Does boost lag add character?

The tach isn't going to be related to lag, though.  A laggy turbo is laggy no matter the engine speed.  Obviously it is going to be better at higher RPM because things just plain happen faster at higher speeds (Deep Thought of the day ) but it is still going to be there.

In the Group B era, Audi had little idea what they were doing and mostly had the laurels to rest on of being first with all wheel drive.  When everyone else did that too, they focused on making more power at the expense of drivability and handling, which is kind of backwards for the kind of roads driven on.  Anyway, toward the end, they had hotsides so large that the turbos would not build full boost until 4000-5000rpm and the turbos had so much mass that the lag was absurd, so Audi basically invented the first recirculation antilag to keep the turbo spinning when off throttle.  They also invented DSG transmissions so the drivers did not have to lift to upshift.

In reply to Pete. (l33t FS) :

yes of course, I was saying without looking at the tach you don't know if you are above or below the boost threshold so you don't know it you have all there is or you're about to be clobbered.

In reply to mke :

Watch an average person drive and notice how twitchy their foot is on the throttle.  It's no wonder manufacturers have had to add lag to make things feel smoother and/or keep emissions down at times. 

In reply to rslifkin :

that and how slowly they take action I guess.  My wife never noticed the throttle lag thing that made me just hate the car.....I usually get the hand-me-downs but I told her I wouldn't take that one, I hated it.

Am I wrong?  Isn't it just a matter of selecting the right combination of sizes to eliminate lag? Lots of power requires a big turbo. But gives you lag. Smaller turbo gives you quicker reaction / lack of lag but you trade off peak power.  ( power only useful on the race track) 

    A turbo can be cheap if you aren't concerned about the latest high tech stuff. Or originality. 
     I can understand bragging rights.  Making that extra 100 hp over a properly sized turbo. But if lag bothers you get a smaller turbo.  Your Porsche/ BMW/ Nissan etc.  won't care. And if you're not all out racing it will feel better. 

frenchyd said:

Am I wrong?  Isn't it just a matter of selecting the right combination of sizes to eliminate lag? Lots of power requires a big turbo. But gives you lag. Smaller turbo gives you quicker reaction / lack of lag but you trade off peak power.  ( power only useful on the race track) 

Do you like engines that fall on their face at 4500 RPM?  That's what you get if you aim for a "zero lag" turbo.

Well, sure. But we want power, that's why it has a turbo. It also needs to be sized large enough to handle the flow at high RPM, or you will choke the motor and will need to heavily rely on large wastegates.

EFRs use a lighter alloy wheel than other manufacturers, giving them better response than anything else on the market in a comparable size. The tradeoff is turbine geometry (due to the shaping ability of the alloy) that leaves a little efficiency on the table, compared to say a new Garrett G-Series. Once you get sizing as perfect as possible, there is still a trade-off between power and response, that's just the way it is.

Or just use a supercharger

mr2peak said:

Or just use a supercharger

indeed.  24psi as fast as you can slam the throttle to the floor at any rpm.  It doesn't make as much power as a similar boost turbo but its instant, smooth and predicable.

Still no replacement for displacement though 

codrus (Forum Supporter) said:

frenchyd said:

Am I wrong?  Isn't it just a matter of selecting the right combination of sizes to eliminate lag? Lots of power requires a big turbo. But gives you lag. Smaller turbo gives you quicker reaction / lack of lag but you trade off peak power.  ( power only useful on the race track) 

Do you like engines that fall on their face at 4500 RPM?  That's what you get if you aim for a "zero lag" turbo.

That BGN engine I mentioned made power to 7000+. 810 at the wheels on E85.

The guy had a blowoff valve for whatever reason (on a Buick!) and cruising at 35mph, the turbo was spooled up enough to make the valve chitter.  High compression, high flowing heads, good intake and exhaust, well sorted camshaft, the works. Not a bolt on and pray setup.

Definitely a wild ride, but too rich for my blood.  Plus totally unusable except on a prepared dragstrip.

The guys in "stock appearing" classes (iron heads, stock manifolds, stock appearing turbo) could make similar power but at the expense of response. Need 90-100psi in the exhaust manifolds to make 30psi boost.  That 4.5 made the power at only 23-25psi boost.

codrus (Forum Supporter) said:

frenchyd said:

Am I wrong?  Isn't it just a matter of selecting the right combination of sizes to eliminate lag? Lots of power requires a big turbo. But gives you lag. Smaller turbo gives you quicker reaction / lack of lag but you trade off peak power.  ( power only useful on the race track) 

Do you like engines that fall on their face at 4500 RPM?  That's what you get if you aim for a "zero lag" turbo.

 Most guys with those silly power numbers make a pass or two at the drag strip and then use the car for bragging rights until the engine dies or everybody catches up. Forget about practicality. 
      
