FireHawk409

Pagan picture it like this(correct me if im wrong injuneer). Get a plastic cup, fill it up with water. Then squeez it. The water will spill. Same size cup, just diff shape, and it wasnt able to hold the same amount. I think this is wat Injuneer is trying to explain to you, i just didnt use all those formulas.

1racerdude

Damn good analogy.

Injuneer

LR....

You went beyond my knowledge with the oval "collector".... now I "think" you are affecting the dynamics of the system by having two different collector shapes, but I am just guessing. Once you get past the collector, its no longer an issue, but in the collector is a bit more complex.

1racerdude

Yea and I ain't up to speed on the difference.
Do ya think they should be the same? I do to make them equal-- good/bad-- or in deferent.

96speed

LR: This has no tech behind. Just a SWAG. The normal mufflex style ypipe has ifferent bends in the right and left sides. I wonder if anyone with an onboard wideband has seen a difference in the right and left banks with a "normal" mufflex-ish ypipe? Being so close to the engine you'd assume there would be a difference.

On the driver's side, after my collector, my Ypipe turns 90º to the center of the car and then 90º to the rear of the car. The passenger side makes a nice smooth 45º into the Dr. Gas 3.5 -> 4" merge. My point is that having different routings on each side, given same tubing diameter, still makes a difference in the exhaust pulse/scavenging, right? I'm not the pro here. Ideally we'd have a perfectly symmetrical dual exhaust on both sides.

What's the point? Well...

I looked into the frame clearanced tubing. You would probably gain one inch over a well designed (read: tucked up/in) round exhaust. Putting one of those "frame tubes" on the passenger side would be overkill. I don't have the money to test, though. If you are onsidering it, you probably have more money than I. I think you are the kind that squeezes every thing out of anything (I mean that in a good way ). I had to pick and choose my expenditures a little more closely. It wasn't worth it to add the tubes.

I'm running the 1 7/8 headers with a 3.5" -> 4" exhaust. All tubing is round. I had to "notch the driver's side collector to clear that bump in the frame you are trying to clear, as my collectors are pretty long. Not sure the actually length, but they go a hair past that notch in the frame.

With all this in mind, my car hasn't run anything to brag. I haven't even dynoed it. 383/LT1 heads/solid roller/lt1 intake. So, everything I typed is basically a summary of what I did. Doesn't really belong here in advanced tech or help much for that matter .

12.0 @ 118 with a 2.0 and lots of excuses is the intial shakedown (3550#). Embarrassing, but that's the time. I have learned something valuable...there is much more to drag racing than bolting a motor in with the best go-fast parts .

Ryan

1racerdude

Yep,a lot more than meets the eye,when it comes to racing.
The frame clearance tubes WILL BE the collector. To put a semi necked down collector on one side and not the other doesn't seem "equal" to me.
AFTER the collector is not a big deal as far as bends and different lengths as long as the capacity is there.
Having to remake the Muflex 4" out the back anyway because it won't go over the hump and fit the shootout muffler with the gas tank sump in the way. Had to move the muffler all the way to the panard rod support to get it high enough so ya can't see it hanging down and nothing fit's after that.I wore out a Sharpie drawing lines to cut the right angle on the two bends from the muffler and over the hump. Then were the 90* turns and comes forward in front of the axle it had to have the floorboard reshaped all the way down the tunnel to get it up off the ground and clear the drive shaft and meet into our merge collector that is where the Spohn TA mount goes and it's all a tight fit and try to keep it from rattling. Pretty much got the "Y" pipe made,it's just the collector's that's got me boloxed up now.
If one collector is different than the other one,both banks won't be doing the same. To what degree I DON'T KNOW.
I need to watch Mr Wizard and see if he knows.

FASTFATBOY

I saw a TV commercial the other day..ask this guy, he knows..


www.askjeeves.com

LMAO

Just kiddin Pops, I dont see where it would make a bunch of diff with just one frame notch on the drivers side..it is made to keep the same volume the way it is shaped. The above post is right.....the y pipe is different in lengths anyway, I could see it if we had true dual exhaust.


David

1racerdude

Might as well ask Jeeves.
Ya ain't considering the effect on the individual pulses from each cyl.

Injuneer

You are correct LR.... different lengths on the Y-pipe branches is a different problem than altering the shape/cross-section of the collectors. You can't equate the two. I have actually used a larger diameter pipe following the collector of the driver's side header, to compensate for the fact that is has a wicked bend in it to route the pipe straight back, rather than in front of the oil pan like the stock AS&M Y-pipe.

Until someone comes up with some hard facts, its just opinions and guesses. But symmetry of the collectors would seem to be much more important than anything that happens after the collectors.

1racerdude

Thanks Fred,
That's the way I see it, but those tubes are $100 each and other people don't want to spend the money.
I will probably just order two and make the collectors both the same-- and hope I don't make for a bad running engine.
I know I wouldn't put on one necked down merge collector and hope for the best!!!!!

FASTFATBOY

That sounds good on paper as much of your stuff does, but we have asked EVERY header maker if the engine "SEES" the collector type or length and if changing it makes any difference with a complete exhaust system.....know what ALL of the answers were? "We dont know"....and if they dont know if collector length makes any difference..why would smooth bends or length or a "notch" in one side? It is made to have the same volume as a non notched pipe. Has anyone disconnected and exhaust behind the merge, ran the car, then removed the y pipe and ran the car?? I bet you one thing, I bet it makes little or no difference at all with a 3.5 inch y pipe like we are building. Whenever the car is done we will have the ability to do the above test if we put the o2's in the collectors.

Just thinking out loud.


David

96speed

Like FFB/David mentioned earlier. If the LS1 doesn't have different bank to bank tuning, the answer is found. The Ls1 has a smached flat tube on the driver's side, and round on the passs side. Does the LS1 even have bank to bank tuning?

If it does make a difference, you'd think GM would make intuitive changes...

Ryan

1racerdude

It's the collector I am talking about,the pipe after the collector don't matter much as long as the volume is there.
Do LS1's have headers with 3-1/2" collectors?

Brady

Hey Dave and Larry, does it get confusing setting at the same computer side by side logging in/logging out, replying to each other? Just curious Great thread BTW!

1racerdude

His ya got to pump up to keep it alive.
I've got one that's slightly better.
Ya got any answers? The header people that I have asked about weather the collector is "seen" as part of the "Y" pipe or not(collector & "Y" the same size)same size either don't know or aren't saying. I have talked to more than a few. They say they deal with open headers not full exhaust.
I think I will get two of the frame clearance tubes and be done with it. That way it will be equal either good or bad.

Ya lurking huh..

Happy New Year Everybody