Which is better - NA or FI?

Leonard Hofstadter

Just curious more than anything, but which do people prefer in their petrol engines - for it to be natually aspirated or to be turbocharged (or use some other form of forced induction), and why:)?

I will start by saying "it depends".

One the one hand, the newer generation forced induction petrol engines manage the power of a larger NA engine but lower fuel consumption, but with a lot more torque, which makes them feel more like a diesel at low revs in that they can move you about.

Electrically driven turbos are coming too, so the days of worrying about turbo failure because someone forgot to leave the engine idle after a hard drive so as to let the turbo cool down are over.

On the other hand, I don't like the fact that in larger engined cars they are used, in combination with direct injection, to replace larger displacement petrol engines with smaller engines and fewer cylinders. I don't really like the idea of a 5 series with a four cylinder engine - I would much rather a large capacity straight six no matter how much "worse" the less advanced engine might seem.

Also, as the current crop of turbocharged petrol (and diesel) engines are driven by exhaust gases, so if you don't leave them cool down they will give trouble, and remember with the usual Irish attitude towards servicing etc my bet is that only a very smally minority of Irish people leave the car idle for a minute after a hard drive, meaning that a turbocharged engine is likely to give more trouble.

So then, tell us why which you prefer, and why:)!

Edit: could a moderator please include a poll? I tried to but it wouldn't let me:o!

VolvoMan

I don't agree with FI in the likes of M cars and where manufacturers start downsizing bigger engines with them.

MetzgerMeister

My current car is a 2.3 4 cylinder Turbo and I love it. I do let the engine idle for a while before turning it off but only when I feel I've given the turbo a good blast.

My last car (RX8) could have done with a turbo. It was N/A but the rotary needs a turbo to get rid of the lack of torque in the low rev range.

When it comes to supercharged cars like the Mercedes Kompressor, I honestly don't see the point! After driving my own car and hopping into the parents' C180K, it feels very slow for a car with an SC. I know it might be a small SC but it often feels like an N/A 1.8.

I suppose when the correct mode of F/I be it turbo or supercharger are mated to the correct engine it's worth it. Otherwise it's a bit pointless.

captainspeed

captainspeed wrote: »

Just curious more than anything, but which do people prefer in their petrol engines - for it to be natually aspirated or to be turbocharged (or use some other form of forced induction), and why:)?

I will start by saying "it depends".

One the one hand, the newer generation forced induction petrol engines manage the power of a larger NA engine but lower fuel consumption, but with a lot more torque, which makes them feel more like a diesel at low revs in that they can move you about................

Just out of curiosity have you driven many of the newer generation forced induction petrol engines you are referring to?

einheisserschre wrote: »

....... I know it might be a small SC but it often feels like an N/A 1.8............

Flat out acceleration is not at all bad though in them

Anan1

I prefer NA, there's a softness to the throttle response of forced induction cars that i'll never be totally happy with.

MetzgerMeister

RoverJames wrote: »

Flat out acceleration is not at all bad though in them

That's true but when you don't want to/can't do flat out acceleration, there's no real kick like you'd expect. Maybe there isn't supposed to be due to it being what it is.

Matt Simis

I have had both heavily boosted twin turbos and big CC NA.

Im not sure which is better.. I guess large CC plus turbos is the best driving experience. Driving my parents 2.3 4pot Turbo (sorry einheisserschre!) drives me mad, I hate its power delivery and lack of power outside turbo and 4pot clatter.

On the other hand the Audi V6's I had with twin turbo's had no real "turbo on / turbo off" feeling, which was nice. Stock they only have the same BHP as the smaller engine above, but with a bigger base engine and 2 small turbos (vs one big) torque is much higher and power delivery deceptively smooth/linear.

Big CC NA is good too, you always have power, rev's fast and gives a more racey bouncing off redline feeling.


PS: Im all on for BMW going back to FI!

-Chris-

captainspeed wrote: »

Edit: could a moderator please include a poll? I tried to but it wouldn't let me:o!

