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.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7192_zpsf21b6347.jpg

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. :wink:

http://i17.photobucket.com/albums/b90/compost_bin/car/exhaustbeforeandafter_zps2ca36ec2.jpg

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

Greg

[cali yaris]

Sweet! Maybe we should make more of those. :wink:

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]

Sweet! Maybe we should make more of those. :wink:

The dyno test is a nice selling point, Garm. :thumbsup:

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

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]

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.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7176_zpse831107b.jpg




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]

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. :smile:

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]

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7176_zpse831107b.jpg






Greg

I need this manifold :eyebulge::bonk::coolpics::drool:

[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. :wink:

[Ryze268]

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

[cali yaris]

^ eh? :iono:

[Golddeenoh]

^ eh? :iono:

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

[tooter]

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.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_6332_zps66f09c4a.jpg


Greg

[tooter]

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

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]

I need this manifold :eyebulge::bonk::coolpics::drool:

Hey Luis, :smile:

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.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7525_zps06864a7f.jpg

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7524_zps2131d921.jpg

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7526_zps6c1ef5b6.jpg

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7527_zps98c43c79.jpg

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

http://i17.photobucket.com/albums/b90/compost_bin/car/tqcursor_zps31bfdefb.jpg



Greg

[Ryze268]

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.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_6332_zps66f09c4a.jpg


Greg

Thanks much Tooter :thumbup:

[malibuguy]

Wow didn't realize the axle back makes that much of a difference.

I recently switched out my Borla for my old Flowmaster and absolutely love the mid range grunt I got back. But I've never tested it...

[tooter]

Wow didn't realize the axle back makes that much of a difference.

I recently switched out my Borla for my old Flowmaster and absolutely love the mid range grunt I got back. But I've never tested it...

That surprised me too, but I don't believe the difference in exhausts is quite that drastic, as the first dyno run was done with summer blend gas while the other was done with winter blend. The fuel definitely accounts for some of that disparity as my mileage always drops off when they switch blends.

Greg

[cali yaris]

Still shows that at least that axle-back doesn't LOSE power in the low to midrange. I think that can be safely generalized to any axle-back that flows more freely than the stock exhaust.

[tooter]

Still shows that at least that axle-back doesn't LOSE power in the low to midrange. I think that can be safely generalized to any axle-back that flows more freely than the stock exhaust.

Yes. That's a pretty safe assumption to make. It's likely because the rest of the exhaust (specifically the small midpipe) already provides enough flow resistance for decent low end torque.

I also think that the modifications I had made on my intake allowed the engine to take better advantage of the increased flow more than an engine with a stock intake, which would also increase the difference.

Greg

[TOLMACH]

I am still confused about the huge difference in the air/fuel ratio (((

[tooter]

The sniffer was likely not reading correctly. It wasn't in the best of condition, and there were no other symptoms that anything was out of kilter. The car drove so good with the stock exhaust I didn't even think there would be any difference at all.


Greg

[yarisgeo13]

Nice exhaust. It looks like someone wants to spin the wheels off his/her car..Cool!

[tooter]

Nice exhaust. It looks like someone wants to spin the wheels off his/her car..Cool!

Thanks, man. :smile:
I really like it. The stainless steel resonator tip mellowed it out nicely.

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7316_zps9461223c.jpg