I thought there were rumors of a straight 6, but haven't heard anything about that for a while.

 

I’ve been driving a 365bhp turbocharged straight 6 since early September. It lacks the instant go of the supercharged V6 when changing up - and to a lesser extent when just planting the loud pedal regardless of rpm.

Oddly, the 228bhp normally aspirated straight 6 I also drive has an even more immediate throttle response than the supercharged V6.

All fun, but in different ways...

 

New Jaguar straight 6? Surprised you were allowed to post about this.

I hope they take a hard look at BMW 3.5L M30 engine for inspiration. My favorite I6 engine, very reliable.

Key problem with turbo 6 is that due to block length when it is mounted longitudinally for a RWD car is that exhaust pressure doesn't build up quickly. This makes turbo lag more pronounced.

 

As with most things, it's fashion. A little like using Facebook instead of having real life friends.

 

Isnt it also that turbos are more fuel efficient for road cars? I'd prefer the supercharger myself.

 

Categorically no. However, turbos are more efficient at passing government fuel consumption tests. Turbo engine can be almost as efficient as naturally aspirated not boosted equivalent when it is driven off-boost.

So let say you have 75HP NA engine, and 125HP Turbo engine that acts as 75HP when off-boost. Nobody in North America would buy a car with 75HP engine, it is just too underpowered for highway driving a 2500lb+ car. So manufacturers boost engine, so it is possible to get it moving, and then test it at off boost.

In normal driving, since you do use accelerator, you do not get anywhere near posted economy. Because you use boost.

So it is all about cheating on EPA tests, not actual good engine design.

 

I love my F-type R, but there's absolutely no doubt that turbocharged engines provide better torque and efficiency than supercharged ones, especially roots blowers which have heavy parasitic losses. If you need more proof of this, I can provide you with a list of cars that make well more than a my F-type despite having much lower displacement: the 911 turbo, GTR, all McLarens, Ferrari 488, California T, etc. Try getting 1500+ HP out of an F-type like you can with a GTR.

 

I'm guessing you haven't driven a modern turbocharged car. Lag is pretty-much non-existent on well-designed modern engines, including the N63 and S63 from BMW. Naturally aspirated and supercharged cars simply can't match the power output, delivery, and efficiency. Supercharged engines sound better because the exhaust isn't obstructed, but lose power due to parasitic losses, whereas turbos are spun by exhaust. It's not a fad. It's that carmakers couldn't provide the power output from naturally aspirated engines to be competitive. And with lower displacement they are providing better output and higher efficiency. This is why the AMG GTS is so much faster than the F-type R, because the power band is wider and comes on earlier.

Again, McLaren, Ferrari, Porsche, and the GTR have turbo engines for a reason, and they dominate at the tracks. If you still don't think a turbo engine can do well on the track, I'll just say...Formula 1.

 

I agree, but the Jag I-4 engineers didn't get the message.

 

Technically I'm in the "Millenial" category, even though I detest that designation. Yet, I own one of these. So we're still on the same page between generations. Maybe it will become timeless?

 

I'm sorry, but i disagree with Mark G. Who the heck cares about "efficiency" when you are talking about a two seater sports car. That's like saying my Main Battle Tank gets better mileage than yours. And "parasitic" losses, come on, how about the water pump, and the air conditioner. Sure it takes power to run a supercharger. So what. The fact that a turbo uses waste energy may be significant when you are talking about other classes of vehicles, but not when you are talking about sports cars. And as to some turbos developing significant power. So what. It is simply a question of how much boost you set the release valve for. A supercharger in inherently better in terms of performance. Period.

 

Well, uh, hmm. I guess everyone is entitled to their opinion, but reading this just makes me want bring out my inner Yoda, "And that is why you fail."

To be brief, efficiency always matters when you are talking about performance. How the power is delivered and what it costs in weight, added heat, losses, and other things that need to be compensated for, are all important to performance of a sports car. The goal is performance, right? All cars have losses to accessories (for now, anyway), but if you have two cars with equal power and one takes 30 hp to spin a supercharger and one doesn't, which one is going to be faster? So yes, of course it matters.

