[vince3]

Originally Posted by ChibbMD

My research suggested that 2" headers were a better match for the supercharged ZL1 and 1-7/8 was all you need for the naturally aspirated LT1. Bigger is not always better.

See my “research” was the opposite. The only reason to consider 1 7/8ths would be fit.

[DaveC113]

Originally Posted by vince3

See my “research” was the opposite. The only reason to consider 1 7/8ths would be fit.

Velocity helps with scavenging, or having a relative vacuum behind the exhaust valve when it opens to help evacuate the combustion chamber more efficiently. So the smaller diameter headers may be better at a lower rpm range vs larger. However, this is "in general", how it applies to the LT1 or 4 I have no idea.

[ChibbMD]

Originally Posted by vince3

See my “research” was the opposite. The only reason to consider 1 7/8ths would be fit.

If it was about fit why does a manufacturer make both size versions for the same car? Using that logic, you'd assume one version would fit and the other wouldn't. But you can get and use either for your car.

I don't mean that to be argumentative at all. Just saying that I don't think fit is the driving factor. I could be wrong.

[vince3]

Originally Posted by ChibbMD

If it was about fit why does a manufacturer make both size versions for the same car? Using that logic, you'd assume one version would fit and the other wouldn't. But you can get and use either for your car.

I don't mean that to be argumentative at all. Just saying that I don't think fit is the driving factor. I could be wrong.

You didn’t do any research. A 10 minute search would show numerous members posting about fit. Anything you say at this point i won’t take serious. Even TSP tells you straight up that 2” will have fit issues on their website.

[Megahurtz]

1 7/8 inch is the right size for NA LT1 stuff. 2 inch causes more low rpm torque loss making the car feel sluggish and you will gain almost nothing up top over the 1 7/8 on an LT1.

[GreyGhost702]

Originally Posted by Megahurtz

1 7/8 inch is the right size for NA LT1 stuff. 2 inch causes more low rpm torque loss making the car feel sluggish and you will gain almost nothing up top over the 1 7/8 on an LT1.

Not to mention unmolested heads exhaust ports are still smaller than the OE manifold. Going from blowing out of a straw into a cup vs blowing out of a straw into a bowl still leaves you just blowing out of a straw. This is also why jet coating can be worth it if you can get it done for a good price, as keeping the exhaust gases hot through the collector helps keep air velocity up. As well as a bunch of engineering I can't readily regurgitate. But everyone is always "Bigger is better" and they'll hog their heads, buy a random cam, and strap 2" headers on and say look at my peak numbers baby! Nevermind everything under the curve.

@Vince, don't rely too heavily on forums and reviews. I should say, take it with a grain of salt. The vast majority of people leave a review or make a forum post when they have a bitch or a problem. Compared to the total population of the forum membership over the years, the number of posts about header fitment issues is probably less than .5% of the membership and I'm not even looking, just taking a wild guess. I made a post about the GM OEM shifter design being a WTF-Terrible design and the engineer should be castrated to prevent further dumb engineering. I never made a post about how easy it was to bleed my clutch slave cylinder thanks to Tick Performance's bleeder line. I'm just saying, knocking long tubes because a few people had frustrating fitment issues doesn't mean they're all not worth doing. You will naturally have more fitment issues with 2" headers because they occupy a little more space and bends have to be a little bit longer. Aside from getting my header flange trimmed by like 1/8" to assure it was perfectly flat, I have Zero fitment issues. Mine are $600 Kook's knock-offs essentially. $100 to the machine shop, $180 to the exhaust shop to mate the collectors to the OE midpipe, and I'm still in them less than a set of real Kooks. I like to do all my own work most of the time, but there are certain things letting a pro shop do is just worth the money to not suffer the headache. My headers are so easy to install and remove, I have to have my wife hold the driver side header when I feed it up so I can get out from under the car to bolt it up, otherwise it'll literally just fall out of the bottom of the car. Texas Speed and other Vendors are going to warn of fitment issues because they don't want to hear customers bitching about fitment issues. You'll get on the phone with them, mad as hell you just shucked ~$1500 +/- and they don't just bolt on and fit flawlessly. Then they'll point at their disclaimer and tell you to pound sand. Then customers come here and vent to forum. Then Joshinator or some other forum vet will post up, Suck it up and roll up your sleeves or take it to a shop. On occasion there is a more serious defect in a set of headers, which most big brands warranty these defects. Sometimes it's a battle, sometimes they treat you real well, I think a lot of it is customer approach, if you come at them like a tazmanian devil I think you get the bronze customer service treatment. I've had a great experience on the phone with Katech/GPI/Phastek/BTR (except their cam engineer... he really doesn't like that I'm boosting their NA cam lol) so when you buy parts just keep it in mind they are who you'll deal with if you have issues, too.

[ChibbMD]

Originally Posted by vince3

You didn’t do any research. A 10 minute search would show numerous members posting about fit. Anything you say at this point i won’t take serious. Even TSP tells you straight up that 2” will have fit issues on their website.

Wow, I think you really took that harshly despite my statement that I wasn't trying to be argumentative.

Just to clarify even further, I didn't say fitment couldn't be an issue. It can even be an issue with some models of the 1-7/8" headers. All I'm saying is fitment isn't why manufacturers make two size options. There are performance pros and cons to the two versions that a guy might want to consider.

[s346k]

there is a gain to be had from headers on a basic stock long block motor, but it appears to be minimal.

i followed these cars when they were new. the fastest of the bolt on cars only gained .05 and <1 mph going from manifolds to headers. at the time they were low 10 sec cars, trapping high 12x.

my car had 2" primary headers. it had no problem spinning tires and black tracking on the factory 1LE wheels/tires at any speed under 60 mph. absolutely no noticeable tq loss at any engine speed.

[DaveC113]

OEM exhaust manifolds are 4>2>1 headers. This is generally an advantage over 4>1 for midrange power.

[vince3]

Originally Posted by DaveC113

OEM exhaust manifolds are 4>2>1 headers. This is generally an advantage over 4>1 for midrange power.

Dumb this down for me. What does 4>2>1 mean?

[vince3]

Originally Posted by s346k

there is a gain to be had from headers on a basic stock long block motor, but it appears to be minimal.

i followed these cars when they were new. the fastest of the bolt on cars only gained .05 and <1 mph going from manifolds to headers. at the time they were low 10 sec cars, trapping high 12x.

my car had 2" primary headers. it had no problem spinning tires and black tracking on the factory 1LE wheels/tires at any speed under 60 mph. absolutely no noticeable tq loss at any engine speed.

When I was researching, I read some of your posts. Do you think that Mamo ported MSD was worth it over a non ported MSD?

[arpad_m]

Originally Posted by vince3

Dumb this down for me. What does 4>2>1 mean?

From the exhaust ports, the 4 header pipes first join pairwise into 2 pipes, then those unite into 1 that then continues towards the cats/muffler.

[s346k]

Originally Posted by vince3

When I was researching, I read some of your posts. Do you think that Mamo ported MSD was worth it over a non ported MSD?

on a basic bolt on setup? hard to say. i had very little data comparing the 2 on my car. i went with it because i had planned to do hci. it didn't make the car slower, but is an expensive gain at that stage.

for whatever it's worth, i also have a mamo ported msd on my swap (project) car.

[tortilla-flats]

Originally Posted by arpad_m

From the exhaust ports, the 4 header pipes first join pairwise into 2 pipes, then those unite into 1 that then continues towards the cats/muffler.

Older thread but thought I would post a pic of the factory headers/exhaust manifolds.