My exhaust experiment!

[fuji]

Well I decided to try some different combinations as far as exhausts are concerned. Just a bit of background. i have a 08 Yaris HB auto.

Initially I tried a 2" crush bent - this would be bit more free flowing than the stock 1.75" mandrel bent tubing. I did not have a resonator and placed a very free flowing straight through exhaust system from Maxspeed. I really loved the sound but was surprised by the dramatic loss of low RPM torque and power. It did however free up some kick in the upper RPM range but most of the time I do not drive like a maniac. The auto transmission may have had something to do with this as well. It seemed confused as to when to shift.

Next I switched the piping from 2" crushed to 1.75" and a smaller more restrictive Dynomax Super Turbo exhaust. The torque all came back and some. I did lose all the gains on the top end though. Overall drivability was much improved in the lower RPM range where most driving is done. I am assuming the overall exhaust velocity increased and therefore the low end torque returned. One issue was the muffler I choose was very small to make sure it didn't grind against the ground when lowered.

Well, what did I learn? Our stock mandrel bent 1.75" is actually pretty darn good for those not going crazy with headers and forced induction, I should have kept mine. A less restrictive exhaust would probably have been perfect for my daily driving needs. I think the other thing that makes a BIG difference is the auto VS manual transmission. My current thinking is the auto transmission with its lower RPM shift points is not well suited for mods that only make power in the upper RPM range. If I had a manual this would be a totally different story. Much more control over the RPMs you run your car at as well as different gear ratios.

Hope my experiments help those in the future trying to figure out what exhaust will work for them

[fuji]

Here are some pics.... The small one is the Dynomax super turbo and the bigger one is the Maxspeed.

[808_Yaris]

nice pics. to help with your rpm shifting, the blitz throttle controller can compensate for that.

[fuji]

The blitz throttle controller can change the shift points?

[botchilah]

I was thinking of doing the a similar experiment myself with the exhaust. I have an '09 Yaris hatchback myself. The stock exhaust system does seem perfectly suited for an automatic (I have an a/t myself) but I'm thinking there might be SOME gains at the top-end without resorting to a bigger exhaust pipe by simply replacing the exhaust piping AFTER the axle and going with a straight-through muffler that has a bigger inner diameter, ilke a 2' or even 2.5'? The OE chambered muffler looks like a really convoluted snorkel!!! The piping I'd be replacing looks like it'll be about 2 feet long before going to the muffler. I was also thinking of making an exhaust tip cut-out on the stock bumper to install a bigger, straight-through canister muffler without worrying about ground clearance issues at the back. The new piping after the rear axle would be something like 2' big then onto the muffler, probably a dolphin-tail tip design. Comments?

[fuji]

I would not change the piping after the rear axle if possible. It is mandrel bent and good quality - not restrictive. Our mufflers on the other hand are a different story. Just change the muffler to a freer flowing kind to see if this will increase the power in the RPM range you want.

[808_Yaris]

Originally Posted by fuji

The blitz throttle controller can change the shift points?

from my experience, it does. fyi i have an automatic too

[fuji]

What diameter tubing do you use? Is it crush or mandrel bent???

[1nz]

Originally Posted by fuji

Here are some pics.... The small one is the Dynomax super turbo and the bigger one is the Maxspeed.

Wow! our rear looks identical, tein coilover, i use ultra racing 19mm anti rollbar and exhaust are the same shape except for the tip mine is AMG replica and my muffler is lukey ultra flo

[808_Yaris]

Originally Posted by fuji

What diameter tubing do you use? Is it crush or mandrel bent???

2-1/2" out just for the muffler, it's mandrel bent.

[fuji]

No problems with loss in the lower RPM range??

[808_Yaris]

Oh sorry, 2-1/4" out. I haven't experienced any loss of the lower rpm range but I'll check again

[N3misiS]

NIce Guys, I am doing some development my self, well, with Viper Exhaust over here in SA, and this is for the T1, Manual, we are developing dyno tuned header and exhaust for my Yari, I will also post pics and see if I can get the Dyno Charts as well... I already have been playing and found around 2" works well, but it depends on your driving style, aplication and situation....

Keep on the good stuff....