1 3/4" vs. 1 5/8" headers

BoeingMan · August 4th, 2006, 03:31 PM

Gentlemen, I was wondering if those who have ran both types of headers can chime in with some much needed advice.

I was wondering how much more power does one header size offer over the other.

Or is it a matter of when the power kicks in and/or tops out over the RPM curve.

I am almost ready to make a purchase and this info would help tremondously.

As always thanks in advance.

99 RT/10 · August 4th, 2006, 03:39 PM

For a N/A car, 1 5/8" header would be fine. Even if you were to add a cam, the 1 5/8" should be good, but if you plan on adding NOS, S/C you want to go with the larger 1 3/4". The larger tubes will aid in A/F and develop more HP.

BoeingMan · August 4th, 2006, 04:07 PM

Quote:

Originally Posted by 99 RT/10

For a N/A car, 1 5/8" header would be fine. Even if you were to add a cam, the 1 5/8" should be good, but if you plan on adding NOS, S/C you want to go with the larger 1 3/4". The larger tubes will aid in A/F and develop more HP.

For an engine that is stock would I be giving up any HP/TQ using the larger diameter hdrs?

The reason I ask this is why would anyone buy the smaller diameter headers therby chocking themselves from airflow when future HP upgrades are installed?

There has got to be some good/bad when installing one hdr over the other on a stock engine.

...and when does the HP/TQ kick in or peter out is this a factor as well?

Thanks

FE065 · August 4th, 2006, 04:52 PM

On the one hand, a 488ci Viper engine can be thought of as a 390ci 8cyl with a couple cylinders added. What size tubes would a mild 390 use?

Primary Tube Length
Determines torque above or below the peak horsepower RPM point. Shorter tubes add torque above the peak RPM point and reduce torque below. Longer tubes add torque below the peak RPM point and reduce torque above it.

Primary Tube Diameter
Determines peak horsepower RPM point. Use small diameter tubes on small CID engines to produce mid-to-high-RPM torque. Use large diameter on large CID engines to produce mid-to-high-RPM torque. If in doubt, use smaller diameter tubes

..You could just go with the bigger tubes and incorporate the Z06's exhaust butterfly valves

GTS Dean · August 4th, 2006, 05:09 PM

If you run the car on a 2+ mile road course with any degree of frequency and a moderate amount of skill, you should get the bigger tubes. If most of your time is street with occasional wfo romps, get the smaller tubes and enjoy the torque.

FE065 · August 5th, 2006, 07:42 PM

Aren't the 2001s (and other creampuffs) known to not respond to headers as well as earlier models? - At least when the headers and maybe catback are the only mods on the engine?

**Chuck 98 RT10** · August 5th, 2006, 11:31 PM

Quote:

Originally Posted by BoeingMan

The reason I ask this is why would anyone buy the smaller diameter headers therby chocking themselves from airflow when future HP upgrades are installed?

It's not just bigger is better. It depends on many other things. Cam duration being one of them. Too much flow and you will just be pissing unburned fuel out the exhaust as well as affecting compression.

opnwide · August 5th, 2006, 11:38 PM

383 chevys routinely use 1 3/4 inch. I wouldn't go 1 5/8. The Viper has plenty of torque already.