stupid long or shorter headers?

[carbuff]

Originally Posted by Flash68

What's the approx power level here?

^ this...

I wouldn't worry about sacrificing 10-20HP in a car if it's going to mean a big headache. It may sound sacrilegious given how much time we spend talking about how to make HP. But when you are driving it, unless you are fighting for that last tenth in some kind of race, you will be a lot happier to have a cleaner/no-clearance-problem solution. Heck, I've been driving my car for a year now without getting it on a dyno to try and tune it for the best HP, and I'm loving having it on the road! (note to self - I need to schedule that dyno session. ).

[WSSix]

Should be a 500hp 383 if I get the supporting mods correct. The company that's doing the heads and suggesting the cam said cars are typically in the 420-440rwhp range with the setup I'm going with. The heads flow just under 200cfm max on the exhaust side. I'm looking to redline at 63-6500. All my math tells me I need 1-3/4" headers. While I'm not trying to build a race car, I don't mind trying to do it as best I can so that I can hopefully surprise people that usually look upon LT1s as junk.

Thanks everyone.

[Flash68]

Yeah I hear ya Trey. I'd go 1-3/4 and the easiest path, which sounds like the shorter ones from your description. Should be a fun and drivable motor with those numbers.

[WSSix]

Thanks Dave. I'm leaning that direction. I figure that so long as I do a good job on them, I should be able to sell them to someone else should I want to try a different design. I believe a big part of making a good header is making it look good and not just function well. So I'll be working on that aspect as well through all of this.

[speedjohnston]

The flat 4 into one collector does not work well on a naturally aspirated car because you lose a lot of the vacuum effect of the exhaust pulse before it. When they are square the pulse before it helps draw the next through, but when they are flat the outside tubes are too far apart. Probably not the best explanation...
You will lose more power with the flat 4 into 1 than if you make long, short or improperly size primaries. If you are supercharged this is less important because you are forcing everything through from the other end.
If it was me, I would consider removing your bracing bars, build the headers the way you want and then see what you need to do to re brace everything. Mind you, I always seem to do what costs too much and takes too long so maybe don't listen to me. Lol

[WSSix]

Those were my thoughts on the flat 4 collector as well.

Redoing the brace may be an option. We'll see. I don't mind coming up with neat little fabrication stuff like that.

Thanks

[tungstenkiller]

Originally Posted by speedjohnston

The flat 4 into one collector does not work well on a naturally aspirated car because you lose a lot of the vacuum effect of the exhaust pulse before it. When they are square the pulse before it helps draw the next through, but when they are flat the outside tubes are too far apart. Probably not the best explanation...
You will lose more power with the flat 4 into 1 than if you make long, short or improperly size primaries. If you are supercharged this is less important because you are forcing everything through from the other end.
If it was me, I would consider removing your bracing bars, build the headers the way you want and then see what you need to do to re brace everything. Mind you, I always seem to do what costs too much and takes too long so maybe don't listen to me. Lol

Absolutely correct on the flat 4 collector and you don't want to check the price on that collector and if you do make sure you are sitting down.

[WSSix]

Figured I'd bring this back up to the top instead of starting another thread.

I'm building the headers now and have decided to go with a traditional long tube design and am in need of opinions/information. I've got the number one primary laid out at about 32 inches long. I think I'll be able to make the others on that side the same length. If not, they will be within a couple inches. I'm not so sure I'm going to be able to make the passenger side work that well though. I'm not even sure I can get the number 2 to 32". I'm not trying to make equal length headers. I don't want to make a poor design though.

How important is it that the primaries be close to the same length between all cylinders? How much difference in primary length is too much? I'm just a street car with a street engine.

On a positive note, the driver's side header hangs no lower than the oil pan which is about 1 inch higher than the front cross member. They will also be less than 1/2 inch below the front subframe rails when looking at them from the side. The rest of the exhaust system is going to hang that low as well. Ground clearance is going to be good considering how hard it is to run exhaust on these cars. Cutting Hooker long tubes like Woody has done would have been a lot easier, but where's the fun in that?

Thanks