I had a junkyard Jaguar with a pair of T2 turbo's from Junkyard Saabs.   It would smoke the tires. But made short of 500 hp. It was designed for Chump Car racing because I built it for $500 ( early days rules)  

 When they threatened penalty laps and possibly crushing the car   I decided not to race with them and sold it.  It still shows up once in a while so I guess it's pretty durable. 
      Factory red line is 6500, but stock the camshaft is so mild it runs out of breath at 5500 so it's not all the size of the turbo.   
   
   Road racing rewards different than drag racing. But I suspect part of the reason the Nelsons don't do as well in the autocross 

mke said:

mr2peak said:

Or just use a supercharger

indeed.  24psi as fast as you can slam the throttle to the floor at any rpm.  It doesn't make as much power as a similar boost turbo but its instant, smooth and predicable.

Still no replacement for displacement though 

Superchargers don't make the silly chassis twisting  numbers the Big Turbo's can but they make a much more responsive and fun car to enjoy.  
 My only objection to superchargers is visibility. Front engine and your blind to the front.  Rear engine You're blind to the rear. 
   You can crank drive  a supercharger. They don't add that much weight to the front.   Mine weighs 45 pounds and pumps 250 cu in per rotation. But you loose a little boost with the plumbing.  

Yes, it adds character.  But not the good kind.

Some people with a lot of character are shiny happy people.

I still think that twin charging is the answer.  Yes, a suitably small turbo gives close to instant response but it also limits top end power.

Look at the Volvo Polestar - with a small supercharger for bottom range and a large turbo for top end they were pushing 362 bhp and 347 Tq out of a 2.0 engine with bottom to top flexibility.. It just adds cost of course.

In reply to wspohn :

That's why I used 2 smallish turbo's. ( T3's)  rather than one big turbo.  Basically turned it into 2  2&1/2 liter six cylinders.  Using low boost at rpm below 4500 rpm and building up to a comfortable 12+psi at peak RPM.  At least if I'm reading the Turbo charts right.   Yes I know the really big silly numbers come up in that 30 psi  range. 
    But the smaller  cheap turbo's are not difficult to swap out for the next size. 

Seems like, to me, depends what you are trying to do and what you like personally. 

I will use my most laggy car as an example, 1995 Mitsubishi Lancer Evolution III. I just love that when I am driving that car it is a time machine. It isn't the fastest car around, it isn't the best handling car around.. back in 1995 Japan it was but times have changed. It is very engaging to drive, gives you great feedback, very sharp, direct. 

If I wanted a car that is super capable, fast out of the box just buy a new Corvette and you're done. I am not the type to fundamentally change a car to try and make the car into something it was never intended to be. But, I did do some things to help improve spool, ported the exhaust manifold, removed some volume on charge pipe system, full exhaust. 

So yeah, I like it, it adds a level of engagement, another level of thing to think about while you're driving but that car I have for driving. My evo 7 is my daily now, smaller twin scroll turbo, probably 400-500 sooner rpm spool (that then falls off at the top). I like that better for that car. 

So, depends what you want, what you like. Certainly adds character to me, character being a quality. 

crankwalk (Forum Supporter) said:

mke said:

In reply to crankwalk (Forum Supporter) :

 

I had 1990zx6 motorcycle that from the factory the power dropped between 9000-9500 then the climbed steeply to 12500.  On the track you had to keep it above 9500, miss a down shift and mid-corner the you'd find the back walking out  as 9500 throttle was WAY too much 2-300 rpm later..really dangerous.  Lag is like that...bam! the car is spinning.  Nothing charming about it.

All about preference my man. Talking about motorcycles and lag, my 71 H1 does nothing below 6k and then rockets to 10k with the front wheel up. I love it.

But what about blow through carburetors and old school turbo tech (the worst of the worst to some)? My 82 Seca Turbo does nothing until 5k then boost hits and stretches your arms straight out. On a 120 tire. From an engineering perspective this would all be trash and leave room for improvement and you wouldn't be wrong in a sense.

 

But I LOVE a turbo rush that makes you E36 M3 yourself occasionally.The question is does it add character and some people like it. When you are familiar with it's characteristics and can control it by respecting and anticipating an imperfect power delivery, it's really enjoyable to me.  Different strokes for different folks.

I think for me it depends on if it's possible to keep in the boost once you've decided that you want to do boosty things.  The Seca Turbos that Crankwalk and I have are a great example. They have all kinds of turbo lag.  They're completely gutless off the boost.  I mean they're low compression 650cc engines with a restriction built into the exhaust until the boost comes up.  On the boost they're capable of running sub 11 second quarter mile times, although I suspect you have to abuse the heck out of the clutch to do that.

On a twisty back road though it's possible with some practice to keep them in the boost all the time and the throttle is fairly linear even under boost.  I have lots of practice with mine.  I've owned it since new.

The original Pontiac Sunbird Turbo was terrible.  It was also laggy and gutless off boost and fairly powerful under boost but the power was either all on or all off.  It also had terrible torque steer and was a crummy car on top of that.  Off boost it was a boring econobox and on boost it would be trying to turn you into oncoming traffic unless you were shifting in which case it would head for the ditch.

