Before some days I put a valve bypass on final exhaust. Look some pics:

Here is the UPS that gave me the voltage of drill.



Creation of hole.



Here is the button.


The valve.


Start with the tube. OEM was 38mm and now 42mm.



Change on first muffler.




Here the valve on the muffler.



On the car.



And finally the back side of car.


Now from 1000rpm until 2000rmp the noise is little louder from factory because the valve do not close perfect but there is about 0,5mm opening on it. When the valve is open the loud is big.

When I check it on road with chronometer I will post again.

 

sound clips?. looks intersting?

 

^+1 on soundclips or video...how long did it take to do? Looks hella crazy.

 

+1 on sound clips here too...

 

Why you didn't just install it before the rear muffler.

 

So look some tests that I did:

I did two meters on different roads but the same start point each time and I
had my watch and push the “start-stop” buttons my shelf.
Close valve:
1st road:
In 4th gear (is auto but I pushed the “7speed mode” button) from 1600rpm until limit revs(about 5500rpm) was 21,20sec. and 2nd road: 25,03sec.

Now on open valve.
1st road:
21,0sec and 2nd road: 24,39sec.
So us we can see the first road power was better about 0,20sec.
The second road there was better power too (0,64sec).

Now I did the same meters but this time I use petrol. (My car runs LPG)
Close valve
1st road:
20,32sec until limit revs.
And 2nd road:
22,77sec limit revs.
Now open valve
1st road:
19,79sec until limit revs.
2nd road:
22,69sec until limit revs.
So us we can see the first road the power was better (0,53sec) and the second road too (0,08)
Us I have said before the test I did my shelf on a watch chronometer so this is not the best way to see the different.

Now if someday I use dyno I will post again.






Because the valve close about 98% not more so sometimes oxygen comes in tube. So if someone (exhaust emission check) stops on road to se what emission goes out from exhaust, it will see more O2 that normal (this is comes on if there is a hole in exhaust) so he will suspect something.

 

How much you paid for the valve.

 

About 200$ and another 200$ for exhaust work.

 

Wow $400 that's too much for very little gain. I paid $320 for Hotbits header from Malaysia and shipped to Egypt and the gain is very good. You can see the diffrence at the clips that i have in youtube under Honda City Top Speed before and after the header.

 

If you're feeling a little too crazy,someone should fab the valve in right after the header.But get a valve that doesn't leak at all.And make sure you open it up often so it doesn't carbon up.That would be too crazy!

 

thumbs down...

 

I was just thinking of that it should be after the header, so it will be free flow like open exhaust.

 

THAT WOULD BE SO DOPE.

 

Yes but, I do not want extra noise, only power. So when i need the extra power I open the valve. So the car is quite like before because I run often on freeway.
Also if I chance the header like you, I will win another extra power us you told me.

 

Did you buy it from the States, but still again you should have spend the money in a better thing.

 

I bought from Greece.
And I say again. I do NOT want more exhaust noise.

Kimo, I saw the video that you told us. Do you have Honda City?
Because the City has better drag coefficient, than Honda Fit(or Jazz)

 

Yes I have City 1.3L auto Idsi

 

Kimo, do you know about CD (coefficient drag ) your car?
Jazz has 0,31.

 

I don't know. About the valve, I guess there is some gas will still flow into the muffler.

 

Kimo:
Look I think that when the valve is open is like to do not have any muffler. I mean that if I had a free muffler will be the same flow like now.
Now if (IF) our vehicle has the same power, it is normally your vehicle to has more top speed, because your vehicle has better (DC) so lower resist on air.

*[on my mistake is not CD coefficient drag but DC drag coefficient that I wrote before]