Based on your reading of posts here at maxima.org and your own personal opinion / findings, please answer this question honestly

 

I don't know about manuals, but for automatics the PopChrager is a rather poor choice if you are looking for off the line performance. The low end is recreased by what feels like a good 20%. It does make up for it in the upper range, but since the VQ is torquey everwhere (except from about 2100 to 2500), it is of little consequence.

 

so is it normal that my car feels slow in the 2100 - 2600rpm range or is it just you and me? is there a torque dip in there or what?? shifting at 2000rpm vs 2600 feels the same to me

 

Not really slow, but the acceleration takes a little pause in that range, then is very noticeably increased after that.

 

i think it gives more HP, especially the CAI but it alters the torque curve, giving it more peak torque but less total torque. the curve isn't quite as flat but the peak of it is a few ft/lbs higher. teaming the intake with a udp, esp. on an auto is a good idea. mine is already ordered, (udp)

 

I really don't know what everyone is talking about regarding this. My Stillen intake gives my car considerably more torque, and much better high end HP.

 

You missed the fact that everyone talking about losing low end torque has an automatic. I stated this in the very first sentence of my post. Manuals can overcome the torque loss by reving past the valley when taking off, but there is no way for a automatic to do this.

 

HP is a mathematical function of torque. If HP goes up, torque at that same RPM has gone up. There's no personal opinion about it.

 

I should have worded my question just a little better.. I was going for the fact that the pop charger will shift the torque curve so that you have less on the bottom end but more on the top which is why for city driving people will notice more power with a stock intake, but for highway driving at higher rpms there is a very distinct gain from the pop charger

 

I knew what you meant, I was just being an a$$. Anyway, you are generally correct.

 

get a high stall torque converter, that's next for me after the shift kit and UDP. maybe level 10 will cut me a deal on the shift kit and tq converter.

 

The point is that there is no way of getting around the lack of low end torque in an automatic. The high stall would work at the track, but I figure it would hamper performance on the street and cause worse gas mileage.

 

I'll let your know how much the UDP helps. hopefully 2 tenths on the 60'.

 

or different functions. Why does the 4th gen have 190 hp and 205 ft-lbs torque, while the new RS-X 200 hp and only 140 ft-lbs torque?

Even engineers have personal opinions (ones worth their salt) on how they want to tweak things and what results they are seeking to achieve. Plenty of functional issues involve trade-offs, and I think that's what the poster was trying to poll. Maybe you don't mean to come across the way you do, then again maybe you do.

 

The function is dependent on where maximum HP and torque are produced.

 

It also has to do with gear ratios. If you've got 190 horses running to a larger gear, you get more torque than someone with a smaller gear. BUT, what the first guy said holds true too - in the same car HP and torque are directly proportional.

Just my .02 .

 

the RS-X Type-S has 140lb-ft of torque because it's still a dinky little 2 liter 4-banger. It's a well known fact that larger engines will always have more torque (this is not, of course, taking turbocharging into account.)

 

None of the bolt on Maxima mods "shift" the torque or HP curves at all. They just raise it in some parts of the curve (especially high RPM's) any loss you feel off the line and at low RPMs is a figment of your imagination. A high flow intake doesn't affect "low end torque" at all. If you don't believe me, have you every looked at a dyno chart of tha stock maxima and then of an intake modded maxima? The curves are almost identical until you get near 3000 rpms becuase the engine isn't straining for air below 3000. With my current mods I can engage 1st gear at about five miles per hour with the clutch all the way out, and then floor the car...and it will break traction immediately and continue to do so until it redlines (it could NOT do this when it was stock). Now if that's not an increase in low end torque, I don't know what is.

 

that if HP goes up, then torque goes up, and there's no personal opinion about it I believe. After the years of hp measurements at the wheels on this bbs, how could anyone believe that? Virtually all motors have torque peaking at lower rpms than hp. Once you pass that peak for torque, torque is not increasing it's decreasing (kinda what a peak is eh?), yet hp still has quite a few revs to go before it peaks. So hp is increasing and torque is decreasing after you pass the peak rpm for torque. I simply can't understand how anyone could think torque and hp are directly proportional from 0 to 6500 rpm after all the dyno charts that people have posted, especially an engineer. Bizarre.

