Well after spending most of my morning reading and rereading articles on engine hp and torque, I believe that having more back pressure=more torque. I also believe that opening up exhaust and other things without maintaining back pressure hurts your torque. The question is how does one maintain enough back pressure(without turboeing) while installing a catback? Is it by taking in more air through either a cai or sri? Or does that also create a loss in back pressure?

I guess I want to know how big of an exhaust is too big for our 4g94 engines? Is 2.5" the max without losing back pressure? Does an intake cause a loss or gain in back pressure?

I am asking all this because I currently have two 05 Lancers in my posession, until later today when I finalize the trade, and have noticed that my bone stock 05 OZ takes off what seems to me and others way faster than my modded 05 ES (see signature for mods). If that is the case then my understanding about all this back pressure stuff tells me that I have lost back pressure somewhere on my 05 ES enough to lose low end torque. I have also noticed that the 05 ES has more top end power on the highway.

Now this is my thought on all this, if my above obversations are correct. Unless you do some sort of racing, whether it be on the track for quarter mile runs, or other, it is pretty much useless to mod the car as I have unless you want cool sounds and looks because if you are like me and just street race Honda's etc. from red lights in town, you are losing low end torque which is what matters most.

 

35 views and no comments, so IMO my thoughts are correct.

 

i know, but i'm not going to tell you, because i'm an ***.













/doesn't know

 

You are correct.

 

^^^
Then which mods will cause the LEAST amount of loss in back pressure? I thought that if the catback causes a loss in back pressure, then the cai was supposed to help compensate for this by bringing in more air than stock filters do My butt dyno doesn't seem to feel it that way.

 

Just read the other night that 2.25" should the largest piping (downpipe to 2nd cat) to be used. Just what I read, don't really have experience (yet) with a full exhaust set-up.

 

Is this what you were reading?
https://www.evolutionm.net/forums/sh...ad.php?t=65648

If not, it's what you should read next.

 

it all depends on where you want to make power. backpressure makes more torque, but also restricts air flow at higher rpms. restricted airflow means loss of power. it all depends on where you want your power band to be at. a good flowing exhaust will make power a bit higher in the power band, which is usally good for cars with small displacements (and have the ability to rev).

the real trick is to find a good compromise! thats the whole secret to building cars! find the happy medium

 

Yes, already read it, twice. What is your opinion on what I should do Hobie? I don't really want to lose the back pressure, but on the other hand want it opened a little if possible. In other words I want to keep my low end torque. Sort of sucks to take my two rides and run them side by side and the unmodded one beats the modded one from a take off in what is about an eighth of a mile here where I live with two equally skilled drivers driving.

 

I wouldn't sweat it that much. Figure out what you want to do to your car and pick an exhaust accordingly.

 

long tube header and a nice catback will be a great setup. long tube header maintain backpressure but still free flowing. i believe rpw makes them and i hear good things about it. short tube header loses back pressure but its more freeflowing.

 

Well I don't want to lose low end torque period, so I now have no idea what to do.

 

if you want an exhaust upgrade and have a good set up- it is said the if your piping is bigger on the exhaust side thern gets smaller as it goes towards the muffler, then you should see better gains thatjust going 2.5 all they was, which i belive is a little big, for the kinda of gains that you want.

get a header(and downpipe if you want) and have you exhaust piping be like 2" so your set-up would really look like a >, that should help you maintain the backpressure,

my 02.:
i didnt lose enough noticable TQ when i went witht he header DP (kamikaze), but i did gain a lot of High, go with a header, and youw ill be fine

RPW: does have a really nice header& DP combo, but it expensive, and uncoated
Kamikaze: i liked it, but i have boost plans and cant really use that header with the boost that i wanna go with
RRM: Good quality header, no DP, but you can get one from bushur if you really want a DP, which in the end will cost the Same as the RPW one(unless you find a used header for sale) but is already ceremic coated

for more info: Please read the header thread, a lot of good info in there

 

you need to go back even more....

https://www.evolutionm.net/forums/sh...hlight=exhaust

To increase torque, you need intake, TB, IM, headwork, timing adjusts, different piston/rod combinations. Opening your exhaust will (maybe) give you HP at the very top of the RPM band, but will hurt your torque. Keeping the exhaust restrictive will hurt HP, but help torque, generally.

 

To get the best of both.... get a 2.25 crushed bent exhaust(like you'd get at a midas) its restrictive enough but lets it free flow at the same time depending on your acceleration and speed.