tooter's exhaust experiment...

[tooter]

Up to today, all of the before and after tooter intake manifold dyno runs were with Garm's MagnaFlow center exit exhaust installed. My wife wanted her car a little more quiet, so Scott sold me a nice stock Toyota axleback exhaust, and I put it on the car. It seemed to me to run just fine, but my wife who drives the car more said that it seemed sluggish.

So I got curious enough to do an experiment today, and took the car down to Harry's dyno shop at 15020 Oxnard Street in Van Nuys. (818) 908-9650 It's just East of Sepulveda Blvd. a few blocks.



We did a couple of runs with the only change being the stock axle back exhaust, and there was quite a difference. The difference between summer blend and winter blend accounts for some of the difference, because my gas mileage drops about 2 mpg in the winter. But even disregarding that it still made a considerable difference.



Needless to say, I put the MagnaFlow back on today.

Greg

[cali yaris]

Sweet! Maybe we should make more of those.

Another important factor is temperature (I think more important than the gas blend, actually). If it was colder out this time, you'd make more power as well.

[xnamerxx]

Why is your AFR in the 14s?

Looks like there is a massive exhaust leak in there somewhere and given that line corresponds with the lower power output I'd be looking at an exhaust leak.

[tooter]

Originally Posted by cali yaris

Sweet! Maybe we should make more of those.

The dyno test is a nice selling point, Garm.

I added a stainless steel resonator tip to mellow out the sound even more. Now it sounds like a Borla...

http://youtu.be/FL4CcjF8Z18

Another important factor is temperature (I think more important than the gas blend, actually). If it was colder out this time, you'd make more power as well.

Ironically, the run with the MagnaFlow was done on a 93 degree day and the run with the stock exhaust was done on a 63 degree day.

We looked at both charts SAE corrected and the difference was still 7 horsepower.

Greg

[tooter]

Originally Posted by xnamerxx

Why is your AFR in the 14s?

Looks like there is a massive exhaust leak in there somewhere and given that line corresponds with the lower power output I'd be looking at an exhaust leak.

There were absolutely no changes made upstream on the exhaust system. Everything is tight, the engine idles rock steady and smooth, and there are no codes. Exactly the same tooter et intake and 1ZZ throttle body.






I don't know why it's lean with the stock exhaust. The only thing that's different besides the axle back is the winter blend gasoline. I can tell it's different because the gas mileage takes a hit. The only way to know for sure would be to do another dyno run in the summer.

Greg

[cali yaris]

Looks like there is a massive exhaust leak in there somewhere

Axle back isn't going to change the AFR. That sensor is way up front on the header.

[xnamerxx]

I can't imagine their pulling the data from a front o2 sensor, or a thread in Wideband sensor. Most dyno shops use a wire sensor that sticks into the back of the tailpipe.

Given the rest of the engine is fairly stock, I'm gonna go with there was an exhaust leak at the axle back joint. Exhaust leaks don't hurt performance by affecting AFR they hurt performance because an exhaust leak creates turbulent air flow which restricts flow in the tube. Even small exhaust leaks can cause huge losses of power.

[tooter]

Originally Posted by xnamerxx

I can't imagine their pulling the data from a front o2 sensor, or a thread in Wideband sensor. Most dyno shops use a wire sensor that sticks into the back of the tailpipe.

Given the rest of the engine is fairly stock, I'm gonna go with there was an exhaust leak at the axle back joint. Exhaust leaks don't hurt performance by affecting AFR they hurt performance because an exhaust leak creates turbulent air flow which restricts flow in the tube. Even small exhaust leaks can cause huge losses of power.

Excellent point. I believe you hit the bullseye.

We did use a tailpipe sniffer for the A/F reading, and it was likely indicating a problem that did not actually exist, because there were no other negative symptoms like rough idle, thrown codes, bogging down, etc. The engine ran good, just not as good as with the MagnaFlow exhaust.


Greg

[LuisPRTRD]

Originally Posted by tooter

Greg

I need this manifold

[BEEF]

dude... He sells them (not sure if he has any left).

[cali yaris]

tooter, if you dyno again, try it with no axle-back at all. Just for me.

[Ryze268]

Where can I can just the intake section with the MAF bracket?

[cali yaris]

^ eh?

[Golddeenoh]

Originally Posted by cali yaris

^ eh?

that is how i felt but i just wasn't sure how to respond

[tooter]

Originally Posted by Ryze268

Where can I can just the intake section with the MAF bracket?

I bought a used Simota intake, sold the filter, and chopped off the front end short to fit the oversized velocity stack filter. This particular intake tube flares out to fit the larger 1ZZ throttle body so that's why I used it.




Greg

[tooter]

Originally Posted by cali yaris

tooter, if you dyno again, try it with no axle-back at all. Just for me.

Sorry, Garm... I won't be able to remove the exhaust as paying for the time to remove and reinstall parts while it's on the dyno stand more than doubles the cost.

The next dyno runs will be with the tooter I.V spacer, and it will be done with the center exit exhaust because I already have the stock manifold dyno runs with the same exhaust to compare it to.

Greg

[tooter]

Originally Posted by LuisPRTRD

I need this manifold

Hey Luis,

I recently got another Corolla manifold to make into a tooter, but the parts to make it won't be machined until next year. When it's built it'll be $575 including shipping and will look just like this one.









These are the dyno runs...

Red: stock intake, 46mm stock throttle body
Blue: tooter intake, 46mm stock throttle body
Green: tooter intake, 55mm 1ZZ throttle body





Greg

[Ryze268]

Originally Posted by tooter

I bought a used Simota intake, sold the filter, and chopped off the front end short to fit the oversized velocity stack filter. This particular intake tube flares out to fit the larger 1ZZ throttle body so that's why I used it.




Greg

Thanks much Tooter