 

They arent directly proportional. That's my point. If you read my post, I said if HP goes up then torque has increased at that RPM. The formula is:


HP = (Torque X rpm) / 5252



If you have 100lb-ft of torque at 3000rpm, then you have 57HP. But if you have 80lb-ft at 4000rpm, then you have 61HP.

There is an example of torque decreasing with RPM and HP increasing. They ARE NOT A DIRECT PROPORTION, but they are forever related. Torque is a measure of force, HP is a measure of power (work done over time). Force(torque) over a distance is work, rate of work per time is power(HP).

Yes I'm an engineer. I know that math makes the world go around and being able to work with differential equations is a basic life skill.

Math always wins.








I will bust out my HP-48 calculator and blast if I have to.

 

...which explains why the RSX-S engine which is 2.0L has only 140 lb-ft of torque (or something around there)

So torque is more or less limited by displacement, but engines that small make 200 HP by being able to maintain what little torque they have at extremely high RPM's.

Horsepower = (Torque x RPM) / 5252.

I forget where the RSX-S makes it's horsepower peak, but it's like 7600rpm or so, so with 200HP @ 7600rpm the RSX-S engine is still putting out 138 lb-ft of torque.

Small engines that come from Honda/Acura are typically like that, and they're able to maintain that torque at high rpm's via high-performance intake systems and variable valve timing on both the intake and exhaust valves.

Larger displacement engines like the VQ30 or the J30A1 in my Accord V6 make their power by just having more torque to begin with, since they're larger-displacement, and by spinning a bit slower. If the J30A1 engine with 195 lb-ft of torque could maintain that torque all the way up to 7600rpm then it would have 282HP!!! But alas, the engine would spin itself to death at those speeds since it's not built for high-RPM work, and the stock intake manifold is VERY restrictive and becomes a severe bottleneck after our horsepower peak of 5700rpm.

The Honda S2000's 2.0L engine is similar to the RSX-S engine. It only makes about 153 lb-ft of torque, but it can maintain that all the way up to 8300rpm, so if you go through the equation that's about 240HP.

The problem with small-displacement engines is that they still have no low-end torque and will get dusted by larger displacement engines on the low-end.

BTW, I'm an engineer too

 

With the intake in, the car feels like it has more kick pass 3k rpm (yes I have an auto). Below that it seems like you have to push on the gas more to get it going.

Think of it this way. If you bought a brand new 4th gen with a JWT popcharger as the stock air filter and drove the car for about a year, then I sell you an air box and said it'll increase torque and HP. Guess what? You'll probably believe me. It'd be quieter and smoother, and you'll be like wow!

So my question is: If you don't race, wouldn't a stock airbox be better?

 

At least on my Accord V6, I didn't notice any low-end torque losses with my AEM CAI AFTER resetting the ECU so that it would redo the fuel-mapping and learn the new airflow patterns.

Even if a stock airbox was a bit better at the low-end, you're only going to be in the low-rpm range for your launch. After that it's all going to be top-end work where an intake will really help you, and enough so that it'll make up for any low-end torque loss that you experience.

If you want more low-end torque, then try some Denso Iridium spark plugs. The Accord V6 is already pretty weak at the low end, but these things gave very nice gains all throughout the rpm range, including low-rpm from idle up.

Even if I did lose a little low-end torque with my CAI, the plugs more than made up for it.

 

I think that most automatic drivers would be happier if they kept their stock airbox in if they only do 'regular' driving. The low end delay is undeniably there with the aftermarket.

 

My Aunt at Bell Labs is a lover of math too. I'm not sure if she ever tried to invalidate someone's question or their personal opinion, but then again she only uses a 15C. Everything is subject to interpretation and evolution when it comes to ideas and questions. Many people could have designed or envisioned the Brooklyn Bridge. It took a couple of Roeblings and a wife to see it completed, and a lot of politics and politicians. As we all know politics is full of opinions. Tunnel vision is the worst.