I need a new set of extractors for the race car. I was hoping to find some information that would help me decide on which to go for:
1) JTS 4-2-1 for about $324
2) Hurricane 4-1's for about $500 [EDIT $250 direct from Liverpool Exhaust]
3) Hi-Tec for ????
4) Genies (need to find second hand)
5) Custom made race headers from a reputable local manufacturer for $800.

Also, does anyone have better prices than these?

you will probably be best getting some custom made to suit the 1000 as others usually foul on the steering bits or firewall o something silly

yeah, I've tried one set of 2nd handies. I couldn't tell what make they were but they were 4-1's. It fouled on the 1000 steering idler arm big time, but just dropped into the 1200.

Jeff Taylor tells me his JTS set will fit 1000's no problem. I've also heard from two people that the Hurricane's fit 1000's.

Custom headers are the most expensive, but may be the only way to get a good set of tuned headers. I would love to know the length of the primary pipes on the Hurricanes and Hi-Tecs.

jts ones, if they fit without a doubt. we made great power with these on. Wouldn't hesitate recomending them.

all things being equal, 4 into 1 headers are 'the go' the reason tri-y types work well on V8s is due to some other V8 specific shenanigans (due to a 90 degree crank phasing and uneven firing of each bank).

Generally you need to look at those which have enough meat around the flanges so you can open them up so they are about 1mm larger than the exhaust port exit. If they are smaller, it's a blockage to flow. If they are a mm bigger, it creates an anti-reversion step (pics on request) and helps extend the lower rpm range of the extractors with no loss up top. Similarly, where any joints are - mostly the collector on 4 into 1s - it's important that the next pipe along is flared and slips 'over' the pipe it connects to. On cheaper ones they slide the pipe inside and weld around, and on the inside, where the exhaust flows, it's like a big air dam/parachute and rules out 90% of the effects.

Beyond those issues, which are mostly those workmanship rather than application specific (i.e. they apply to all extractors) the next thing is a fairly well known about 'science' . Basically if you know the capacity of each cylinder, and the rpm range you intend to run it in (in your case the racing rpm range, with little thought for anything below it relatively speaking) there's a formula for working out ideal primary pipe diameters. Conversely, if you know the pipe diameter, and cylinder capacity (easy enough) you can work back and determine what rpm range they will work in. Of course pipe _length_ does influence the powerband, but it's _very_ mild compared to pipe diameter. People harp about equal length primaries - and that's all well and good - as long as they are all equally the 'right' length. In practice, since the length isn't the big influence it's made out to be, a couple of inches difference from pipe to pipe is nothing to lose sleep over.

The 'formula' is based on the fact racers over the decades (well before I was born) noticed that if the average (not peak) exhaust gas speed was up around a certain speed (and I bloody forget exactly what that was) it'd produce the biggest lift in torque at the rpm where that happened . So based on a cylinder volume, if it's spinning at a certain rpm, and has to push all the exhaust through a cross section area of a known size, you can work out the gas speed.

Rather than go through all the stuff, here's the formula (and note it's based on pipe INNER DIAMETER - and most extractors are listed by pipe OUTER diameter. I usually just take 1/8th of an inch off the id and am done with it.


R= rpm
P = primary pipe area in sq inches
C = capacity of one cylinder in cubic inches

R = (P x 88200) / C

TO get the primary pipe area simply divide the id by 2 then multiply that by half the id, then by pi - 3.14159

i.e. (id/2) x(id/2) x 3.14159

If you need to calculate the cylinder capacity, there's a small calculator called engsize.exe or similar on http://billzilla.org

And for converting cubic inches to cc or vice versa do a google search for 'convert.exe' a brilliant freeware program.

Let's do an example :]

A 1200 engine (which is technically what - 1171cc??)

a12 - 1171cc or 292.85 per cylinder or 17.8708 ci


and we have extractors with a 1 3/8 od or 1 1/4" i.d. (approx)

1.25/2 = 0.625

so 0.625 x 0.625 x 3.14159 = 1.22718359375 -

I round that down to 1.227

So the pipe cross section is 1.227 sq inches and the cylinders are 17.8708 ci


R = (P x 88200) / C
R = (1.227 x 88200) / 17.8708
R = 108221.4 / 17.8708
R = 6055rpm

So what that means is that for a std bore 1200 motor, 1 3/8 OD primaries provide the strongest torque boost at 6055rpm. That doesn't necessarily mean that the torque peak will be 6055rpm - not at all - just that these extractors will be in _their_ sweet spot at 6055rpm. In practice, they happen to function very well a good 1500rpm either side of that, often as much as 2000rpm either side of it.

If we did the same on a 1500cc engine, it'd be more like 4750rpm for the same exact extractors.

