If the tailpipes are a larger enough size and are mandrel bent, they're not hurting performance. Show me a dyno or track test to prove otherwise. On a street car you won't notice the 1-2 horsepower they may possibly rob above 6000rpm so it doesn't matter. Mustangs and Camaros are still live axle and their tailpipes aren't making them pigs, as long as they're not 2" tailpipes with kinked bends from being crush bent, it doesn't matter. Most every muscle car from the early 60's to mid 70's had tailpipes out the back and they still made 450hp back then.

 

Ok guys i was talking with my dad on this subject and he said. In the 60's and 70's what they would do with the exhaust and headers is, run the car hard for about 15 min take a crayola crayon and mark the exhaust from the header all the way back. When the crayon stoped melting that would be the part in the exhaust where the most h.p would be. Anything past that point they would loose power. So to see if this actually worked i tryed it and mine was just ubove the rear diff, and also these engines need back pressure to run good, the back pressure it what actually cools the valves off

 

Only on older carbureted engines that couldn't adjust properly for the increased airflow. Any modern EFI engine will be more than capable of running with open headers without any valve damage.

 

so now it seems like you're back tracking on your arguement 88vic.



you sure sound like a guy who needs to put his money where his mouth is taking him!

uncork you '92 brother, and let me drive her for awhile, i'll make you eat those words of yours.

that's not a threat, it's a promise. i've burned more drivelines than most of you guys combined. unless it's a off-road application only (meaning drag, drift, road coarse, you get the point) it will need that BP. never mind the legal & enviromental issues. forget all that, we're talking strickly on what the engine can/can not deal with & survive.

and before you go touting, "where's your proof?" lets me tell you, i burned a 4.3 in my '92 by running a punched cat (a big no-no, i know), and a super free flowing muffler. so your author of said article can go blow free flowing exhaust out the back door of his shop.


well enough for one night, i've got work in a couple of hours.

 

Nah, this thing has more issues than Time magazine, so I fully expect it to buckle under any sort of abuse. It was a miracle it even had a current inspection for the $1400 I paid for it.

However, if you want, I'll haul my old beater 1992 Toyota Camry up there. Ran her as a daily driver with a blown Y-pipe and then later open headers for the better part of two years before I finally got around to putting everything together. Ahh, the Toyota 3VZFE engine, how I love thee.

 

What are you talking about? Back tracking what arguement? I said it the first time and i'll say it again, side exhausts are not harmful, that was a Ford only problem, you were the one saying because Ford had a problem with side exits that they were all bad, which is false.

Also no cat and a free flowing muffler will not burn valves, wrong again. That was a coincidence, i've been running a highflow cat and a Magnaflow which is the best flowing muffler you can buy, for over 10 years and no burned valves, and only in the past couple years have I had a cat, before it was no cat at all just pipe, and if you don't think I push it hard it used to tow a gooseneck. It has over 202,000 miles with no problems. You must have just had a worn motor and you blammed the exhaust for it's problems.

 

Mehh what ever vic88 ive been wrenchin on cars for 10 years now, my dad has been doin it for over 38 years. And even he said in todays engins meaning from the early 80's and up. They were DESIGNED to run EFFICIENTLY with BACK PRESSURE, now you can call me a liar and you can call my dad a liar i dont really care. But you can go in anywhere you want to and ask them if running a side exit is a good idea? And just wait for the reaction you get from the older WISER tech's. Unless the engine is built for side exit or just headers? Which im guessing yours is not!!?? You will actually lose power and fuel economy

 

Wrong wrong wrong wrong wrong, unless you're running a 2-stroke, you will never lose power by eliminating backpressure. Next time I can get access to a dyno, I'll A/B my old camry just to prove you wrong. You won't gain more than say 4 whp under most situations, but you certainly won't lose power.

Mayhaps, but if you're worried about fuel economy, you should be driving a turbodeisel, not a gasoline anything. Better torque and 50mpg, that's what I call a win-win situation.

 

Just to chime in here... Engines requiring back pressure is a myth as vic88 stated. Burning exhaust valves can happen, but not as a result of an exhaust system change. This is typically due to a malfunctioning EGR system and/or out of spec AFR (lean).

You can get to a point of diminishing returns with exhaust pipe sizing. Too large and the flow velocity slows down, exhaust gases cool off/shrink - slowing down further, and things domino from there leading to lower performance. A properly sized system will keep the exhaust gases as hot and flowing as fast as possible to promote scavenging.

Here are just a few threads to help clear this up:
Backpressure
exhaust instead of lift kit
good idea?

For more information,a quick google search for "back pressure myth" will turn up a LOT of write ups explaining things in more detail.

 

Exactly, backpressure is a myth. High exhaust velocity is needed to run efficiently and make more power. The key is proper exhaust size and design. Too small is restrictive but too large slows down flow. Think of a garden hose, the flow of the water speeds up as you cap off the end a little bit with your thumb. You need to use the right size piping for your engine's power output and eliminate as many restirctions as possible.