Turbo lag... How much are we talking about?

[whitefrs]

Full Blown turbo kit owner right here and let me tell you, with a prefect tune you can have no lag to really minimal lag.

[mike the snake]

I had a BMW 135i before my BRZ. It had twin small turbos with relatively little lag.

I'd say turbo cars will always be a little harder to drive for AX, where things happen more quickly. You're on and off throttle and back on before the turbo can respond, and so the power comes on inconsistently, and usually HARD, which can be harder to control. For AX, I bet supercharging, with instant power would be easier to drive.

For track use, I'd say turbo cars would be easy enough to learn the power delivery to not be an issue.

I know on my 135, it had 400+ hp, and when the power hit, it hit hard and was difficult to handle at street speeds.

[nelsmar]

Originally Posted by Adeets

From someone who owns a few turbo cars, if it's sized properly and you have a good exhaust it's barely noticeable, on my forester I get full boost by 2500, in mashing the pedal at highway speed that's about 1 second before you feel the torque hit. My STI I got full spool by 3200, just mashing the pedal at high way speed it's about 1 1/2 seconds before you feel the torque kick.

I also upgraded the turbo in the forester to a vf48 and fool spool jumped to around 31-3300, torque hit took about the same time as the STI. As long as you do a free flowing exhaust and get a header that has high exhaust velocity (I suggest el) you won't notice it that bad. If you don't upgrade the exhaust (OEM forester fool spool was at 3200, STI OEM was around 3600) you will notice the lag. I think OEM fozzy was around 2 1/2 secs and STI was around 3secs just mashing the pedal at highway speeds.

Hope that helps

As for my decision to go vortech with my BRZ, it's because I've never had a sc car before. Same reason with buying a BRZ it was my BRZ vs buying a WRX which is the same as my fozzy, just slower. I think I made the right choice, my fozzy for winter now and my BRZ for summer.

I went with a vortech as well since I have always wanted to try a daily driven supercharged car with "moderate" power. I recently drove a friends STI with a "canned tune" and an exhaust and after driving my FRS under boost for as long as I have the lag in his STI felt like I had time to read a book when attempting to throttle in at 3-4k RPM starting points. People tend to talk about lag when it comes to RPM. But this really has to do with engine load... If you have an immense amount of load sure you can spool low! That however isn't a fair look at "lag". You are the first person I have seen in a while that understands the fact that it takes a time in seconds, not RPM to spool a turbo.

It really comes down to what you want driving wise. I personally recommend a turbo to most people that ask about my car and what they should do. But I also know that most people dont care about the throttle response. For my driving style I couldn't be more happier. The only downside is I wish i had the ability to lazy shift and spool up in higher gears on the highway, and the economy of a turbo. But when it comes to spirited driving? I wouldn't even consider changing my current setup out. My "lag" is in the ms, not seconds... Though I would love to drive a twin that has a nicely balanced turbo setup for quick spool. However I am extremely confident it wouldn't change how I feel.

OP if your mostly driving in town, having fun around public streets and casual aggressive cornering? Youll love a turbo. Just make sure to get a nicely sized one like some of the vendors recommend instead of going for something "huge". If you are more into autox, or aggressive canyons / mountains then you may enjoy a supercharger more, as it literally just feels like you added a few more cylinders to your engine.

[jamesm]

Below is a map of throttle input, boost (absolute, so subtract 14.7 to get gauge psi), and rpm. this is basically stabbing full throttle at a bit under 4krpm. as you can see, lag is minimal to say the least. making boost within a little over a quarter of a second and hit peak (7.3psig) within around 0.75 seconds. from low rpm the car makes boost by around 2500rpm and is at full spool by a little over 3k. this is with a gtx2867r.



imho it's not even remotely worth giving up the 150+ potential horsepower you stand to gain over any supercharger to improve this, if you even could. sure 'transient response' and all that, but that's forum talk. no one actually analyzes that shit in real life because you're too busy having a blast to care.

there's a reason that nearly every car available today (ok maybe an exaggeration, but the number is quickly growing) has a turbo variant where you hardly ever see superchargers at all from oems, certainly not centrifugals. there's a good reason, because turbos are improving so fast that the argument for a supercharger for all but the most narrow use cases is quickly becoming very hard to make.

just my .02 (as a completely biased long-time turbo guy).

[nelsmar]

Originally Posted by jamesm

Below is a map of throttle input, boost (absolute, so subtract 14.7 to get gauge psi), and rpm. this is basically stabbing full throttle at a bit under 4krpm. as you can see, lag is minimal to say the least. making boost within a little over a quarter of a second and hit peak (7.3psig) within around 0.75 seconds. from low rpm the car makes boost by around 2500rpm and is at full spool by a little over 3k. this is with a gtx2867r.


imho it's not even remotely worth giving up the 150+ potential horsepower you stand to gain over any supercharger to improve this, if you even could. sure 'transient response' and all that, but that's forum talk. no one actually analyzes that shit in real life because you're too busy having a blast to care.

there's a reason that nearly every car available today (ok maybe an exaggeration, but the number is quickly growing) has a turbo variant where you hardly ever see superchargers at all from oems, certainly not centrifugals. there's a good reason, because turbos are improving so fast that the argument for a supercharger for all but the most narrow use cases is quickly becoming very hard to make.

just my .02 (as a completely biased long-time turbo guy).

