...3 Missi...GO!

 

Read what you quoted very closely. 2.5 seconds from no load to 90 PERCENT OF MAX TORQUE is not the same as no-load to WOT where you start feeling boost.

 

I did read closely. The test opens the engine to WOT, and records how long it takes for torque to actually arrive. In this case, when you go from no load to wide open throttle, it takes 2.5 seconds to reach max torque. On an NA engine, that would happen instantly.

Don't get me wrong, you'll probably have 50% (200+ ft lb) in ~1 second. Not awful. But still lag...

 

Yeah, imagine if you had to first rev the engine to 4500 rpm to get 90% of max torque.

I don't think some people have driven a modern turbo and it shows....

 

First off, I'm not trying to find something to complain about. And every car I've ever owned has had a turbo in it, until I got my canyon - so I'm well versed with how they behave, even the modern ones. What I'm trying to do is point out that even though the L3B is no doubt an engineering marvel and a great engine, and is the right engine for 90% of people...it's not some perfect "solves every issue" magic bullet. I've seen way, way too many people on youtube or this forum or elsewhere claim that it has "zero turbo lag", which just isn't true. All I'm doing is pointing out that it does in fact, by GMs very own testing, have somewhat significant turbo lag. I didn't say that the engine was bad, or that I want my diesel or bust, or anything else. Just that this engine has turbo lag, and that as far as turbo lag goes, it's not good. Things don't always have to be black and white, right and wrong, yes and no. I'm just trying to add some objective data for people trying to make a decision.

Yeah, imagine if you had to first rev the engine to 4500 rpm to get 90% of max torque.

Yes, on an N/A engine it would happen instantly...and fall on its face because 1,500RPM is not where an N/A engine makes peak torque, you'd need to downshift. GM's test is holding the engine at 1,500RPM, where peak torque happens, and goes from no-load to WOT with no change in RPM. Look at where the 6.2L makes peak torque; 4,100RPM.

If GM did the same test with the 6.2 at 4,100RPM, great, but how many people cruise at 4,100RPM? How long would it take to go from cruising RPM to 4,100RPM to reach max torque on the 6.2L?

I mean, the L3B makes it's peak torque at 3000 RPM. The LGZ is at 4000 RPM. The minimax is 2000 rpm. More importantly, the LGZ has piss-all for torque at 1500 RPM, whereas the L3B makes 90% of it's peak, and the minimax is very close to it's peak. But the point isn't about what RPM the engines are at. Your transmission will shift it into whatever gear it needs much more quickly than 2.5 seconds. All three engines will shift into their peak torque RPM nearly instantly. The difference is regardless of what RPM you're in, the L3B will have turbo lag - the others won't. There's a very good chance that in spite of that, the L3B will already be putting out more torque, and will still feel just as good if not better. But it will drive like a turbo does - not like an NA engine does - and that involves turbo lag.

 

Yes, on an N/A engine it would happen instantly...and fall on its face because 1,500RPM is not where an N/A engine makes peak torque, you'd need to downshift. GM's test is holding the engine at 1,500RPM, where peak torque happens, and goes from no-load to WOT with no change in RPM. Look at where the 6.2L makes peak torque; 4,100RPM.

If GM did the same test with the 6.2 at 4,100RPM, great, but how many people cruise at 4,100RPM? How long would it take to go from cruising RPM to 4,100RPM to reach max torque on the 6.2L?

Just seems like you're looking for something to complain about...

 

that said, theres still a lag with an NA vehicle, drive by wire is not an instant reaction.

turbo lag, is not really about peak power but more so the delay it take to get the turbo charger to spool up fast enough to produce more then atmospheric pressure.

as Drax stated, what NA engine even at 50% of the 2.7T max power at 1500rpm can produce equal power god knows for my V6 canyon to do that i would have to wait till 3000+ rpm

 

It's a turbo engine. What's your point? Complaining about lag is easy. Go read up on turbo sizing for given boost pressure and engine size, then come back. Making any boost at 1500rpm is amazing, especially for how much boost these engines target. Most high performance turbo engines don't make that kind of power under 3500rpm.

You also seem to forget that every vehicle these days has a transmission. The second you demand that power, it will downshift to the appropriate gear and you likely won't even notice any lag.