As for collector sizing, it's more down to experience. On a 1.2 you'd be looking around 2 inches, and probably 2.25 on a 1.5litre for most apps though you'd tweak it either way depending.On primary length, it'd depend heavily on cam choice etc, but you'd not be hurting with up above 32-34 inches on a 1200 (which is in all probability far longer than any off the shelf unit would actually have.

If you can discuss the combo a little more, a more specific answer could be given. I've taken the stance that it's better to talk about the dimensions/design you'd most want rather than brands, as believe it or not, amongst different brands, their headers for some engines are really excellent and for other engines are woeful.

The above math has been refined above and beyond what I've outlined above. There is software that can calculate it down to the half inch for lengths with no sweat. I don't actually have it, but know someone who does, and I reckon they'd be willing to plug the numbers in if I emailed them about it, if you like.

My vote goes for 4 into 1 stepped headers. Especially since its for the KB10 track car.

big post and i can see you dne your homework
and heres some extractors i bought a while back that seem to be quite nice dont knw if they bolt into a 1000 though

My vote: Custom,with 3 bolt
flange followed by a flex joint.

if its for a race engine 4 into 1 would be best normally and 4-2-1 better for street, but the JTS would have the reputation and i bet probably tuned length, if its for racing u want the best which would be tuned length for every last hp edge.

j-mac, 4 into 1 are most popular on 4 cyls now because most afre fwd and work out a lot neater fitting with the limited room between block and fans, they often do end up with massively long primaries snaking right under the engine and make peaky powercurves with gutless bottom end. I think u meant straight 6's about the tri-y's.

1000coupe - I was talking tri-ys on v8s where eac 'side' has 4>2>1 (which is 3 Ys - 1 for each of the primaries to secondary pipe, then a final one (per side) from the secondary to the main collector. I wasn't suggesting they are popular on 4s, just aiming at a quick once over as far as why they exist at all. There are indeed tri-ys for 6s - 6 into 2 into 1 - but I'd suggest they are done to make for less total piping/space taken up, 6>1 still work better.Sorry if my post is confusing - I'm far from an expert, but my biggest drama is I tend to understand stuff a little bit better than I can effectively/clearly discuss it!

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opkey dokes - in that one the final pipe out of the collector might be tucked inside the 4-1 flange. Here is a pic (it was done for another forum some time back so please ignore the fact there are only 3 primaries - it was done to show an inline 6 with 6-2-1 pipes. The 'blue' area shows where it would trap heaps of exhaust flow. On some I've had (one for a hemi 6 in fact) the final pipe tucked a good 1.5 inches inside the flange, making a big obstruction to flow. In your example, nobody could say without cutting it off. If you cut carefully around the weld you could pop the pipe out without cutting all the way through, then flare that same pipe and re-attatch.




The second picture is as referenced in the first post - at the top is a 'typical' extractor - where the flange obstructs the port exit ever so slightly. The second is 'port matched' which is good, but the bottom one is opened a touch further to create an anti-reversion step (if the exhaust tried to go back in the port, it'd hit that step/edge and less would get in there). The green on that final picture is to show that in some cases, you might have to add weld (mig is good if you have access, I've actually done it by oxy a couple of times, because that is what I had) on the outside meeting point of flange and primary pipe.




Last thing I'll show - is photos of some extractors a mate got for a hemi 6. The port 'holes' in the flanges weren't cut straight - so when it looked 'lined up' on the outside, it wasn't on the ports. In the worst case, it blocked more than 1/4 of the port on the worst one. That had to be welded up to buggery to get it to line up - I had to actually add steel to the flange because I had to grind out past the end of the flange to line them up!! On which note, they were coated (they weren't manufactured by) jet-hot - a great coating. but since they had to be modified, that coating had to go for the welding to be done. I'd _strongly_ suggest sourcing extractors as is, then ensuring they fit optimally (or making them do so) and then and only then get them coated if you wish to.













The extractors were fitted originally at an exhaust place, and when it started to leak, we took them off to look, and you can see by the carbon deposits how far off they were. In the last pics, you can see that the entire left wall of the flange is actually new material. Given the amount I had to add to them, I thought for sure they wouldn't last, but they ended up on the car for a fair amount of time (approx 12 months) and didn't crack (he ended up upgrading to new pipes with larger primaries anyway)


The only other thing that comes to mind - Although I discussed the rpm sweet spot of headers vs their primary pipe diameter, it should be noted that pretty much _any_ extractors (the aforementioned issues notwithstanding) will provide a power boost - simply because they (combined with a freer flowing exhaust from there back) reduce exhaust backpressure vs the factory cast iron style stock (the GX ones, that I've only seen pics of, are likely a different story) and less heat under the carb - all of which boost power. What it's about however, is getting hold of all the potential gains - the drop in backpressure/heat _as well as_ the gains from optimal pipe sizing.