i have a b16 i put a high flow cat on when before i was running a straight pipe..it feels like it slowed me down when vtech kicks in it doesnt feel like it pulls..but when i had a straight pipe i could feel vtech and felt a little faster????

 

VTEC


no it did not slow you down what so ever

your butt dyno told you it was faster cuz it was louder.

 

kinda what i was thinking thanks for the reply

 

define "high flow cat"
are we talking about a $30 ebay "high flow cat" which is really a short resonator...or an actual catalyic converter such as an catco.

if you went from a straight pipe to an actual cat it's gonna cause a little more backpressure and you MIGHT lose a horsepower or two but i can't imagine it being much on a stock b16. I'll agree THC07...it wasjust louder.

 

yea it is a cheap 30 cat ...i have megan 4-2-1 header,intake and 2.5 pipe from cat back

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigjake22 &raquo;</TD></TR><TR><TD CLASS="quote">yea it is a cheap 30 cat ...i have megan 4-2-1 header,intake and 2.5 pipe from cat back</TD></TR></TABLE>
that's what i have.
I couldn't imagine that doing anything as far as hurting performance goes, it should jsut give you a better note. all it is is a short resonator.

 

Im using a catco and for 50$ it was a great deal.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicVX94 &raquo;</TD></TR><TR><TD CLASS="quote">
if you went from a straight pipe to an actual cat it's gonna cause a little more back-pressure and you MIGHT lose a horsepower or two but i can't imagine it being much on a stock b16. I'll agree THC07...it wasjust louder.</TD></TR></TABLE>

If your car is stock and i mean stock i/m/e and you were to put a straight pipe on you might get half a pony. back pressure is important in most cases of cars that are not internally built. take my H for example, i had intake header exhaust 2.5 straight pipe, absolutely zero back pressure, got a ref ticket, put back on the stock intake and exhaust, keeping the 2.5 catco piping. with that little more back pressure i gained a bit of tq. back-pressure helped in my conditions, helps pull gasses out of the head, blah blah blah. goes to show that it all depends.

 

thats b/s....cats are environmentally friendly...your not losing that much noticeable horsepower...help the environment while ur racing...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">
If your car is stock and i mean stock i/m/e and you were to put a straight pipe on you might get half a pony. back pressure is important in most cases of cars that are not internally built. take my H for example, i had intake header exhaust 2.5 straight pipe, absolutely zero back pressure, got a ref ticket, put back on the stock intake and exhaust, keeping the 2.5 catco piping. with that little more back pressure i gained a bit of tq. back-pressure helped in my conditions, helps pull gasses out of the head, blah blah blah. goes to show that it all depends.</TD></TR></TABLE>
butt dyno FTW!

so now a aftermarket intake creates too little back pressure and hurts performance. I think I've heard everything now.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blazedevo781 &raquo;</TD></TR><TR><TD CLASS="quote">thats b/s....cats are environmentally friendly...your not losing that much noticeable horsepower...help the environment while ur racing... </TD></TR></TABLE>
there are quite a few other things in the world that hurt the environment to worry about other than the small number of cars that don't run a cat.

 

ahaha butt dyno!

 

it hurts the environment

 

put the cat back on, your VtAk ain't gonna hit any harder

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">Im using a catco and for 50$ it was a great deal.

If your car is stock and i mean stock i/m/e and you were to put a straight pipe on you might get half a pony. back pressure is important in most cases of cars that are not internally built. take my H for example, i had intake header exhaust 2.5 straight pipe, absolutely zero back pressure, got a ref ticket, put back on the stock intake and exhaust, keeping the 2.5 catco piping. with that little more back pressure i gained a bit of tq. back-pressure helped in my conditions, helps pull gasses out of the head, blah blah blah. goes to show that it all depends.</TD></TR></TABLE>

not true, back-pressure does absolutely nothing for a car's performance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wudini &raquo;</TD></TR><TR><TD CLASS="quote">

not true, back-pressure does absolutely nothing for a car's performance.</TD></TR></TABLE>

Backpressure is what helps close the valves in the engine. Tell me how that's not key in reliable engine setups?

