Decent set of AE86 headers ??

[QikStarlie]

What ever you end up with, run a big exhaust after the collector. Got massive midrange gains running a 3" system on my old big cam setup, started off with 2" system then went to 2.5" then ended up with 3." while there wasn't big gains going to the 3" from 2.5 was still worth doing. the more cam overlap you have the more effect it will have. but there isn't going to be any negative effects other than weight, if you dump it into a massive system after the "tuned length" of the collector.

for example, i ran the same 3" system on stock cam engine, with no negative effects. made 90kw on torque performance dyno. nice fat power band.

also, im running 193b kelfords now. which are similar to those ones i sold you awhile back. maybe bit bigger? so our setup's are pretty similar now i would think.

[jondee86]

Ha I thought I had a 60 dia exhaust system , but I got fooled by the cat
delete pipe which was over-sized. Actual first section is 54 dia... smaller
than I had believed, and it steps up a size for the over diff section.

I'm going to run with it to begin with. If it proves to be a restriction I can
replace it with a larger custom system later. Gotta start somewhere

Cheers... jondee86

[Celica RA45]

unless you are making over 200 hp at the flywheel the std cast iron exhaust and engine pipe in std form is good to 200hp

[touge_ae101]

I hope you are talking about flywheel hp not at the wheels...

Even at the flywheel 200hp is a bit far fetched..

What quickstarlie said is 100% correct in my experience. and there is no magic back pressure etc involved with modern engines - the engine just wants to suck in air, make it go bang and get it out of the exhaust. the free-er the engine revs the more power it will make so. There is no point having a standard restrictive manifold if it isn't helping your engine breath at the level it wants to depending on mods etc.

[Celica RA45]

group A sprinter with plenum and std cast exhaust made 185hp at fly for bathurst 1000 and 215 hp for the sprint races of 20 laps or so power band was 5500 to 8500 rpm .these came with 11.5 to 1 comp 320 duration cams better rods and steel crank etc .was in the boot lid AE86

[jondee86]

Don't lose sight of the fact that GroupA/GroupN HAD to use the factory manifold. I think
it would be a pretty safe bet that if exhaust manifolds were a free item, they would have
had some custom racing exhaust manifolds on there instead of the cast iron piece

The fact that the engine could make good power with the factory manifold indicates it
is a good design, but you won't see such short primaries on ony of the current crop of
performance manifolds. This leads me to believe (hope) that there are performance gains
to be had from alternative designs,and that is what I am investigating.

Cheers... jondee86

[Celica RA45]

but you havnt seen the exhaust gasket spacer that was on the head before the engine pipe was bolted on
think it was either 75mm or 100mm long

[jondee86]

Pretty much confirms what I was thinking. I'm not bagging the factory manifold
as I'm using one at the moment, and I don't think that it is a restriction. If anything,
it is the 2" exhaust system and triple pass muffler that limit exhaust flow.

But if I can bolt something on that can give me (say) an extra 5kW for not a lot
of money, then it has to be worth looking into. Actually, what I'm looking for is to
enhance torque thru the midrange. If a header can do that even without increasing
peak power, then I would be happy

Cheers... jondee86

[touge_ae101]

Ill post pics of our progress on the manifold hopefully sometime in the next few days. Long primaries + short secondaries all tuned to slightly different lengths etc.

[flying_wedge]

^^ just further what Rhys was saying with Harris pipes and the 2zz.
This was the build he was referring to, similar kind of thing to what Rhys has done, I think they sized the lengths and cut to suit, and these were given to you numbered to assemble as you wanted.
Nick did this as pics below.
I had this 2zz engine with this exhaust dyno'd at 175whp, few other differences from factory, but still stock ecu.
That's roughly 210hp at the fly assuming 20% transmission loss. Good gains from factory (190hp at fly), with CAI and no stock ancillaries (p/s, a/c).
Power curve on dyno graph is linear and predictible, good for an all-round driven n/a car.

One of my exhaust runners half made, Im using a stepped header design. Each header exits, rises up and then turns down. This is to obtain the length I need.
Each runner is 1 5/8th (41mm) and steps up to 1 3/4 (44) part way down. These turn into 2 50mm secondary runners and then join to a single 2.25 flexi and then a 2 3/8 Harris Megaphone. I will have a bolt on 2.25 section after this which has a large muffler to bring it down to road volume. (Should probally be 2.5 but who cars for road driving)
Each of the runners is fully individual, the collectors are slip-on and will be bolted in place. They have to be separable to get them into the car.
Im going to need to check it running just a megaphone, if its just way to loud I think I'll need to add a bullet muffler or something similar, really want a good straight trough for the track, shoot a few flames

Secondaries finish and join on entry to megaphone




130wkw = 175whp = roughly 210hp at the fly for 20% transmission loss.

[QikStarlie]

any reason for the uneven cylinder grouping?

[jondee86]

Good question And it gets asked a lot about the Martelius R1 exhaust...



I never saw an explanation, but the R! works and was the result of a lot of
trials and experimentation. So perhaps the grouping of the primaries is not
as important as is commonly believed ?

