i have afr eliminator 195 heads and hedman 68470 headers. the ports on the heads are 1.5" x 1.5" square, and the ports on the headers are 1.5" round, so the headers are kind of blocking the flow out of the heads. does this pose a threat to an exhaust leak, or will it hinder performance any? i have attached a picture to show you exactly what i mean. thanks.

 

You have a very nice set of heads. You will be killing the power with those headers. You were wise to check things out as a lot of people would have just bolted them on without checking. You need to find a proper set of headers that do not cover up the exhaust port. Be sure to check the header gasket so that it does not cover up the exhaust port.

 

I have the same problem. I have an old set of square port headers that I know wont fit my car, I was going to try to cut the flange off of those and try to mate the two headers together. maybe I can ,maybe I cant. problem to me is where do you find square port headers for a third gen?? I have never seen any. I'm pretty handy working with metal so I'll be the first to know. unless some one can save me the headache and tell me where to buy some

 

Dyno Don makes a very nice set of headers. He hangs out on the Southern California section of the forum. I have a set on my car and there is plenty of clearance. I have the Dart Pro One 200cc heads on the car.

 

You can use LT1/LT4 flanges. I know that Dan Lemons sells them as he put square flanges on my headers when he built mine.

You will or are killing a bunch of power with those small headers. If your handy with metal it is easy to change out the flanges.

SPD (specialty product design) in Rancho Cordova also sells flanges.

 

SLPs are square port headers, those are them on top... Here

 

I think i might have exaggerated on the picture of how it looks just a bit, after rechecking again, it doesnt look like that big of deal, the head port is between 1/16" and 1/8" inch bigger than the header tubes only in the corners, i have attached a more accurate picture, as you can see the the red portion is where the exhaust would be restricted, the picture is close to the actual scale of the ports. im trying to avoid buying different headers to make this work because i just got the headers back from jet-hot cost me about $200 total shipped both ways. and i think i paid like $50 dollars for the headers used. and the only headers that i found for our cars that have square ports are the slp's and they aren't even matched correctly to the size of the afr ports, they are tall and skinny ports, where as the head ports are a little wider than they are tall, plus i dont want to shell out over $700 dollars for headers. unless someone knows of a header that i haven't thought of that has square ports, i think im going to have some kind of restriction on the headers, no matter which i choose. if i would have checked out the port design more closely before i shipped them to jet-hot, i would have did a little fabrication on the header ports to make them more closely matched, but i dont think its a good idea to be grinding in to them now that they are coated is it? so what do you think i should do, should i just put them on and have some restriction or is there a better idea? and how much of a power loss would i be looking at? if it were only minimal loss then it wouldnt be that big of deal.

 

i have D port aluminum heads on mine that came from a vette and headmen headers makes shorties which is what i have for them but there a bitch to get on and you have to do some customizing i wouldn't recomend getting them but there out there.

 

step up to 1-3/4" headers.. haha

 

Not to revive an old thread but gathering info

 

Afr heads require 1.75" header ports to cover port. 1 5/8 could work but do block some areas. Not a huge concern as most of the port flow comes out the middle at high velocity anyway. Usually only a concern when looking for that last hp in all out race motors

 

Actually, most of the exhaust flows at the top of the port, with the short side radius done correctly. That is why most cylinder heads now have raised ports.
I ran across this same problem years ago, after changing to the correct headers I had to completely retune the motor.