So, predictable and controllable I'm fine with it and it adds character. Otherwise, it's just annoying.

frenchyd said:

In reply to te72 :

That is exactly the path I don't want to follow.  Replacing turbo's to achieve my goal. 
 I've gone conservative trying to avoid that process.  I don't need power down below about 3500 rpm I don't want to go over 7000 rpm. I'd like to. Stay around 9-10 Psi would be comfortable. But 14 is still in my comfort zone 

Knowing what you intend to do with the car is #1 priority here. I didn't really have any interest in autocross since my nearest events were 3+ hours (one way!) to enter. When some local guys started putting events together, I realized how much fun it was. If not for autocross, I'd have left that old turbo on there, plenty of fun and pulled HARD from 4k+ in 1st and 2nd, 3rd or higher and it was happy to pull from 3k or so, all the way to 8k+.

Despite the experiences of others in the thread, I never really found it to be uncontrollable, but I have my Supra set up quite well, it's really well behaved for a car that goes from no torque to all the torque in a 500-ish rpm window. With the G25-660 though, it's far smoother of a ramp up and WAY easier to drive. Almost boring, in a way that's weird to say about a car like this.

My experience with turbo pretty much starts and stops at a '95 Eclipse GS-T and a 2020 X3. In the Mitsu it was fun in a childish kind of character way. Starts were undramatic (boring and slow) but in 2nd it got fun, esp with a mild turbo upgrade.

Then I drove a Terminator Cobra and instant torque stole my heart. IMO supercharging is akin to the feel of all motor, which is just a better driving experience. 
 

When I drove that twin turbo X3 last year it made me hate lag (or whatever it's technically called) all over again. Compared to the published power, dead starts were pathetically slow (when else are you really wanting to use your power on a daily basis --besides the occasional overtaking?) and I despised it. They've eliminated the "suddenly fast" feel that was present in the GS-T and so there wasn't even that to look forward to. 
 

So I guess to answer the original question: yes, the sudden boost was fun on the street, which is where FWD cars like that Eclipse happen to belong anyway... but character isn't necessarily the kind of thing you want in a DD. 

In reply to P3PPY :

You should drive a Super Coupe.  The supercharger was laggy.  Modern turbo cars are much more responsive.  Heck even my 16 year old Volvo with its old-tech turbo engine (low compression, port injection, large turbo) is more responsive.

I could also detect lag in Buick supercharged V6s.  Not nearly as bad as those T-birds with six feet of plumbing between the fixed-speed blower and the engine, but it is noticable.

In reply to Pete. (l33t FS) :

I hadn't thought about the plumbing part. IIRC in the Mustang the blower is right above the water intercooler, but Id forgotten about piping

In reply to P3PPY :

There will always be a SMALL amount of lag because of the way the blower runs at a fixed ratio to the engine, and how it is not a compressor.

What is enlightening is running both a manifold pressure gauge and a Dash Control in my Volvo. Volvo does not use a MAP sensor but it does use a charge pressure sensor pre throttle body, which is what the Dash Control reads.  I will see vacuum in the manifold and 4-6psi in the charge pipe, because the turbo is generating pressure, the throttle plate is holding it back.  Open the throttle and instant boost, as long as the turbo is already awake.

Then something from a GRM article about driving 930s on track made even more sense: holding maintenance throttle before the corner-out not only ensures the rear end is loaded, it also prespools the turbo.

codrus (Forum Supporter) said:

frenchyd said:

Am I wrong?  Isn't it just a matter of selecting the right combination of sizes to eliminate lag? Lots of power requires a big turbo. But gives you lag. Smaller turbo gives you quicker reaction / lack of lag but you trade off peak power.  ( power only useful on the race track) 

Do you like engines that fall on their face at 4500 RPM?  That's what you get if you aim for a "zero lag" turbo.

That simply isn't true.

The GM LNF uses an EFR dual scroll turbo well sized to the 2.0 engine and has little lag plus it peaks power at 5300 but continues up to 6200 and a mild tune gives a higher peak rpm with little or nothing lost down low.

In reply to wspohn :

For racing  if I select the right size turbo's  I don't care if power falls off at red line.  I can gear for the track I'm racing at. I not only have a transmission that allows me to select the sets of gears that work best.  Changing  them between sessions only requires a little time.   I can also change the diameter of the final drive by altering tire sizes. Between different final drive ratio's  and transmission gear ratio choices, plus  tires.  I can exit each corner at peak power  

   OK, I give up a broad power band.  I don't need or even want it.    I'm not being stupid on a public street. Where that matters. 

In reply to Pete. (l33t FS) :

Pop off valves can be set to bypass boost at a given point either mechanically by dialing it in  or electronically. And when it's bypassed it can either be wasted or sent back around  behind the MAP sensor and before the throttle body. Helping to keep the turbine spooled up. Thus eliminating  lag in shifting. 
    OK it eliminates some of the cool turbo sounds.   Seems like a good trade off.