Header question

[ShagFestiva]

For an N/A, stock, 1.8 sohc, what would be the best header primary diameter? I was thinking 1 3/8".... 1 1/2 just seems too big.

[FestYboy]

holy crap!!!! you live!!

for the b8/BP engine (N/A) i would go with a tube diameter the same size of the HIGHT of the manifold gasket hole and then step up 1/8" after the ENTIRE port length reaches the same length as the intake runners (including port length). gasket matching will help here as well, you don't want a step right after the valves (it shrinks the port size).

[ShagFestiva]

ha yeah im alive, school and work got me busy. Making a header in my minimal spare time though. I milled out the flange, matched to the gasket. Hardest part is making a smooth transition from the oval shaped ports on the head. I took (i believe 2" OD) seamless pipe and crushed the end with a press until it was the same shape as the holes in the gasket. It actually worked out pretty well, I was surprised. Im not sure what you mean by "step up 1/8" after the ENTIRE port length reaches the same length as the intake runners (including port length"

[FestYboy]

the primary tube should step up in diameter once the tube (and port) length matches that of the intake runner (and port) length. then move onto a collector and whatnot.

[Pu241]

Denver, PA!
They make a great Hot Dog!

[FestYboy]

oh yes they do!!! just got another case last week, it's future is looking bleak

[Pu241]

oh yes they do!!! just got another case last week, it's future is looking bleak

You could drive over and I'd fire up the grill.
Or do I hear it's time for another Winter get together at the Firebase?

[FestYboy]

tempting...

[91mcnasty]

I MUST have more dogggsss!!!!!

[Pu241]

It can be done!
Going to be there next weekend anyway!
But only Festyboy has the inside source for the Denver Dogs!
So he must bring them!

[ShagFestiva]

I live in denver and im not sure about these so called denver dogs haha. I have the gasket at school, i'll measure the height of the port today and see what we get. I'm trying to do a try-y style header with a twist....cylinder 1 and 3 will come together and cylinder 2 and 4 will come together. They will stay seperate and exit the sides in front of the rear tires. Since the firing order is 1-3-4-2, 1 and 3 will be exiting one side and 2 and 4 will exit the other side....I'm interested to see what it sounds like. I'm not really worried about performance gains, just as long as it sounds cool haha.

[Movin]

With the probable difference in pipe volume - length it
will sound like one of those Can Am Spyders !

[blkfordsedan]

IIRC, for optimum scavaging effect, 1&4 and 2&3 should be paired up (based on 1-3-4-2 firing order). Why the 1/3 - 2/4 design, just for the sound?

[ShagFestiva]

.

[ShagFestiva]

IIRC, for optimum scavaging effect, 1&4 and 2&3 should be paired up (based on 1-3-4-2 firing order). Why the 1/3 - 2/4 design, just for the sound?

Yeah just for the sound. I'm not too worried about performance... i was always curious about what it sounded like...cylinders 1 and 3 firing on one side of the vehicle and then 2 and 4.

The height of the port is 1 1/16" so I think im just gonna go with 1 1/4" the whole way