what kind of power gain or loss can be expected when running open header on an ITR?

supporting mods is basic bolt on's with some tuning

 

Generally without any backpressure the low end will suffer a bit. Once you're on the high cam, you can expect a small increase in hp/tq. If the header is a really good header, ie: RMF, SMS, HyTech, you can probably see improvements from 4000+ running open header.

If you're at the strip it can be beneficial, but on the street, no.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92TypeR &raquo;</TD></TR><TR><TD CLASS="quote">Generally without any backpressure the low end will suffer a bit. Once you're on the high cam, you can expect a small increase in hp/tq. If the header is a really good header, ie: RMF, SMS, HyTech, you can probably see improvements from 4000+ running open header.

If you're at the strip it can be beneficial, but on the street, no.</TD></TR></TABLE>


You want the least amount of back pressure possible. That's some old myth that stems from having too large of exhaust piping which allows the air to cool and slow down before it exits the muffler thus creating MORE backpressure than a smaller pipe that would retain the heat/velocity.

However, there are other things (pulse waves and other crap I haven't really tried to understand yet) that could cause power loss going open header in some cases.


With the stock ITR manifold I picked up several MPH (1-3 depending on night) at the drag strip going open header.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ActiveAero &raquo;</TD></TR><TR><TD CLASS="quote">You want the least amount of back pressure possible. That's some old myth that stems from having too large of exhaust piping which allows the air to cool and slow down before it exits the muffler thus creating MORE backpressure than a smaller pipe that would retain the heat/velocity.</TD></TR></TABLE>

Thats a pretty bold statement. You sure about that?

 

Running an open header on the streets isn't a bright idea. You get dizzy as hell from the fumes at a stop light, car sounds like *** and draws attention from cops/theives/ricers not to mention it's slightly illegal. On the track, it's loud and loud.

A lot of drag racers like to run an open header, but the gains aren't really worth the headache if you ask me. I believe that more hp is gained with a testpipe and then a dump tube thats a few ft long in comparison to an open header.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jowee 1162 &raquo;</TD></TR><TR><TD CLASS="quote">Running an open header on the streets isn't a bright idea. You get dizzy as hell from the fumes at a stop light, car sounds like *** and draws attention from cops/theives/ricers not to mention it's slightly illegal. On the track, it's loud and loud.

</TD></TR></TABLE>


it is definately loud, but sounds oh so good w/ spec b's........

not driven on the street....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jowee 1162 &raquo;</TD></TR><TR><TD CLASS="quote">Running an open header on the streets isn't a bright idea. You get dizzy as hell from the fumes at a stop light, car sounds like *** and draws attention from cops/theives/ricers not to mention it's slightly illegal. On the track, it's loud and loud.

A lot of drag racers like to run an open header, but the gains aren't really worth the headache if you ask me. I believe that more hp is gained with a testpipe and then a dump tube thats a few ft long in comparison to an open header.</TD></TR></TABLE>

slightly illegal?? lol, i know u live in texas, but in california, the no cat fee's are REALLY high. dont expect to get 2-3 miles from where u live without getting pulled over. i agree about the fumes. i had an exhaust leak and i was running a test pipe and i got the biggest headaches and crap from smelling gas all day.

the inside if your car will also get a lot warmer. it's just spraying really hot air under your car. what you can do is get a pipe that connects to the end of the header to get the air to shoot out to the side of the car.

 

open header daily driver

 

would the car need to be re-dyno-tuned to achieve any benefits from running an open header when the car was originally tuned on a 2.5" catback?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jowee 1162 &raquo;</TD></TR><TR><TD CLASS="quote">Running an open header on the streets isn't a bright idea. You get dizzy as hell from the fumes at a stop light, car sounds like *** and draws attention from cops/theives/ricers not to mention it's slightly illegal. On the track, it's loud and loud.

