Steve Ference

How do they fit , how is the quality , they look ok on the website.

I will ask xspower the dimensions of the flange ports.

fishslayer143

2 inch primary? what are you putting them on ?

Steve Ference

434 ci sb 13.5:1 with Big Shot NOS system. No street use anymore. 1 7/8" headers at the moment.

tektrans

Idk what you're 434 makes power wise but FWIW, my old Lsx 441 made just about 750-775 fwhp-I switched from 1 3/4" primaries to 1 7/8" primaries and I gained absolutely zero.

So assuming your 434 makes 650ish hp and you are using a 250 plate shot, that would put you at 900 hp, the 1 7/8" may well work fine, although 2" couldn't hurt-especially with nitrous.
What #'s are you making and hitting it with?

fishslayer143

If it will spend most of its life at WOT , you may get some benefit ..but a street car would likely see no benefit at all

diehrd

I wonder if it will require a flange set up to allow installing them ? I run 1 7/8 myself and 2" would be a tight fit I am sure of it.

If you have them or can make them go for it, It is win win on any car to have a free flowing exhaust

gkull

I have owned and worked on non spread port sbc. We used the big primary tube header adapters. The typical tube size on high power sbc s is 2 1/8th or 2 1/4

Generally speaking it is more desirable to purchase spread port heads and go with custom weld up headers with merge collectors

ajrothm

Interesting....

On my buddy's 11.7-1 420", dynoed it with 1 3/4" and it made 630, he switched to a 1 7/8" and it gained 10hp, made 640 on the nose. Definitely not worth the expense of the headers but...it did gain a LITTLE something...

I would definitely think at 800+hp, I'd run a 2" headers, especially if its a 6500+ engine

jb78L-82

I have the XSPower headers on my 355 L-82 and they are a great deal. My only issue was that I had to dimple one of the passenger header primaries to clear the idler arm before I had they ceramic coated. No other issues other than I had to loosen the starter to get them in on the passenger side from underneath and remove the clutch Z bar on the drivers side. No issues with spark plugs. Read this thread as well:

https://www.corvetteforum.com/forums...re-back-4.html

Steve Ference

Thank you Sir for answering my question.

And to all others for their input.

jb78L-82

Welcome!

I had to read your original post because I could not follow based on the responses before I answered your question.

tektrans

Just my luck

ajrothm

Mine too.. lol

diehrd

OP my bad , You called them 2" headers the XS power are 1 7/8 I have them on my 1980

They do HIT the idler arm , BUT no need to dent them, just loosen motor and trans mount correct the alignment of the motor and trans. Tighten trans mount and then motor mounts and you will be set

Steve Ference

Are these the headers you have ? No part number so can't tell what the Chinese guys have made.

http://xs-power.com/chevrolet-headers-4.htm

It says these are 2" primaries.

I will call them and ask what they are selling. I already have 1 7/8" primaries.

I was going to buy these then change the collector for merge collectors i already have.

diehrd

Exactly that set.. 100% I have photos of them on here somewhere

Steve Ference

Ok, so info on website is wrong, how surprising.

jb78L-82

I have them also and they are not 2 inches,,,,,

MotorHead

They look like the headers I helped to design 6 years ago.

Unless they changed the primary tube to 2" which I don't think they did,mainly because there is not enough room to go that big on a 23 deg. head.

BTW they are a steal for the price. I have had them on my 427ci small block for 5 years and they still look nice.

diehrd

I will add this NO ONE FROM ANY site sells headers as good as these . NO one... Not even a close second they are for sure the best header I have ever laid hands on for a SBC and lucky us they fit a c-3