Why the low torque?

[Ubersuber]

The torque isn't low, it is high. 75 lb ft per litre is very good torque.

100 bhp per litre is also good.

Do the math and find engines more powerful, Porsche Cayman isn't. For example.

[Tromatic]

Originally Posted by Target70

with the danger of going wildly off topic, I'll say that i bought this car with the intention to modify it for more power, and I do not feel like I bought the wrong car. It was either put a turbo kit on my 240, then go about replacing the open diff/axles, the 15" 4 lug spendles/wheels/rotors brakes, the cooling system, fuel pump.. etc, etc.. and end up with a dented, faded, rattley, worn out 2500lb 350hp car with no ac, and a busted rear defroster. Or I could finally break down and by a new similar platform/weight car and spend the same or less money modding it, and have a higher performance, cleaner, more reliable car, I can enjoy for the next 20 years.(if I live that long)

You had the right approach from the start. I don't think anyone would complain about it. It's the endless complaints about the near-perfection awesome little stock car that are all tarded.

[pushrod]

Emphasis mine:

Originally Posted by Target70

I think OP is curious not why it is weak overall, but ratio of tq to hp is so low, at least that was my inital thought. my ka24de 240sx has as much or more torque than hp, which is why I liked it over the sr20, with the lower torque higher hp. I take his question to mean: why aren't they more even 180hp/180tq. I could be pulling this out of my ass, but I believe it is because this block has a square bore(same bore to stroke).
Displacement counts for power, but the design also determines what type of power. With an 86mm bore and 86mm stroke It makes for a balanced bottom end which is good for high revs. But for good low end torque, you need more leverage. To maintain the same size engine, if the stroke goes up, the piston size has to go down. If the stroke was longer, that would mean that the rods would have to be longer and or the crank lobes would have to be pushed out away from the center line. This would throw the balance out at higher rpm's but would provide a longer lever. With more leverage you get more torque, but less balanced, so it will spin slower top end, thus lower hp. Also increasing stroke would mean needing more crank case room, and taller cylinders, which would mean a wider engine. We already have to jack up the engine to change the spark plugs, so I do't know how much wider they could make it. I wouldn't mind sacraficing a little higher rpm's for more bottom end umph, because I DD, and almost never get over 5k rpm's. That's my assessment anyway.

1,2) There isn't really such a thing as "more torque than power", or any other comparison between the two, really. The crankshaft has power, in the form of torque about a rotating shaft. More torque for a given RPM, more power. More revs for a given RPM, more power. Torque is one of the components of power, do you can't compare them like that.

3) You might be shocked at how small the effects of bore to stroke ratio really are. Manufacturers have converged on roughly square bore:stroke ratios probably because a square cylinder has the highest volume to surface area ratio, which makes the engine block lighter. It also happens to give a good valve area. Speaking of valve area, if you think of a 2-valve V8, most of them have very big bores, so that the two valves that are in each cylinder can be nice and fat. Check out the bore and stroke of various engines like Chevy 350, etc. Then look at the Honda F22C1.

4) The stroke is only half of the equation for the piston putting torque on the crank. The stroke is the leverage, and the piston area (from the bore), with the cylinder pressure acting on it, is the force. The way the math works, any 500cc cylinder will make the same torque with the same cylinder pressure. There are secondary differences: friction, etc, but theoretically inches are inches, regardless of bore and stroke.

[vividracing]

As others have said before me, this 2.0 engine delivers a pretty good amount of torque for its displacement and other driving characteristics (fuel efficiency, reliability, responce, etc)

[reni]

Originally Posted by raven1231

To answer this question we must first know what a babby is.

They need to do way instain mother> who kill thier babbys. becuse these babby cant frigth back? it was on the news this mroing a mother in ar who had kill her three kids. they are taking the three babby back to new york too lady to rest my pary are with the father who lost his children ; i am truley sorry for your lots

[Tromatic]

Originally Posted by reni

They need to do way instain mother> who kill thier babbys. becuse these babby cant frigth back? it was on the news this mroing a mother in ar who had kill her three kids. they are taking the three babby back to new york too lady to rest my pary are with the father who lost his children ; i am truley sorry for your lots

Robots have a ways to go.

[raven1231]

Originally Posted by reni

They need to do way instain mother> who kill thier babbys. becuse these babby cant frigth back? it was on the news this mroing a mother in ar who had kill her three kids. they are taking the three babby back to new york too lady to rest my pary are with the father who lost his children ; i am truley sorry for your lots

Oh I see! Makes perfect sense now

[billwot]

Originally Posted by stonenewt

What'll make more power a 2l turbo engine at 1 bar boost or a 3l turbo engine at 1 bar boost?

What will make more power a 2L NA engine, or a 2L turbo engine at 1 bar boost?

[Marco_86]

Just trade it in for a stang bruh.

[ftc~brz]

When people would ask if it was fast I would just reply with it's fun.

There's nothing wrong with it n/a. If people complain about it being slow I just assume they haven't ventured into the powerband.

I didn't boost out of boredom. I wanted to build a car out further than I had in the past. I'm old enough to appreciate it n/a as well as the way I have it now. I've learned a lot from this car and the friends I've made because of it.

[Target70]

Originally Posted by pushrod

Emphasis mine:

1,2) There isn't really such a thing as "more torque than power", or any other comparison between the two, really. The crankshaft has power, in the form of torque about a rotating shaft. More torque for a given RPM, more power. More revs for a given RPM, more power. Torque is one of the components of power, do you can't compare them like that.

