I am getting a cam, and longtube headers.. Right now I have the corsa pasecar exhast system but it's not 3 inch.. Do I need to get the 3 inch exahst since im getting headers and a cam????

 

"Need" is a VERY relative term .

The larger the exhaust the less back pressure on the engine and the more hp it will make. You could add all the bolt ons and internals you want and even reduce the exhaust inside diameter, but the car won't breath as well as if you went to a larger, or 3" throughout. The restriction will be decided by the smallest diameter tubing in the system.

I don't know what size the Corsa pace cars are, but if they aren't the same size as the headers or X pipe (or H) or cats, then you will simply need a reducer for them to fit.

Again, the larger 3" throughout should make slightly better hp (in theory).

Speed

 

i had the same question, no one answered it in the c5 tech section...

i have a 2.5" x pipe and catback(magnaflow) and want headers, but they have a 3" collector and the x pipe is 2.5. what will i need to make the TSP headers fit, and where do i get whatever i need to make them fit?

 

We have seen a gain by going up to a 3" kit on the C6 cars by using some of the Borla Z06 kits. For C5 owners there has been a limited availability of parts to make a 3" over the axle kit.

We have built and designed our own 3" muffler kit, dubbed the 'The Big 3'. This should be in our hands this month and ready for shipment by the first of December. Final pricing should be set soon, and I will have pictures for all of you as soon as the production units arrive.

They will come in either your choice of a two tip or four tip, and come with all of the adapters to work with our LG Pro's to make a full 3" setup, or bolt onto the stock section for those wanting to upgrade to headers later on.

We are taking names and deposits on these now.

 

Cut/Paste from AU N EGL...in the tech section...just interesting reading regarding header length and backpressure. Includes a link for a more indepth discussion.


Headers

The LONGER primaries of the LG's & Dynatech tend to LOSE their scavenging effect above 3500 rpms.. They are GREAT for LOW END TORQUE at LOWER RPMS. Perfect for street driving & road racers..

However for DRAG racing, the brands with shorter primaries KOOKS, AR, TPIS, will OUT PERFORM from 4000-7000 rpms, exactly where the power band is @ WOT....

The dyno results may only offer minimal if any gains, but on the drag strip, a .05-.1 quicker ET can be had.

Dyno tests with headers having primary lengths adjustable in three-inch increments show that lengths between 24 and 36 inches have only a minor effect on the power curve of V-8s that you and I can typically afford, although the longer pipes do marginally favor the low end.

PRIMARY PIPE LENGTH
"The overall length of the primary header pipe is governed almost exclusively by the target engine's rpm range, which is dependent upon wave tuning. Typically, a lower engine rpm range likes a longer primary pipe, while a high rpm engine prefers a shorter primary."

The length of the primary pipes also affects torque. Where diameter affects the torque peak relative to rpm, the length affects the shape of the torque curve. Longer primaries provide more torque below the peak and reduce it past the peak. Shorter primaries provide more torque above the peak at the expense of below-peak torque. More torque in the low- to mid-rpm range is important to drivers who want that feeling of seat-of-your-pants performance on the street. Longer primaries also reduce the chance of escaping exhaust's being drawn back up another pipe.

In order to keep the torque curve the same for all eight cylinders, it is important that primary pipes be equal in length. Exactly how equal they have to be is more critical on uncorked race cars than for the vast majority of mild-engined street cars running through mufflers. In most applications, pipe length deviation of 2 to 3 inches on a set of full-length headers is not a problem.

Backpressure

From a certain perspective, you will always have backpressure. The only Zero-Backpressure system out there is in outer space. As long as you are running an engine in atmospheric air, there will be "backpressure" from the static pressure at the end of the tailpipe.

I've always found it odd that people don't give more thought to where their pipes terminate, as some placements are better than others. If you dump the pipe into an area of smooth, hi-speed flow, then Bournoulli tells us that you have lower pressure there, and the exhaust flow will be enhanced because it is essentially being "sucked" out of the pipe.

This is why going to big on the pipe diameter can really kill power, because the exhaust flow has more atmosphere to fight against. Pipe diameter is always a compromise-- the ideal only exists for ONE combination of throttle position, timing, load, IAT, etc etc-- everything else is compromised to some degree.


Source: http://ls1tech.com/forums/showpost.p...80&postcount=4

Pipe Size

For exhaust, pipe size mismatch will show up in the power curve, with oversized pipe losing at low RPM torque and undersized pipe suffering upper RPM hp.

1 7/8” headers for low to mid range tq and hp 2” for high end HP or big cube motors


--------------------------------------------------------------------------------
Last edited by AU N EGL : 07-25-2007 at 08:13 AM.

 

And another Cut/Paste from the same thread...by Tony Mamo...even more interesting. Here is the link to the thread if anyone wants to see it in its totality.

http://forums.corvetteforum.com/show....php?t=1766586

To post or not to post.....

