I keep reading about Nissan's mufflers that has this chamber/valve/door thingie that opens at higher RPMs to allow more exhaust gases to pass through, increasing HP in the top end and improving torque on the low end (when the chamber/valve/door thingie is closed

So, do you think something like that would work on our car? Has anyone ever tried it?

 

On paper it is great... but people have replaced them on 4th gen maximas(95-99) and probably gained little to no hp. I think potentially it would be great if that was the bottleneck in the exhaust system. But in a Maixma, the y-pipe is the biggest power killer. A y-pipe plus intake replacements yeilds 20 dyno'd wheel hp...

-Shing

 

[QUOTE]Originally posted by shingles
[B]On paper it is great... but people have replaced them on 4th gen maximas(95-99) and probably gained little to no hp.

 

Hi Mingster,

I've considered a valve on the pipe going to the left muffler. I spoke with an exhaust guy about it and he didn't think it would do much good, but I'm not prepared to leave it at that.

I guess the thing to do is get some dyno time and do a run with a rag stuffed in the left tip and then one without.

What you're hoping for is higher power at lower revs and lower power at higher revs. Overlay the graphs and the crossover point is the valve open point.

The product would simply be a short piece of pipe with a valve, solenoid, some wire, and a tap into the tacho.

 

People have done it... and the most I've read are things like "it feels faster at xxxx rpm". I don't think I've ever actually seen any proof of it. I have no doubt that the 5th gen's flow better... but atleast on the 4th gen max, I don't think it would help.

As for the S2K... it would appear that the exhaust isn't that restrictive... is that true? If so, I donno if it'd help that much.

You know, I never realized that you own a max too.

maxima.org is getting pretty big, and rowdy too.

-Shing

[QUOTE]Originally posted by mingster
[B][QUOTE]Originally posted by shingles
[b]On paper it is great... but people have replaced them on 4th gen maximas(95-99) and probably gained little to no hp.

 

Why not just add a butterfly valve to the one of the pipes right after the split? Have the valve tensioned by a clock spring that opens proportionately to the exhaust pressure. I'm guessing that this would maintain back pressure at lower RPMs and open wide to reduce as much back pressure at high RPMs. This also minimizes how much "hardware" is needed to "wire" and "engineer" this onto the exhaust tubing.

I'm not sure if this is doable, but was just an "under-educated" idea after seeing a throttle body at work.

 

They all sound good, and I just might try it with this setup:

1. custom single exhaust piping
2. muffler: Nissan Maxima or the new Sentra SE-R Spec V (both uses this butterfly thing) muffler.

Dyno.

Crazy, I know. I'll get flamed, I know. People will laugh, I know. But it'll be fun, I KNOW!

 

Not so crazy, actually. The high-end modern sportbikes like the Yamaha R1 and Suzuki GSX-R1000 use just such exhaust valves.

From Suzuki's website: "The GSX-R1000 also incorporates some all-new designs. It has an all-new digitally controlled Suzuki Exhaust Tuning system, which uses a butterfly valve to change the volume of the exhaust system. It actually tunes the exhaust pipe to suit running conditions and improve torque across the powerband."

From Yamaha's: "Yamaha's patented Exhaust Ultimate Powervalve (EXUP) monitors engine rpm and adjusts exhaust flow for maximum acceleration."

There's additional info to be found on the web, if you're interested.

Now, these two bikes are pretty much the creme de la creme of the sportbike world. In that world of oneupmanship, I'd be totally suprised if either maker would put any sort of gimmick on the bike that didn't have a positive effect. On the other hand, the F20C uses very little motorcyle techniques to get its power - it has car tech taken to an extreme. So it might not benefit from such a system as much as the bikes do. However, if somebody has the time, expertise, money and dyno access, I think it'd definitely be a worthwhile investigation.

 

i'm hoping that i'll get the time and money soon - after finals (yuck!).

hmm, maybe i should bring along somebody to help with the installation...

 

Yeah, it sure seems like a lot of trouble and expense for what appears to be small benefit.. but if you find it entertaining