And you cutoff the quote right before the good bits about your "long" lag time.
For the L3B, it only takes 2.5 seconds. That’s the kind of response you especially appreciate when towing, but it helps every time you need to pass or dust somebody at a stoplight. In Cadillac tune, the engine produces an extra 15 horses (325 hp) thanks to premium fuel and more aggressive timing. Engineers prioritized a quick spool-up and low-end grunt, the downside of which is that the turbo runs out of steam in the upper revs.

 

It's a turbo engine. What's your point? Complaining about lag is easy. Go read up on turbo sizing for given boost pressure and engine size, then come back. Making any boost at 1500rpm is amazing, especially for how much boost these engines target. Most high performance turbo engines don't make that kind of power under 3500rpm.

You also seem to forget that every vehicle these days has a transmission. The second you demand that power, it will downshift to the appropriate gear and you likely won't even notice any lag.

And you cutoff the quote right before the good bits about your "long" lag time.
For the L3B, it only takes 2.5 seconds. That’s the kind of response you especially appreciate when towing, but it helps every time you need to pass or dust somebody at a stoplight. In Cadillac tune, the engine produces an extra 15 horses (325 hp) thanks to premium fuel and more aggressive timing. Engineers prioritized a quick spool-up and low-end grunt, the downside of which is that the turbo runs out of steam in the upper revs.

I've noticed the turbo lag, but not often. It's a truck, not a corvette. The engine is fine for my purposes.

 

No...just no.

The tiny 1.5 liter turbo engine in our former 2018 GMC Terrain didn't feel like it had much turbo lag. The 2.0 turbo in the VW Tiguan my wife drove before that didn't have much lag either. It actually was pretty peppy. This new 2.7 turbo sure as hell is not going to have much lag either.

Sure, there is always going to be time for a turbo to spool up, but it seems like you don't know what your actually talking about.

 

Alrighty then...we get it. But your first post here makes it seem like you really think it takes two and half seconds for anything to happen once you put your foot down...which is very far from true.

 

I didn't mean to imply that nothing happens for 2.5 seconds...it's not like you just sit there waiting for the car to acknowledge your input. But it does take 2.5 seconds for the turbo to finish spooling. Where along that curve it's spooled sufficiently to be "good enough" is purely subjective, and up to the driver. And at 1500 RPM it's got everything stacked against it...if you're already turning 2000 RPM that number is only going to improve, to the point that in most cases most people won't care or notice.

All I'm trying to point out is that there is turbo lag. Many people don't mind, and that's totally fine. These are trucks after all, not performance cars...

...but some people do mind, and there is now finally a stated number that reflects the spool time at a given RPM. I would be very upset if everyone had told me that a new turbo had "no" or minimal turbo lag, only to find out it was actually somewhat significant. But then again I'm the type of person who's supercharging my V6 because I want the max performance I can get.

Again, not trying to argue or **** talk the new engine or anything like that. I have amended the original post to clarify my stance, without changing any of the existing content.

 

It is worth pointing out that no-load on a dyno is not really a real world scenario, outside of rev'ing in neutral. If you're driving at part throttle, at speed, there is still a load, and much more of a load then a vehicle strapped to a dyno. So 2.5 seconds of lag would be a worst case scenario in a tested condition, not necessarily analogous to cruising at 45 with the turbo under partial load, needing to pass and hammering the throttle (nevermind you're going to trigger a downshift anyway).

 

What is the lag on the Silverado with this engine? Has anyone driven one?

Seems like it should be easy to do - all the Silverados on the lot by my house were the 2.7L, which is why I had to drive 90 minutes out of town to a rural dealership who had a 5.3L V8.

 

I test drove a CCSB silverado with the 2.7 a few years ago, 2019 or 2020 model, and I was impressed by its power and throttle response. That would’ve been the “first Gen” 2.7 with the lower tq numbers. This engine should be pretty sweet in the Colorado. Fuel mileage probably isn’t going to be what we hope for though.

 

Maybe I am old school, but believe there is no replacement for displacement.

I am sure the 4 turbo will work fine and all, but have no interest in owning one.