Thank you for this post! Finally someone actually posted their logs showing actual response. That is actually the turbo i was originally considering before purchasing my supercharger.

[nataku]

I doubt I can add much that hasn't already been mentioned, but I will at least chime in for the "small" turbo crowd.

The "worst" turbo lag experience I have is when I drive like a moron. If I'm in 6th gear at 35-40 mph the car feels just like it did stock. It will bog and bog and make nasty noises and ask me why I'm being so dumb. A shift down to 5th quickly gets me back in business.

Other than that absolutely moronic situation I seriously have no issues with lag. Yes there is a feeling of surging that the car did not have before, but I personally prefer this as it indicates to me that the money I poured into my FI solution is actually DOING something. And boy does it do something...

[Pete156]

Originally Posted by nataku

I doubt I can add much that hasn't already been mentioned, but I will at least chime in for the "small" turbo crowd.

The "worst" turbo lag experience I have is when I drive like a moron. If I'm in 6th gear at 35-40 mph the car feels just like it did stock. It will bog and bog and make nasty noises and ask me why I'm being so dumb. A shift down to 5th quickly gets me back in business.

Other than that absolutely moronic situation I seriously have no issues with lag. Yes there is a feeling of surging that the car did not have before, but I personally prefer this as it indicates to me that the money I poured into my FI solution is actually DOING something. And boy does it do something...

Couldn't agree more. It's all how you drive.

[pmccut]

I'm probably the minority here, but I love the slight lag before boost kicks in and knocks you into your seat. It's addictive.

I was in your shoes 6 months ago, leaning towards the supercharger route. I saw a couple detailed reviews from people who have or had turbo cars in the past, and they were let down. If you hate the slight feeling of lag before boost then you already know which route to go.

[nataku]

Originally Posted by pmccut

I'm probably the minority here, but I love the slight lag before boost kicks in and knocks you into your seat. It's addictive.

I was in your shoes 6 months ago, leaning towards the supercharger route. I saw a couple detailed reviews from people who have or had turbo cars in the past, and they were let down. If you hate the slight feeling of lag before boost then you already know which route to go.

Well even if you're in the minority you're not alone

[cantholdanymore]

Originally Posted by nataku

I doubt I can add much that hasn't already been mentioned, but I will at least chime in for the "small" turbo crowd.

The "worst" turbo lag experience I have is when I drive like a moron. If I'm in 6th gear at 35-40 mph the car feels just like it did stock. It will bog and bog and make nasty noises and ask me why I'm being so dumb. A shift down to 5th quickly gets me back in business.

Other than that absolutely moronic situation I seriously have no issues with lag. Yes there is a feeling of surging that the car did not have before, but I personally prefer this as it indicates to me that the money I poured into my FI solution is actually DOING something. And boy does it do something...

Wow my whole commute is moronic driving

[nataku]

Originally Posted by cantholdanymore

Wow my whole commute is moronic driving

Haha I meant if you think you're gonna get power in that situation. Certainly coasting in 6th at such low speeds is great for MPG and still works just fine. If I floor it at that point though it's no good.

[gdrider77]

Just wanted to chime in, and coincidentally just got a dyno plot to comparebrz turbo and supercharger yesterday. I have an @AVOturboworld turbo, and obviously, i am biased. But as most others have stated, it really depends on your driving style. I would say, yes...there is a bit of "lag", but its not really an issue in my opinion. Its all before 3k or so. You really dont want much boost down low in my opinion. Tires spin and you go nowhere fast.

Even without FI, below 3k in 1st off the line, you will spin the tires if you are aggressive at launch. So thats why i feel its not really an issue.

I have road in the vortech brx mentioned. And it is much more smooth, but feels alot different. So if you are just looking for that smooth delivery throughout, then yeah, supercharger would be good. You want to really feel the power, and get instant response, then turbo ftw.

Thing is, i am not really looking for the top end that it provides. I want the power down low and pretty much as soon as i punch the gas, i spool up and go...just didnt feel/see that in the supercharger.

In all honesty, had i purchased and installed the supercharger, i would have been really, really sad after riding in a turbo version. Like pissed. Its really noticeable in my opinion.

In the end I want the torque....HP up top is worthless to me in my driving. Of course, we shall see soon how it works on the track, may be eating crow...

Comparison.

[FReSh]

I think some people in this thread may be confusing lag with boost threshold... The boost threshold refers to the minimum RPM at which the car produces full boost. Lag refers to the amount of time it takes to build boost after you hit the throttle while the engine is already at an RPM at which full boost can be made(above the boost threshold).

[nelsmar]

Originally Posted by FReSh

I think some people in this thread may be confusing lag with boost threshold... The boost threshold refers to the minimum RPM at which the car produces full boost. Lag refers to the amount of time it takes to build boost after you hit the throttle while the engine is already at an RPM at which full boost can be made(above the boost threshold).

Yeah... 98% of the time someone asks about lag all the trubo-heads get in and start talking about thresholds -.-