Well, in my quest for more power out of the S2000, i'm redoing the intake system of my car. I'll have an aluminum intake tube of 3.5" diamt4er feeding into a new 75mm Edelbrock Throttle Body. The idea here, is to feed the motor as much air as it would have if it were being fed with ITB's... well, thats the plan anyway. Because i'm planning on boosting this car, i didn't want to spend the kind of $$$ and time involved in setting up a proper ITB setup, so a huge bore Throttle body will have to do.

Along the lines of installing the bigger TB, i also want to open up the plenum a bit, and allow for the added airflow of the TB. I don't want it open TOO much, so i'm just adding a little bit of extrra displacement in the manifold. Also, hopefully this will help out a lot when i boost the car.

So, here is what we're starting with... a plain-jane AP1 intake manifold...

I went ahead and drew the line where i was going to begin making my cuts.




And then, i started chopping away!






And here we go! an open intake manifold! yay! First thing i noticed about the intake, was how smooth and lightweight everything was from the factory... the transitions into the runners are absolutely gorgeous... i'm going to be having this cleaned up and ported slightly, but not much at all... its already in great shape! go Honda!




Next up, was to begin welding on the adapter for the 75mm throttle body... i don't HAVE to weld it on, since it is an adapter plate, and i can use the oem tb screws to hold it down, but i just felt like welding it on.. i think it'll look better




Here you can see the size difference from stock to the 75mm bore that i'm going to run...




More welding... also, a better picture of the runners... next stop... the porter!




Well, i got it back from my porter... he's local to us, and does REALLY clean work. He cleaned up the runners, polished the inside of the plenum to aid in air velocity, especially around the cast velocity stacks... also, he port-matched the manifold to the throttle body spacer i welded on, and port matched the manifold to the head... here is the result of that work...








Here, he ground down the air vents, and the cast 'bosses' that extend into the plenum near the velocity stack edges..




Shot through the TB showing the new bore.




Nice polished/cleaned up runners




Hard to see, but you can see the port matching done on the head.... can't go more than 1" into the head.




Next up, its time to wrap it all in sheet metal... so, i dug out some aluminum, and built the back side of the manifold first... again, i m not looking to add a TON of volume to the manifold, just a little bit... also, i didn't get any good shots of it, but it is also fully welded on the inside other than the top cover piece, cause... well... i just can't get in there to weld it haha!


















And there you have it! Hopefully this works out well... im still not done yet... next up is to re-install the spot for the Idle Air Control valve, and then i also need to fill in the old IAC air chambers that are left where the porting happened to open it up for the 75mm throttle body.

 

John,

looks real good and top notch fab., but I have two questions:

1. Why do you want such smooth runners? My take is that the boundary layer should not be perfectly smooth or you actually loose air speed.

2. Did you work the exhaust side? I usually like spending more time on the exhaust side on turbo cars, as the intake will be pressurized and therefore you can see more benefits from the ex side in order to spool up sooner.

You should dowel the manifold to the head in order to take advantage of the port matching. I have an old Celica Alltrac turbo and both the intake and exhaust manifolds got small dowels in them to line them up.

Again, very nice work.

J

 

Clean work!

 

 

Thanks guys! I'm really happy with how it turned out...


R1: The idea with the smoothness/polishing is more for the velocity stacks... and the runners aren't polished mirror smooth, but they aren't sandpaper grit rough either. i think it is a good in-between...

I did not do anything to the exhaust side... i'd love to polish it up, but we're only allowed to extend any port work into the head by no more than 1", and by that point, it seemed like a lost cause.. lol!... on my next motor, it'll be different.. but for this motor, i'm going to leave it as-is.

As for the doweling... i can't. yea, rules sometimes suck... lol! But i don't think its necessary with the Honda heads. The manifold fits so snug, it doesn't move around enough at all when on the studs imho.

 

Suh-weet!

 

i'd like a full report on how this effects the car. This is a mod i've been very interested in, but from the research i've done I've heard mixed results... But most people just slapped a bigger throttle body on and did none of the port work and manifold augmentation.

as usual, very clean nice work John.

 

What are you going to do about the idle air valve?

 

Very nice! Beautiful fab work. My guys at the shop have been doing the exact same thing but with over 25 cars to work on they haven't the time to do it now.

If I were you I would take a stock one and that one to someone that can flow test it. That way you can really tell how much the flow is increased.

Another cheap way to do it is dyno your car with a stock intake and put your's on and dyno it again.

I wouldn't be suprised if you lose HP on a stock car. Honda does a really good job of maximizing the HP with the flow in and out of the head. Keep up the good work I always love to see what you p[lay with next.

How are the fender flares coming?Update