...small turbos, torque curves, and power (oh my!)..

[...m...]

...just a bit of a thought experiment this morning: what would it feel like to drive a car tuned for a big torque boost very early in the powerband which tapered off with a long slope to produce a flat horsepower curve?..

...i'm thinking about throttle response which produces more-or-less the same power at any given rev, rather than building linearly (or parabolically), and i'm having difficulty visualising the driving experience...

[RichS]

Think Telsa.

[...m...]

...the tesla i believe has flat torque, not flat power, and that's the key difference i can't quite wrap my head around...

[RichS]

Is there a difference in feel between something that has a flat torque curve and a flat power curve?

[lotus69f2]

What about a car with a CVT programmed to keep the engine at peak torque.

[Bender Rodríguez]

It would probably be uncontrollable without at least adjusting the gearing. If you want a flat horsepower curve your going to have to make allot of torque right from idle and have it drop off fast. Power = Torque x Angular velocity, since it's a liner relationship. You'll have allot of torque at low rpm's, and even less at high, with stock gearing it's going to go from uncontrollable to boring as you sweep thru the band. Well that’s my guess anyway.

[Viggen]

I like it however I do prefer having the power more up top which is how the car is now after a new ecu. On the street having low end tq is great & easy to live with. From about 2500-5000 rpm's I am close to 250wtq & from 4K - redline (about 6.5K) I am in the 220whp area.

[Mr. Oz]

Go drive a diesel......big bottom end torque while tapering off up top.

[Randy Chase]

All of our tuning efforts with the Elise were to move the power band lower. Ultimate hp is great for bragging rights, but what matters is corner exit speed, which often requires more torque earlier.

I am in the planning stages now of DECREASING hp on the Noble, by switching to smaller turbos.

[Confidential]

Come drive my 08' GTI w/ APR stage 2. ~320 lb-ft of torque hits early then tapers off. Makes for a very fun DD.

[Murix]

Yep. Drive a GTI. My GTI is the perfect compliment to my Elise. On the street it is much easier to drive, but on full throttle the Elise is more fun.

[DWebb]

Originally Posted by RichS

Think Telsa.

Electric motors have a constant torque regardless of RPM. This would look more like a ramp, HorsePower wise. Kinda like a rotory engine, (greater rpm's = greater torque).

Originally Posted by Bender Rodríguez

It would probably be uncontrollable without at least adjusting the gearing. If you want a flat horsepower curve your going to have to make allot of torque right from idle and have it drop off fast. Power = Torque x Angular velocity, since it's a liner relationship. You'll have allot of torque at low rpm's, and even less at high, with stock gearing it's going to go from uncontrollable to boring as you sweep thru the band. Well that’s my guess anyway.

yea, pretty much like that.

(torque x rpm) / 5500 = Horse Power

So...............
guess what it would be like would depend alot upon gear selection.
Check out the torotrak If you want to see a great CVT. I think it's one of the greatest things I've seen. The addition of the planetary allowing for a 0 ratio engagement is simply gorgeous. varying ratios by oscillation<---brilliant

IMHO 8k rpm's is more exciting than 4k rpm's.

Psychologically, hmmmm, well you know the dumbasses who put the coffee can on the honda and race around making all that racket yet get their butts handed to them by an old run down pickup, because the can and the hood scoop are their only mods they could afford.

Well it sounds faster. It must be fast. So I drive fast! I can hear more power so I perceive more power, I believe there is more power. So much that I can feel it, and you'll never convince me otherwise. The $400 bucks I wasted on this piece of crap is the best money I've ever spent.

Well, We are not so different when at 6200rpm's that lift comes on and oh yea, It sounds and FEELS soo much faster that even though you were pulling as hard from 4k to 5k you appreciate the 6500 to 7500 soooo much more.
As much as I like to believe that I'm a higher life form than ricer boy, in the end we are the same type of organism, I'm just a bit better informed than He and a little less informed than others.
I'll end my day with some thinking, "what an idiot" and others thinking,"That man is a genius."

Unfortunately, I'll wake up with one of the prior.
But if favor shines my way I'll go to bed with one of the latter.
For those moments in between, do what you want, but I'll spend mine as close to the rev-limiter as possible.

anyways, crap here's your thread back.

[dfa2100]

If the horsepower curve was made to be flat by essentially having an ever decreasing torque... I imagine the driving experience would be disappointing. A big kick in the pants that just declined as the rev's went higher, then came back a bit when you shifted, only to decline again. Frustrating. I bet you'd try to shift as early as possible.

[Vulcan Grey]

Originally Posted by DWebb

yea, pretty much like that.

(torque x rpm) / 5500 = Horse Power

not quite

[DWebb]

Originally Posted by Vulcan Grey

not quite

ahhhhhah! yea there ya go, thank you.

Forever appreciative of correction.

[aschen]

That is pretty much exactly how turbocharged race cars with rules mandated restrictors drive. The WRC cars have to have restrictors on them which limit overall flow rate (hp). However with antilag and mega boost at low rpm they make about 300 hp everywhere. 300 hp at 3000 rpm is like 500 ftlbs of torque! For road cars alot of cars with undersized turbos have their powerbands very low and un out of breath at higher rpm: see mazdaspeed3 and 335i. Notice that both of these cars are DI. I have read that there are challenges for these fuel systems to get enough flow for high HP so they intentionally shift the power band lower in the rpm range. Lower RPM = more time for injectors to get fuel in for DI cars. Also both of these cars accelerate better than theif hp figures sudgest.

[Viggen]

I do not feel there are issues with getting fuel in the upper RPM range, just look at the HP many cars make. To me it's that they are designed for the public thus normal day to day use. Most people do not take their cars close to max rpm's & spend their time in the middle of the powerband. So that's where car manufacturers tune their cars...... I think they also do this for reliability since turbo's cannot take developing full power from 2K to 7K redline since there would be to much heat in the small turbo's mfg's use.

I recently upgraded the ECU in my car & it moved the tq & hp towards the top so now I rev it to redline to get full power. I do not have the tq spike down low that I did have but there is still plenty, I am suppose to gain 40-50hp & 50-60ft lb of torque.

[JLSELISE]

Originally Posted by DWebb

Electric motors have a constant torque regardless of RPM. ...

Hardly--peak torque is "reached" at 0 rpm (i.e., stall)--torque then decreases as rpm increases. For example, see:
Electric motor basics

[DWebb]

Originally Posted by JLSELISE

Hardly--peak torque is "reached" at 0 rpm (i.e., stall)--torque then decreases as rpm increases. For example, see:
Electric motor basics

Thank You for the link I will study it closely.
It never ceases to amaze me how many times my sources are wrong.
It continually amazes me how much better informed I am with your corrections.

Thanks Again
Darrell

[marcinr]

Originally Posted by DWebb

Electric motors have a constant torque regardless of RPM. This would look more like a ramp, HorsePower wise. Kinda like a rotory engine, (greater rpm's = greater torque).

That's true under certain circumstances, but not in an electric car like the Tesla. The motor can only handle so much amperage before the windings melt, so the controller limits current so that this doesn't happen. It means you have a very flat torque curve until you reach the maximum discharge rate of the battery pack. Once you've reached the maximum wattage of the pack, the controller has to back off on the torque to stay under this maximum, so your torque drops off.

Tesla posted a torque curve at this link.