Just saying a supercharger is better in terms of performance doesn't make it true, but feel free to offer up some valid reasons if you have any. I'll give you one...unlike roots superchargers like we have, centrifugal superchargers (which are basically turbos on the intake side), have excellent top end. The top end is better than a turbo, which tends to lose efficiency and make less boost up top. But the downside is parasitic losses which kill low end power. The powerband is basically parobolic. It's not linear. I had an Aston Martin Vantage previously that I had supercharged with a centrifugal s/c kit from ESX. It was a beast up top and made 535 whp. But it was an absolute dog off the line and I got couldn't beat a Nissan Sentra in a stoplight race. Literally, this happened to me. On the freeway, it was a monster. Unfortunately, you can only drive 140 in so many places. And supercharger belts slip and break, which is a major pain, especially when you have to remove thousands of pieces of melted rubber from under your hood. I traded it for the GTR which would destroy it in 99% of situations and performs flawlessly.

Your comments on the "set[ting] the release valve," in which I'm guessing you are referring to a blow-off valve, show that you have no idea how modern turbo cars work. Maybe that's how things worked in the 50s. No offense. Whatever the case, pretty much all top end performance cars are going turbo for some very good reasons. People didn't understand how the GTR could be so fast when it first came out, because they didn't pay enough attention to "area under the curve." Now everyone is going that direction because they see how much better the performance gets.

 

No efficiency does not “always” matter. Say we are talking about a 20 megaton device. If it is 90% efficient or 85 % efficient doesn’t matter. The volume of power overwhelms any inefficiency. This is what you see in a Chevrolet Corvette. It may not have the most efficient power plant, but the volume of power renders the efficiency question mute.

 

Well if you can find a way to get a 20 megeton device to power a car and put the power to the ground, I'll definitely concede that point.

But efficiency still matters with a Corvette. The regular Corvette isn't all that powerful, but it's very light and has a a good power to weight ratio. Plus it is very performance oriented, with a low, wide chassis, good balance, and wide rubber. It's all about performance, and getting the most out of that power. If it had 465 HP, but had a heavy, narrow body, they put it on a soft, floaty suspension, lubricated the differential with sand, and put it on lead wheels with 215/50/17 tires, it wouldn't get that power to the ground very efficiently.

 

I think the 6 was planned for the next version, maybe 2020 0r 2021. that was the story last year.

 

I driven all the cars you mention, plus I have WRX in my stable (boxer 4 turbo engine). They all lag. It just if you drive automatic gearbox, it is very good at hiding it. Plus many drivers were trained to accept delay in input that was the norm with old automatic slushboxes. This doesn't mean that turbo lag isn't there.

This is false. It just happen that EPA pushed everyone into tiny turbo engines. This is designing to pass the test and nothing else.

There is no reason, other than space and costs, why NA engine wouldn't be able to deliver comparable power to boosted engine. Sure, it will have to be higher displacement requiring a bigger block. All turbo does is allows to cram more air in at higher RPMs. You can do that without boost by increasing displacement.

On delivery of this power, you are mind-bogglingly wrong. I don't think you ever drove naturally aspirated modern V8. They cost more, so you only find them in high-end cars, but they are VASTLY superior in delivery to turbo I4 even if nominally they would produce the same peak HP.

NA V8 will have fantastic torque curve delivering full torque from 2500rpm, unlike current high-revving bulshit drama of small turbocharging engines. This means that driver's problem is how to put all that power down (good problem to have) instead of how to keep the car in the power band, on boost, without bouncing off rev-limiter or money-shifting into wrecked engine (bad problem).

Again, you are wrong. Trubo also introduces losses. Try following - stick a potato into your exhaust pipe to block flow of exhaust. You WILL notice loss of power. To be technical, parasitic loss from turbo manifests when pistons take up power from crank during exhaust cycle to push exhaust past turbo.

As I explained in the example above, "and one [that] doesn't" is only the case with naturally aspirated engine. Turbo also takes power to run. Still, to answer your question - two cars of similar weight and power, one is turbo and another is supercharged. SC will beat turbo car in almost any situation. Why? Because SC delivers better torque curve and provides boost at earlier RPMs. Plus, turbos are very heat-sensitive, more so than superchargers - so on a 100F day I would take SC (or even better NA) engine over turbo any day.

