I recently swapped an H22 into my accord and soon i will be welding a custom exhaust for it. I need to know from anyone who might be able to tell me. Is a 3" exhaust going to drop the backpressure too much to get good performance out of the engine?

-Josh


-94 Accord H22A

 

It will be fine as long as you tune.

 

Most people who have a Normally aspirated H22 go with a 2.5" exhaust. The is no need to go over that.

The only people who usually go to 3" are turbocharged to reduce back pressure.

 

3" FTW

 

The 2.5" on my ~200whp setup netted me 99% efficiency compared to an open header.
This was OPEN@Cat VS Closed-no cat-no res-2.5" Vibrant muffler

 

3" sounds good to me if you are never riding dirty

 

What did you think of the Vibrant muffler? Do you like it? I need to build another exhaust for the track car, and I was thinking of using Vibrant's muffler and ultraquiet resonator.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ::NirVTEC:: &raquo;</TD></TR><TR><TD CLASS="quote">The 2.5" on my ~200whp setup netted me 99% efficiency compared to an open header.
This was OPEN@Cat VS Closed-no cat-no res-2.5" Vibrant muffler
</TD></TR></TABLE>

 

I may be doing some 3" testing this summer......Trying to get the quietest exhaust that makes the most power. Going to be playing with resonators and different mufflers. I may be going after the HyTech twin loop.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 117 &raquo;</TD></TR><TR><TD CLASS="quote">What did you think of the Vibrant muffler? Do you like it? I need to build another exhaust for the track car, and I was thinking of using Vibrant's muffler and ultraquiet resonator.

</TD></TR></TABLE>
With no cat/no res the Vibrant is stupid loud......not sure if you remember it from NPM06. I was almost as loud as you.....

 

https://honda-tech.com/zerothread/2197695

 

Which muffler model? I was hoping the Vibrant would be a bit quieter.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ::NirVTEC:: &raquo;</TD></TR><TR><TD CLASS="quote">I may be doing some 3" testing this summer......Trying to get the quietest exhaust that makes the most power. Going to be playing with resonators and different mufflers. I may be going after the HyTech twin loop.

With no cat/no res the Vibrant is stupid loud......not sure if you remember it from NPM06. I was almost as loud as you.....
</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 117 &raquo;</TD></TR><TR><TD CLASS="quote">Which muffler model? I was hoping the Vibrant would be a bit quieter.

</TD></TR></TABLE>
The black dual 2.5" one

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">https://honda-tech.com/zerothread/2197695</TD></TR></TABLE>
And there you have it....
Although I think a WELL flowing mandrel 2.5" would do about the same as a crappy crush bent 3".
I think alot comes down to $$$ at this point.....3" crush bent is super cheap.

 

Here's to hoping the Vibrant Ultraquiet resonator paired with the 6" round muffler will be quieter than my current setup!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 117 &raquo;</TD></TR><TR><TD CLASS="quote"> Here's to hoping the Vibrant Ultraquiet resonator paired with the 6" round muffler will be quieter than my current setup! </TD></TR></TABLE>
I am going to try some resonators this year....my ears bleed at 7000rpms.

 

I forgot to mention that I have Headers, a cat, underdrive pulley, AEM cam gears, a custom twin filter intake(short ram/cold air) and soon Ill be getting a Skunk2 pro series intake manifold and 76mm TB. I'm not sure how much of that would have any effect on my backpressure on not but it might help you to tell me.

-Josh

 

you dont want backpressure.

 

from what ive read you want or dont want backpressure depending on where in the rpms band you want power. In a drag car however, you do want some backpressure but that amount is accomplished from the header alone. With no backpressure from what I understand during overlap the mixture would pass through the cylinder and decress cylinder fill. Low backpressure helps in high rpm applications. At low rpms you can not create the velocity in the exhaust to help to max scavenging of the cylinders. Therefore when the velocity comes up (high rpms) with a large exhaust velocity will increase but down low velocity will not be very high. This is why you see most drag cars running open exhaust. This is all from memory feel free to correct me or disagree.

This is a topic that will be fought about forever.

 

Yeah I do get what you're saying. So pretty much, Drag racing cars do 2.75 or higher and track cars that are NA do 2.75 or lower? I'm going for a Mostly track car but somthing that can still put up a good fight in a drag race WITHOUT going turbo.

-Josh

 

heres a small article i did on the topic:

http://bbmoto.net/wiki/index.php?ExhaustTheory

makes a lot of sense to me. Really the only thing that limits how large of an exhaust you can run is ground clearance. I just dont see how you could get too large of an exhaust after reading a few articles that made me write that up.

 

all ive heard is 3" gets rid of too much backpressure

 

i understand your theory there completely, however doesnt exhaust gas velocity affect cylinder scavenging ? Running a huge exhaust would obviously cause lower velocity at low speeds. This doesnt mean that 3 inch is too large on an h22, there iobviously is sufficent exhaust gas velocity with 3 inch to scavenge properly. However does this mean that if we had a 4 inch on it that it would make more power or the same ? I wouldnt think so what do you think ?

 

i would think that the bigger your make the piping, the closer it gets to making open header power.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">i would think that the bigger your make the piping, the closer it gets to making open header power.</TD></TR></TABLE>

I wish someone would put a 4" exhaust on there n/a to see if that theory holds true. I know for a fact that I am putting a 4" exhaust on my turbo lude this time around.

 

i'm going 3" on mine. Mostly because i would prefer the ground clearance than the exhaust get all beat up. Its gonna be a shorty exhaust with a turndown so i would like it to really tuck under the car.

cant wait to feel that difference. running 2.25" now

 

running 2.25 and making the power you do? wow, you should see some nice gains with that 3". I plan to run 3" under the oil pan then flair to 4" because as you said... ground clearance. Show us the graphs when finish the new 3" exhaust

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ProjectBB6 &raquo;</TD></TR><TR><TD CLASS="quote">running 2.25 and making the power you do? wow, you should see some nice gains with that 3". </TD></TR></TABLE>

ha, yea. I'd imagine it will be a pretty significant jump. It'll get dyno'd with the 2.25" exhaust tho (once its F*CKING RUNNING). I dont have the funds to make the exhaust i want yet.