How to decide header size? 1 5/8 or 1/3/4.

[kickascii]

I have an 85 Capri running a slightly larger cam .493/.510, E7 heads, a powercharger 174 pushing 11-12 lbs. of boost. Currently, I have MAC shorties and h-pipe but I am looking at changing the complete exhaust to:

Full length headers, OR H-pipe, Flows, turndowns...

How do you make the decision between 1 5/8 or 1 3/4 headers? I plan on going to Victor Jr heads one of these days but maybe not for a year or so.

I estimate 350-370 hp right now...

Thanks!

 

[86bluecobra]

the more power you make the bigger the exhaust you will need. I have 1 5/8's on my current combo. Seem to work well. If you are upgrading though it maybe worth your while to go with bigger headers. specially if you push the power north of 4oo ponies.

 

[kickascii]

The reason I ask is because I was reading other posts about torque loss on lower HP applications... I didn't know the recommended header for my car...

Hey, who makes the tubes that connect to the back of BBK H-pipes to flows? And where can I get them? Jegs have em?

Who has better prices than Jegs/summit for exhaust?

 

[Grn92LX]

1 3/4".

The 1 5/8" will restrict the victor jr exhaust ports.

 

[kickascii]

Thanks. Just to get off-topic for a sec, are they good heads for boost, or is something priced close to it that would be better?

 

[speadfreak]

1 3/4".

The 1 5/8" will restrict the victor jr exhaust ports.

I agree 100%. My motorsport 351w swap 1 5/8 headers line up perfectly (top to bottom) with the ports on my Vic Jrs, but side to side is a whole different story. There is enough of the port on the head being covered by the headers that there is no way I will even try to use these headers. The ports on the Vic Jrs are square and the 1 5/8s are rectangular. Buy the bigger ones and only have to buy them once, don't make the same mistake as me.