--------------------------------------------------------------------------------
I have been biting my tongue ever since I read this thread for the first time a few days ago. Some of the info is good and some of it is of course just a bunch of BS from cheerleaders of certain products who usually have some agenda you may or may not know about (welcome to the performance automotive related message boards).

There is no one size/one brand header fits all....I have extensively used and tested BOTH in question and they both have their place in the market and will enhance and subtract from different parts of your power curve. Each is better suited to it's own set of parameters and driving styles.

Phil....it was pretty much a no brainer that a shorter 1.875 tube was going to enhance your track times, power, and high RPM charge. You have a high strung solid roller small block with the breathing capacity to turn it 8000 RPM's or better and still effectively fill your cylinders. The much longer primary pipe of the LG design simply won't work at that RPM....not to mention the smaller diameter pipe at that RPM (and power level) was also not as optimal any longer (but IMO the tube length was the larger issue in Phil's very unique combination). Phil...on a side note your Mustang project looks sick....saw some pics in another thread

But back to the topic at hand.....if I were selecting a header for a mild hydraulic roller 346 (mainly street oriented) that spent most of its time below 6500 the LG system with it's very long primary pipes are IMO the header of choice. If I road raced a slightly more aggressive conbination they are probably still the header of choice (having to come off a corner at say 3-4K and having to be more concerned with area under the curve power).

Now if I was looking to skew the curve a bit higher up and was more interested in drag racing, street racing, or simply punching big HP numbers on the dyno the shorter primary pipe and very detailed collector the ARH features is a no brainer. Add a blower or increase displacement or RPM (solid roller) and the ARH design makes more sense again. Craftsmanship and ease of install is also another plus of the ARH system (the tig welds are artwork), although the LG install is alot faster to install than quite a few other brands available and you wont be cursing when your done.

The bottom line is I recently swapped the headers on my current 383 combo looking for a stronger top end charge and better carrying power past peak. As some of you know, I have been running the LG system for some time now with it being extremely effective on my former mild 346 very optimized high output combo. It was ideal for that build and was still surprisingly effective in my 383 solid roller motor. BUT, like most of us there came a time I was looking for more and I always felt a shorter and fatter primary pipe would enhance my top end charge. The ARH system was well constructed and just what the doctor ordered but like big cams and most other things engine related there is no free lunch. I fully expected to lose some midrange TQ and I did....about 20 ft/lbs at 4000 RPM (optimized versus optimized combinations). BUT, I got exactly what I was looking for upstairs with a bump in peak HP of 8 HP and 10-12 more HP past peak. From 5K and up the ARH system started making gains over my former power curve with the largest gap from 6K to redline (as you would expect). If I roadraced the car with this combination or was more concerned with low midrange grunt this swap wouldn't have been the right move for me, but seeing as I mainly street and dragrace the car (with a six speed trans) the reality is when I'm really serious about getting from point "A" to point "B", I spend all my time at WOT between 5500 and 7300 RPM's so in my situation I felt the swap was beneficial (and a spirited four gear to redline pass later that evening confirmed that to be the case).

Which header is better?? Neither of them....what you need is the right tool for the job and better evaluating your own combination will hopefully help you decide which piece will work best for you. IMO, they are two of the topshelf choices you have to choose from and you can't go wrong with either. In fact the point I have been trying to make here should really have been more of a generalized statement (not brand names) comparing header system "A" with 38" long 1.75 primary pipes to header system "B" with 28" 1.875 primary's. Both offer very different benfits and compromises to the end user, but choosing either one of these systems will leave you with a big smile on your face.

Hope this helps clear up a few things with the great header debate....although I'm sure a thread just like this one will pop up in a week or two. Seems to just be one of the hottest topics on this board (and others) and for some reason no one ever seems to get tired of it.



Regards,
Tony

PS....The point I am trying to hit home above pertains to many products on the market....my own included. As good as the AFR 205 head is, it only makes the most sense in certain applications....obviously not all applications. Sure then our 225 might fit the bill but that comes with certain compromises and of course also has it's limitations. The entire combination (every component) and its main focus (primary usage) must be carefully evaluated and matched if you really are trying to build a world class combination thats somehow better than the sum of its parts. Choosing the right header will be a key factor in the build and will help shape your engine's power curve and personality.


--------------------------------------------------------------------------------
Last edited by Tony Mamo @ AFR : 07-27-2007 at 10:37 PM.

 

Maybe a bit off the OP...sorry about the hijack...

Speed

 

so does that mean that i can use the 2.5"x pipe with the texas speed headers or not?

 

Oh oh. am I in trouble???

 

If you do some math, the 1/2 inch differance in diameter gives you a better flow in the neighborhood of +50%.


The better the motor breathes, the more HP you make.

 

 

No, the majority of people on this forum who have gone above and beyond what you're planning don't have 3" exhaust.