AirBusPilot

My 71' has a cnc motorsports 415ci engine that came with a dyno sheet showing 551 hp.

551hp - 6000 rpm
550hp - 6100
551hp - 6200
545hp - 6300
533hp - 6400
526hp - 6500
532hp - 6600

I bought the car this way. The PO installed "tri y" headers, and I just measured the primaries at 1 5/8".

I called cnc and asked what headers they used for the dyno session and was told 1 3/4 stepped to 1 7/8".

They also told me to switch to standard 1 3/4" headers and sell the tri y's.

I should have asked them, but how much hp is being lost by using those small tri y's?

Second, installation. Just eye balling the car it doesn't look hard, but any tips on installing new headers?

Third, I have AFR angle plug heads. I assume there is no issue between those heads and the Kooks headers?

Any info appreciated, thanks!

AirBusPilot

Dang, I thought this new thread would be swarming by now.

pauldana

I run kooks 1 7/8 tubs on Afr comp-ported 220 heads,,,, they fit very well with the exception of my rac-n-pinion .. But I just had to make a small demple in one tube

They are amazing headers ..... Mine are SS and ceramic coated..... Get apr studs and nuts 12 point .... But they will be a tight fit!!!

AirBusPilot

Thanks, Paul. Yep, I'm not skimping out and supporting China on this..it'll be Kooks. 1 3/4" size.

BTW, I have the Borg PS system. I'm thinking I have even more room for the install.

pauldana

You have a 415ci... Go with the 1 7/8" ceramic coated SS

AirBusPilot

Yeah, it's on the border with the ci and hp to go with either. Just depends if I want to shift the power higher or lower.