Exhaust after the Longtubes

[vetteboy86]

If I am going to get headers now is the time to do it. I can order a set of the TPIS longtubes, that comes with the Y pipe. What should I put behind it? My brother had a test pipe made. My cat was no good, and it is in the dump somewhere. I hate to buy a cat just to gut it, but the hangers, would bolt everything right up. What has to be done to guy a cat?

Which rear Y pipe should I go with? Anyone make a good pipe that will fit good, and look clean? I am going to use the mufflers I have now, because I am running low of funds. IN the spring I can play around with the muffler eliminators, or just get mine back from my brother


Thanks

 

[C4Tom]

As far as I know... you have to separate the cat at the seams and remove the catalyst, then find a way to seal it back together. You got a MIG welder, possibly a TIG?

Indiana doesn't have vehicle inspections... just get a pipe made or make one, to replace it. Use stainless steel pipe, it's pretty hot at the cat location.

 

[Vettefan87]

Just run open headers out the Y for a while... That was fun for the two weeks I had it like that

 

[Edmond]

Just run open headers out the Y for a while... That was fun for the two weeks I had it like that

If I remember correctly, Heidi blew an engine because it didn't have an adequate amount of back pressure.

Why don't you ditch the cat and weld something to hang that exhaust pipe where the cat would've been?

 

[Vettefan87]

That is a myth of "not having enough backpressure" I asked my grandfather who used to race stock cars, and he never heard of any such of a thing...

 

[Dr-Pepper]

The length of the exaust pipe does create a certain amount of back pressure and it is needed for low end torque. check the Edlebrock site there is a lot of testing on this subject unless you are running a blower or some artifical atmospere device back pressure does a certain amount of useable power at least on the low end...
Dr-Pepper

 

[G Winter]

I have an 89 Riv with the 3800. I replaced the muffler with a walker super turbo . It did give the car just a little more power for passing. Then last fall the cat rusted off. Replaced with a piece of pipe. I lost noticable low end torque. It just depends on what rpm range you want the power.

 

[Vettefan87]

The length of the exaust pipe does create a certain amount of back pressure and it is needed for low end torque. check the Edlebrock site there is a lot of testing on this subject unless you are running a blower or some artifical atmospere device back pressure does a certain amount of useable power at least on the low end...
Dr-Pepper

Oh I realize that, but the whole myth of not having enough back pressure will cause you engine problems is not true.

 

[78SilvAnniv]

If I remember correctly, Heidi blew an engine because it didn't have an adequate amount of back pressure.

Yuppers.

1974 Camaro w/ 350 and TH350 auto tranny. Boyfriend put on straight headers with no pipes. Engine was a goner! Melted a piston top.
Engines do need backpressure to run efficiently, I don't understand the where's and why's but I'll never do that again!
Heidi

 

[vetteboy86]

I think with running striaght headers the exhaust valves will run hot becuase possibly of a lean condition. I have heard about this type of thing before with straight headers. I guess you have to watch your timing, and perhaps go with a colder heat range plug, or even increase the valve duration with the cam.

Many people go to great lengths to prevent this type of thing. That is why we now have knock sensors on our cars. This pulls timing in effect dogs out the car really bad.

 

[Mad-Mic]

Yuppers.

1974 Camaro w/ 350 and TH350 auto tranny. Boyfriend put on straight headers with no pipes. Engine was a goner! Melted a piston top.
Engines do need backpressure to run efficiently, I don't understand the where's and why's but I'll never do that again!
Heidi

cast pistons, low compression, low octane, lean condition after open headers, too much timing = blown motor.

pack pressure makes torque but you don't need much. too much backpressure robs both torque and HP. backpressure helps the piston make it's revolution by forcing it down in the chamber. as i said you don't need much. what comes in the motor should go out as fast or slightly slower. this is your backpressure. obviously if you have 600 cfm coming in PLUS fuel. now when that explodes you have energy coming out plus more air/exhaust with little to no fuel so cfm just jumped to 900 cfm coming out. trick is to balance the change rate in the cylinder from pressure and heat that comes out. once balanced the car will run good.

ever look at top fuel dragsters? they have little skinny pipes coming off each cylinder that are about 14" long. thats all the back pressure they need to make 5000 lbs of torque due to how much air the blowers are pulling in.

 

[Bob Chadwick]

I think with running striaght headers the exhaust valves will run hot becuase possibly of a lean condition.

You introduce too much air at the head and can cause it to run hot. I've never heard of it from open headers but rather from a bad exhaust leak at or near the head.

 

[Vettefan87]

Yeah I could see that being a problem if you didn't have headers or anything on the motor, but I just don't see it happening with running open headers.

 

[Mad-Mic]

You introduce too much air at the head and can cause it to run hot. I've never heard of it from open headers but rather from a bad exhaust leak at or near the head.

with a header/manifold gasket leak you can burn valves up real easy.