 

i got 3" straight back piping on my civic love it. there is tons of back pressure with it 2

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chadalac1712 &raquo;</TD></TR><TR><TD CLASS="quote">i got 3" straight back piping on my civic love it. there is tons of back pressure with it 2</TD></TR></TABLE>

whats the set up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbociviccoupe &raquo;</TD></TR><TR><TD CLASS="quote">

whats the set up?</TD></TR></TABLE>

Yes do explain. Turbo?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ek forever guy &raquo;</TD></TR><TR><TD CLASS="quote">

Yes do explain. Turbo?</TD></TR></TABLE>

not even for turbo its too big. unless your pushing alot of power 3 inch exhaust will hurt more than help.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbociviccoupe &raquo;</TD></TR><TR><TD CLASS="quote">

not even for turbo its too big. unless your pushing alot of power 3 inch exhaust will hurt more than help. </TD></TR></TABLE>

Yeah I knew that.

That's why I asked about FI and was like

 

A reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.

The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.

Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.

Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. While a bad design, it was nonetheless used in a lot of vehicles. Once these vehicles received performance mods that reduced backpressure, they no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.


source = http://www.uucmotorwerks.com/h...h.htm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbociviccoupe &raquo;</TD></TR><TR><TD CLASS="quote">

not even for turbo its too big. unless your pushing alot of power 3 inch exhaust will hurt more than help. </TD></TR></TABLE>

ANY turbo car will notice large gains w/ a 3 inch exhaust. Think about the insane amount of restriction that a turbo has....the larger exhaust=faster spool/more power.

I'd love to know why so many turbo supra guys run 4'' exhaust, and dsm's always put 3'' exhaust and dp on first, if a 3'' exhaust will hurt performance.
It doesn't matter if you have a stock d series boosted and pushing 150whp...putting a 3''exhaust on it will give you gains and alot less lag.

 

^^^ werd... UUC is a good company btw imo so i find that information valid and will base my opinion on that... good research

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ek forever guy &raquo;</TD></TR><TR><TD CLASS="quote">

Backpressure is what helps close the valves in the engine. Tell me how that's not key in reliable engine setups?</TD></TR></TABLE>

How did you ever come up with that idea.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicVX94 &raquo;</TD></TR><TR><TD CLASS="quote">
butt dyno FTW!
so now a aftermarket intake creates too little back pressure and hurts performance. I think I've heard everything now.
</TD></TR></TABLE>

dude you need to read a little better, how the hell did you get that from what i said.
Dont post stupid comments when you dont know any better.

fyi back pressure has nothing to do with an intake. back pressure is whats in the exhaust half of the car. not only helping the valves but helps pull gasses out.

"Most engines are set up from the factory for a certain level of backpressure. Changing the exhaust can create a situation where the cam has too much overlap for the RPM range it's being driven in. In that case, the incoming fuel/air will come in the intake valve, only to have part of it sucked straight out the exhaust valve without getting burned! Obviously, engine power will suffer if it doesn't get a full fuel charge to burn. Proper backpressure will prevent this. So will choosing a more appropriate cam for your RPM range, however.

It isn't that the engine needs more backpressure, it's that static pressure is only half the equation. The equation for the "equivalent" pressure at the exhaust port is P-pv^2, the static pressure minus the exhaust density times the square of the exhaust velocity at the port. A 5" pipe may see a slight reduction in static pressure but will kill off the velocity making it harder to push the exhaust out."



Modified by THC07 at 7:23 AM 3/29/2007

 

I like how you cut and copied that long post up there. go back to the link and read the very first sentence. then go read this kids first question. and ask your self if he needs back pressure.




Modified by THC07 at 7:24 AM 3/29/2007