formula17

iTrader: (4)

I want to get a set of 1 7/8 headers from kooks for my L92 in the works. Question is Do I need D port flanges or can I use regular LS1 style flanged headers? Saw a couple used set on here and was wondering how they would work or if they would effect performance because of not being the D port?

Thanks,
Nick

RGKSR

iTrader: (9)

I'm going to use my Dynamaxx's for my L92 heads. LS6's also have "D" exhaust ports. I'm not aware of specific "D" port headers?

Some people got with 1 7/8 primaries, but I'm going to wait to get new headers.

Bob K.

osuqsz06

iTrader: (2)

no, ls7's have d ports. i went with american racing 1 7/8 ls7 (d port) flanged heards w/ 3' collectors

the_merv

iTrader: (88)

I was looking at Pace Setter 1 3/4 Headers just to keep it with a little bit of Back Pressure in the Exhaust, I was going to run from there a X-pipe, and then into 2 Bullets dumped infront of the Rear Axle, all 3" setup.

EarlSS

osuqsz06

iTrader: (2)

for best results ur still gonna want to have a d port flange for the l92 heads.

WKMCD

iTrader: (2)

I'm running American Racing LT's w/ a round flange on mine. CNC'ing makes the port rounder anyways.

Before and after L92 pics of the WCCH Stage 2 heads.

jtl12419

iTrader: (13)

For the best effect of the D-port on the cylinder head, you DO NOT, DO NOT want D-port on the matching exhaust face. Round is best,

superssport

iTrader: (150)

I am not trying to be difficult, but why? I am also looking into this and called kooks today. They told me that for an extra $175 they will put d port flanges on your choice of headers.

formula17

iTrader: (4)

Id like to see an ls1 exhaust manifold gasket held up to those cnc'd heads to see what it looks like, Im sure somebody has a set not on their engine yet Makes sense if the round port 1 7/8 header is bigger then the the D port why you would want to use that one.

WickEdSix98

iTrader: (4)

What he said.

jtl12419

iTrader: (13)

D-porting of the exhaust port is one of the key developments in latest head design.

"The "D" shaped exhaust port is designed to provide a larger area for increased flow and velocity as well as to create a mismatch between the exhaust pipe and the exhaust exit. This purpose-built mismatch reduces "power-robbing" reversion by keeping the majority of the exhaust gasses from going back into the engine."

Keeping the port and exhaust shape/size mismatch actually increases the flow/velocity of exhaust gas pass the port.

That's why you do not want to match the port with the exhaust. You cetainly dont want to lose the benefits of the D-port port by matching the shape of the header to the hole.

Hard Core Z28

Makes total sense. I just think d shaped headers are just a way to make more money. Round flanges will do just fine.