Again, you are wrong. Hot rod scene had no issues building big block pushrod V8 400HP+ with carburated engines since 80s. If you apply direct injection, variable timing, and modern tolerances you will have no issues getting even more. For example, Mustang with "regular" Coyote 5.0L V8 pushes 435HP. Corvette C7 pushes 460HP with LT1 6.2L V8 engine.

Personally, I'd take that C7 NA engine over JRL's supercharged V6 or V8 any day and I would take SC V6 over turbo I4 any day and twice on Sunday.

 

A good point the new gen3 Coyote Ford are using in the latest MY18 Mustang makes 460HP on Octane 91 from a 5.0l NA motor that spins to 7400rpm with a great torque curve (420lb/ft).

Cosworth/TVR took the gen2 Coyote (435HP) upto 500HP for the new TVR with some mapping work and no doubt different intake manifold.

As such 500HP NA from a 5.0l V8 is indeed very possible, fantastic power band (1500-7500rpm), linear power and torque, zero throttle lag in a proven and reliable engine.

Downsize all you want (not aimed at quoter as I am agreeing with you) but a V8 NA or V8 SC is simply unbeatable for sound and power delivery/response.

Yes turbo might be more efficient, but man are they dull to drive with a lower rev limit and a smaller power band, plus you have the whole on boost and off boost issue when trying to balance car mid corner, though admittedly the modern stuff is way way better, I think Porsche have done the best with turbocharged flat six for response and linearity but they sound absolutely dreadful and even though insanely quick I would take the older NA flat 6 everytime for that glorious soundtrack.

Efficiency and performance is not everything, in a sports car there is so much more than just efficiency and performance. Sound, soul, character how it makes you feel and the current V6 and V8 F types make me grin like a child, I doubt the turbo motors will do that or certainly not as much.

 

"Lag is pretty-much non-existent on well-designed modern engines, including the N63 and S63 from BMW."

Poor throttle response is the new norm, because of turbo charging, and with BMW's exploding engine record of recent years, they are hardly the best example of "well designed modern engines".

Because turbos are spun by impeding exhaust gases, they also suffer power losses, especially at lower rpm, exactly when the smaller engine can least afford to.

"This is why the AMG GTS is so much faster than the F-type R, because the power band is wider and comes on earlier."

Ignore maker's claims; back to back, (1) It isn't. (2) It isn't. (3) It doesn't.

"Again, McLaren, Ferrari, Porsche, and the GTR have turbo engines for a reason, and they dominate at the tracks. If you still don't think a turbo engine can do well on the track, I'll just say...Formula 1."

The track is not the road.

On the track, all one needs is to be able to extract maximum performance at high rpm, for a short while, even for endurance racing such as the Le 24 heures du Mans, if the engine explodes as it crosses the finish line, it doesn't matter in the least.
On the road, one needs instant response to changing situations, and reliable long term performance; I have seen many naturally aspirated and supercharged engines still performing strongly at over 300,000 miles, never having had even the heads off, but have yet to encounter even one example of one of the cars you mention which has passed 60,000 miles without at least one major overhaul.

 

Unfortunately the car - along with the engine was built in Germany.

 

Ok so please post a list of the NA engines in production making over 100 HP/L. There are two that I know of. And also the NA V8s making over 550hp. While we wait, here's a list of the top hp/liter in current cars.

14 New Cars That Make Crazy Horsepower Per Liter

They're all turbo. For comparison, the Corvette makes a whopping 75 hp/L. And the Mustang GT makes even less. And the flat plane crank GT350 with a 5.2 L, 526 HP NA V8, which barely breaks 100hp/L, is slower than a 425 HP M4 with a 3.0L I-6 turbo. Go figure.

For the record, I've had 4 different cars with the BMW V8TT in different tunes from 400hp to 555hp, logging over 200k miles, and no problems.

And of course I've driven a NA V8. Yes they have linear power delivery. And yes a small 4 banger is going to be more likely to have turbo lag than a V8 turbo. But if they could compete with those engines, they'd be doing it. Unfortunately, power needs have gotten higher and it's just not efficient or reasonable to produce a 10 L engine.

Regarding track benefits of superchargers over turbos, I'll just point out that the Z06 has been plagued with overheating issues. And again, F1.

But I'd recommend that you guys call McLaren, Ferrari, Porsche, and Nissan to tell them that they're doing it wrong. ;-)