Who is happy the engine will be Naturally Aspirated?

[Dimman]

Another issue with the 3.5L NA vs 1.5L turbo, yes the turbos were superior at the track, but what of the driveability. I'm no former 80's F1 driver, but I don't think it's a stretch to say the power delivery of those little motors with giant turbos would make a light-switch seem like a delicate throttle controlling device.

[Homemade WRX]

^^^oh, no doubt the turbo 1.5L engines were undriveable for transient response in a corner but they still won...that wasn't my point anyhow, I was just having some fun with quotes

Originally Posted by Ryephile

I beg your pardon, but you've no basis to diss me like that.

Didn't mean it as to be offensive. One of the fastest drivers I know still struggles to adapt to a larger turbo application. He came from a V8 background and also did FSAE. Really, no harm meant!!

Originally Posted by Ryephile

...since you so adamantly refused to accept that man/machine interaction. I tried to clarify that my linear comment was a relative example relating to pedal angle or travel versus torque requested.

I understand that but I think what you're trying to get at is you want a shorter transient response from that input, right?

Originally Posted by Ryephile

What that means is; if I depress the pedal 10% to the floor, I expect to get 10% torque from the engine at that RPM. If I depress the pedal 50% to the floor, I expect to get 50% torque available at that RPM.

I understand your explanation and I thought I hit on it a bit with my response...maybe not. That approach is actually quite common and if you've ever designed or studied up on cable throttlebody design, that is rather common. Though it does airflow (power) instead of tq, since it is a fluids problem.

Originally Posted by Ryephile

Why can't you let us enjoy N/A being a desirable solution for everyday street driving?

I'm not. I'm trying to understand (from more than just you) what people have against it (supercharged or turbo) for this platform.

Originally Posted by Ryephile

Your original question when you came into this thread was "why not [boosted]?" The answer is, soul.

And yes, I have your answer, thank you.
If one can deliver 50% more power with no trade offs, is the 'soul' ruined?

Originally Posted by Dimman

There was more going on there at the time. You know anyone that is running straight toluene in their turbo car so they don't blow up under ridiculous boost? Plus street cars don't have to fight the retarded amounts of drag that the high downforce cars were making back then.

When fuel and downforce were limited the DFV owned everything for years. Plus Cosworth didn't only make F1 engines.

What does that have to do with the quote anyway. a rulebook is a rulebook, just so happened the NA engine lost the battle for power...however yes, on tight courses where power didn't matter as much, the Cossie motors did put up a great fight.

They also weren't on straight toluene, despite common internet folklore but it was a large % of the various recipes.

As you said, Cosworth didn't only make F1 engines, that is true...as well for Honda, BMW, etc.

Originally Posted by serialk11r

If you're so convinced about the engineering superiority of turbocharged engines, how about the huge amount of wasted energy that goes out the exhaust? How about pumping loss, loss from intercooling, increased cooling loss (okay I suppose as a proportion of power it's slightly lower since pressure increases faster than temperature), loss due to backpressure? The more boost you run the lower efficiency goes, and a turbocompounding system (not implemented on any cars to date) can only recover <70% of what a piston can.

you do realize that turbochargers reduce wasted exhaust energy, right?
So you do have me with the energy lost from the compressed air's heat (intercooler) but that trade off is well made up with the benefits from the added flowrate and cylinder pressure. Same answer goes for the pumping losses in the system. The lost energy is very small compared to what energy is gained.

What efficiency goes down with turbocharging? The only efficiency in a system that goes down with a turbo would be the thermal efficiency as for the same given block, you have to reject more heat because more power is being created from the same given unit.

What do you mean by turbocompounding systems? are you talking about a turbine engine or the use of turbocompound (turbine driven shafts that turn the flywheel) on diesels?...which is another method, other than a turbo, to regain power from exhaust that is otherwise wasted energy on a naturally aspirated engine.

[Dimman]

What are we arguing again? I seem to have forgotten...

