SoFla01SSLookinstok

Here's a question.

Say in Pipemax. The primary pipe diameter they give you. Is that say 18 gauge tubing OD? Which is what everyone goes by. Or is that pipe ID? Which is what headers should be sold by IMO.

I could have 2" headers, corporate terms, made from 10 guage. The pipe ID would be around 1.75".

If Kooks 2" headers fit with stock k-member? I like. The ID would be right around 1.9" or just over 1 7/8".

SoFla01SSLookinstok

I guess I should have looked first. Pipemax "all pipe diameters are OD & based off .0625" pipe thickness".

SoFla01SSLookinstok

Hey guys,

Just for a little pre update. I am going to jump the 1 7/8" & go with the 2'' headers. A couple guys I talked to at the track are still on the "bigger headers aren't always the best". From what I've seen from the LS heads..they love big headers. My race car buddies are with me.

I really don't care if I lose a little tq down low. I want that top end 5000-7000. Martin was cool enough to run my combo through pipemax & the 2" primaries are right on there. Hopefully now I'll be over the 500rwhp mark instead of floating right under it. I'll post dyno results when complete.

Darth_V8r

iTrader: (4)

Cool! Actually if anything I think you'll GAIN torque down low. Larger primaries can help with your midrange volumetric efficiency.

Good luck!!

scotty2000ss

iTrader: (2)

Nice man! Good luck!

SoFla01SSLookinstok

Thanks guys.

Jtm2085

iTrader: (1)

2in header is a no brainer on a 383 in my mind. Hopefully you hit the numbers you want

sxc Z28

383 will push more air. 2'' primary is the right call. 5-7k will be stupid gains.

big hammer

http://www.hotrod.com/articles/mopp-...orque-headers/

Bill00Formula

iTrader: (4)

First off, I'm no expert. But if I was thinking my issue was gears, I would be looking for something that built low to mid range power. By saying you need gears aren't you saying your motor is having difficulty getting into the motor's sweet spot. 2 inch headers or an msd intake would be the last things that I would be looking at. Seems like it's moving in the wrong direction. In fact, I don't see how an msd intake would help any cathedral port head. They appear to be awesome, at least in ported form, for the ls7 style head.

When I look at my logs in 1st gear, i'm going from 2,000-2,500 rpm to my shift point. In the upper gears the lowest I see is 5,300 at wot.

scotty2000ss

iTrader: (2)

Getting rid of an exhaust restriction is a bad thing now?

big hammer

Larger headers can significantly raise lower rpm tq, depending on the setup

SoFla01SSLookinstok

Hey Bill,

I actually thought you might take that the wrong way. I wasn't talking about you when I said " A couple people at the track". There was a pretty much race car f-body. Said it weighed around 29xx. He had a carb setup on a single plain manifold. When I looked at the headers they looked pretty small. I asked the guy & they were 1 3/4. I said a couple things about bigger headers & he was in the mind the 1 3/4 were big enough.

Also it is true that if I wanted to run any ok et I would have to get gears. Although I enjoy the car as is. The bigger headers is just looking for more top end horsepower. The msd intake doesn't really appeal to me.

How did you end up running?

Bill00Formula

iTrader: (4)

Never got to run. They tried cleaning the track but ended up sending everyone home at 11:30. Kind of sucked. I would have run the modified hellcat which would have been fun. I'm sure that was the last reasonably cool night of the year.

I was talking about et but I would think the goal of anyone would be to maximize your power curve. If the 2" headers versus 1 7/8" headers shift your power curve up seems like your power band is even more difficult to reach.

What's kind of interesting is your peak so much higher than mine. I would think the 1 3/4" headers would have prevented that. My heads/cam car ran great with 1 3/4" headers. It also peaked around 6,100. I had a big cam in that. The LG G5X-3.

Bill00Formula

iTrader: (4)

I never heard bigger headers could increase low end power.

NAVYBLUE210

Engine in that article had a NEGATIVE Exhaust Split Cam, not a valid
Determination of appropriate header size for most of our Applications
IMO.
Somewhere between 650-700 Crankshaft HP is Usually the transition from
1 7/8" to 2" headers NA. Obviously E/I head flow ratio, camshaft
exhaust valve events (split +,-), RPM Range, and exhaust after headers
X, H ,single, dual, and diameter have their affects as well, along
With intended application i.e. from auto-cross to Bonneville
From one extrem to the other.

big hammer

Yes, there are a lot of factors involved in if larger headers will gain, lose or not make hp. But LS don't often lose hp with larger headers. Generally at worst they don't gain much. 2" have even shown gains on a stock ls3 over 1-7/8. I think only around 5 hp but still.

If a guy is upgrading his 1-3/4 which imo are too small, I don't see much reason to not go to 2" in this application if the guy chooses to.

handyandy496

iTrader: (9)

I wouldn't want to loose over 30lbs of torque for a few hp. I have seen this happen on here even with Frankenstein ls7 heads. The 2" pipes is risky.

SoFla01SSLookinstok

That sucks. Like you say, as that probably will be it for our cool air as well.

I see what your saying. This really will just be a test. As different combos may react different to mods.

It seems the 1 3/4 did a pretty good job. Just hope the 2" frees up power. I really would think the vacuum pump has something to do with where the peak is.

You think it may loose that much? In what rpm range maybe 2000-3000?

It really is risky. I'm gonna go for it & see what happens. Heck if it's that bad I'll still have the 1 3/4 to put back in. Lol.

big hammer

On a stock ls3, 2" headers made more peak and average HP and TQ than 1-3/4 and 1-7/8 headers

http://www.camaro5.com/forums/showth...y+headers+test