I have a .030 over .454. It has cast heads that are ported, dual plane intake and 850 holley. The primaries im running now are 1.75". I want to go bigger. I am thinking 2" but found a deal on 2.125". It is a dual purpose car street/strip. runs 12.0 now. Bigger better or bigger badder?

Whats the rest of your combo? Cam,compression,gear..all that important stuff smile.gif
Current trap speed?

Bigger is not better or badder. In the parlance of Ed Henniman you would be making a 3 tube size error. I would stay with the 12 second headers on the 12 second car.

Pass. Those are for some kind of 750+ hp beast. They'll lose so much velocity you'll wonder where the heck all the bottom end went.

onovakind 67&427L88 ....... gave you good info , if you really want to understand header sizing go to Headers by ED 's site or call Jere Stahl .......I bot a set of custom made tuned length headers from Stahl and primary pipe size is 2" for my BB ( I told them to size for open drag strip use ) but right on the edge for 1 7/8 so they made collector 3 1/ 4 to bring back some torque ..... my motor dyno'd at 594hp .....ED has a chart that shows primary pipe and collector size as it relates to HP .... after I dyno'd motor I checked the chart and it was bang on graemlins/thumbsup.gif ...... Bill

[oops sori

There were members here running 10's with 1.75" headers. The 1.75"s are probably the near perfect size for your application. What is you collector diameter? What is your tube length? What are the peaks for torque and HP?
Are you running open headers at the track? or some type of exhaust system?

Primary tube diameter is just one part of the design of a good set of headers. Other things to consider are primary tube length, collector diameter and length, collector configuration, downstream components like x-pipes, crossovers, tertiary pipes, etc.
Jack Burns has designed some headers for the mid-11 second 327/350 SBC's in G/H/J/SA that use a 1.5" primary tube diameter, not usually seen in an 11-second car.

Originally posted by lwop2000:
I have a .030 over .454. It has cast heads that are ported, dual plane intake and 850 holley. The primaries im running now are 1.75". I want to go bigger. I am thinking 2" but found a deal on 2.125". It is a dual purpose car street/strip. runs 12.0 now. Bigger better or bigger badder? =
To sum up,, HUGE MISTAKE :(
Pun intended :D

Sorry,,, couldn't resist,, no self control :rolleyes:

sounds like its unanamous.

to answer (whats the rest of the combo)

comp cam 578/574 @.050
248/246 dur
10.4:1 compression
3.73 gear
3500 stahl conv
12.0 at 110mph
60ft 1.68

OK, I've spent the last 30 minutes searching for this chart by Ed Henniman..... and still haven't found it. Can someone please post a link to the chart? Thank you in advance!

The chart is not on web site ........... part of package that you get when you buy his headers or I beleive you can buy his Info pkg.and it is included