Exhaust HELP!
 

ok, i am trying to get my parents to let me get the borla exhaust, but they want to know what in fuel economy, hp increase are compared to the cost of the different exhaust sytems. please help
-thanks

from my understanding you not going to get much of either out of just an exhaust. If your looking for a little fuel economy and a small amount of hp check out a cold air intake. If you want the best bang for your buck check out a rp supercat or a catless midpipe/race pipe. You'll get some decent hp and it should lean out the air/fuel a bit to increase mpg

:newbie: :op:

go do a search or u can listen to my answer... it'll do nothing. just change your exhaust note. work for your own money and buy ur own exhaust

The exhaust will add maybe a couple of hp, when I installed my Greddy exhaust I found the milage got slightly worse. I am assuming this is due to reduced back pressure. An intake will yield a few hp also but when i installed my racing beat REVi I noticed a couple more mpg than before.

Oh and dont worry alot of people are haters and will make comments about your parents buying an exhaust for you, just ignore them.

I don't have a 9-5 job but i still make my money through various business ventures and also through investments. But I'm 21 and my parents support me financially and I do pay for all the mods on my car. I dont think theres anything wrong with that as I'm still a student and do well and take care of my responsibilities. I personally don't see why its so horrible to ask your parents to buy you something on ocassion, I also dont see the need for such a derogatory tone with this guy...usually you learn by asking questions

agreed, but it won't do any of that, it will just be loud and annoy your parents

^i did see some gains from just the exhaust that i got from turboxs. Granted I have the revi,duct, and a cz(which was turned off during the stock cat+turboxs exhaust dyno). I have to check the dyno again so don't quote me on this number but i think the max gain of that exhaust was 8whp

Hey! Thats a plus! I am in my middle thirties, and I still get a kick out of annoying my parents! (Though I only see them like once a year though)

You could always lie like the manufactures do. K&N seem to make a mint out of that policy.

well I didn't see increased WOT power on his parents list of items for consideration ;) that's what I was referring to by "won't do any of that"

Understood.

BTW, I realize he is 21 and all, but I think it is cool that his parents show at least a minimal interest in moding his car. Perhaps his parents will go for an OBX header, and a RP supercat to go with the borla cat back ;) ! That at least has a minimal chance of double digit gains in WOT power...Maybe. Header is at my mail box, btw. Thx!!!!

Answering your original question, no particular exhaust has shown to give more or less hp or mpg than any other exhaust. If you're set on an exhaust, choose it based on sound.

Now if you're looking for a mod that will yield higher hp and better mpg, you should look into the REVi and RamAir set-up. A nice little bonus is a cool sucking sound that makes your car louder. ;)

wouldn't a high flow cat or midpipe give more gains in hp and torque as well as lean out the AF mixture?

Not sure about the leaning out of AF

A high-flow cat and/or midpipe would give a slight increase in hp, I'm not sure about the torque.

From what I understand, a high-flow cat won't necessarily lean out the AF mixture, but it will definitely allow more air to leave the engine, thus allowing more air in. More air in, more air through the rotors, more hp. Since the O2 sensor isn't effected with the high-flow cat, logic leads me to believe that the AF mixture is not effected.

The midpipe can lean out or richen the AF mixture, depending on whether or not your O2 sensor is working properly. If the O2 sensor is not working, it doesn't tell the car whether or not to give more air or more fuel properly, thus either running lean or rich, but not "right." Only tuning or a good sensor can fix this. The 8 runs rich stock.

Both the high-flow cat and the mid-pipe are separate components from the exhaust.

^yea i just figured a high flow like the rp would give you more hp then a exhaust while still sounding louder and deeper...and you could maybe save a little bit of cash...thats just what i would do if i had to choose between one or the other

If you had to choose between an exhaust or a high-flow cat? Yep, I'd probably do the same.

You have wise parents.

Read everything on this page and you will find what you seek.

http://www.racingbeat.com/FRmazda4.htm

^Jaguar, I'm not trying to start some controversy here as I know many people on the forum trust Racing Beat with myself included. But at the moment I think some of the info they have posted is suspect. While the gains they post sound reasonable and I'm sure they have done alot of R&D I have a problem through my personal experince last week. I went to turboXS and they gave me their racepipe and exhaust. They did the dyno pulls with me there. 6 pulls with my setup(revi and duct with cz turned off),6 pulls with the only change being their exhaust. I belive with just the addition of their exhaust i picked up max 8hp the dyno's are posted a few threads down. With their racepipe and exhaust I picked up on the at the least 21hp and at the most 34hp. So when RB says you can only get 5 hp from the car without a muffler at all then I would ask them for some more information. Granted it could be pure luck that i got those gains but personally i'd like more data. And polak is taking in his car to turboxs today so we should get his results as well to. Sorry for the long winded message but i would refer to Racing Beats claims and a few threads down about the tuboxs thing and take both with a grain of salt until there are more dyno's

^^^Submit Dyno graphs or this forum will suspect you. Just a friendly warning

guys, it's being discussed in this thread, and Polak is there today getting his car dyno'd

https://www.rx8club.com/showpost.php...&postcount=129

the next person who posts the RB site claiming it to be gospel despite having nothing to back up their claim but blind faith is going to get a virtual kick in the :moon: I swear ...

^^I was trying to say it in a nice way


I know i just figured that people could easily hit "back" and scroll down 2 threads rather then me having to repost the same info which would also get me flamed

racing beats is not god they make good parts just not for hp. and with most car when u remove the muffler and pipe the car does not gain much power because of the reverse flow back in to the motor on the exhaust for pistion motors usely running open header burns of the valves then give hp power out of a exhaust is about the tuning of the bends in the exhaust system its self like getting the right flow and back presure and stuff

^^thanks for the explanation i never read about why different exhausts make different gains. i thought i was all just more airflow...

but youngen you started the thread any idea on which way your thinking about going?