I don't think it was that NA was equal to turbo for power, that's not really sensibly arguable. Turbos own that area.

Right, happy about being NA.

The directness and response is what makes a lot of people happy. The crazy power turbo people should be happy that it's NA, too. Because there won't be as much competition, as it were. Makes your custom hi-po turbo build more special. Not just some kid who buys a turbo BRZ and installs a BOV and 'tunes' it with an AP and thinks he's turbo-fast shit hot all of a sudden.

[Homemade WRX]

see, somehow I got pegged that I was trying to say a turbo is the answer or something ...I really don't care to make a turbo kit for the car as I'm fairly sure one of the FA turbo variants will be released down the road.

I was simply asking about forced induction, and supercharger more specifically (as to retain that crispness), so that you have more tq when you ask (or should I say demand) it from the throttle pedal.

[madfast]

i also tend to agree that a roots SC is the best form of FI for retaining as much "soul" as possible. i mean the only thing that it really affects from the NA "soul" is the SC whine, which for me is rather pleasing. is it better than a well tuned NA engine? of course not. but it has its own appeal...

[fatoni]

Originally Posted by madfast

i also tend to agree that a roots SC is the best form of FI for retaining as much "soul" as possible. i mean the only thing that it really affects from the NA "soul" is the SC whine, which for me is rather pleasing. is it better than a well tuned NA engine? of course not. but it has its own appeal...

check out whatever a rotrex is

[Dimman]

Originally Posted by Homemade WRX

see, somehow I got pegged that I was trying to say a turbo is the answer or something ...I really don't care to make a turbo kit for the car as I'm fairly sure one of the FA turbo variants will be released down the road.

I was simply asking about forced induction, and supercharger more specifically (as to retain that crispness), so that you have more tq when you ask (or should I say demand) it from the throttle pedal.

Something like a Lysholm compressor sounds like a balanced solution (good efficiency and near-instant boost). But for me, I've gotten excited over the idea of a supercharger.

The two cars I owned that gave me the happy vibes were a bone-stock Civic Si, (1.6L SOHC VTEC) and a lightly power modded (stock twin turbo) JDM (real JDM, steering on the wrong side) 1JZGTE Supra. The Civic was my first car, and the first car I was ever in that hit over 7k rpm and sounded incredible. The Supra had some response mods (power steering delete, aluminum driveshaft) and also seriously revved (same 7200 limit as the Civic) and sounded even more amazing. But it had a very slight pause for boost.

It's possible that it is the sound in addition to responsiveness (of the car as well, not just the motor) that does it for me, and I haven't heard too many SC cars that make me excited. Probably also part of why I hate rotaries.

The the 86/BRZ's case, it will depend on the drive. But from the reviews, it sounds like it will be somewhat in-between my old Civic and old Supra in terms of power and weight, it trades off some power of the Supra (100ish hp) in return for the Civic's lag-free response and about a 300lbs weight penalty over the Civic and a similar wheel-base, weight distribution and driven wheels to the Supra. From my perspective the thing is looking damn near perfect. No turbo required.

If I get bored later, there are custom options I can look into. Turbo being one. H6 the other.

[madfast]

Originally Posted by fatoni

check out whatever a rotrex is

im not convinced on the rotrex units just yet. for me personally, i value the low end and flat tq curve that is common with the roots. if the rotrex can come close in the low end but offer much more up top, then yeah im in. but until then i'll stick with the roots

[serialk11r]

Originally Posted by Homemade WRX

you do realize that turbochargers reduce wasted exhaust energy, right?
So you do have me with the energy lost from the compressed air's heat (intercooler) but that trade off is well made up with the benefits from the added flowrate and cylinder pressure. Same answer goes for the pumping losses in the system. The lost energy is very small compared to what energy is gained.

What efficiency goes down with turbocharging? The only efficiency in a system that goes down with a turbo would be the thermal efficiency as for the same given block, you have to reject more heat because more power is being created from the same given unit.

