Why are runners on 4age and 4agze headers different?

[_gear2]

I am just wondering why in a number of headers I have see for the 4age and 4agze that their runners often follow a different pattern. I tried searching but couldn't find an answer. I assume the firing order for the 4agze is the same as the 4age – 1-3-4-2.?

These two headers might illustrate my question more clearly

These are for the 4agze

[URL=http://i280.photobucket.com/albums/kk163/x--chaos--x/Picture024.jpg]

Same type but for a 4age

[URL=http://www.corollaae92gts.nl/images/Coupeproject467.JPG]

[oldcorollas]

they both look to be ordered correctly, just in opposite directions.
still it enters the collector as 1-3-4-2

there is no difference in practice, or spinning either direction, and arguably not of much benefit to a GZE, as they don't tend to rev high enough

[beerhead]

From my reading on exhaust tuning I'd say the long runners on the 4AGE variety are to pick up bottom on torque. With a GZE you have boost, no need for NA tricks to make bottom end power so go for short runners to free up the top end.

[_gear2]

weird thing is I just checked my own headers (which are the same as the second one shown, the 4age ones) and the little jasma tab said its for a 4agz.

[oldcorollas]

measure the primary length from valve to collector, and see what rpm they are designed for?
apart from flowing nicely, chances are the 4-1 has no sonic "tuning" effect to help pull exhaust out anyway, unlike 4-2-1 for more normal rpm

[beerhead]

Have you got a picture of inside the collector? Interested to see if there's bends and a proper merge hiding in there. That's not a traditional merge collector design, there isn't a restrictive taper and expansion point. Well tuned merge 4-1's with step's are meant to be 95% as good as a 4-2-1 extractor at low revs and 110% better once your engine is on song, the guys at comp coatings in Brissy have the software to tune them perfectly.

[trdee]

They look like cusco powerball headers amirite?

Firing order is the same for 4AGE>4AGZE at 1-3-4-2, the difference in design could possibly be to clear the exhaust-side alternator configuration found on 4AGZE's.

Also as per oldcorollas; they would need to be a LOT longer than what they are with that short 4-1 design to be of any real benefit to a regular 4A in terms of exhaust pulse tuning. They do look/sound nice though, kyle had a set on his adub if i remember right

HTH

[_gear2]

measure the primary length from valve to collector, and see what rpm they are designed for?

Sorry if this is stupid but how do you do that? - I actually have a book on exhaust design that i am about to start reading. But i'm in the middle of exams and don't have time right now.

Have you got a picture of inside the collector? Interested to see if there's bends and a proper merge hiding in there. That's not a traditional merge collector design, there isn't a restrictive taper and expansion point. Well tuned merge 4-1's with step's are meant to be 95% as good as a 4-2-1 extractor at low revs and 110% better once your engine is on song, the guys at comp coatings in Brissy have the software to tune them perfectly.

[URL=http://www.corollaae92gts.nl/images/Coupeproject469.JPG]

The top of that pyramid is approx 60mm to the end of the 'ball' while the pipes
are approx 90mm. They do go quite a way into the ball itself - the ball being roughly
140 mm in length

They look like cusco powerball headers amirite?
Firing order is the same for 4AGE>4AGZE at 1-3-4-2, the difference in design could possibly be to clear the exhaust-side alternator configuration found on 4AGZE's.
HTH

Yer they are cusco powerball headers - finally found them wasting time when i should of been studying (though these are not photos of mine).

I have also noticed this difference on FGK 4-2-1 headers

[URL=http://tsikot.com/classifieds/data/46/DSC00278.JPG]

[URL=http://i425.photobucket.com/albums/pp337/Johnn_Q/08042011381.jpg]


thanks for all the input guys.

[beerhead]

Ah, the pyramid is welded on top! Is the person who made those pipes drunk or is the offset to create a swirl? Dam I hate the internet is crap for proper theory, I'm gonna have to go to the library again!

If the motor has a SC, exhaust to intake pulse tuning doesn't mean that last 10% of peak HP like an NA race car. Your intake pulse is force fed, so getting out the exhaust gas as efficiently as possible will net more peak HP, and who gives a stuff about loosing a little of bottom end when you have 10psi as the clutch comes out! Almost double the torque off the line!

BTW Primary length is from the flange to the collector.

[_gear2]

BTW Primary length is from the flange to the collector.

- this is what i was unsure of the end of the collector itself or the end of the pipe inside the collector.

[oldcorollas]

BTW Primary length is from the flange to the collector.

really?
hmm, how does that work?

[oldcorollas]

anyway, since you are trying to pull exhaust out of the cylinder (not the cylinder head), the length for tuning is calculated from the cylinder, ie from the back of the valve. there is no point tuning the length to the head, when there is still a finite time difference between arrival of the reflection at the flange and at the cylinder...

the diagram below is from Bills site and is a rough guide, but quite good, and shows the total "tuned length"
total "tuned length" is from the valve to the first restriction/reflection point.. ie usually the first muffler or cat or whatever.

for a 4-1 system, the 4 primaries join at half the total length, so you have the same length in the primaries and the secondary.
for a 4-2-1 system, the 2-1 merge is halfway, ie same distance as the 4-1 merge..
the 4-2 merge is halfway from valve to the 2-1 merge

if you measure from the flange, you are adding an extra 4" or so to the primary length without realising it.

further to that, in a "tuned system" you will have positive and negative effects from the tuning..
generalyl you tune the length for peak power or torque witht he 1st order reflection, and then you have 2nd and 3rd order reflections lower in the rev range, but the positive effect decreases as the order of the reflection increases.
between those, you have a negative effect, and again the magnitude of the negative effect decreases as the order increases.
so at lower rpm, there is little positive or negtive effect from actual "tuning"