lbrohez

I am going to use the Headman longtube headers, no cats and no Mufflers. I am not doing the no cats and no mufflers for more power but because i dont have the money to pay for them now. But i need to now how far back on the car do i need to run the exhaust to keep from cracking a valve from the cold air rushing up the exhaust. I also need to know with doing it like that how small of pipe to put on after the collector to keep my scavanging happening.

NJITIROC

iTrader: (2)

ok, so what exhaust costs 300 bucks and made you lose HP?
and for the cat, i think you can get a catco cat for about 60 dollars. and mufflers will usually cost about 40 dollars each. so for a dual exhaust you would have 100 dollars plus the cost of pipe, should be under 300 dollars

Mark A Shields

You can run open headers no problem with out pipe. No worry about burnt valves. There's a reason why cars at the track that have open headers don't mess up their valves.

lbrohez

i am not worried about burnt valves. I am going to drive the car year round and like in the winter, when it is all snowy i dont want all the cold air to rush up my exhaust because it is so short, causing a valve to crack.

I would be getting Headman Longtubes, Flange reduciers, with o2 senser bung, s pipes, and just exhaust pipes to about the back of my doors, and turn downs. all held to geather with exhaust clamps. That will be right about 300$ plus shipping costs.

lbrohez

for my stock lo3 how small of pipe off of the duals to keep scavenging, since my exhaust after my headers are going to be like 2 or 3 feet.

TBI305Camaro

man Mark no way in hell you could drive our cars without an exhaust everyday. 1500rpm open headers hurts my ears and im half deaf...screw that.

Mark A Shields

I never said he should run open headers, just that open headers are safe.

dimented24x7

iTrader: (2)

if your not gonna run mufflers. just put turn downs on a set of LT headers. It will quiet things down some although itll be loud as hell and probably sound like **** on a stock 305. Have you considered a chambered exaust?

SLP IROC-Z

iTrader: (1)

my 305 sounded like absolute *** with open headers, and ive got the largest factory cam and TPI. ur nuts to do that. :nono:

SSC

Well since your going with long tube headders and cant afford eveything right now Id suggest just putting the headders on and using a muffler that bolts directly onto the headder. Flowtech makes the purple hornies that bolt directly onto the headders and a few other exhaust makers make similar setups. Open exhaust is way to loud for everyday use if all else fails just buy some glasspacks and two clamps. Youll probably have to buy new collectors when you install the full exhaust system but it will save your ear drums.

lbrohez

I will look into mufflers that will bolt directley to the headers. Any suggestions or how much do they cost? What do you mean i would have to buy new collectors?

Mark A Shields

I think like $15-20 for cheap mufflers to hold you over, each.

383backinblack

There is no possibility of cold air climbing into the exhaust, even if it could, the heat inside the tubing and around the ports would heat it up to the same temp as the exhaust anyways.....if you only have a 305 and your gonna put duals on it, dont use more than a 2 inch pipe, if you do your gonna lose alot of low rpm torque

five7kid

iTrader: (14)

I agree that 2" dual exhaust would be adequate for an LO3. But, I disagree that it can't be any larger than that in order to maintain low-end torque. That's a function of the header primary tube diameter, especially with long tubes. Hedman long tubes are 1-5/8" diameter primaries, which is actually a little large for a 305 that doesn't spin over 5000 RPMs. If you really want to maintain low-end torque, go with 1-1/2" primary headers.

For the sake of growth, however (350 or upgraded 305), go with 1-5/8" primaries.

383backinblack

header primary and collector size play an important role there.....but think realistically about the fluid dynamics at play here. The pipe even after the collector is still activeley involved in pulling exhaust away from the engine....if the tube diameter is too large, the velocity will fall and scavenging will suffer dramatically.

for example, when the exhaust was built on my car i drove it to the exhaust shop with open headers (oh man was that nasty....scared the hell out of everyone in a 5 mile radius) the motor makes awesome power anyways, but without an exhaust system behind the header the low end torque was not optimal.....

several hours later when i left the exhaust shop i pulled out of the driveway completely sideways, because i was not used to the greatly increased low RPM torque.....but still open exhaust will build more high RPM horsepower