Done

si_guru

Anan1 wrote: »

I prefer NA, there's a softness to the throttle response of forced induction cars that i'll never be totally happy with.

You've never driven a CLS55 then... no softness there.

Give me a turbo any day.. lots of lovely torque, which is what you need in the real world on the road. Had a VX Mervia turbo as a rental last week in the UK. MPG was not great (33 over 200miles) but she did drive nice around town.

I want to try the new Fabia vRS (TSi).. I used to have TDi vRs which was great fun!

stealthyspeeder

I love the sensation of boost, ok lag sucks but once you get used to what gear to be in its not an issue.

I have has the same 2.3 turbo as einheisserschre and loved it. Then went to a 5.7 N/A, and it was great too, I loved the power throughout the rev range but it lacked that special sensation in my opinion. Now have a 4.2 twin turbo and its the best engine I have driven. Revs up to 7k and the turbos are low pressure so torque is always accessable. Despite the low pressure there is the distinct feeling of boost when on the throttle.

Dont think I would want to go back to a N/A car unless it was something very special.

TBH though, its all subjective, ones mans love of boost is anothers hatred of lag etc.

MetzgerMeister

Matt Simis wrote: »

Driving my parents 2.3 4pot Turbo (sorry einheisserschre!) drives me mad, I hate its power delivery and lack of power outside turbo and 4pot clatter.

What car do your parents have? I don't mind the turbo lag because sometimes I want to conserve fuel and not having the turbo kick in immediately helps this. At least there's a good middle-ground and you don't have to use huge amounts of fuel all the time.

With that said, when I put my foot down a good bit the turbo kicks in with very little lag and I'm very happy with the power delivery and the way it performs.

Big Nasty

I've driven all types of N/A's up to 6L+ engines but only small 4-pot Turbos.

Like the delivery of power in N/A's better than turbos, but haven't experienced larger TC / SC's so I voted 'It Depends'.

Large engined N/A's would be easier / less costly to maintain than smaller FI's though!

Matt Simis

einheisserschre wrote: »

What car do your parents have? I don't mind the turbo lag because sometimes I want to conserve fuel and not having the turbo kick in immediately helps this. At least there's a good middle-ground and you don't have to use huge amounts of fuel all the time.

With that said, when I put my foot down a good bit the turbo kicks in with very little lag and I'm very happy with the power delivery and the way it performs.

Its my fathers car.
Mazda CX7 2.3T, same engine as the 6MPS and 6speed manual box. Dunno how different the gearing is, assume it isnt the same as the 6mps and its likely a slightly heavier vehicle.


Have to drop to 2nd to take 90degree bends with any speed on the exit compared to 4th or 3rd in my own 2 turbo-less cars. But as I said, I do like turbos on bigger base engines, I just think pulling 260bhp from a 2.3 4pot is a poor design choice (its a good pre-2008 tax choice, but that doesnt help living with it).

RobAMerc

there is no replacement for displacement as they say, however I think its very hard to say, it's hugely dependant on the engine and the gear ratios.

I have to agree with Anan1 though, N/A cars do have a much better throttle response and also are much easier to get the best out of ( no need to keep one eye on the rev counter ! )

I drove Fords new 200 bhp diesel the other day and was shocked by the amount of lag that existed and how narrow the power band was, maybe I've just got too used to autos

by the way @si_guru isn't the CLS55 supercharged / not turbo'd ? although SC is F/i there is no need to wait for the SC to spool up, therefore the throttle response is much better.

Anan1

si_guru wrote: »

You've never driven a CLS55 then... no softness there.

Isn't that supercharged? Superchargers won't be as bad as turbos, as they at least spool up immediately.

si_guru wrote: »

Give me a turbo any day.. lots of lovely torque, which is what you need in the real world on the road. Had a VX Mervia turbo as a rental last week in the UK. MPG was not great (33 over 200miles) but she did drive nice around town.

I want to try the new Fabia vRS (TSi).. I used to have TDi vRs which was great fun!

