Just a few questions:

Why does it generally seem that people prefer a naturally aspirated v6 over a Turbo v4?

If they produce the same horsepower and torque with similar fuel efficiency, is there any difference between the engines?

Has there been a lot of problems with turbos in the past?

(I am looking at the 08 TSX rumours v4 turbo compared to the IS250)

Thanks.

 

The TSX would be a V4, not an inline 4?

A couple reasons that many prefer a larger displacement normally aspirated motor over a smaller motor with a turbo are:

1. Instant throttle response -- no turbo lag
2. Longevity -- less stress on internal components.

Turbo motors are far more tunable though; you can often make big power for small money.

 

it is i4 not v4

 

turbo 4 sucks from 0 to 30 MPh unless you rev it up on every stop, but its a blast after that.
V6 has much smoother power delivery.

I think its totally different driving styles, I personally enjoy both (my second car is a modified 2003 WRX)

 

I would wait if in fact they are coming out w/ a turbo tsx... If you are into performance, then the turbo will definitely be more mod friendly.

Also, on the comment about turbo lag, it will most likely have a very small turbo (much like VW's 2.0T) which has a broad torque range and maximum torque at very low rpm's.

 

I saw an interesting comparison test with a bunch of fun cars. They tested a parameter that I don't usually tested, it was something like 20-50mph. Even the fast cars like WRX and EVO were quite slow compared to other cars with a V6. For an Evo or WRX to get those impressive numbers in 0-60 and 1/4 mile I think you really need to abuse them.

~Jay

 

yup turbo lag

 

Much smoother with the 6. Turbo lag makes for inconsistent ride.

 

NA engines - flatter torque curve, no sudden spikes to accidentally break traction. Better BSFC (brake specific fuel consumption) so they are inherently more fuel efficient. Can be designed to run well on lesser fuels. Very expensive to make large increases in power without forced induction.

Turbo engines - large output from small displacement. Poorer thermal efficiency, poorer BSFC, require better fuels or water/methanol injection to compensate for strong tendency to detonate. Potentially very large torque spikes over small range of rpm when turbo hits boost, can cause loss of control on corner exit if the driver is not prepared or is without electronic traction control devices. Relatively inexpensive to make large power increases until turbo performance limits are met.

That's about the whole story. As a '93 TT Supra owner, I have a little experience with boosted engines.

 

I currently drive an evo, which has a considerably larger turbo than the VW 1.8t (my previous car). The response on the vw felt like the is350 at low speeds, even though it only has the same hp as an is250.

The tsx will probably use the same motor found in the upcoming rdx, ~ 240hp depending on who honda wants to compete against. I think i've read that peak torque is reached @ ~4500 rpm... Which suggests that they might be using a slightly larger turbo than the vw's (peak tq @ under 2k rpm). A vw w/ a k04 turbo peaks @ ~4k rpm... Possibly some slight lag in the tsx in exchange for bigger tuning potential

As far as pros/cons, I've never heard of BSFC, but other than that, I would have to agree w/ lowbuxracer.

 

Turbo cars can get off the line just as quick as a na V6... I won't go into detail, but at the most basic level, it depends on the size of the turbo and other things that may help it along, i.e., ball bearing center, etc

 

turborush is correct. turbolag has a horrible reputation of being worse than it really is. a proper turbo installation can be more effective, just as reliable, and without any noticable lag when compared to a supercharger

 

Marketing is a large part of it, as is the packaging and the way they produce power. Peak hp is one thing, and looks good on a window sticker, but a flat torque curve (N/A I6) contributes to a more predictable and smooth driving experience. Weight is also an issue (turbo components), but it can be worked around with proper engineering. With regard to the amount of displacement (and once again touching on marketing), in Europe and Asian domestic markets, you pay more for greater displacement. As such, you can make an overall car cheaper, by using a small displacement engine running a turbo, which will now make up for the difference in power offered by larger competing engines. In the US though, this does not apply, as displacement and # of cylinders sell; the sales of the V6 Acura RL vs its competition (which offers V8s) comes to mind. For this reason, its at times cheaper for a company to forgo investment in a bigger engine, if cars in their lineup don't require it, just as they'll also share a particular engine among cars in the brand.

Lastly, some companies have a philosophy, where they want to focus on N/A performance with certain vehicles. Superchargers/turbos are viewed as a 'crutch'...and apparently, some consumers also feel this way.

Turbo lag isn't really an issue IMO, as most makes would use smaller/effecient twins, and probably see boost as low as the 1k RPM range nowadays. Transition time has been vastly improved since the early 90s, and they can be very streetable, especially with the incorporation of new technology such as variable geometry turbos. I'd expect to see more turbo cars reaching production, while advertising the benefits of both low and high end power once this technology trickles downward.

 

variable geometry turbos like on the RDX and new 911 turbo help nearly eliminate turbo lag, the power of a turbo engine with the response and control of an N/A, best of both worlds

 

Turbo lag is a funny thing, I remember reading about the Syclone a long time ago, it did 0-60 in well under 5 seconds and the 1/4 mile in the low 14s, but the reviewer complained about "turbo lag"

I guess that if you don't plan carfully the power isn't always available on a turbo car. But I did take a short test drive in a Syclone and it was awesome. I really wish I had bought it!

~Jay