NA Motor Discussions regarding N/A KA24E, KA24DE, and SR20DE

afermarket throttle body questions...

Old 08-16-2008, 07:22 AM
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afermarket throttle body questions...

so after spending ample time rebuilding the body of my new 240sx and having it painted (i bought it in feb and it was a little damaged from a wreck) and putting in a new (and better) sound system since the old one didn't work. i now have some time and money to put into the engine. i have decided the first mod i do will be a lightweight battery and a custom intake (the one where u cut a hole where the battery originally went). anyway i was searching a bunch on the forums about throttle bodies and intake manifolds so i could do the best full intake system i can. at first i thought bigger was always better, so i was going to match a 3 1/2" pipe to a q45 throttle body (85mm) then to an afermarket intake manifold to match. however, after reading some posts (and bigvinnies amazing knowledge) it would seem that biggest is not the bestest (yes i know that isn't a word). i believe the reason for this is because when u go too big the spooling or "vortex" effect of the air no long occurs, is this correct? also, shall i assume that then the best intake system would be for me to do a 3" pipe to the original throttle body (but bored to 62mm-64mm) and then to a aftermarket intake manifold to match?

and in case you need this info also, i race autocross, so the motor will be staying n/a, and i can only do bolt on applications, no internal engine mods. which basically means i will be doing the full intake system, exhaust system, cam gears (but not cams), light weight pulleys, and then computer reprogram to max it out, i think thats it for the engine...
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Old 08-18-2008, 08:18 PM
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contact RC engineering they can over bore your stock throttle body. i was quoted $250 to have mine over bore. oem s13 sr20 tb is 60. it would be 64 when returned. then have the manifold port matched to the throttle body.
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Old 08-18-2008, 09:30 PM
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i believe max bore will do the same for about $150 but honestly i'd save that money. i was considering having it done but a very credible source informed me that it would be best to keep the 60mm tb as is. that is unless you're shooting for something over 300hp.
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Old 08-19-2008, 03:55 PM
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If you really need to, I'd say bore it out. Cheaper for very similar results.
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Old 08-22-2008, 07:12 PM
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ok thanks for all the input guys, i think i will be boring out the tb to 64mm and then ill have the intake manifold matched
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Old 09-08-2008, 09:17 PM
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The stock ka24de TB is already enlarged. I would focus more on head work, or manifold work.
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Old 09-10-2008, 03:28 PM
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ah ok, so u think my next step should be to port and polish the head and swap our the intake manifold?
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Old 09-10-2008, 03:57 PM
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Buy a ported manifold from Vince.
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Old 09-10-2008, 09:57 PM
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Originally Posted by NiSmO Knight View Post
Buy a ported manifold from Vince.
Actually I have 2 OBD2 manifolds for sale for use on DE OBD1 ka's that will improve high end power.

I have stock OBD2 mani for $80, and one ported and extruded for $250.
I put serious man hours into the extruded and ported manifold...
Either way both types will make gains on an OBD1 KA24de.
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Old 09-12-2008, 12:43 PM
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hmmmm ok, not ready to purchase one right now, but i will definitely keep that in mind for a few months down the road.
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Old 09-12-2008, 03:40 PM
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I just saw that you had another thread up in regards to the intake piping size? Vince could help you on that too.
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