I went down the road of very long primaries (1.5" x 28") baffle collectors then short secondaries (1.75" x 12") then a merge collector to a 2" diam. tailpipe.

Info for these dimensions is from "Four Stroke Perormance Tuning" by A Graham Bell.

These pipes perform like 4 into 1`s but with more midrange.

Cost only $280 in 316 stainless mandrel bends and tube. but about 30 hours of work!

A15, 271deg cam, hi comp, 500mm intake runners and injected.

I will have a look at a set I have tomorrow because I know they foul the idler arm in my kb10.

What they actually foul on is the grease nipple on the idler arm, so fingers crossed if I take the nipple out and plug it with something it might work. l'll let you know when I know.

Cheers

Daniel,make sure you guys do a trial fit before parting with any dough,i still think they'll foul on the idler arm.
Cheers

Also they are 4 into 1

you could always look into Coby extractors from Coby Manufacturing in Hamilton, NZ. I use them and they look good, although how they fare in terms of ultimate performance I'm not sure. Also unsure whether they would fit the 1000 but they would probably be able to tell you. The model you would want is the twin carb model, it doesn't fit when using the standard inlet manifold. I could probably give you some measurements ie tube dia. and approx length if needed. I would say looking at them they would be approximately tuned length but not exactly.

Thanks for all the input guys!

Jmac: Excellent information - Thanks very much! I've tried similar methods to the one you presented. Your method produced the same length and slightly larger diameter than the method I've used previously.

Datto1000wagon: They look like a decent set of headers. They are the shortest shortest primary length I've seen on any 4-1's for a Datsun.

My gut feeling is the same as yours, Benny & 1000coupe. 4-1's are for the track and 4-2-1's are for the street. Thats the main reason why I'm kinda snobbing the JTS units at the moment, despite all the good reports they get on this website.

Got a price from the manufacturer, 'Liverpool Exhausts' for the hurricane 4-1's. They are $250 direct plus postage (which sounds really cheap to me). He's going to give me the diameters and lengths tomorrow. I'll post them up when I get them. Oh, and the Hurricane headers are Mandrel bent, unlike the Hi-tec's.

Also, just to clear the air for others, the parts Stewart Wilkins Motorsport sell are the JTS items.

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.

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.

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

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