gavine

I know Neuronbob is always asking for more low-end torque and I remember hearing many years ago that exhaust backpressure can increase low-end torque. Then I put 2 and 2 together, realizing that Bob has a modified exhaust system which gives more total horsepower and more torque at higher RPM's, but all at the expense of low-end torque and understand why he might be suffering in the low RPM range.

Here's some good reading on the subject ->

http://www.autolounge.net/tech/exhaust.html

http://www.flowmastermufflers.com/backpressure.html

It seems the experts agree that a little backpressure is good for driveability and low-end torque. Personally, I'd rather have low end torque than high RPM power because I typically don't drive in those high RPM ranges.

Does anyone know if there are baffles which are compatible with the stock RL exhaust that can increase backpressure a little and give better low-end torque?

neuronbob

Great post! The articles are interesting, too.

Unfortunately, the torque curve in my post-mod dyno was screwed up and we never figured out why, but taken at face value it looks like torque dropped. I'm not sure I believe it because of the other issues surrounding that dyno. I feel that the only way to properly figure it out is to remove the propeller shaft to make the RL FWD for the dyno--takes SH-AWD out of the equation.

Upper rpm power was clearly increased, but low-end torque doesn't feel much different to me.

In any case, my modding solution has made itself obvious....I'm looking for a cheap sports car..... ...probably an S2K or Corvette if I can find the right deal.

LegendaryRL

Can never get enough power. Only if there was a way to make the car RWD. Good luck with finding another car. Those S2K is way too small. The 2000 models are a little bit bigger but I couldn't even move my legs in 2006+ models.

geronimomoe

How about a low mileage Turbo Toyota Supra from the 90s or a previous gen M3 with the sport package (19" rims)?

neuronbob

Pretty much decided on an S2K. Those cars are freaking amazing, handling is telepathic and in that car I don't care about low-end torque because you can rev it to 9k rpm (at least in AP1s). I fit perfectly into the seats, so not an issue for me. This will keep me from a) modding my RL any further and b) from trading my RL for a CTS-V--I'll be able to hang on to the RL until the FMC.

geronimomoe

HA! So you're just trying to find a reason to hold off until the RL FMC!!!!

TampaRLX-SH

I am eyeing a S2000 stablemate for my RL also. My intentions to take a barely used RSX last weekend were aborted.

I need to get some drive time in one before writing the check. I am 6'3'' 242# and the S2000 may need a bigger zipper.

That would definately allow me to keep the RL long(er) term until post fugly comes into fashion with the FMC RL.

JPSMAN

From a RL and S2000 owner, its a great combination. There are certainly good deals out there for a used S2K; just be patient to find something that wasn't abused. Its widely known the S model is in its twilight years, but there is much fun to be had with a classic creation from Honda.

Just be mindful that S2K will get loose on turns if pushed (I think MY06 added VSC, prior to that the S will oversteer, requiring driver intervention). Its a great combination either way - just keep the S in the garage in foul weather.

JPSMAN

I should add too, since this thread is about low end torque, there isn't much from the S2k. Its a track car in my opinion, so its more about high revs out of turns, excellent handling, braking, etc.....

Don't expect to blow anyone off the line....but it gets fun in the twisties....

fstshrk

Lotus Elise.

I had one for about a year. That is a true sports car. But ingress/egress and lack of luggage space was hard.

neuronbob

I'm sorry I brought up the S2K, but I will say I just made a deposit on a nearly mint 2002 with only 11k miles today. .

Back on topic: can anyone else comment on the OP's questions? I know there is someone interested in low-end torque in the RL other than me and gavine.

geronimomoe

Hey now! Can you say 9K RPM, here you come???????

TampaRLX-SH

Holy Crap!

I just got home from puting a deposit on a 2004 S2000 White over Tan with 15k miles today!

I think we need a new thread for RL Stablemates, my brother from a different mother.



Oh...torque, yeah ummmm....torque.

geronimomoe

Did you call each other or what????

Congrats to both of you on your new toys...

Jeez, I'm envious... Disposable income!

neuronbob

Copycat! thhhhhhpt!

