OK, there are some of us modding our 2G RLs. Don't laugh, the guys who've done it are probably getting that little bit more power the RL needs. I'm asking in the TL section because there are more people here who are knowledgeable about these mods.

So to keep it short, here is my question.

On the RL, the available HP mods are modded AEM intake (thanks Touge!), cat-back exhausts (Mugen and 5zigen), and a highly modded underdrive pulley. No headers as yet, which brings me to the question.

The Mugen and 5zigen exhausts are freer flowing exhausts than the stock. Alone, can the exhaust add significant (say, 5-10) HP? I understand that in order to maximize the HP gain, there has to be more air into the system (e.g. intake) and more air out of the engine (e.g. headers). How can a cat-back exhaust help performance when the headers still act as a bottleneck for exhaust?

Thanks for your learned answers.

I am planning to install the 5zigen exhaust and do pre- and post-mod dynos so I can learn more about all this.

 

Have had time to do a little searching. I came up with Bolt-Ons 101. This answers my first question.

However, my second question still stands--how can a cat-back exhaust increase power when the headers are still a bottleneck in the exhaust system? Just curious, and can't find an answer to that question in my searching thus far.

Thanks!

 

alot of the mufflers on cars are very restrictive and increase back pressure with the bottleneck of the headers. If the mufflers are changed out, the tone and amount of emmisions escaping will change, resulting in either gains or decreases. I am a total noob when in thechinal stuff, but this is what i can come up with

 

Just a heads up. The crank pulley for the 04+ TL also fits the RL. No need to modify the stock setup.

 

Didn't know that. It's good to have other options.

 

neuronbob,

As you know, I have had some recent modding expereinces. From this expereince, I offer you some heartfelt advise.

Of all my mods, there is a common theme that SCREAMS out loud and clear.

Reduce the rotational weight !!!!

It is DAMN AMAZING !!!! I was surprise to learn this too. However, I learned it firsthand - not from reading it on the internet. And, when an expereince SLAPS you in the face, you listen.

I feel SOOoo strong about this advice that I can say FORGET all other mods (except Nox or supercharger obvisouly). NO MOD CAN TOUCH what I am telling you.

BUY THE LIGHTWEIGHT PULLEY AND LIGHTWEIGHT STOCK DIAMETER RIMS. Highly recommend the same rims I got. They are inexpensive and the lightest that I have found. See page 10 of my "TL Diet" thread for info on the rims. On the pulley, it is not important if it is underdriven or stock diameter. It is the pulley's light weight that does the trick.

 

Sorry I missed this post. I am a bit uncomfortable with changing out the pulley for one that underdrives. However, changing out for a lighter one makes sense. Does this have long-term consequences on the engine?

 

Only if you love to rev it fast and full all the time, otherwise see below.

The underdrive ratio crank pulley is good as long as you are not running 600 watts or more stereo, is so use the light stock size

www.unorthodoxracing.com is the makers website and has all the tech details

 

Here is my standard response when this question is asked.

I had these initial fears too. But, here is what "sold me".

The Second generation TL guys have the identical engine as the Third gen TL (the J32 engine). And, these Second Gen TL guys have been running the UR pulley for many, many miles on their daily drivers for several years. No one, I repeat, NO ONE has EVER had a problem !!!! That fact sold me !!!!

 

UR has a stock size pulley. The underdrive is generally 10-20%, usually on the lower end. There have been some members that have tested the voltage before and after and haven't noticed much difference at all. The only concern there is if you have a large stereo system (over 600 watts RMS) then you would definitely want to go with the stock size pulley. But like I said you can run the stock size if you want. The underdrive pulley just will make about 1-2 hp more.

 

By lowering exhaust resistance you save some pumping energy and convert it to useful power. It also makes pressure at the end of exhausting cycle lower, which means less residual gases in the cylinder and more fresh air in the next cycle, what also increases power. To see how it works you can plug one of exhaust pipes and try your car. Of course this is exactly opposite of what you want, but it will give you a picture how exhaust resistance works.

Headers are generally overrated. Their role is quite complicated, but let me try. Pressure in the exhaust pipe is constantly pulsing related to engine RPM. Ideal case is to create resonance, so that lower pressure first sucks all exhaust gases from cylinder, then sucks some fresh mixture into exhaust pipe and at the end higher pressure push back that fresh mixture into cylinder just before the exhaust valve is closed. In order to do that exhaust pipe has to be exact length for certain RPM, camshaft profile, pipe diameter, gas temperature... And if you manage to do all that it works only in the narrow field of RPM. It is easy for racing engines. Header pipes length is adjusted to work around maximum power. To what RPM would you adjust pipes for daily used RL? To solve that dilemma for us Honda cast headers together with cylinder head on third generation TL's.

Underdrive pulley gives you as much power as it saves from alternator, aircondition, power steering and water pump. It is hard to save any from alternator because regulator is compensating for lower RPM. I would not really save on power steering and cooling, especially when I am racing somebody. It is way simpler to turn off your megawatt stereo and aircondition.

Lighter pulley is also overrated. It doesn't increase power. Smaller mass makes it only easier to be accelerated. Besides mass of rotating part, main factors of its acceleration are its diameter and RPM. Pulley has relatively small mass compared to all rotating masses and its diameter is not too big either, so gain with lighter pulley is minimal, if detectible.

 

mishar,

Quick question for you. Do you have or had a UR pulley on your car ?

 

http://www.bulletproofautomotive.com...lt.php?make=27

I thought this might be useful for you neuronbob.

 

And what do you think based on what I sad about it?

 

What do I think ? I think that nothing productive will come out of this dialog. You have your experiences, and I have mine - Which sure as hell differs from your experiences.

 

That is exactly what I think. At least we agreed about that.