Cheers... jondee86

[QikStarlie]

guess scavenging effect could be increased

my 4-1's i ran the primary's into the collector in order. 1-3
................................................................2-4
not sure how much it helps but was easy enough to do at the time. have tried some 4-2-1's on same engine, got a bit of revision in midrange, and a little more peak. pipe sizes were a bit off 38mm primary's and 50mm 2nd. as used what i had hanging around. went back to the 4-1's as they worked better all round.
haven't had any decent results with megaphones. tried a big range of straight collectors also. from 1.75" to 2.5". stuck with 2.5" straight collector into 3" system. with 38mm 4-1's. would like to try some bigger primarys, maybe a stepped setup. but dont have the motivation.. haven't got any dyno results of latest setup. but done a 13.8@162k in kp starlet chassis.

[jondee86]

The megaphone thing was big in the glory days of the Manx Norton and AJS7R
Worked well on single cylinder (or one pipe per cylinder) engines for tuning exhaust
scavaging, but I've never really seen it applied where multiple cylinders combine
into a single exhaust pipe on a car... too loud I guess, or doesn't work with a muffler.

If I remember correctly, the Group A Corollas had a side exit exhaust that ended
with a kind of long megaphone... and geez were they loud !!! I think that was in
the days before tracks had decibel limits

Cheers... jondee86

[BattleSnayke]

Hey, those headers above that were made by frost were for my car. He does awesome work, however they're not a cheap option. I've heard good things about mac built and I called them about headers for my at before going to Frost.



I wouldn't bother with Bam, he does amazing work but is expensive and takes a long time to complete jobs. He's currently making the headers for a mates 2JZ WRX.

[touge_ae101]

yeah stepped headers are definately the best way to get gains and tuned length (not all primaries the same length)

ae82 headers all done. only change required is moving the megaphone up right to the end of the final collector.



Do some more research into megaphones they are used extensively in highly strung 4cyl engines and are highly effective. Hondas see really good gains from them as well if tuned correctly for the cams/setup.

[Flannelman]

The theory behind the megaphone is that it kills the pressure waves created by the tuned length headers, effectively creating an ending of the header system. Without it, the entire exhaust system becomes the collector.

Above is an awesome example in that it can be broken down into each section. Primaries at the top (from port flange to first merge, 4 individual pipes) Secondaries in the middle (first merge to second merge, 2 shared pipes) Collector at the end (second merge to megaphone, 1 pipe for all)

As seen on other engine tests, length and pipe size do go hand in hand. Too small and too long will yield good low to mid range improvement with a loss at the top as the pipe size chokes airflow and can be the wrong length for wave tune in the high RPM. Too big and too short can push the power band beyond the RPM range of the engine. They will still be an improvement over stock, but when up against a properly matched engine/exhaust system combo they will be inferior in power, torque and economy.

Building a system like this for myself is a goal for me this year to achieve, hopefully with good results too. The theory suggests for me to use 1 3/4in primary @ 22in long, 2in secondary @14in long and a 2 1/2in collector @ 32in long. While these numbers are not a perfect match for a specific RPM, hopefully they will give improvements over the entire range and that can only be found by a before and after dyno power run.

[QikStarlie]

touge_ae101: what tube sizes are you running? primary, secondary and rest of system

any links to megaphone tech? with results?

would be good to see some back to back dyno testing. 4age specific even better,

[touge_ae101]

iirc 38mm then steps up to 41mm primaries, 45mm secondaries and 2.5" exhaust. the collectors have little restrictions etc in them as well (not sure on dia of these..)

yeah hopefully it will get some good gains. It will be on the dyno by the end of this month/early next month. Keen to trial a 3" exhaust as well at some stage we don't really have a noise issue compared to rattly noisey 3sge beams... haha
did you trial 3" with a full system or side exit? our whole exhaust system is only another metre or so on the end of the extractors (room for one coby silencer and thats it) so not sure how much restriction will be after that..

[QikStarlie]

how far away from the head is the first step? mine are 38mm all the way. one day want to try a 41mm step like yours

2.5" should be ok, but definitely worth trying bigger, if you only have to change that amount of tube.

Mine is a street exhaust. 2 straight though reso type mufflers. and a tripple pass on the back, which i built with 3.5"+ internal diameters, to try to keep it flowing as much as the 3" tube. Extractors have a 2.5" straight collector that slides into the 3" system, so is an instant step down. Way i see it, after the collector the rest of the exhaust is just there to make it quiet. so bigger the better

Tried a lot of different setups with my old engine. but short version was testing it with open headers, then trying to build a system that would match the open headers.
Done some dyno testing on it, not really back to back stuff. but it gained around 15kw in midrange going to a 2.5" system, with a 3" tripple pass on the end. the original 2" system was pretty rubbish, but shows how much it can kill the power. interestingly enough. the peak power stayed around the same, (likely due to other restrictions in this engine) but it had a fatter powerband. Couldn't get any cheap dyno time after going to the 3" system with even bigger rear muffler. but going by the change in afr based on other gains, would have been around 5kw or so.

above engine was a fairly stock smallport, with 300deg cams, itb's and high compression