Don't get me wrong, I have (and like) a turbo petrol myself. Weight aside though, I think a larger NA petrol would be nicer. Everyone likes the midrange shove from a turbo on boost, but there's (IMO) no getting away from that spongy gases-being-compressed feeling when you first floor it.

I would probably side with turbo myself. You cant beat that surge you get from a big turbo when it spools up, I love the sound of it too. I also like the vvtL-i and vtec where you get a similar sort of sudden surge of power.

Ive never really driven big engined n/a though so cant really compare but leaving out supercars I think I would prefer power delivery from a turbo car.

Funnily enough I actually like the way they can get big power from smaller engines now, for instance I though that the 1.4 TSI engine with 170 bhp was some achievement. As I have no experience with anything over 4 cyl either my own cars or cars in the family growing up power is the bottom line to me not the number of cylinders.

Matt Simis

Peyton Deafening Albacore wrote: »

As I have no experience with anything over 4 cyl either my own cars or cars in the family growing up power is the bottom line to me not the number of cylinders.

More cylinders typically add to the torque output which is specifically what you like about turbos (its not "power" as such, its the torquey shove that sticks out). A large NA V8 or V12 will have Torque delivery earlier and for far longer than a virtually any FI car baring turbo'd V8s.

A centrifugal supercharger on a V8/12 would be sweet though, low down power and instant response thanks to the big engine but top end performance like a Turbo, but with no lag.

Matt Simis

Matt Simis wrote: »

More cylinders typically add to the torque output which is specifically what you like about turbos (its not "power" as such, its the torquey shove that sticks out). A large NA V8 or V12 will have Torque delivery earlier and for far longer than a virtually any FI car baring turbo'd V8s.

A centrifugal supercharger on a V8/12 would be sweet though, low down power and instant response thanks to the big engine but top end performance like a Turbo, but with no lag.

Yeah I understand about the torque the comment about power being the bottom line was in relation to things like M cars having less cylinders and turbos. Once they have the same or more power/torque it wouldn't bother me.

Matt Simis

Peyton Deafening Albacore wrote: »

Yeah I understand about the torque the comment about power being the bottom line was in relation to things like M cars having less cylinders and turbos. Once they have the same or more power/torque it wouldn't bother me.

Yeah agreed, they sound like the best of both worlds.

RobAMerc

Matt Simis wrote: »

A centrifugal supercharger on a V8/12 would be sweet though, low down power and instant response thanks to the big engine but top end performance like a Turbo, but with no lag.

I've always wondered why AMG went with a supercharger on the 55 range - surely the big V8/V12's low end grunt would negate the lag and then when it cut in all hell would break lose no ?

stevenmu

It depends a lot on what car the engine is in. The 1.8T engine in an Audi A8 seems a bit ridiculous to me, but is fantastic in an A3. Conversely it would be insane to take the epic W12 engine from the A8 and try and fit it into an A3.


(disclaimer: I haven't been in an A8 with the 1.8T engine, it just seems like a stupid idea to me, but it could work very well)

Eric Cartman

depends on the reason

in the case of taking a powerful engine and adding more power by FI then its all good to go

in the likes of bmw where your making the engine smaller and using FI to match the power i think is entirely wrong

Induction is no replacement for displacement

I just wish somebody would have turbo/super charged bmw's M73 V12 engine , that is a FI engine id love to see

RobAMerc

Eric Cartman wrote: »

I just wish somebody would have turbo/super charged bmw's M73 V12 engine , that is a FI engine id love to see

is that not what a 760 has ?

edit : I just googled it look at the fookin torque curve !

sweet jebus!

Eric Cartman

RobAMerc wrote: »

is that not what a 760 has ?

edit : I just googled it look at the fookin torque curve !

sweet jebus!

no , the only turbo 7er was the alpina b7 bi-turbo afaik , and that never came in an e38 shell

edit : i stand corrected, good lord f*ck me youd tear tyres apart from a standstill with that , yet again the e38 problem though

ofcork

Merc have gone down the twin turbo route now with the 63amg engine in the bigger models now eg s/cl/sl it will be a 5.5litre twin turbo but in the c63 etc it will be the 6.2 na engine.