boost at a slightly higher RPM than you would at sea level.

 

So, your car will feel like a dog out of boost, and it takes a higher RPM to reach boost...

 

BUT, the actual lag will be the same or lower

Turbo lag is how long it takes the turbo to hit boost when you are already cruising above the boost threshold and you slam on the gas. Since the density and pressure are lower at altitude, the air flow has less momentum. This means that the time required to accelerate it through the pipes from low velocities to high velocities is actually lower up here

^^^

yay!

 

K... IF you want to reduce you boost threshold somewhat you need to free up the restrictions before and after the turbo.

 

the standard stage 2 mods will help. You could throw in a TMIC and a few others things but it becomes a game of declining returns.

It may sound odd but, my FMIC greatly reduced lag. But, it's true at feel more laggy.

^^^Did it reduce lag or boost threshold (also known as spool)?

^^^Did it reduce lag or boost threshold (also known as spool)?

Boost treshold

Thanks for the input guys.

 

Praedet, Thanks for the explanation. I never really thought about it, but it makes perfect sense. I always figured it was lag, but yes, I am referring to off boost/on boost. Cruising down the road in auto and stabbing the throttle is an exercise in patience. I'm in the Springs by the way.

Ooooh. What part of the Springs are you in? I live near Bradley and Powers.

 

(and I have a Tactrix cable if you want to flash your ECU)

 

strike

 

 

Thanks for the input guys.

 

Praedet, Thanks for the explanation. I never really thought about it, but it makes perfect sense. I always figured it was lag, but yes, I am referring to off boost/on boost. Cruising down the road in auto and stabbing the throttle is an exercise in patience. I'm in the Springs by the way.

Boost treshold

That's what I guessed. Lag might JUST BARELY go up, but since the core is very efficient, I am not suprised we are seeing boost thresholds coming down w/ FMICs...