 

Yeah, GM. Where’s my turbo 5.3? Make trucks interesting again!!

 

2.5 seconds from 1500 rpm to 90% of max torque sounds GOOD to me.
what is the RPM for max torque anyway? 3000?? (that is great if true) This would be important to know.

 

1,500, except for the recent change that bumps peak torque quite a bit and now it peaks at 3,000RPM. That's why the no-load to max torque test was done at 1,500RPM, to show how quickly it responds to torque demand with no other variables/changes in operation like RPM.

The non-HO versions of the engine are going to be different, of course.

Still... 2.5 seconds from no-load to 90% of torque @ 1,500RPM is no joke. That is not slow and anyone that thinks it is misunderstands the test and results, is making poor assumptions, or is just being hyperbolic.

Save the opinions for until you've actually driven one. Then tell us it's slow.

 

Chill out Francis!

 

Please do us a favor and just go test drive the new HO turbo 4 that's in the new Silverado, and then come back and report your findings.

 

4 banger... ppffttt...

 

Try a T3/T04E 57 trim hybrid on a GM 2.4L Twin Cam engine. That has some turbo lag and made less power than the 2.7T does. I was also only running 8-10 PSI though, but when power did come on it was a serious rush of power.

Based on what I hear while driving around, the Silverado seems to have fairly quick spool up given the size of the turbo. Sure its not as quick as the GM 1.3L-1.5L turbo engines, but those engines also have undersized turbos designed for very quick spool, but they run out of steam well before rev limit and just start pumping a lot of hot air. The tiny turbos also have fairly high failure rates due to heat, shaft speed, and driver ignorance/incompetence.

 

Being that the OP has owned only turbo vehicles, he should know there is a balancing act required for turbo selection(s) with spool speed, boost, heat, efficiency, cooling etc etc so the fact that anyone suggested there is any perfect engine (especially a turbo engine) that excels in every situation I don't believe has ever happened.
And how many times has anybody held their midsized truck at 1500 rpm and floored it and NEEDED 90% of the efficiency - seems like an arbitrary test.
If you really want people to make an informed decision as you stated, let them drive it and decide. If they feel like there is no lag - let them. It may not be scientifically true, but those types of numbers on a sheet from a controlled test won't overrule someone's seat of the pants feel and then are about useless.
My 2 cents chipped in.

 

Ive driven 2 turbo diesels and 1 centrafugal SC car and there is night and days difference. with that said on most gas dyno graphs 1500 rpm would be cut off. This would be a bigger issue if it was up in the power band.

 

I have a couple of LNF turbos they are are stout stock and incredible with a tune.
The gas turbo 4 should have been offered years ago it will be a better power plant than anything offered in the past
The V6 is lame compared to them

 

The OP just got their 2022 Canyon in June. I have a feeling this goes deeper than just speculation about turbo lag... 😂 🤷🏻‍♂️

 

Speaking from the perspective of someone that currently has a 2017 canyon 3.6 and a 2021 ranger 2.3 Ecoboost, turbo technology has come a long way in recent years to help overcome turbo lag. Throttle response is crisp on both trucks and off the line, the turbo charged 2.3 makes lots more torque at low rpm much like the GM 2.7 shows on Dyno graphs. Torque is what's makes them feel quick taking off from a stop light. I believe people will appreciate the torque curve the 2.7 delivers once they have had a chance to drive one. I'm excited to take one for a test drive eventually. Most likely focused on a canyon elevation or at4 for my purposes.

 

I think people are stuck in the past where they think turbos are either big or small. There is such a thing as Variable Turbine Geometry.

 

those are normally only on diesels, i think you meant twin scroll.

 

Currently you can find convention design turbos, variable geometry turbos, twin scroll turbos, and dual volute turbos. The 2.7 uses a dual volute style. Each has its positives and negatives, but for the application of the 2.7 it seems the dual volute is the best configuration. The 2.7 is designed around that style of turbo as well. If you look at the exhaust outlets on the head you will see that cylinders 2 and 3 are using the same port on the head. If you follow the runners in the exhaust housing of the turbo you will find 1 and 4 paired together. The locations of the ports in the head and runners on the exhaust housing are arranged to provide as close as possible to equal length exhaust paths. I have not driven a vehicle with one of these engines in it, but I have to imagine that actual real world turbo lag is very minimal.

