A bit on turbo lag...

[toozday22]

Hey there Diamond Star Motorsports guys...
A friend of mine has an Eclipse and frequents these forums. The other day he stated "Turbo lag is only on an automatic transmission car. A blow off valve prevents turbo lag"
I called him an idiot and told him what he needed to know. He said "tell the guys at dsmtuners.com that"...so I am.
Now I've been reading through your guys posts and have seen some pretty intelligent, in depth conversation and don't think I needs saying; but I'm saying it anyway. and if this is in the wrong forum, move it....

A turbocharger doesn't create boost immediately, which is one of the biggest disadvantages. It takes exhaust gases to get the turbine spinning, resulting in boost. I need not explain how a turbo works, I hope. Turbo lag is the time you wait for the turbo to spool up. When you step on the gas, it feels like a...well...a lag....until boost is created.

It doesn't only happen on cars with an automatic transmission. As a matter of fact, automatic transmissions are ideal for turbo applications. With a standard tranny, you let off the gas to shift. As a result of letting off the gas, you are obviously reducing engine speed and slowing the turbo. In an automatic car, you never step off the gas to shift, which reduces turbo lag. 'Good' automatic transmissions can also shift faster than the average human. Look into level-ten transmissions for some top of the line equipment.

To my knowledge, a blow off valve doesn't prevent turbo lag. It releases pressure...

To reduce turbo lag, reduce the intertia of the moving parts. This is basic physics. A turbine/compressor with less intertia will spool faster, but not achieve as high boost levels. On the other hand, a larger turbine/compressor will achieve higher boost levels, but take longer to spool because of more intertia.

Hope that cleared things up for those of you who told my friend that stuff. You guys dont seem like the type to spread information of such idiocy, but I dunno.

peace

 

[LandoAWD]

Ummmm...yeah. He may have heard that stuff here, but not from anyone with the frontal lobe of their brain. There are always going to be the people who post what they think they know or what their friend told them, but simply posting does not make one an expert. There are alot of folks in here who's knowledge STUNS me, your friend just parroted a piece of someones unresearched reply.

 

[Ludachris]

I'm sorry that someone came away from this site being told that only automatics suffer from turbo lag and that BOVs help the problem. We all know this isn't true - at least I would hope we all know that.

And hopefully the person who gave that false info reads this message and learns. There's plenty of informed, educated people here, but like in any forum, there will be some who spread misinformation too.

 

[LandoAWD]

Beat ya by about a second, Chris . And toozday22, welcome.

 

[toozday22]

Thanks for the welcome.
I figured an idiot must have spoken to him hah.

 

[jpolizo]

Actually, perhaps your friend misunderstood what was said. BOV design can, in fact, change boost response. That, for example, is why the APEX'i BOV uses a twin chambered design. That's not the same as turbo lag, but it does impact how quickly the system responds. A friend just changed BOVs in his Audi and it made a significant change in how the car responds to throttle.

 

[Bohrn]

hehe, funny stuff

As for the BOV increasing pressure that part is wrong too.

They are there to recirculate the compressed intake air so that it does not rebound back against the turbo compressor blades when the throttle plate is shut. It also assists in keeping the turbo spooled up between shifts.