backpressure

[LITTLE FOOT]

how would a stock y pipe right to 3ft 3'' tail pipe (no cat)affect gas mileage and power, do to very little backpressure?

 

[Wicked_Sludge]

you would loose fuel economy, loose a considerable amount of bottom end power, be highly illegal (due to no cat), and it would sound horrible.

your idea would increase backpressure, not reduce it.

 

[LITTLE FOOT]

i dont care if its legal or not my 93 hasent had one sence iv had it

but anyways this one will not be going on a road legal truck.
how so increase bp?

 

[Hahnsb2]

how so increase bp?

Lower velocity causing reversion. And your idea sounds like shit, literally. And it performs even worse.

 

[LITTLE FOOT]

well i gues ill just use a cherry bomb on it to.
that will be better right? its just for offroad use

 

[jax4bangin]

a smaller diameter pipe will improve exhaust gas velocity and give u more low end power

 

[rurouni20xx]

+1 id run 2 1/4 all the way out over the axle, it acts like a jet syphon and helps pull exhaust out, install a muffler or pact of some sort to slow it down to create some backpressure to help idle, but still allow full flow when 30% or more throttle is applied. its been proven over and over again that all an exhaust does on these trks is noise however.

 

[shadetree]

+1 id run 2 1/4 all the way out over the axle, it acts like a jet syphon and helps pull exhaust out, install a muffler or pact of some sort to slow it down to create some backpressure to help idle, but still allow full flow when 30% or more throttle is applied. its been proven over and over again that all an exhaust does on these trks is noise however.

How does backpressure help idle?????????shady

 

[LITTLE FOOT]

^x2

 

[rurouni20xx]

your engine has no pressure on it to help keep the fuel in the cylinders while idling, a lil pressure keeps it where its at and keeps your idle speed up a hair as well. while idling the engine is still trying to overcome the load of the alternator water pump etc and is fighting those things, keeping a hair amount of pressure will help stabilize the idle and keep it where it should be. (so you dont lope miss and die, either idling or bumping the throttle to take off.)

 

[pickuptrucker]

so what about a header? along with small diameter pipe all the way back to a glass pack? on a 2.3?

 

[jax4bangin]

so what about a header? along with small diameter pipe all the way back to a glass pack? on a 2.3?

sounds good to me..

 

[RangerFabWorks]

so what about a header? along with small diameter pipe all the way back to a glass pack? on a 2.3?

i hope it has a cat, if it doesnt, did someone order chinese? i smell rice

 

[shadetree]

your engine has no pressure on it to help keep the fuel in the cylinders while idling, a lil pressure keeps it where its at and keeps your idle speed up a hair as well. while idling the engine is still trying to overcome the load of the alternator water pump etc and is fighting those things, keeping a hair amount of pressure will help stabilize the idle and keep it where it should be. (so you dont lope miss and die, either idling or bumping the throttle to take off.)

Rurouni20, please take this as constructive criticism, not flaming you. I don't know where you get your information, but a lot of the information you pass along is incorrect, including the above, and your comments on the workings of ignition systems. I don't want to sound like an ass, but I would think you would want to be correct in what you say as there are many on here who are here to learn. A quick web search will give you a thousand threads on backpressure.

The engine management system richens the fuel mixture during idle to keep the engine running steady, it has nothing to do with backpressure. shady

 

[rurouni20xx]

i understand where your coming from shady, this is from engineering textbooks and ive practiced these techniques w/ marvelous results over and over. granted it may be working in another way and i dont have a way to show you a dyno sheet and such but working an exhaust is almost like working a cam, the right grind or tune if you will produces a very nice result. for example on my trk the muffler was plugged up come to find out, the trk was breathing thru the leaks in the flange gaskets and other various places. the engine was choked from excess pressure, the engine thought it was under load and adjusted to try and over come the load, running rich as hell etc. i cut the exhaust off and it was a straight pipe, the engine breathed better but leaned itself out and would die when you mashed in the clutch to stop, no pressure on the engine. i installed to fart cans in line that cause a slight restriction to flow, the engine richened up a lil, dashpot was normal (doesnt die when you depress the clutch) and actually accelerates better than w/ a straight pipe. why? the exhaust pressures are slightly restricted and adds to the torque curve slightly, pulsation was reduced helping the horsepower band and was an overall power boost. granted w/ the straight pipe if the trk was tuned for it it would have run correctly, just no real torque to the engine but excellent hp numbers. the slight amount of backpressure helped the torque number and slightly lessened the hp but balanced the engine. correct me if im wrong or tell me what really happened but this is my interpretation of what my personal experience/end result was. proper tuning of the engine to match the exhaust combination can yield wonderful results as well, i just tuned the exhaust around the tune that the trk was already supplied w/. btw, i dont take offense to anything, and i highly appreciate experienced opinions and constructive criticism. between shady sludge gofast and a few others here i consider you to be of substantial knowledge and more than capable of creating a legitimate and decent/informed argument, even if it leads to us agreeing to disagree.