im in the process of getting qtp longtubes i was gonna get 1 3/4, well if i get 1 7/8 would that make me lose any power or hurt performance since im fairly stock for now? i figure might as well get the 1 7/8 for when i do do a heads/cam swap, would the 1 3/4 give me more power gains than the 1 7/8 since im fairly stock? I want the 1 7/8 but dont want to lose any power since i donthave good cam and heads thanks

 

do a search
Tons of info on this topic.

My opinion stands, 1 7/8 is too big with stock engine, h/c or 346 cubes. I went with 1 3/4 after debating for a long time.

Some people will think otherwise and have the number and times to back it up

 

I have seen craploads of debates on this as well. Sometimes people will have me leaning in one direction and then a knew point is brought up and I sway the other way.

I'm interested in seeing your proof.

 

I think with 1 7/8, you will lose some low end, but probably have more top end, but you will lose low end anyways with the LT's, but I with the big tubes you will probably lose more. If anything, I would look into stepped headers, kooks, and edelbrock carry these.

 

agreed

Louie, i dont really have proof. I bought the headers almost a year ago when I was looking. I got the 1 3/4 b/c I wasnt going higher that 346 cubes, and wanted to maintain the low end for daily driving.

In some of the threads, some people would post #'s of 5rwhp or so more made with the larger primaries, and some people would post higher trap speeds. Then on the other hand some people would post losses of power/tq or no gains at all. In the end i went with what was proven and recommended to me from the people ive talked to with headers. I think i made the right decision.
If you are going with larger cubes in the future, 1 7/8 might be the choice so that you only have to buy 1 set of headers. I think that 1 3/4 is perfect for a heads/cam car or any bolton car.

 

Find a local tuner & ask him if he's tested headers. IMO, you will find that the 1-3/4" is gonna be the better choice for your current & future plans. As you've stated, it's best to have the proof.

Last Summer, I tested headers on my supercharged car & the smaller diameter header made more horsepower mid-range than did the larger header. Slightly higher torque was seen through the RPM range w/the smaller header. They both made the same peak horsepower. From what I saw, it would have taken approximately 100CFM more air movement through the header to get any benefit out of the larger header. I mention this as reference information related to a specific set-up. BTW, was moving 350 CFM through the header via a blower producing 9 p.s.i.. Header diameters were 1-5/8" & 1-3/4".

 

The tendancy seems to be that people to think that bigger primary tubes are better, but that's just not the case for those that are running stock cubed engines. Follow the manufacturers recommendations and you'll be happy.

 

1 3/4 is all you need, but i would look at the hmvc style. IMO its tops!

 

1 7/8 would be a very poor choice for a stock or less than HEAVILY modded 346. IMO you don't need/want them on a 346 unless you are spinning over 7000 and a drag car. definitly not on a daily driver for most applications. on my 408 I saw NO gains untill 6500 and lost a lot of TQ down low. if it was a DD, I would have swapped back to 1 3/4

 

I agree ih 383ss. The 1 7/8 are for big cubic inch motors. even with a head and cam, i would stick with the 1 3/4 headers. good luck.
Jon