snitm

Hi,

I'm aware that there are negatives associated with increasing to 74mm but I have a 2.4L stroker. I recently upgraded to a 3.5" intake that will soon expand to 4" just before the TB (to slow the air down, increasing pressure, before tapering into the throttle body).

I'd like to upgrade the intake manifold but there are fairly limited options that aren't $2k or more.

SO long story short: I'd like to temporarily pair a 74mm skunk2 TB with my stock AP1 manifold. But I have my doubts the throttle plate won't hit the AP1's 64mm intake manifold inlet. Yet Skunk2's site says their 74mm will fit the 00-05 s2000...

But this post says that a 69mm TB is the largest that can be paired to a stock AP1 manifold.

Thoughts?

AlexSobe614

They may have somehow made it work? I would contact them to confirm this though as I've heard that they wont fit.

snitm

Once I get the TB (wednesday) I'll at least measure how wide the throttle plate is at WOT (where it'd stick out of the back of the TB) so we can get some closure on this question.

snitm

Used my calipers and measured the throttle plate to be 62.4mm wide at WOT. Given the AP1 intake manifold inlet is 64mm I'm pretty sure it'd fit fine.

The 74mm TB just wouldn't be all that useful unless the stock intake manifold were ported as large as possible (apparently 69mm).

snitm

I ported my AP1 IM as large as I could to match the 74mm TB, here is the result.. not as smooth as I'd like (nor does the full 74mm extend all the way back).. but I think this will work just fine:

Slowcrash_101

I'd at least take some 200 grit sandpaper and clean that up a bit. How are you planning to get the little metal shavings out of the manifold? Vaccum?

snitm

I may do that.. but I'm pretty exhausted with this project. Tedious and a mess. Really doubt additional shaving/sanding will help much.
With the 1st runner protruding in front of the TB and lack of space elsewhere, I may not see much airflow improvement, but throttle response should definitely be better.

As for cleanup, I used shop towels to block the plenum and runners. But shavings/metal dust was still a problem. So I used a garden hose and after that I used my kid's old little swimming pool to repeatedly dunk the entire manifold (filled with water, shook, dumped).

Amazingly, after the repeated dunking and flushing I found a piece of an old AEM AIT sensor's plastic shroud that had broken/heated off. I just assumed it went into the combustion chamber of my old motor and burned up.. turns out it somehow went in the IACV air pathway (1 in a million shot). I used tweezers to pull it out of the IACV point on the manifold.

Sideways

My 70mm BDL self destructed so I enlarged the manifold and added a 74mm SkunkII.

More welding and grinding and it is ready to go. The TB needed to have the idle air passages blocked so I used JB Weld.

It works great and my last dyno was 554 rwhp and 334 torque with a few pounds of boost.

snitm

Wow, yours turned out much nicer than mine (port-matched AP1 IM to 74mm skunk2 TB):



what did you use to get the IM's inlet so uniform and smooth?

Why did you feel the need to JB weld those passages? Also, looks like you blocked the passage for the MAP sensor.. odd. I didn't do any of that..

Sideways

The passages are not necessary with the idle air valve on the side of the manifold injecting idle air.
I have a map sensor elsewhere. A two inch drum sander does a nice job.


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