Honda Intake Manifold

[Apu]

Hmmm, B18 you say...

Dann...suggestions?

I wanted to put a K20 engine in but is was going to cost too much, this is the next best. I now have a Honda intake, throttle body, sensors and a Honda radiator... what next?

I actually think these could be investment cast very easily... well at least the runner section. When I get time, I want to 3D print an intake and then use investment casting to make an ally one.

I like! I have a DC2 Integra Type R as well, so your B18 part caught my eye.

[madjak]

Thanks. Will be interesting to see your results.

Agree with the previous posts, it looks like it belongs, good work.

That's what I'm most happy about... it looks like it was designed to go in the Mazda engine bay. The angles of the throttle body and clearance at the back around the brakes and clutch are pretty much perfect. I think you really need very solid engine mounts or you'd have to angle it up a bit more that I have. There is good clearance underneath but not enough for lots of engine movement. There is a little upturn on the chassis right under the throttle body and I might trim it down a little as there is only around 20mm clearance between the tps and that lip.

[project.r.racing]

If you were to do it again, I'd say remove another 10mm from the runners. Should negate all those clearance issues. It is quite a good bit of parts bashing.

[madjak]

If you were to do it again, I'd say remove another 10mm from the runners. Should negate all those clearance issues.

Yeah you're probably right. Because the runners taper inwards I didn't want to loose too much as the port spacing starts getting off at the end runners. As it stands the runners align and angle perfectly with the porting of my head... not that 10mm would move them much, maybe inwards another 1mm or so.

I can get a bit more clearance if I mill a little more off the top of the flange too which I might still do. It will angle it up a few more degrees.

[Lokiel]

Front-runner for "DIY of the month/year", great work - looking forward to reports on the performance.

[speed]

Looks great in the bay. Keen to read how it performs

[Dweezle]

How are we hoping the gains are made??
Genuine question.

Is it the larger TB, longer intake runners, just flows better???

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[plohl]

Great work dude!

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[NitroDann]

Higher mass flow rate. Its a no compromise performance manifold aimed at high throttle percentages and rpm, not compromised for midrange, straight runners instead of compact curved etc

[madjak]

yeah this intake only really needs to work for me in a very high rev range between 5,500 to 8,500 rpm... I'm not really interested on anything below that. The stock manifolds are designed for more torque down low and to suit a smaller airflow target at higher revs. My engine has much higher requirements to get air into the engine, with very big cams and oversized valves so I suspect the stock manifold is the main restriction in the engine. This manifold has a small plenum with very nice bell mouths on the runners and it the runner cross sectional area would be 40% more than stock. Plus it fits which was my main concern.

I think the stock throttle body would be fine, however given this 70mm one came with the manifold I figured it was worth it. There is an issue with high reving engines where the shaft in the stock throttle body breaks due to harmonic vibrations. If this happens the motor ingests the shaft and it's not pretty. One solution is to use the MX5 specific Skunk2 64mm throttle body but this costs more than the Honda manifold and throttle body together. I'll report back if it affects throttle sensitivity etc.


Machining it on the mill... mounting the runner piece was a bit fun. I took it nice and easy so it didn't pop out of my hack clamps.


A quick sand with a flat board and it came up pretty good. Not quite machine shop level but smooth and flat.

Next task is to clean up the inside of the runners. I purposely undercut the flange so I could match the angle into the head so it needs a fair amount of grinding. Dyno is booked for Tuesday next week so I have a bit of work to do this week!

[NitroDann]

If your budget allows please back to back this, for science

[hks_kansei]

Nice looking mill too.

old bridgeport one?



A mill and a lathe are on my garage list, the downside is that they're all 3 phase which isn't an option for me at the moment (renting)

[madjak]

If your budget allows please back to back this, for science

I'll be running it on the same dyno as previously. Nothing else has been changed on the engine so it will be a good test.

Due to circumstance I dont have a dyno plot, although I know how it looked and the max values so I can estimate the gains. We were scrambling to finish the car before my first event and cleared the various dyno runs to do the last one. Just before doing the final run we had some issues and it was never completed. It wasn't a priority at the time to have the chart as I intended to go back once I had larger injectors.

[madjak]

Dyno is booked in for Wednesday.

Here are a couple of shots of the engine bay all complete. Still need to tidy the wiring from the flex sensor etc but I'm waiting for the Honda TPS and AIT plugs to rock up before wrapping them. I've fired the engine up and it's now running on E85. Smells a bit different!





Also, I've installed one of the $25 ebay oil pressure senders and it looks like the ECU is picking it up fine. I still have a few spare inputs on my ECI so I'm going to get another now for the fuel pressure. I'm going to use the oil pressure sender to drop the engine into limp mode if pressure drops as I don't really get to see the gauges when driving. I'll probably hook up a warning light at some point too.

[Apu]

Very interested in seeing the outcomes!

It might be a good opportunity for me to take the manifold off my B18 and hack it up for this, and get the Skunk2 unit for the B18