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  1. #1

    Default Header Rebuild Help

    Hey guys, Im interested in a redesign of my header, its just a shortie with short primaries that are 1 5/8 I think. Ive been reading online about designing the header to match the engine (3sge) and I think id like to give it a shot, modifying the current one, Ive got the fabrication skill and tooling but i need a hand wrapping my head around all the numbers.

    So Far ive got

    Engine 3s-ge 1st gen (stock cams, sorry im having a hard time finding the degrees),1 5/8th primaries, Want to aim for the power increase to be at the current max torque of 125 ft-lbs@4800 rpms

    Primary Length = ?
    Collector Length and Diam = ?

    Rest of the exhaust = 2.125''

    I want to keep the design a 4-1 for simplicity, Im minaly looking to lengthen the primaries and adjust the collector to the correct length.

    If anyone can give me a hand, or show me the formulas i would be forever grateful.

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  2. #2

    Default

    I can't say that I'm able to help much, like you, I can fab it, but the math loses me. I do know that most designers use a program to get their starting points and then just trial and error with dyno runs to get it perfect. This might be a bit more than you're looking to do which is why I say....
    Leave it. I assume the header you have is the stock one? If it is, consider it rare. It is a very well designed header done by Yamaha who, in case you're new to Celicas, has designed some of the best heads used in Toyota engines. The reason it's rare is that the only place you find them are on '89 USDM GTSs (which are far and few between) and 1st gen 3sges from over seas, in which case are quite hard to get a hold of, not to mention insane shipping costs. I personally use one on my 92 GTS and I love it. But I imagine it's even better on the 3s.
    If I was in your shoes, I would consider trying to redesign the stock secondary. You mentioned wanting a 4-1 but a 4-2-1 will be easier to tune to the range you want, and you could probably get close just by tweaking the secondary.
    Another thought is that the 3sge doesn't have the best low end response and the 4-2-1 will help to boost this while retaining a good high end response. I believe a 4-1 would leave you with a nasty dead spot down low.
    In any case, since I use the same header, I am interested in what you come up with so keep us posted. But remember- should you want to go back to what you had to start with, it won't be easy.

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  3. #3
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    Default

    sorry to thread jack, but any idea where to get an 89 GTS header?

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    Originally Posted by Murgatroy
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  4. #4
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    Default

    I can tell you exactly what you want to build if you're willing to do it...

    Need to know where you want peak hp, the header will have an effective tuning range of about 2500, aiming for peak tq 2000rpm lower and the tuning range will carry 500rpm above peak hp.

    Only if you're serious, will take me a bit to crunch.

  5. #5

    Default

    Thats MrWOT, I have an aftermarket 4-1 already, but its a crap design. its for an MR2 but its adapted it to work on the 3sge.

    Im 100% ready to get down to it, i want to keep it simple, more or less extend the primaries, modify the collector.

    The spec of the engine stock are 135 hp at 6000rpm, 125 ft-lbs@4800 rpms. I want to have the header compliment the stock cam, peak hp 6000 rpm, torque 4800 rpm if possible.

    I want to keep torque increase mainly in the midrange, i dont liek the current disign aimed at high rpm torque increase, id liek improve on the stock configuration if that makes sense.

    the Primaries gotta stay at 1 5/8s, but besides that let me know what ill need for best results, i can go 4-2-1 if its worth it, but i was thinking long primary 4-1 would be easiest.

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  6. #6
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    Default

    The primaries aren't nearly as important as the collector, alright, I will calculate for torque peak at 5000rpm. I'll get back to you tonight after I'm off work.

  7. #7

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    Default

    Quote Originally Posted by Grot
    sorry to thread jack, but any idea where to get an 89 GTS header?
    Off an `89 GT-S obviously.

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  8. #8
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    Default

    Quote Originally Posted by Murgatroy
    Off an `89 GT-S obviously.
    Thanks Murg...

    Stealership be able to get part still or will i have to hunt for it thru yards and forums?

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    Originally Posted by Murgatroy
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  9. #9

    Default

    Quote Originally Posted by Grot
    Thanks Murg...

    Stealership be able to get part still or will i have to hunt for it thru yards and forums?
    Never tried the stealership but it's possible. Good luck hunting the yards. So far I only know of one found in a yard in Indiana. I found mine on ebay several years ago and they show up there from time to time, but don't hold your breath.
    Now, if your willing to beg and pay some stiff shipping charges, go to ebay and check out international sellers in the U.K., they have several, but the I tried a few years ago wouldn't ship to the US and I didn't bother with the others. The only other way would be to catch one of our members that lives in Europe or Aus and get them to send you one.

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  10. #10

    Default

    Quote Originally Posted by Meph
    I have an aftermarket 4-1 already, but its a crap design.
    So I take it you no longer have the stock header?

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  11. #11

    Default

    I have the stock header, but my engine isnt an 89. My old header had a O2 sensor mount on the front, but when I got the car the EGR was attached to the opening instead. Im not sure if the header I had was an 89 header, but as far as my 4th gen skills go I dont think there was a difference of much between years besides EGR and O2 hookups.

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  12. #12

    Default

    On the '89 GTS they put an actual header on it from the factory that was designed by Yamaha. Everything else just came with a crappy standard exhaust manifold. If you don't have the original engine that's a bummer.

