VX Intake Questions

[gork57]

I have been considering installing a new intake system (such as K&N) for my 1992 VX. Manufacturers claim that this helps the engine breath better, boosting hp while improving mpg at the same time. However, I have not been able to find an intake specifically for the VX (other Civic models galore). Here's my questions:

1. Do the claims of improved mpg and hp hold true for the VX model in particular (does it justify the cost)?

2. Can anyone point me to a website to get the correct intake for my model of Civic? Reusable filter element is a definite plus.

The VX is a great vehicle whose design was way ahead of it's time. However, it's lone glaring flaw is that it is a bit underpowered. A little more hp wouldn't hurt.

[jadziasman]

The VX does not have a "special" OEM air intake to my knowledge. It is the same for every trim level (CX DX, LX, EX Si) during the 1992 model year.

[StorminMatt]

From what I have seen, the VX uses the same air filter element as other Civics of the same year range. BUT, it has a smaller intake 'arm'. For this second reason, you will have a problem finding a suitable aftermarket intake. But you could probably use a K&N OEM-style pancake filter to get you a little more airflow. And given the meager airflow requirements of the D15Z1, intake restriction is probably not much of a problem.

One more thing. When it comes to acceleration, gearing is hurting the VX more than a lack of HP is. You might look into gear ratios of other D-series transmissions to see if you might be able to build a custom transmission that gives you better gearing for the city, yet keeps the tall fifth gear for efficient freeway cruising. With better gearing for the city, you might even gain some MPGs around town.

[suspendedhatch]

Drop-in filter is your best bet. Replacing the entire intake in this situation will most likely hurt your mileage. Most certainly it will hurt your freeway mpg.

[StorminMatt]

Originally Posted by suspendedhatch

Drop-in filter is your best bet. Replacing the entire intake in this situation will most likely hurt your mileage. Most certainly it will hurt your freeway mpg.

At least on more performance oriented Honda motors, intake systems seem to help mileage somewhat. I don't see how it would actually have a negative effect on mileage with a D15Z1. But I can certainly see how it probably would not help power much.

[GasSavers_Ryland]

If your engine is hitting high revs alot of the time then the after market air intake might help with mpg, but it will also most likely hurt your low end power because of how fluid dynamics work.
If you think that your vx is under powered then you should ask your self what laws you are braking, I've had 5 adults in my vx merging on to the freeway and felt like it had plenty of power to do whatever I asked of it.
I use a drop in foam air filter and love it, better air flow then paper and catches more dirt then a K&N.

[Danronian]

Stick with the OEM intake. I had a short-ram intake with a "high-flow" k&n filter and the car's power wasn't as smooth and it got worse gas mileage.

[suspendedhatch]

Originally Posted by StorminMatt

At least on more performance oriented Honda motors, intake systems seem to help mileage somewhat. I don't see how it would actually have a negative effect on mileage with a D15Z1. But I can certainly see how it probably would not help power much.

The VX intake is much narrower than all the other intakes. The whole car is setup to have low RPM power. Low as in being able to cruise at 1000 RPM. The problem with low low RPMs is that there is very little air flow. So you "pinch the hose" so to speak with a smaller intake (it's the same idea with closing one intake valve). When you put an intake on it that was designed for a 16 valve motor you throw the whole setup off balance. The car actually loses power. The D15Z1 with it's 6000 RPM redline never reaches high enough RPM to see any benefit from increasing the intake diameter.

Honda put roller rockers, special low friction piston rings (usually reserved for the Type R only), a lightweight flywheel, an aluminum engine mount and alternator mount, a wideband O2 sensor, as well as a rear diffuser and a front lip spoiler. Honda made a special ECU and tuned the calibration to the bleeding edge (yet they used the same P28 for a D16Z6 and a B16A). Basically Honda put just about as much attention into the VX as they put into the Type-R. And like the Type-R, almost anything you do to try to improve upon it is only going to hurt it.

[StorminMatt]

Originally Posted by suspendedhatch

And like the Type-R, almost anything you do to try to improve upon it is only going to hurt it.

Actually, it's not that hard to make more HP with a Type-R. I don't know if the same thing applies to MPG and the VX.

[suspendedhatch]

Sure, I could pick up some peak hp by removing my intake and unbolting my exhaust, but that would be at the expense of power all throughout the RPM band. Typical bolt-on's only MOVE the power around. Often times it moves the peak of the power band beyond the redline. It's not worth the compromise unless the car is ONLY for racing. In an article I read, the Honda engineer responsible for the Type R in response to a question about people who want to tune the Type R even further said something to the effect of "please don't mess with the car. It's been tuned to perfection." It makes more sense to start with a GSR motor.

The only way to get a significant, consistent, cost-effective improvement in mpg (from the EPA estimate) on a VX is with driving techniques.