 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Nissan / Nissan Z Cars / March 2005Exhaust backpressure question
I have a 1987 5 speed non-turbo model. I have heard exhaust back pressure is required for N/A. Why does an engine need backpressure? Do you want to clear the exhaust as fast as possible? P.s: I lost my muffler recently and I am thinkking putting a resonator type (like a bullet shape that is about 4" in diameter) of muffler. Is it a good ideal? >I have a 1987 5 speed non-turbo model. I have heard exhaust back pressure >is required for N/A. Why does an engine need backpressure? Do you want to >clear the exhaust as fast as possible? I think the problem with a lot of those low-budget wannabe tuner cars is not enough backpressure. Have you ever noticed a little Honda civic with a bazooka muffler accelerating at a relative crawl, even though the driver is flat-out gunning the engine? I dunno if reducing backpressure is good for increasing top speed, but I've seen it hurt acceleration. But again, I'm not necessarily talking about a Z; its intake/exhaust system might be completely different. > I think the problem with a lot of those low-budget wannabe tuner cars > is not enough backpressure. WRONG! You 'think' wrong. > Have you ever noticed a little Honda civic > with a bazooka muffler accelerating at a relative crawl, even though > the driver is flat-out gunning the engine? Because he hasn't TUNED the engine for the mods. No one seems to want to do anything but buy cool -LOOKING- parts, they won't spend $5 on tuning. how many of these rice boy cars have tunable stand alone EFI etc? Maybe .1%? > I dunno if reducing > backpressure is good for increasing top speed, but I've seen it hurt > acceleration. BS, the accelleration is hurt because the car's -tuning- isn't changed with the mods. Those Honda's have a "speed density" type EFI that is the worst as far as compensating for changes. Add something like a cold air intake and in most cases they lose power because it throws the tuning off (they go lean). With a Z it's a little better cause that have a MAS system than can compensate to a point for changes done to the car's air flow. > But again, I'm not necessarily talking about a Z; its > intake/exhaust system might be completely different. Doesn't matter what kind of car, backpressure is BAD. But you have to tune the car after doing mods or you can lose power. People add a part, don't know how to tune and the car loses power so this kind of "You need backpressure" BS gets started.  SignatureSteve http://www.atlantaracing.com >> I think the problem with a lot of those low-budget wannabe tuner cars >> is not enough backpressure. > >WRONG! You 'think' wrong. Hey, it's cool, man. I was wrong. It's happened many times before, I'm sure. I'm just passing on the information that I was told by my mechanic, and you've taught me that he didn't know what he was talking about, and I shouldn't have listened to him. Lesson learned, everyone's happy. No need to burst a temporal vein over this.. >>> I think the problem with a lot of those low-budget wannabe tuner cars >>> is not enough backpressure. >> >>WRONG! You 'think' wrong. > No need to burst a temporal vein over this.. ??? I do have to wonder why people who appear to know nothing, post information like it's gospel? Or ask questions to then say "I figured" something else? SignatureSteve http://www.atlantaracing.com > I have a 1987 5 speed non-turbo model. I have heard exhaust back pressure > is required for N/A. Why does an engine need backpressure? Do you want to [quoted text clipped - 3 lines] > (like a bullet shape that is about 4" in diameter) of muffler. Is it a good > ideal? backpressure is always bad, what you want to maintain is exhaust flow velocity, no flow = no suction = no scavenging effect in the cylinder. > I have a 1987 5 speed non-turbo model. I have heard exhaust back pressure > is required for N/A. Why does an engine need backpressure? Do you want to [quoted text clipped - 3 lines] > (like a bullet shape that is about 4" in diameter) of muffler. Is it a good > ideal? One analogy that you could use for Steve T's explanation actually pertains to motorcycles. But the general concept is the same. Think of the countless numbers of guys that have went out and purchased 'drag pipes' for their Harley-Davidson motorcycles and installed themselves--completely ignoring any "tuning" modifications to the bike. Such as re-jetting their carbs. Then they can't understand why "the bike doesn't run right". Although this isn't a direct comparison why cars, again, the general concept is actually quite similar. R.M. > I have a 1987 5 speed non-turbo model. I have heard exhaust back pressure > is required for N/A. Why does an engine need backpressure? Do you want to [quoted text clipped - 3 lines] > (like a bullet shape that is about 4" in diameter) of muffler. Is it a good > ideal? Maybe my turn to learn something, but to my way of thinking, backpressure is bad when you're racing or going for all out horsepower but actually aids in reliability with a street car. Running with little backpressure will shorten the life of your exhaust valves. The strait pipe exhaust on dragsters are tuned so that at peak horsepower a pulse returns up the exhaust and helps scavenge the exhaust from the combustion chamber. This pulse is a form of backpressure even if it is minimal. Same idea at a lower RPM for headers. Steve T is right in that you have to look at the whole thing as a package. Change engine components and you should make sure the car is tuned for the new parts weather its a new intake, a cam, the exhaust or anything that affects the way your engine breathes. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.