Intake manifold blues, please chime in.
 

I close to finishing up with my swap. 2002 Honda Insight with a 2008 Honda Fit Sport automatic. Goal is good milage (50 would be awesome) In a reliable, cheap to maintain car. I will be running 185/60 or 65/14s, 11" front rotors and Ground control coil overs with Koni Yellows/GAZ adjustable shocks. For a beefy and safe feel. The car will be driven 95% at freeway speed and it is what is most important.

I will also have Hondata Flashpro, Long block and trans will be left stock and I will tune for 87 octane.

3 things will be custom
--------

1 is the exhaust, I will use mandrel bends and have room for two mufflers/resonators as well as my 'free flow cat'. What size do I run? quiet yet free flowing muffler strategy?

2 Is the header, My father is a header builder (from the 70s) and I have the ability to do what ever I choose within reason. Ports are 1.25"..... Tri-Y? 4into1? stepped?

#3 is the reason for my blues. I need to make a custom intake manifold since the stock one would poke through the hood. The intake runners are 16" stock from plenum to head.
The easiest way for me to deal with this is buy a $500 custom Weapon R Intake manifold and cutting all the bends out, re welding and leaving the runners 4" long.
I can also build a header like intake with a small collector plenum into throttle body and get the runners within 2" of equal but can be 18-20 inches long or mimic the stock Insight 3cyl intake design.

Or I can cut my hood (and move my battery) which I really don't want to do

Im afraid of loosing all my bottom end as it is an automatic. Im hoping that with the tuning ability and a great exhaust system, I can make up for the intake manifold compromise. Im not looking at trying to win any races but do want the car to be as efficient as possible.

Im not for asking anything other than ideas and opinions on this.

If I build a short runner intake, can I build Tq with a long intake tube before throttle?

Im willing to go slightly smaller tire diameter as well (Flashpro allows you to adjust speedometer)


Last thing is if all this is going to be over 5% or less power I think Ill be just fine so thats also a part of my question. does it really matter?

http://ecomodder.com/forum/showthrea...els-23234.html

16 inch runners are less than ideal and you really don't want 4 inch runners.

People have customer stainless exhaust headers built...why not have a custom stainless intake manifold made the same way? Built to keep the same length runners yet fit in the space...

Or flip the intake upside down (cut off and re-weld the flange) if it will fit that way.

Are there any other OE manifolds that fit this head?

I can in fact build hearers and no problem doing the intake, my problem is there is no room, the stock units on these motors all wrap over the top of the engine. it would stick 4" above the hood. There is one aftermarket manifold and its virtually the same as stock except its one piece and all aluminum vs the stock which is 50/50 aluminum and plastic. By cutting the runners down it flips the plenum upside down and puts it in front of the engine, It would be the perfect turbo manifold.

I know you said you could but do not want to cut the hood, but I want to suggest you consider it in another light. Reducing the angle change between hood and windshield can be a drag reduction technique. You see it on all the fuel economy cars now, even the Civics. The Fit is a good example. But there might be small room for improvement on a 2002 Insight (some though).

https://cars.usnews.com/static/image...t_sideview.jpg

http://www.katiekat.net/Vehicles/Insight2.jpg

I'm facing the same problem with my firebird. The intake and air cleaner I want to use won't fit under the stock hood.
The hood is going to have to get chopped but I'm not going with a more compact intake manifold.

I have thought about it, the beauty of driving a Honda Insight (vs a civic) is all the rice racers leave you alone, with a hole in the hood that would be a nightmare.... Im getting ready to head to the shop and mull it over, The header style looks like the only way to get length and it will be tough to get them equal, maybe 2" variance which in header building land is acceptable (every put a 454 in an S10?) but this will be my first intake manifold. My only other option I see is remount the radiator and condenser forward more, again, not ideal.

I think your best bet is to build a tubular intake that mimics the stock tubing length. I believe you can do this by having the tubes stick forward and then turn down, into a plenum located below/to the side of the alternator. Throttle body would be on the driver's side of that plenum with air intake/filter near the transmission. From your picture of the engine compartment, I think you will have enough room.

At part throttle operation, the throttle plate should disrupt any pressure waves, so the tubing before the throttle doesn't really help with tuning pressure waves at the valves.

You may have to do that.
The 16 inch runner isn't even ideal.
You want more like 24 inches of total length to include the runner in the head.
Longer is better for daily driver motors.

What about a cowl induction style hood scoop? They are not truly "race car" inspiring. Plus on an old car they seem to help in the aero department. One would not likely help your newer car's aero. But it might solve your hood clearance problem.