What do you mean by turbocompounding systems? are you talking about a turbine engine or the use of turbocompound (turbine driven shafts that turn the flywheel) on diesels?...which is another method, other than a turbo, to regain power from exhaust that is otherwise wasted energy on a naturally aspirated engine.

Depends on how you look at it. If you look at it as a proportion of exhaust energy, then turbo reduces it. If you look at it in absolute terms (or in relation to total power output), turbo increases it because when you have close to equal compression and expansion, the gas ALWAYS has energy leftover. When you turbocharge you bring up the pressure in the exhaust as well. The pressure in the exhaust is always greater than the pressure at the intake; The energy in the exhaust is greater than the energy needed to supercharge the engine. The higher the boost, the bigger the gap becomes. A turbo behaves pretty similarly to a supercharger (okay, with its own electric drive) with a slightly lower energy input requirement (turbo still produces significant backpressure).

A few pages earlier (edit, in another thread rofl) I ran some very rough calculations for turbocompounding a typical gasoline engine (which has more pressure in the exhaust than diesel), and what you can pick up is rather small with a naturally aspirated engine. I believe turbocompounded diesels today have >2 bar boost, which as I said greatly increases the amount of pressure in the exhaust, allowing a turbine to be particularly effective. Turbocompounding a high boost gasoline engine would yield even better results, but at the end of the day the turbine is not going to be as good as a piston, and you ultimately dump more energy out the exhaust either way compared to a similarly powered naturally aspirated engine (of course high rpm friction makes things slightly complicated but...).

Actually something I'd like to try is connecting the shaft of a turbo to the crank via reduction gearbox. The turbine would have to be replaced of course, with a larger turbine with lower A/R to produce excess turbine power. One day when I have money...

[fatoni]

Originally Posted by madfast

im not convinced on the rotrex units just yet. for me personally, i value the low end and flat tq curve that is common with the roots. if the rotrex can come close in the low end but offer much more up top, then yeah im in. but until then i'll stick with the roots

what i meant was that the rotrex is much better at keeping the "soul" of na simply because it kinda just multiplies what the car is already doing. also worth noting is the effeciency of that thing but that is neither here nor there

[nrclptcnsmniak]

Originally Posted by Ryephile

I beg your pardon, but you've no basis to diss me like that.

dude you diss people all the time lol.

anyways glad the car is NA I would like to get another 50 hp from it. cant wait! my 05 wrx was fun but now its time for something different. I dont know which ill prefer yet. na or fi

[Ryephile]

Originally Posted by Homemade WRX

....And yes, I have your answer, thank you.
If one can deliver 50% more power with no trade offs, is the 'soul' ruined?

Given all else is constant or equal [i.e. sound and pedal response], there is no trade-off unless the added power disrupts the chassis balance, however that is a whole 'nother can of worms.

[old greg]

Originally Posted by serialk11r

When you turbocharge you bring up the pressure in the exhaust as well. The pressure in the exhaust is always greater than the pressure at the intake.

That is incorrect. It is usually the case, but a well designed system will produce higher compressor outlet pressure than turbine inlet pressure over a certain operating range. The thing to keep in mind is that the work balance between the turbine and compressor isn't about pressure change, it's about enthalpy change.

Originally Posted by serialk11r

The turbine would have to be replaced of course, with a larger turbine with lower A/R to produce excess turbine power.

Just ditch the wastegate, problem solved.

[madfast]

Originally Posted by fatoni

what i meant was that the rotrex is much better at keeping the "soul" of na simply because it kinda just multiplies what the car is already doing. also worth noting is the effeciency of that thing but that is neither here nor there

that would be a roots, as its just an air pump. boost is directly proportional to rpm and the tq curve can be tuned to be super flat. it wont make the most power, but if you're ok with what it can make, then you can take advantage of what it does offer namely response and linearity. a rotrex usually isnt as linear, but if its close enough and makes a lot more up top, then we may see that being the more popular route to take.