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Discussion Starter · #1 ·
sorry for the incoherent ramblings from before...im very baked and have taken two valiums. im a little slow right now.

WTF ENGRISH... implying what?dumbass
i have an 89gt. recently i had to change the muffler. so now i have i straight through pipe (no cat) into a turbo muffler.
Now i was told i was going to loss a lot back pressure, and that i would loose power in most of the power band except around 5000rpm when the car has the most ompf. well the later part is true, my car seems more eager between 4700-6000rpm.
i was told to block the hoses coming from my airbox to the engine and that should help gain back some lost pressure. so far i have blocked two of the hoses and one i removed(going to cat) is all this true? is my blocking those tubes helping, or am i doing damage to my car? if i am loosing to much pressure, what can i do?

thnx
 

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WTF ENGRISH?!? dumass canuck

</rant>

If you put sand in your intake tube and run the engine, you will polish the manifolds and you'll get your backpressure just like normal. Works every time.

Have a nice life assh0le!!

love,
siragan
 

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Siragan is a god in the escort world.

What you want to do is go to Lowes/Home Depot, get some nice sandbox quality sand, and slowly pour it into the intake tube AFTER the air filter. This will polish up all your ports and stuff and your car will run better.
 

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Alright... I'll help you out, but you pissed me off by calling me dumbass.

I've never worked on the first gen GTs, but if they're anything like the 2nd gens, the hoses leading from the intake hose go to the idle air control valve. It's en electrically controlled valve that bypasses the throttle plate so your car can hold an idle. Messing around with this will do nothing for your backpressure.

Backpressure is sortof a misnomer. Ideallly, there should be no backpressure in your exhaust... the point of your exhaust is to coordinate the pulses of gas flowing down the exhaust with other cylinders so it scavenges gas out of the other cylinder. The reason why cars want "backpressure" is because they use manifolds and not headers. With an exhaust header, you split each exhaust line up and run them independently for a certain lengh, x, which is a function of your exhaust gas volume. With a manifold, this idea doesn't exist because basically you're just dumping all the cylinders into a pipe and the whole thing is a freakin mess. Anyway, you need some type of pressure in the exhaust pipe prior to that or else your performance goes to crap.

Depending on how your valve timing is, it also helps bring in the fuel/air mix for the next fire of the pistons. Really, this concept of backpressure has nothing to do with pressure and everything to do with vacuum. Any neutonian fluid will decrease in pressure as the mean stream velocity of that fluid increases. This is why planes can stay in the air and why the backside of a spoon will be attracted to the water flowing from a faucet. Anyway...
The reason why you don't want an exhaust that is too large on your engine is because if the volume of the exhaust is too large compared to the exhaust volume of one cylinder, you won't get this scavenging into the other cylinders.

With that said, chances are that the turbo muffler you put on and the cat you put on increased the stream velocity so much that the velocity of the exhaust gas has died PRIOR to the next cylinder firing. One of the reasons why some cars have resonators is because it artifically slows the flow of gas down and helps create some type of scavenging. Because of this, the reason why you're getting the extra feel of oomph in the higher rpms is because if you assume that the time required for the gas to travel down the exhaust is fairly constant, than the number of "exhausts" of the cylinders per unit time increases as your rpms increase. Basically what I;m saying is that you're experiencing the scavenging at higher rpms because you're essentially getting rid of the exhaust in your pipes faster than you should by killing the cat and the muffler.
 

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siragan said:
dumass canuck
I agree easycheesyE either needs to adjust his valium intake, or stop buying cheap drugs, but that Canuk call deserves this:

.................... /´¯/)
..................../¯.. /
.................../..../
............./´¯/'...'/´¯¯`·¸
........../'/.../..../......./¨¯\
........('(...´...´.... ¯~/'...')
.........\.................'...../
..........'\'...\.......... _.·´
............\..............(
..............\.............\

:p :p :wink:

Nice writeup on backpressure for a yankee though :D

Matt 8)
 

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WOW, Thank you for the Info I didn't know.
I have a problem since I put the headers and hi flow cat. My air flow show as if i'm runing real lean but I'm get like 18 to 20 miles and burning twice the full and less power till like 3000 rpms. I was thinking its a sensor . I,m sorry for being Dum but i don't know much about engines :cry:
 

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Discussion Starter · #8 ·
OK Annnyyyywaysssss.......
thnx siragan. sorry if i offend you and we'll let it die.
thats some intresting shit but what should i do.serisouly sand. i also thought about changing the throttle body to a 3.8l throttle body and trying to increase the size of the tubing going from the air box to throttle body.will this work

thnx man, if you have time.
ps. bluging those tubes wasnt bad was it? nothing bad has happend
 
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