I'm not sure why it would matter but I wanted to check with everyone. Is there a problem with running shorty headers without the y-pipe? My y-pipe doesn't fit with the new oil pan but the car is ready to start. I didn't know if this would affect the O2 sensor or anything.

TIA

 

Depends, where did you install the O2 sensor?

At the start of the collector is a good place and the sensor should be as close to the primaries as possible to prevent data lag.

Also, if you say your y-pipe doesn't fit and aren't going to use one, what do you plan on doing for the rest of the exhaust?

Please don't tell me you are going to run open headers. It is actually worse than a lot of setups performance wise and sounds awfull!!!

 

how exactly would it be worse for performance? just curious, trying to learn all i can about exhaust before i purchase a setup of my own. thanks

 

It may not have a tuned sound but you don't see Top Fuel cars running anything other than open pipes. When the time comes and I can afford it, I'll be going with a true dual setup with 1 3/4" LT's or running LT's merged to a single 4". I need to replace these 1 5/8 Headman shorties, they will really choke this motor.

The O2 sensor is located right in the middle of the collector between the primaries and the flange...approx 1-2" from the end of the collector.

 

Running open pipes is not the same as open headers. Obviosuly open pipes(no muffler) flows better than a muffler would. But with open headers the end of the pipe is at the end of the primaries which creates a turbulance that makes the air pressure at the end of the primaries lower than the air pressure in the collector and sometimes lower than the air pressure just outside the exhaust creating "backpressure" just like a low flow muffler would.

Also, staring the car with open headers and the o2 in place shouldn't hurt the sensor or the car, although it will most likely run a little rich due to the backflow of fresher air.

P.S. What sort of motor is "really choked" by 1-5/8 primaries? That is usually enough for a naturally aspiriated 305-383 motor. Not saying it hurts to go bigger, but 1-5/8 flows a lot better than stock manifolds.

 

Dumped headers will flow just fine. When the exhaust hits the open air it will send back a low pressure wave up the primaries essentially helping the next pulse come out of the exhaust port. Because the pipe is so short, it's tuned for high RPM as well, making open headers an excellent choice for a drag car that needs to run in the high RPM range.

There's nothing wrong with running open headers other than it's quite noisy.

1 5/8 flows better than stock manifolds, but if you want 350+ hp, 1 3/4 will get you more gains.

 

I'm looking at over 400hp with a 383 and trickflow heads. There will then be a 150 wet shot put on it.

 

You'll want at least 1 3/4 LTs, 1 7/8 if you can afford them.

Sounds like quite a beasty you got there

 

Thanks, i hope its a beast. Just finished the wiring, waiting on my suspension pieces to arrive so i can throw those on and break in the motor!