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  13. #13

    Default

    Its definitely not a header, are you sure your not getting confused with 2nd gen 3sge manifold (they came in 90 gt-s in europe)? they were actual pipe headers, that can be installed on the 4th gens if you mount your starter tranny side. In my experiences ive never seen a header stock on an 89, and we got a few 89's over at st162.net

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  14. #14
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    Default

    The primaries should be 1 1/8" dia, 32.7-35.6" AND/OR 22.8-25.7" long

    The collector should be 2 1/8" dia, 22.1" long, OR 44.1" if you want more bottom end than top end....

    Collector beginning to tailpipe END (total length)

    560.2 or 1120.5 or 2240.9 or 4481.9MM long

    2500-5000rpm powerband

    THESE NUMBERS ARE ONLY VALID WHEN USED TOGETHER! THIS IS IMPORTANT!

    I also need the lobe seperation angle for this to be right

    edit: btw, the tailpipe end means you need an exhaust termination box there, the actual tailpipe should exit preferably behind a rear tire.
    Last edited by MrWOT; 01-18-2009 at 07:23 AM.

  15. #15

    Default

    Quote Originally Posted by Meph
    Its definitely not a header, are you sure your not getting confused with 2nd gen 3sge manifold (they came in 90 gt-s in europe)? they were actual pipe headers, that can be installed on the 4th gens if you mount your starter tranny side. In my experiences ive never seen a header stock on an 89, and we got a few 89's over at st162.net
    That's exactly the one I mean, and yes, they did come in the '89GTS. In Europe, they came in all Celicas after '90 that had the 3sge.

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  16. #16

    Default

    Thanks WOT, the one issue is that I need to keep the Primaries at 1 5/8 diam, If you check out the pic above im planning to cut the primaries at the collector, extend the , reattach the collector and adjust the pipe diam and length for best results. If we aim for power band between 4000-6500 would it be acceptable to keep the primaries at 1 5/8?

    Ill try to find the lobe separation angle, but its hard to come by

    Thanks again

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  17. #17
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    Default

    It will lose power, but I can't say how much :shrug:

    1/2" too big is WAY too big, like 40% too big. But the primary diameter/length isn't as important as getting the collector right.

  18. #18

    Default

    If we move the power band to a high range, 4000-6500 the needed primary size will increase, making the 1 5/8 a bit less useless? I can Step the tubing down to a smaller diam after the bends coming off the head (once its straightened out) if that will help. If I were to aim for a 4000-6500 power band what would the ideas be? Ill rough up a design a post it if you can give me a hadn with those numbers, thanks WOT

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  19. #19
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    No.

    Even revving to 9k you wouldn't need 1 5/8" at 120% VE. If you can't replace them, don't worry about it. Like I said, the collector is key, not the primaries.

  20. #20

    Default

    ok, I have just a few more question to wrap my head around. Ill try to seperate them as best i can

    1)If i were to tune the collector to 4000-6500 power band what specs would I want to build to?

    2a)Is it worth Extending the 1 5/8 primaries?

    2b)Is it worth extending the 1 5/8 primaries with smaller diam pipe? (first 15" are 1 5/8 last 12" would be 1 1/2)

    3) whats the definition of the collector, the area where the 4 pipes merge or the larger pipe that follows? ( ive been assuming its both)

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  21. #21
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    1) 2 3/8" 14.6"

    2a) Yes, but only 18.2 inches for 4000-6500

    2b) No, the point of smaller diameter is to maintain velocity, once velocity is lost, it cannot be regained without pumping losses.

    3) The larger pipe that follows, but where the pipes merge is also important in regards to the angle, length and a few other things, but unless you're going to spend some serious money (good merge collector is over $300 just for the merge section) or know what you're doing and can weld stainless, the pipe is all you are concerned with.

    Collectively, it's the collector

    The LENGTH refers to the point at which the primaries terminate inside the merge, to the end of the large pipe section.

  22. #22

    Default

    Great info, ive gone out and measured, i the primaries on mine are between 14-16~ inches, and the Inside diameter of the collector is roughly 2 3/8. So Im thinking Ill shorten the Collector (fairly long) a perportional amount to to lengthening of the primaries. (im thinking a 3-4'' extension.)

    The current flange joining exhaust and header goes straight from 2 3/8 collector to 2 inch exhaust, no taper, so im thinking of making a cone , i guess about 3-4 inches long that tapers down to the exhaust diameter. Two more thoughts.

    1)Is there a recommended length for the tapered cone i would be constructing? Ive head elsewhere tapering the collector can have a large impact.

    2)Say I have my 4 inch tapered cone and the collector is 14.6 inches long, should I weld it to the back making the collector and cone a total of 18.6", should i reduce the collector to 10.6 with a 4" cone or split the differience at 12.6 collector, 4" cone.

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  23. #23
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    Default

    Tapering the collector does many things, and the angle and length will adjust the tuning range. You are good on the taper length 4"+. and you need to cut the primaries at an angle so they join together at the end of that cone inside the collector, remember, the collector begins where the primaries terminate. The length after primary termination needs to be 14.6"

  24. #24

    Default

    I was talkign about the end of the collector where it connects to the exhaust system. right now its just a basic flange, but its no good because one side is 2 3/8s and the other is 2"

    like so

    red is what im planning to do, to help the flow. I will also look into making a new cone for the collector, maybe 5" long for that one. This weekend ill probably get it started. Ill keep the thread updated.

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  25. #25

    Default

    I'll be putting the new header together this weekend, I got all the parts ready made to weld on, 3" primary extension and a cone to fit to the end of the collector to merge smoothly into the exhaust system

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