UP­GRAD­ING TOY­OTA EX­HAUST

DYNO­MAX & WALKER FOR THE WIN

4 Wheel & Off Road - - CONTENTS - Harry Wag­ner BY EDI­TOR@4WOR.COM PHO­TOG­RA­PHY HARRY WAG­NER

Bet­ter com­po­nents from Walker and Dyno­max.

WHEN DE­SIGN­ING THE ex­haust on our 2002 Tun­dra, Toy­ota had to con­sider a lot of fac­tors, such as emis­sions stan­dards, pack­ag­ing, and cost. The sys­tem was ad­e­quate when our truck was brand new, but af­ter 16 years and 170,000 miles it was time for an im­prove­ment. Yes, ex­haust sys­tems wear out. This is a re­sult of road salt and rust from the out­side, nox­ious gases on the in­side, and flex­ing as the sys­tem re­peat­edly heats and cools. And all that is as­sum­ing you don’t smash your ex­haust on a rock be­fore it has time to wear out.

Rather than just re­place com­po­nents, we took the op­por­tu­nity to up­grade with bet­ter com­po­nents from Walker and Dyno­max. Walker makes EPA and CARB-le­gal re­place­ment com­po­nents, in­clud­ing the stain­less steel cat­alytic con­vert­ers, res­onators, and muf­flers. The parts are made from stain­less steel with thicker flanges than stock. They bolt right into place and in­clude ev­ery­thing from the hang­ers to the heat shields. Walker cat­alytic con­vert­ers are even cov­ered by a five-year, 50,000-mile struc­tural war­ranty.

We backed the Walker com­po­nents with a Dyno­max Cat-Back Sys­tem with a Su­per Turbo muf­fler. Dyno­Max Su­per Turbo muf­flers use a three-tube de­sign that chan­nels ex­haust flow and re­duces back­pres­sure. Each muf­fler uses fiber­glass mat­ting tech­nol­ogy to ab­sorb un­wanted in­te­rior res­o­nance while main­tain­ing a mel­low ex­haust note. The muf­fler is com­ple­mented by 21⁄2-inch, man­drel-bent alu­minized tub­ing with welded hang­ers and a stain­less steel ex­haust tip.

Wor­ried that the Su­per Turbo muf­fler will be too loud for your daily driver? At the risk of sound­ing old, we’ll ad­mit that this was also a con­cern we had. Af­ter per­form­ing be­fore-and-af­ter sound level com­par­isons though, we are happy to re­port that the new ex­haust is only neg­li­gi­bly louder un­til you get above 3,000 rpm. We also per­formed emis­sions test­ing with the fac­tory com­po­nents and new com­po­nents, and found that the Walker and Dyno­max prod­ucts burn cleaner out the tailpipe. This, com­bined with a mod­est in­crease in mileage and power, makes for a win-win combo, all from com­po­nents that we were able to in­stall on the ground in just a cou­ple of hours.

1

We have a two-post lift, but there’s cur­rently a Bronco with no sus­pen­sion liv­ing on it, so we in­stalled the ex­haust on the ground. Tall

(12-ton) Har­bor Freight Tools jack­stands, lack of rust, and com­po­nents that fit per­fectly made for an easy in­stal­la­tion.

2

The fac­tory ex­haust on our Tun­dra wasn’t as bad as some we have seen, but there was still room for im­prove­ment. The new ex­haust from Walker and Dyno­max is lighter and less re­stric­tive and pro­vides more ground clear­ance as well.

3

Walker uses thick flanges on all of its ex­haust com­po­nents. These re­sist warp­ing, even un­der high heat, and en­sure that you don’t have to worry about ex­haust leaks. We got new gas­kets from Walker for all of the flanges.

4

Some bud­get ex­haust sys­tems use clamps to po­si­tion the hang­ers, but we pre­fer welded ex­haust hang­ers. They don’t leave any mar­gin for er­ror, but that wasn’t an is­sue with the Walker or Dyno­max prod­ucts. And you never have to worry about them com­ing loose or rat­tling.

5

A flex pipe on the Walker cross­over tube al­lows the ex­haust to flex when engine torque is ap­plied. This elim­i­nates the po­ten­tial for cracks that a solid mounted ex­haust sys­tem can some­times ex­pe­ri­ence.

6

Walker re­tains the fac­tory O2 sen­sors in their orig­i­nal lo­ca­tions, so there are no con­cerns about throw­ing codes. We used an­ti­seize on the bolts to en­sure that the O2 sen­sors come out eas­ily if we need to re­place them in the fu­ture.

7

The biggest room for im­prove­ment on the stock de­sign is where the two banks of the engine come to­gether. The fac­tory Toy­ota pipe ta­pers down to half its orig­i­nal size (bot­tom), while the new Walker pipe is con­stant di­am­e­ter to elim­i­nate re­stric­tions (top).

“It’s worth it for the sound alone”

8 The new Dyno­max Su­per Turbo muf­fler is smaller, lighter, and freer flow­ing than the

55-gal­lon drum that Toy­ota puts un­der the truck. The Su­per Turbo muf­fler uses fiber­glass mat­ting to muf­fle noise without chok­ing the engine. Me­ter app from Neti­gen. Be­fore-and-af­ter tests were per­formed on the same stretch of road with the cruise con­trol set to 60 mph and the engine at ap­prox­i­mately 2,000 rpm to repli­cate typ­i­cal cruis­ing con­di­tions with no mea­sur­able in­crease in noise.

9

Dyno­max uses 21⁄2-inch-di­am­e­ter ex­haust tub­ing that is slightly larger than the fac­tory Toy­ota ex­haust. This pro­vides a de­crease in back­pres­sure without be­ing so large that ex­haust gas ve­loc­ity plum­mets and can­not scav­enge the cylin­ders when the ex­haust valve opens.

10

If you live in a rusty en­vi­ron­ment we rec­om­mend soak­ing all bolts ahead of time and hav­ing a torch handy. The in­stal­la­tion on our desert-dwelling truck only took a cou­ple of hours with hand­tools though, thanks to the ex­cel­lent fit­ment of the Walker and Dyno­max prod­ucts.

11

Dyno­max caps its ex­haust sys­tem with a slash-cut stain­less steel tip. It looks clean without be­ing so big or shiny that some­one might con­fuse our Tun­dra with a tuner car.

12

We took sound mea­sure­ments in­side the cab of our Tun­dra us­ing the Smart Sound

13

We went to Jack’s Auto Re­pair be­fore and af­ter we in­stalled the new ex­haust com­po­nents to quan­tify the change on emis­sions. Mike Eck ran our truck on the shop’s four-gas an­a­lyzer and found that while our truck was still within the al­low­able lim­its to pass emis­sions test­ing prior to the new com­po­nents, both hy­dro­car­bon and car­bon monox­ide were sig­nif­i­cantly re­duced with the new Walker cat­alytic con­vert­ers.

SOURCES

DYNO­MAX EX­HAUST 734.384.7806 dyno­max.com

JACK’S AUTO RE­PAIR 775.359.2240

WALKER EX­HAUST walk­erex­haust.com

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