3) You might be shocked at how small the effects of bore to stroke ratio really are. Manufacturers have converged on roughly square bore:stroke ratios probably because a square cylinder has the highest volume to surface area ratio, which makes the engine block lighter. It also happens to give a good valve area. Speaking of valve area, if you think of a 2-valve V8, most of them have very big bores, so that the two valves that are in each cylinder can be nice and fat. Check out the bore and stroke of various engines like Chevy 350, etc. Then look at the Honda F22C1.

4) The stroke is only half of the equation for the piston putting torque on the crank. The stroke is the leverage, and the piston area (from the bore), with the cylinder pressure acting on it, is the force. The way the math works, any 500cc cylinder will make the same torque with the same cylinder pressure. There are secondary differences: friction, etc, but theoretically inches are inches, regardless of bore and stroke.

I'll start off by reaffirming my "out of my ass" statement, I'm not an engineer, or even a seasond engine builder, I'm just going by my own logical reasoning.
If there is no difference, why are they different lines on a dyno? True they are just different measurable characteristics of a single force, but they dramatically change the charastics of performance. I think it is fine to compare them, because we have a base value to compare with. (that being the current performance of the stock engine) You can call it widening the powerband, but my point was that there is a difference. And that engine design, not just displacement, plays a part of it.
I'll have to take your word on 3, and 4. But I have heard that more, smaller valves flow better than large single ones eg: 2 vs 4 valve head design. Inches may be inches, but I also included crank design into it. By applying the same force to a crank journal that is farther away from the center of that crank than one that is closer, will produce higher torque. Moving the journal away from the center will increase the stroke due to the increase in distance between the lobe in the top and bottom position. So while any 500cc cylinder will make the same torque with the same cylinder pressure, by changing the stroke, and reducing the piston size (to keep the same 500cc's) you have greater leverage on the crank.

[pushrod]

Originally Posted by Target70

If there is no difference, why are they different lines on a dyno? True they are just different measurable characteristics of a single force, but they dramatically change the charastics of performance.

There's two lines on a dyno because at a given RPM, the engine is making some amount of torque. The torque and the RPM are your work and time components, which is the definition of power (power = work / time). We get the torque from the machine, and we know the RPM, so we can find the power. We plot them both on the dyno sheet because we can.

You always want a nice and fat torque curve because torque makes power, but we can only compare torque between cars because almost all gas engines have the same useful RPM range: 1000RPM to 5500-7500RPM. If someone showed up with an engine that made useful power from 7000-14,000RPM with not much torque, it would still be a great engine, besides being noisy, expensive to build, unreliable, and difficult to start.

Rockets have no torque, but lots of power.

Originally Posted by Target70

So while any 500cc cylinder will make the same torque with the same cylinder pressure, by changing the stroke, and reducing the piston size (to keep the same 500cc's) you have greater leverage on the crank.

You're right that increasing the stroke will increase the torque, but if you think about it, it's because more stroke means more inches. So, the 500cc cylinder you started with and then stroked is now >500cc, which means the torque will go up accordingly. If you stroke from 500cc to 550cc, and I bore to 550cc instead, we are going to have the same torque, on paper.

[cycleboy]

Funny, I've never had the impression that it doesn't have enough power or torque. The torque dip is annoying, and solved with easy mods.

It's very easy to feel fast in this car, 1) keep the revs up, 2) go around a corner at twice what the other cars are doing.

It's not a drag racer. It's not stomp your foot down and it does the rest.

I like what someone else said, it's a driver's car. You have to interact with it, keep it in the right rev range, turn and brake well, and so on. It's very fun in that regard as you aren't just jamming down the pedal and going to sleep.

[Target70]

Originally Posted by pushrod

You're right that increasing the stroke will increase the torque, but if you think about it, it's because more stroke means more inches. So, the 500cc cylinder you started with and then stroked is now >500cc, which means the torque will go up accordingly. If you stroke from 500cc to 550cc, and I bore to 550cc instead, we are going to have the same torque, on paper.

call me slow, but I would have to see the math on that for it to make sense to me. It sounds like you are ignoring the leverage point(distance) on the crank. If you bored it out another 50cc's, and kept the same stroke, the WORK the piston would do would be the same as increasing the stroke 50cc's and keeping the bore the same, that is true. Work is force times distance in a strait line, so the increased distance and increased force are interchangeable. But torque is force times distance in a rotation. The work of the piston, creates the torque on, and of the crank, but the work(force) of the piston is only half the equation, for torque the other half (distance) is just as important, and is also a component of the stroke of the piston, the bore is not. The bore only affects the work of the piston.
so if the stroke is 2, and the bore is 2, and the crank journal is 2 from the center, and we increase the bore by 1, we get:
piston work: 2(stroke) X 3(bore) = 6
torque = force(piston work)6 X (distance) 2 = 12

however if we increase the stroke by 1 you have to increase the distance of the lobe or leverage point away from the center of the shaft by the same amount. Since we increased the stroke by 1, that will be 0.5. So when the lobe is at the extreme top and bottom of the rotation around the the center of the shaft, the .5 travel up adds to the .5 travel down to equal 1.
piston work: 3(stroke) X 2(bore) = 6
torque = force(piston work)6 X (distance) 2.5 = 15