I used to have Sonics and a Cruze with the 1.4T and my wife has a Trailblazer with a 1.3T. Those engines use very small turbos that spool really fast but run out of steam quickly. There is no noticeable turbo lag in those engines, but they used a compromised turbo size.

I do not see any real world gains in economy over using a larger conventional style engine of the same power output. It doesnt matter how you get the air in the engine, what matters is the amount of air and fuel going through the engine. You will still need a minimum set amount of air and fuel to make set power figure. The difference will be how hard the engine has to work to produce that power. Asking a 675cc cylinder to produce 77.5 hp (2.7) compared to asking a 662cc cylinder to produce 44.4 hp (5.3) will result in the 675cc cylinder having to work harder. This will have long term potential wear and tear issues. Hopefully it is built well enough to take the extra stress though. This is GM we are talking about though.

 

Currently you can find convention design turbos, variable geometry turbos, twin scroll turbos, and dual volute turbos. The 2.7 uses a dual volute style. Each has its positives and negatives, but for the application of the 2.7 it seems the dual volute is the best configuration. The 2.7 is designed around that style of turbo as well. If you look at the exhaust outlets on the head you will see that cylinders 2 and 3 are using the same port on the head. If you follow the runners in the exhaust housing of the turbo you will find 1 and 4 paired together. The locations of the ports in the head and runners on the exhaust housing are arranged to provide as close as possible to equal length exhaust paths. I have not driven a vehicle with one of these engines in it, but I have to imagine that actual real world turbo lag is very minimal.

I used to have Sonics and a Cruze with the 1.4T and my wife has a Trailblazer with a 1.3T. Those engines use very small turbos that spool really fast but run out of steam quickly. There is no noticeable turbo lag in those engines, but they used a compromised turbo size.

I do not see any real world gains in economy over using a larger conventional style engine of the same power output. It doesnt matter how you get the air in the engine, what matters is the amount of air and fuel going through the engine. You will still need a minimum set amount of air and fuel to make set power figure. The difference will be how hard the engine has to work to produce that power. Asking a 675cc cylinder to produce 77.5 hp (2.7) compared to asking a 662cc cylinder to produce 44.4 hp (5.3) will result in the 675cc cylinder having to work harder. This will have long term potential wear and tear issues. Hopefully it is built well enough to take the extra stress though. This is GM we are talking about though.

I bolded the last part. This is mostly true. But the bigger IF for economy is how well the efficiency within the engine is balanced out. A turbo will have a broader range where it is "efficient" then a comparable 5.3. That is why people see similar highway numbers between the two but the 2.7 does a slight bit better in town... it is more efficient down low/under the curve because it will pretty much always be nearer or above 100% VE. IE it is using that same volume of air and fuel more efficiently.

That all being said, the real world turbo lag in the 2.7 is ~1 second. Nothing horrible.

 

Turbo lag is something that has to be felt to be an annoyance. The OP has owned turbos and knows that but has not driven the 2.7L turbo, yet his post makes you believe he knows it can be felt.

 

I've been following this thread and yesterday I was out and about I stopped at my Chevy store and test drove a new Silverado with the 2.7T. I couldn't get to crazy with the sales guy with me but I really didn't feel much, if any, turbo lag in that 1/2 tn truck.

A ZR2 well have more HP and TQ, is lighter, so should feel even more responsive. I'm excited about the new engine and trans, 3" wheel base increase and body appearance. The lack of a ext cab 6' bed and push to start are major turn offs for me.

 

... The lack of a ext cab 6' bed and push to start are major turn offs for me.

The new ones will have push to start ignition.

 

Interesting testimonial:

"It has plenty of power mid range but really takes some time to wind up the turbo for a 60 mph highway pass."

2.7 Turbo 4 Fan Club

I have a 2.7 Turbo 4 LT double cab 4x4 with the 3.42 rear end as a loaner for a few days. I have to say if you don't tow anything heavy, and MPGs are your goal, this might be the motor for you. Does it sound terrible? Yes. Does that really matter? Probably not. It has plenty of power mid range bu...

www.gm-trucks.com