TRDSilverTC

Ok so i got a Megan Racing header for Christmas. It made my exhaust loud and raspy.(i am currently running the TRD axleback, stock s-pipe and mid-pipe) I could tell a nice little difference after the install HP wise. I mean i didnt expect any big gains being that it is N/A. So to tone the raspiness out i went to a local muffler shop and had them put on a 18" resonator in place of the stock one. To me the power i did gain and then some, seem to be all but gone. I mean it feels alot smoother and sounds alot better than before. I think that pretty much cancelled out any gains from the header i did gain. NOTE I did notice the inside of the resonator before they installed it looked more chambered not straight through like the stock muffler. also NOTE i had some wheelspin when it was all stock and ALOT of wheelspin and wheelhop after the header install, now i barely have any. Anyone have any input on this situation? any advice would be greatly appreciated.

-Josh

davedavetC

iTrader: (4)

its all in your head.

TRDSilverTC

you think so? thats what i keep telling myself but then again if i put my stock header back on i gotta go fork out 160 for a new o2 sensor due to the other one being all messed up from the attempted removal once already.

davedavetC

iTrader: (4)

i dont think that would be wise. do you have a CEL?

TRDSilverTC

nah not right now the piece where you put the wrench is pretty messed up because my buddy put too much pressure on it so i doubt its ever gonna come out. But i am not throwing a cel with the antifouler trick.

makaveli510

why would you go spend all that money to modify the stock midpipe it is a waste you should have bought an aftermarket midpipe with the resonater already in it and 2.5" at that that would have fixed your problem right there , add an s-pipe and you would have had a full exhaust and would have seen much better gains, just my .02

Aroddalobster

iTrader: (1)

check all your connections, and if there's nothing, yeah, as davedave said, it's all in your head. you got used to it, and while your car was in the garage, you might've somehow exaggerated in your head the gains of your header. so when you got in your car and drove, you were disappointed.

TRDSilverTC

I didnt go spend all that money to modify the stock midpipe. I spent about 30 for resonator and maybe 10 for them to install it. I dont want a full exhaust. If i did i would have bought it. I was just trying to not sound like a HONDA.

makaveli510

well you get what you pay for

TRDSilverTC

Idk maybe....this is my first N/A tuner. I had a SRT-4 before this and just about everything i did made a very noticable gain.

TRDSilverTC

Yea i guess

KINGxOFxSKA

The new resonator shouldn't restrict the airflow THAT much, if at all any different than stock. I think it's in your head.

SePaTc

Newb Lesson Number 1:

- Modding exhaust system alters engine performance.

contrary to a early post, i don't think its all in your head.

if u have an auto, that explains it right there.

if not, its simple-- you lost some of your low end tq by opening up the exhaust too much. Your losing cylinder pressure because there is no backpressure against the exhaust valves and thus they are opening quicker and maybe slightly earlier than before you modded the exhaust. Losing cylinder pressure before the burn is complete.

Mid_Life_tC-risis

If it wasn't straight-through then you will definitely lose high-end hp. Was it a louvered type resonator? Also - what diameter?

Sleep3r

you probably think you've lost power because you need to remember that adding a header will take away your low end. especially megan which i believe is 4-1

Menace

Its a junk resonator. The ones the local muffler shops use are made to quiet down your exhaust and not for performance. You need a magnaflow, vibrant, aero, etc resonator that is made for performance, straight through with a perforated core and packing if you want it really quite. I cringed at the site of one of those resonators when I came across one in the muffler shop. Plus, like someone said, you get what you pay for. You will pay at least 3 times for a good resonator compared to what you paid for yours.

Menace

Your engine theory is a tad inaccurate. You want to relieve pressure in your cylinder as much as possible (reasonably speaking). Thats one of the purposes of a header. The less effort on your pistons the better. Your goal is to eliminate ALL the burned gasses from the cylinder when the piston gets to top dead center. In other words, the more pressure, the harder it is for the pistons to expel them.

SePaTc

:D you want to evacuate exhaust gases from the cylinder AFTER the combustion is complete. you do not want the exhaust valves opening/leaking while combustion is still taking place.

there is a point of diminishing returns my friend, based on your theory then all drag cars should run open headers, right?? :D wrong.

our engine does not vary the exhaust valve timing. thus the valves open at the same point in the cycle, say TDC + 5. This is good for high end power, but you are trading off some torque in the low end. The release in cylinder pressure reduces force on the piston and thus reduces tq, which is a meaure of the force of the pistons applied to the crank.

dude, EVERYONE who knows tuning knows that reducing exhaust backpressure is a tradeoff between low end tq and hi end power. Thats why u don't see 1.6L civics running around with 4" exhausts genius.

Menace

You are mixing up too many things together to make a point. Running open headers and increasing the collector size/length(which is essentially what one is doing by installing a header) is not the same thing. Piping length and diameter through out the entire exhaust should be tuned to whatever you are trying to accomplish. No one is disputing the trade off in bottom end power perceived by excess back pressure and higher end power achieved by increasing the exhaust.

Your back pressure theory is your own understanding of how things work. Please elaborate on your theory of premature exhaust valve and why you indicated that point TDC +5.

I am by no means an expert but I do a lot of reading however and everything I read does not coincide with your theory. Please show me your sources.

Here is simple explanation to a header. In that article is a "How engines work" link. Read that after.

SePaTc

1. i read everthing on Howstuffworks 5 years ago.
2. I never said running open headers was equivalent to using a racing header.
3. I'm the one saying the exhaust system has to be properly tuned for the engines specs, and since the tc doesn't have variable exhaust valve timing, the stock header provides a good compromise of low end tq and hi end power. Most of, if not all of the aftermarket headers are poorly designed and F up the tc's sensitive ecu and throw off AFRs.

Since each valve opens in sequence, the idea of runners on a header is to ensure that the gases all reach the collection point in sequence, which prevents excess backpressure.

I don't need to explain myself, i KNOW what I'M talking about. You want to find out? Drive your car with a full exhaust system, then remove the whole exhaust from the header back and drive it........ see if you have as much TQ/acceleration.
4.In fact yes, there is someone disputing the exhaust backpressure:torque relationship. Do u think I'm talking to myself????
5."TDC +5" is a THEORETICAL EXAMPLE to show to point that the exhaust valves open at the same point in every cylce. IE. THERE IS ONLY SO MUCH EXHAUST THE VALVES CAN EMIT. THE VALVES DO NOT VARY THEIR TIMING TO ACCOUNT FOR HIGHER RPMS AND INCREASED COMBUSTION.
6. If you want to get gains from a header, get a vtec engine. For a NA tc, the best header is probably a stock header with a gutted pre-cat. There is no need for oversized diameter runners, as the 2az in naturally aspirated 9.6:1 trim doesn't burn enough fuel to need a big racing style header.

get it now admitted non-expert?