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hey guys,

Can I have a volunteer or heaps?

Can a few people please measure the diameter of their header primary tubes and report back?

This format please

Engine: 1990 B6
Extractor tube size: 1.5 inches (measured straight after it comes off the head)
Brand: HKS


Im just trying to get an idea at what the competition is doing so I can purchase some stainless bends and start making a couple sets.

Thanks,
Dann

No one has extractors?
Soon you can because Im about to build some..... A little help?



Dann

not that no-ne has extractors....

More the fact it's only been an hour or so since you asked!

Yeah Im getting greedy

Dann

Hi.
My 4 into 1 extractors have 13/4" primary pipes with 21/2" secondary which work extremely well with cams and work at their best up high.
4 into 2 into 1 i have are 11/2" primaries with long over and under pipes from the collectors and merge almost at the flange. Very good for torque.
Hope this is of some use.

Thankyou, thats great information.

You dont happen to know the length of the 4-1 primaries? Also they are BP extractors right?

Thanks, Keep them coming please,
Dann

you should also be asking for the length

I dont plan on making copies. Length is easy to calculate for a certain powerband. The hard part is working out exactly what manufacturers are doing to get the primary pipes to match up nicely with the head flange.

Dann

Hi.
Information on the Cusco ball chamber 4 into 1 extractors which i have for my 1.6 NA.
Primary pipe lengths = 17.25 " to the ball with a further 2" inside.
These have round pipes welded onto the flange. Some brands have the pipes end the same shape as the port which are pressed onto the flange these usually leak and the stainless end which has been formed to the shape of the port cracks.
Will not affect the efficiency if you weld a round pipe to the oval port.
Hope this is what you were referring to.
regards

According to some literature I have, the slight step will actually help prevent reversion, which would be bad on a 2 stroke but good here.

It seems there is multiple ways the manufacturers Ive seen go about it. They either go 1.75'' pipe and leave it round, or shape it.
Or they go 1.5 and shape it, or even 1.25 and they insert it into the port hole in the flange and then use a round mandrel and a hammer and shape it to be the same as the INSIDE of the port and then they weld it in, like factory.

I think Ill stick with 1.5 and 1.75 and leave it round (well the 1.5 will need to be slightly squashed to be as wide as the ports).

Please guys more measurements.

Dann

Just go buy the extractors Dann

I plan on selling them as part of a complete head flange to exhaust tip system. I just want an idea on whether to make a mandrel for the header flange or not. And also see what manufacturers are actually designing them for performance or ease of manufacturing.

Dann

Hang on - is Dann thinking of doing something because other people do it? Holy crap, what will happen next!

Racing Beat website has a good page on their header development.
http://www.racingbeat.com/mazda/perform ... pment.html
http://www.racingbeat.com/Miata-1990-20 ... 56008.html


Racing Beat 4:1
1.6:
1.5" primaries, 2.0" secondary

1.8:
1.7" primaries, 2.375" secondary

edit with better link and raw data

Thanks Matty.

Keep em coming.

Dann

Can you make one for the nc ? shipping is so expensive~