Extractors - 4 into 1 or 4-2-1 for track days

[evil_weevil]

I tried searching but didnt have too much luck!

I know when I had my old V8 Ls1 (many years ago) a 4-1 system was good for more top end power, but it lost some low down and midrange over a 4-2-1 system
However what is the best for a 1994 1.8 clubman?

Its main use is a track car, so I'll be in the higher revs at the track, would it be the same, a 4-1 extractor system for top end on these motors? What do you other guys have/reccomend?

Sorry if it is a noob question! Im new to all this as coming from a skyline for 3.5 years of ownership

cheers,
Chris

[green_comet]

I have always been told 4-2-1 for the road and 4-1 for the track.. I had 4-1's on my old 4age Sprinter, and it was a slug off the line, above 5k however its was heaps of fun, was painful to drive on the road though.

So I would say if its for track go good quality 4-1's

[PUR157]

I know this probably won't be much help but I've heard a well designed set of 4-2-1 headers can cater for mid and not lose out at top end either?
Maybe I misunderstood the information presented to me at the time...

There might be some merit into looking at individual brands or individual opinions?

For myself I have a set of NPower (racing beat copy) 4-2-1 attached to an enlarged 2.25" custom exhaust
compared to when it was stock there is abit less torque down low... once I get to the mid range (say above 3) it starts pulling well
Strangely enough I don't venture much to the redline anymore since I'm already doing silly speeds going at it in the mid range

I also find I'm typically one gear lower than I used to drive (modified compared to stock)

[AB7]

Honestly, in MX5 the difference will be very minimal between the two....unless you build a Hi-po N/A machine. Otherwise, they are pretty much the same.

[RG.net]

Honestly, in MX5 the difference will be very minimal between the two....unless you build a Hi-po N/A machine. Otherwise, they are pretty much the same.

basically, if you do plan to "Hi-po N/A machine" then go for 4-1's, bear in mind they are pricey compared to the 4-2-1 setup's, also not as many companys make them.

[AB7]

Racing Beat probably makes a reasonably priced 4-1 extractors. Most of the japanese one will set you back $1.2K. Some 4-2-1 design one like Maxim Works will set you back over $1.2K. They are not cheap and don't expect massive gains either.

Do a search on Racing Beat website, they published an article a while back comparing 4-1 to 4-2-1 design on their NB.

[manga_blue]

There's not much in it really. Quality and detail design is probably more important than 4-2-1 v 4-1.

In theory 4-2-1 is better for bogging out of corners and easily compensates for the little extra you might get at the top end with 4-1. In practice a good 4-2-1 is better than a bad 4-1 throughout the range and vice versa.

[evil_weevil]

Thanks for the reply guys!!
Yeah there seems to be a bit to think about! Pacemaker headers seem to be ok??
I guess my plans for the motor are going to be still n/a with cams and ecu for a while.
Thanks again, cheers, chris!

[kazjim]

I've built a few 'race' motors and a few 'street' motors, and as above ,the difference will be minimal.... but there will be a difference ...

I've got a calculation around here somewhere that you put cam durations, valve diameters, piston diameter, rod length, stroke, etc etc into and the output was a perfect set of extractors for your motor...

Notice I say "Extractors" - most of us have "Headers" - very different...
Headers = more efficient exhaust than a cast-iron log
Extractors = Tuned-length, designed for a specific rev range.

Examples
On an escort 2.0 litre motor, very cammy (270' duration), pair of DHLA carbs, great ignition system ... Best design for the track was a 4-1 system with 41" primaries at 1.25" diameter .... collector was 3" and tapered down to a 2.5" main pipe with a mega-phone style exhaust (race engine - no mufflers back then )

An 1100cc Mini Street engine (two inlet, three exhaust ports) - twin 1 1/4 SU carbs on BMC 'Log" inlet - we used a "LCB" design (Long centre branch) - the two outside pipes are shorter than the middle "shared" pipe by about 30% ! - very street friendly, and analogous to the 4/2/1 headers most of us run .... probably picked up around 5% under 4000 and maybe 7% above that ... - peak power happened around 6500, so not much point designing anything better

Torque under 4000 was down on the 'stock' motor, but from 6000-6800 the peak torque increased around 15% .. above this it dropped again ...

The secret is to match your components - your diff gearing, gearbox ratios, everything all the way though to the air-box works together ....

On the street and on a 'weekend warrior' its not worth the effort, but for a 'pure' race car its definitely worth the extra work ...

Wow, long answer, but it might help someone

J

PS - the Stroke to rod-length ratio is one of the most important parts of the calculations ..... Hmmm, might have to look into the Na6A engine one of these days .... looks like it might be a little powerhouse if treated right

[Okibi]

... Notice I say "Extractors" - most of us have "Headers" - very different...
Headers = more efficient exhaust than a cast-iron log
Extractors = Tuned-length, designed for a specific rev range...

It's a fine line, I expect that Mazda tuned the headers to produce a specific torque curve and exhaust tone, but they probably had a limited budget and would need to design the headers to be mass produced. The yanks got the horrible cast iron headers on their early NBs perhaps Mazda ran out of time to design a good exhaust system to accommodate left hand drive.

[philz]

What? When did extractors and headers ever become different?

quick squiz on google....

What is the difference between headers and extractors?
None! In Australia, headers were known as extractors through the 60's and 70's by the pioneering companies that developed them. In America at the same time they were coined headers (also spelt hedders). This was in part due to the fact that they (headers) are an extension of the cylinder head. In the 80's new Australian companies, along with the established industry, began to market extractors as headers. The main reason being that these companies intended to change the image of the humble extractor to more of a common vehicle replacement component. Some 'old school' enthusiasts still call them extractors today.