A lot of drag racers like to run an open header, but the gains aren't really worth the headache if you ask me. I believe that more hp is gained with a testpipe and then a dump tube thats a few ft long in comparison to an open header.</TD></TR></TABLE>

i agree, i drove my car open header for two months while i waited for my exhaust and man did i get a lot of attention . It was loud as hell also, i wore ear plugs the whole time, and my car smelt like gas all the time

 

Buttcoin gained 20 peak hp on the dyno at explo 5 from dropping the cat. Not exactly a stock car, but still.

 

I experienced opened header with a stock B16A, it was loud as hell. The rpm went up much quicker when VTEC kicked in, but the sound was bad on the ears.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EG6 SiRII &raquo;</TD></TR><TR><TD CLASS="quote">The rpm went up much quicker when VTEC kicked in</TD></TR></TABLE>

So you're saying that the car revved quicker with an open header?

 

the rpm went up quicker

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EG6 SiRII &raquo;</TD></TR><TR><TD CLASS="quote">the rpm went up quicker</TD></TR></TABLE>

What tangible evidence can you give to support this claim?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Reid &raquo;</TD></TR><TR><TD CLASS="quote">

What tangible evidence can you give to support this claim?</TD></TR></TABLE>

someone just got owned

 

I thought running on open header caused damage to the valves?

I drove around the NYC area for about 2 weeks, got crazy attention but was very lucky not to get pulled over, I make sure to engage the clutch to lower rpm's whenever I saw 5O

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by migs &raquo;</TD></TR><TR><TD CLASS="quote">Thats a pretty bold statement. You sure about that?</TD></TR></TABLE>

It was in an article by Michael Delany and from what I can tell he REALLY knows his stuff.

 

Exactly! i have the jdm itr motor and i ran open header for abotu 1 month and up top you can feel gains but down low you lose

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Splat &raquo;</TD></TR><TR><TD CLASS="quote">Buttcoin gained 20 peak hp on the dyno at explo 5 from dropping the cat. Not exactly a stock car, but still.</TD></TR></TABLE>

Hell Yeah! I got yelled at by the mean track lady too Oh well... It's way to loud for daily driving. Just get a nice flowing exhaust and a test pipe and enjoy the ride

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AssPenny &raquo;</TD></TR><TR><TD CLASS="quote">

Hell Yeah! I got yelled at by the mean track lady too </TD></TR></TABLE>

Was that before or after she ran over Aquafina's tool box?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Reid &raquo;</TD></TR><TR><TD CLASS="quote">What tangible evidence can you give to support this claim?</TD></TR></TABLE>

scott k dynoed his car open header (stock) and full exhaust (stock exhaust) and the difference was significant.... although i do not have the numbers on me. i think it was 8ish whp.

 

ActiveAero, if this is the case, why is everyone not running huge 4" exhausts that would create the least amount of backpressure possible? Theres more than meets the eye per se, the flow velocity will effect exhaust scavenging, exhaust resonance, etc.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Splat &raquo;</TD></TR><TR><TD CLASS="quote">

Was that before or after she ran over Aquafina's tool box? </TD></TR></TABLE>

Be nice. She didn't run over it. She even reimbursed me for my camping fee.

The first drawer in my box still has to be jerked out so I can get my lugnets when I swap my wheels out. Too lazy to just empty another drawer and move them into it...

Here is my contribution to the thread. All behold the mighty Civic Type DX.
http://www.we-todd-did-racing....5NTQx
Right click, save as

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18c1995 &raquo;</TD></TR><TR><TD CLASS="quote">ActiveAero, if this is the case, why is everyone not running huge 4" exhausts that would create the least amount of backpressure possible? Theres more than meets the eye per se, the flow velocity will effect exhaust scavenging, exhaust resonance, etc. </TD></TR></TABLE>



Did you not read what I said?

An exhaust that is too large CREATES MORE BACK PRESSURE. Too large of piping can allow the exhaust gases to cool thus reducing velocity. The fast moving gas right out of the header slams into the cold slow moving air which = backpressure. Proper sized piping maintains proper exhaust heat/velocity.

I already said this once before.