Header size for Nitrous Small block

[HotStreet3134]

I'm in the process of building 445" SBF with Trick Flow high ports (1.600 valve with 1.750 port @ the flange). Looking to make in the range of 850+ hp on motor and spraying in the neighborhood of 2000 pph (500 ish hp), peak hp will be 8300-8500 rpm (roughly), cast intake with single 4 barrel, built for Ultra Street. I've been doing alot of reading on Mr. Elston's website and blog which has me kinda reconsidering my original plan of attack on the header/collector sizing.

I was originally thinking about doing a 2.125 to 2.250 to a merge collector with 4" choke to 4.5" outlet. After reading Mr. Elston's posts, etc., I've started thinking about a 1.88" for 4-6" to 2" and then 2.125" with a 3.5" choke to 4" outlet OR 2" for 8" then to 2.125" to 2.250" with a 3.5" choke to 4" outlet. I don't want to go too big but don't want to choke it with too small of a tube.

Anyone willing to share any insight or experiences on a similar build, would be greatly appreciated.

Thanks,
Ryan

[exhausted]

Match port area at port and step as many times you need to be at 2.25" @24-25 inches from the head. You'd be safe with a 3.375 or 3.5 collector. 1200 hp. You can make it bigger but that is all you need.

[Amilcar]

Calvin,

Could you comment why we can see some hi nitrous users, with barely no collector?
I`m sure someone posted around here and no one gave a good grasp of why.

[exhausted]

Calvin,

Could you comment why we can see some hi nitrous users, with barely no collector?
I`m sure someone posted around here and no one gave a good grasp of why.

Sure, when you get to a power level beyond the exhaust valve and port size' ability to evacuate the cylinder of pressure because the pressure wave is so big and long, there is no longer any benefit to try and use a collector to scavange. It is not able to reduce the pressure in the system and help exhaust get out. The valve diameter and ports simply can not do the job and larger tubes can not fix that problem. Hope that makes sense.
You just need to reduce flow resistance any way possible. I could see how nitrous motors only future against supercharged motors is cubic inch and keeping rpm' down. Just thinking out loud. I don't normally deal with those things.

[HotStreet3134]

Thanks for the reply Calvin!