Turbo Lag?

[DMC]

Hey guys, this is kind of a strange question, and its difficukt for me to ask it how i want, so please bare with me.

On turbo cars they have what everyone calls lag. How bad does lag effect the car?

Is the lag up until the turbo produces any "boost" at all? Assuming the answer is yes........

Like through when the turbo begins to spool till when boost kicks in, how much slower is the car than it would be through the same range on the non-turbo version of that car?

Not sure I explained that too well, so lets say i have 2 identical 240sxs. I put a big turbo on one. The turbo doesnt begin to make boost till 3000(an exaggerated number). Both cars race and both shift at exactly 3000 rpms. How much slower will the turbo one be?

Anyway if you can kinda get what im asking any help would be nice! Thanks!

[DMC]

also i know it depends on turbo size, im thinking for a t28 or a t3/t4

[kuramaya]

I think you are reffering to "boost response" vice Turbo Lag. Everyone always incorrectly says "turbo lag" You have to wait for engine RPM's to raise and create enough exhaust flow to spool the turbo. The time between getting on the throttle at low Revs and hitting boost is known as "boost response". Though people call that time, especially with bigger turbos that take longer "Turbo Lag". "Turbo Lag" is actually the time it takes to spool the turbo when you're already at a sufficient engine speed to hit boost. For example, let's say your engine can make 1 Bar of Boost psi at 4000 RPM. You're cruising along at a steady road speed, engine spinning 4000 RPM but not under boost, like on the highway, and now you floor it. How long it takes to achieve your usual 1 Bar of Boost is your turbo's lag time. My car can hit full boost at about 4,000-4,500 RPMS if I hit it in second gear, but I can also be winding the hell out of the motor at 4,000 RPM's in 3rd Gear on the Highway and not be at full boost...Acuator and Wastegate adjustments can cut down your boost response time, not your Lag Time..does that make sense...I used an article to write this a little more laymans terms..

[HyperTek]

ok its like this.. When you start at zero with no load on the engine "meaning you just press on teh gas from a stop", the car is slow until it builds up rpm, which spins the turbo faster. Once the turbo starts to spool up, the car will pick up more acceleration. So at first, the car is slow, but when boost spools up, the car really moves.

Now another example, is launching the car. If your at a dead stop. Reving the motor to something like 3k rpm, then dropping the clutch, the car will accelerate really fast. That is becuase the rpms have spooled up the turbo.

Get it? N/A cars have better throttle response, possibly easier to maintain a level powerband.

Turbo car in the rain while trying ot drive fast is scary lol

[DMC]

Ok a few more questions

Lets say your looking at a boost gauge. under full throttle the turbo has a negative effect on acceleration up until the boost passes 0lbs, right?

During normal cruising is the turbo producing boost at all?

Btw i have never had a turbo car so i dont really understand this from experience

[Nizzan4u2nv]

Originally Posted by HyperTek

ok its like this.. When you start at zero with no load on the engine "meaning you just press on teh gas from a stop", the car is slow until it builds up rpm, which spins the turbo faster. Once the turbo starts to spool up, the car will pick up more acceleration. So at first, the car is slow, but when boost spools up, the car really moves.

Now another example, is launching the car. If your at a dead stop. Reving the motor to something like 3k rpm, then dropping the clutch, the car will accelerate really fast. That is becuase the rpms have spooled up the turbo.

Get it? N/A cars have better throttle response, possibly easier to maintain a level powerband.

Turbo car in the rain while trying ot drive fast is scary lol

Thats not really correct. Engine load is what builds boost, not rpm. You cant usually cant even build boost in neutral, because theres no load. For example, at 4k rpm you can be at 15in of vac or 15psi of boost, depends on the load youre putting on the motor.(generally speaking)

[PoorMans180SX]

Man no fair, if I would have asked these questions I would have got the classic "SEARCH you retard" answer that most people here give... No offense or anything.
Nizzan4u2nv is correct when he states that engine loads run boost, but it's a very complex thing. Oh and usually the backpressure from the turbo is not detrimental to accelaration before boost kicks in, at least if you have a good exhaust. It's more complex than that (turbo sizing and such) but in general...

[DMC]

well honestly im not asking newb questiongs, maybe your just giving a newb answer. Everything everyone has said has helped, but im not sure how to get exactly what im looking for. I am trying to put more thought into my turbo setup then just simply throwing what i can get on there. I guess I just want some people that have turbo cars to say, it takes till xxxx rpm under full throttle before boost begins to build. And i also would like to know whats going on with the turbo while you are just cruising, under no acceleration.

[Nizzan4u2nv]

Learning to read a compressor map will definitely help in deciding which turbo suits you for your motor.