Has anyone tried to port the intake runners on the GK fit? Has any one done a fully ported head and 5-angle valve job on the Fit? I am just thinking from where I came from in the corvette world, these are the types of things (combined with tuning) to make power. Increase/smooth airflow all the way into the cylinder... (and of course out...) Plus, I like sleeper builds, so porting stock IM, TB, head makes a quick peek inside the engine bay look like all is normal and maybe you just got took by the driver mod... Cheers!

 

in for an answer .... this is something id like to one day eventually do as well

 

 

Yes it is plastic. Doesn't matter, it flows or it doesn't. LS manifolds are plastic and those get ported. FAST and MSI after market manifolds are plastic. I haven't seen a GK with aftermarket. I have seen the weapon r for 2Gs. Im sure the head can be ported on the exhaust side and matched to an RV6. I've seen cams too. I think realistically one could shoot for 150 whp from an NA with ported head, cams, intake, and full exhaust... would be a peppy fit!

 

Have at it ~~~>

 

When I found this forum I wondered if anyone had done an extrude hone on any of the Honda heads with the integral exhaust manifold, and the only memorable response I got was someone suggesting I start by reading about how to size header pipes for big block V8s... I'd do it myself, but like most people who end up with a Fit I'm not in a position to either have the car down for several weeks, or pay probably upwards of a thousand dollars to have the work done.

 

These are some of the things that may come with this territory with this GK5 Fit. I contacted a few people back between 2014-2015 about designing an intake manifold. No-one was even mildly interested and one company quoted something in the 5k-6k range just to see how serious I was. I gave up on it. Purchasing a used one from the junkyard and porting it may be the ticket. Then have it installed.

Extrude Honing seemed cool as I've read about their work back in the day. Like you, I wasn't willing to have my car down for any significant amount of time. I had my doubts on what kind of gains I could get with that as well. Not one to debate on the hypothetical. Simply get it done and test. If someone really wants to go this route, it'll happen.

The GK5 has been out since mid 2014 so it's 4yrs old now. This forum is only 3 pages long. Maybe better to look in the China forums as there seems to be a nice following there or other forums overseas with a similar car. I ran into some cool peeps in other forums. Used Google translator to help with the language barrier.

 

Was thebomb.Com for DSM intakes and heads. Don't know if it is more important for forced induction but I'll find out one day

 

car-parts.com has intake manifolds for around $100, could be worth a shot.

 

liking the way you guys are thinking. Mating the manifolds (intake and exhaust) to the head also helps. SCCA rules only allowed porting 1/2" from the mating surface. Plastic, aluminum or whatever, cleaner, freer flowing air will boost performance any time.

 

The design of the intake manifold isn't horrible, it just has a few pinched areas (for no real reason). For instance immediately after the throttlebody...useless. AND there is not enough meat to port it really.
There is a reason that LRPTEC found 20hp just changing the intake manifold and the throttlebody.
AIRFLOW. And this spot is the first place to look for restriction.

 

I finally ported mine today. What is that giant metal piece that fits in from the underside of the intake manifold, that is connected to the block? I am betting some EGR shit. Can I just cut that whole thing off? What benefit does it provide other than impeding air flow. I'll post pictures later. Myxalpyx, if you remember on your ported throttle body, was the intake manifold side egg shaped to match the intake manifold when you got it back from whoever ported it?

 

After reinstalling, the car is running 18.5 AFR at idle where she was previously 14.7. I got a lot of check engine lights. I only drove her a mile, WOT was fine with 12.6 AFR like usual, she's idling rough. Is it safe to drive around and see if the MAF "relearns?"

If I want to add fuel at idle, what is the best parameter to modify, in what table? Cheers, d'Art

RE: porting: There's not a lot to port, but there was definitely a weird restriction right after the throttle body, kind of like a plastic K right in there. I cut that out completely, then dug in with a die grinder, and then finished by hand smoothing with various sand papers. I ported each intake runner about 1.5" also (as far as the die grinder would go) and then hand sanded those too. There was also a shark finned metal protrusion attached to the engine block that must have something to do with EGR that comes in on the underside of the intake manifold just after the neck. I definitely wanted to cut that off completely, but decided to do this in stages. Also the TB is circular on the inlet and outlet, but the intake manifold is oval shaped at the inlet. I figured I could port the throttle body as well, but again, I figured 1 change at a time would be best.

 

Here are the pics of the port job:

The intake manifold, unmolested. You can see the first restriction.

Chopped off the "k" with a hack saw blade...

Reinstalled on the car. You can see that metal "shark fin" in there also blocking air flow. Pretty sure that is the next thing I'll chop off... I went as wide as I thought I could, and smoothed off a step I found in there. Also filled in a gap that was about 3mm side just after the neck. I used jb weld to fill in the gap.

I went in about 1.5" on the intake runners, as far as my die grinder and bit would go. I smoothed the "step" where I started removing material, and then just tried to flute it going out the best I could.

All in all, she feels peppy now that I got the AFR back to normal and fixed whatetver was sucking oil into the intake. I will port the TB next, and then finally remove the "shark fin..." See ya'll around the track!

 

does that shark fin, actually do something?

 

Probably emissions related...

 

I'm curious as well. Will find out I guess. Great pics! Thanks for sharing.

 

Assuming that is EGR gasses, they are likely looking for two things... Getting the extremely hot air into the middle of the intake for more equal distribution to the intake and making sure that the extremely hot exhaust is not being blasted directly onto the plastic intake manifold.

 

I agree with your assumption and you're probably right about that anti plastic melting arrangement. He's the weird thing. On many EGR systems one sees the "circuit" where the gas comes back around. On ours, the gas just rejoins the exhaust via another port on the back side of the block. I never see the return to the intake. This could very well be it but I don't understand how. I'll remove it and see what's on the underside this weekend...

 

I'll just say..... the look on my face when I saw this shark fin matched the look I had when I first saw the lack of exhaust manifold ports. They have saved a lot of money through brilliant casting technology.

I'll be excited to see what you find out.