Oh hell, we might as well rename the thread....."Why we should buy sports cars so we don't have to worry about torque in the RL". Sorry, gavine!

TampaRLX-SH

Oh Yeah!? Well I traded my TL for the RL before you did!

Just because your birthday is a few days before mine, and you are younger...

What a baby.

oh yeah...torque....yeah ummm...torque.

aznbo187

iTrader: (1)

Sometimes it's just easier to buy a new car instead of looking for performance parts...especially for the RL! hah

neuronbob

Oh yeah? Well, 9>>>>>>>>>8!

TampaRLX-SH

See, I even got a BETTER intererst rate than you!

B+O

I didn't read all of the responses. i stopped at Neuron Bob's plea for elaboration so please forgive me if it's already been answered.

As one of my mentors way back when told me "if it was really back pressure that gave you torque, stick a banana in your tailpipe and go pull stumps"


it's not backpressure that increases your torque. It's actually exhaust flow velocity.


At low RPM hot exhaust gasses have a greater propensity to cool off in the exhaust pipe before exiting. Increasing the area (i.e. diameter) of the exhaust increases surface area (more surface area to cool) also the flow from the engine is less and the volume of gas isn't as great farther into the exhaust stream.

this relative stagnation in the exhaust stream caused by large diameter piping causes the slow down of exhaust gases leaving the combustion chamber.

The reason these large diameter pipes work in the upper ranges is because they match the engines flow rates at higher RPM. but at lower RPM it's a drag.

I could go into sonic pulses from the exhaust valve and calculating runner lengths, but just know the larger the diameter the piping, the more lowend you lose. It's controlling volume and flow versus back pressure.

lumpulus

No need to be sorry, I would have had one from day 1 if I wasn't 6'8".

Miata my a$$.

On topic...I think the RL has excellent torque off the line until you hit 2nd gear,but that's the tranny.

dwboston

Between you and Tampa, we might as well rename it the "Mid-life crisis 2008" thread.

plastikman

^ +1 or the old geezers with new toys thread

neuronbob

I was 90% certain of a C5 Corvette until the guys in Car Talk turned me on to the S2K. After the first test drive running at 8k rpm between shifts, I KNEW that was the weekend warrior for me. Not to mention that I get to remain a "Honda fanboi". Already looking for a set of AP2 17" wheels and new RE050s to complete the car.

Remember Plastikman, you will be "old" before you know it. When I was 33 and walking uphill to the hospital, backward, barefoot, in the snow........

B+O, excellent explanation, thank you.

TampaRLX-SH

I was walking uphill to work, BOTH ways, backward, barefoot, in the snow WITH broken glass under the snow.....

Gotta run.....Early Bird Special at the Golden Corral.

db22

So everybody here bought a VTEC and then complains about torque? This is a smart group so I can't beleive that the lack of torque came as a surprise.
I must say, I agree with the 2nd gear ratio issue. If they re-engineered the ratios then the torque issue would be less of a discussion.
BTW - any of you in Canada ever try the TVR for a weekend drive. It's just like the S2K but with torque instead of RPM's?

gavine

I thought the whole idea of VTEC was to increase low-end torque while still allowing power at high revs by changing the valve timing based on RPM. Without VTEC, the engine would have to sacrifice either low-end torque or high-end power.

The reason I started this thread was to bring to Bob's attention that his exhaust "upgrade" probably made his low-end torque worse than stock but increased his high end power which is less noticeable thus his constant request for more low-end torque.

neuronbob

And you made a great point, gavine. I'm sorry the thread got so hijacked.

The lesson I learned from my experience/experiment is that there is no replacement for displacement to gain low-end torque. Further, the gearing can help in some ways.

Hey, the exhaust on my car sounds great, at least!

The current RL drivetrain is basically for those who like to reach into the VTEC range to get their power--e.g. long-term Hondaphiles like myself. This experience is clearly not for everyone (OK, not for most people given RL sales. ). I'm not actually bothered by the relative lack of low-end torque compared to the competition, I was curious as to what could be done other than displacement to gain torque.