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MD:

how do i go about adjusting the SMS adjustable headers..? should i make the collector part longer? or should i make the part where it goes 4 into 2 longer? i am not sure quite how to do this... my goal is to have as much whp in the upperband as possible, i don't really care about midrange..
 

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http://209.197.120.239/showthread.php?s=&threadid=4971

Dave supplies you with slip over secondaries of varying lengths...if you look at the pic of the SMSP B20VTEC side exit race-only header you can see what I mean...this is similar to the one Erick Aguilar used to set his old all motor record 10.60 et.



here is the standard 1.8L ITR header...



notice the secondaries slip over the primaries. You can add tubing of varing lengths in between.
 

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Discussion Starter #3
MD

thanks for the response

but how should i adjust it gaining as much possible in the high end? on the ITR header (which is similar to the gsr one), you can't really add varying lengths in the middle.. what you can do, is move the sections around, but you can't add any tubes unless you get some custom tubing

based on the header article, it says for maximum power, i need the header to be as short as possible.. in this case the only thing i can do is adjust the primaries to secondaries and the collector part..

so my questino is this.. should i adjust it so the primary connecting to the secondaries are as short as possible? or should i make the collector part as short as possible? i am not sure how to go about adjusting these...

oh ya, and another thing.. the headers i have are for a GSR. This is from SMSP in an email regarding the gsr headers.

"You can't run the brackets with that header and you may have to remove the flywheel cover for the install. The cover may need to be modifedafter the
header is installed. The #4 tube will probably come in contact with a small
area of the oil pan. Just take a small ball peen hammer and give the header
some clearance at that spot. I built 2 simialr GSR stlye headers back to
back. Yours and another's and that one went on fine. I suspect your
problem was with the flywheel cover and oil pan. once those 2 thing are
taken care of the header should go on. The tubes are laid out that way for
the best ground clearance."

in my case, engine stabilizer bracket on tranny needs to be removed, oil pan needs to be modified for the #4 tube to fit, AND the flywheel cover either needs to be removed or shaved in order for the headers to fit.. otherwise it will not fit.. please change that on the honda-vision header article. i will try and get a picture up asap.
 

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again it's a trade off. You shorten too much and you gut the midrange that you had. From my way of thinking acceleration is hindered by anything that slows the rate at which the power climbs. Unless you have a 7 speed close ratio tranny, an ultrashort primaries header in an N/A would have a very narrow peaky powerband location which is not useful. You see this when people slap on that kamikaze 4-1 header with short, large diameter primaries onto an N/A motor package. If you are looking for some more up top, a shorter collector and larger diameter collector are safe ways of adding more top end. Dave has done that for you already by using a 2.5 in. collector and having a much larger diameter on the last step of the header at the secondaries.


Remember we are adding length to the header for fine tuning to gain back some midrange torque lost by going to short larger diameter primaries or larger diameter collector.
 

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The 4-1 pictured above is the header used on the Hocus-Pocus car. Erick's used a 4-2-1 under the pan header built for a B20VTEC with a stock oil pan(AllMotorMadness on the H-T board). I believe Erick was using it while AllMotorMadness' engine was being built.

As for ToDa003's header, that was built for maximum ground clearance and that's why the mounts have to be removed. I can build the header to clear the mounts but it will hang lower.

For tuning, the primaries and secondaries can be lengthen with slip on extensions or shorten (by cutting up to 2"). There are many possibilites of set ups. Shorter primaries with longer secondaries, shorter primaries and shorter secondaries, longer rimaries and longer secondaries and longer primaries and shorter secondaries. Plus going through and varying the lengths of each change. Most folks will be very happy with the gains as the header is received. How serious you are will determine how much you tune the primary and secondary lengths.

Throwing different cam profiles into the picture also changes the equation. I've seen where changes to a header's length have had completely the opposite effect compared to what theory would suggest. If engine, intake or exhaust design was as simple as an equation life would be so much easier.

It takes an extremely large amount of testing to find the optimal set up. If it didn't, race teams would have their best cars of the season at the first race.
 

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Dave,

the reason the theory doesn't work is because people are not only throwing in different cams...they are changing CR and displacement into the mix.

Those header articles from Jim McFarland assumed fixed valve timing, displacement, CR, rod ratio. It was based on changing one variable at a time...not 2-5...
 
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