intake mods

[kitkat]

just looked it up on the website. it's a pretty expensive mod for what it is... i'll have to save up

yep, very expensive shiny metal.

Personally if i had $620 to spend on shiny intake stuff i would save up a bit more and go for a pnp megasquirt... then you could make a complete custom dodgy intake and have a MUCH better base for future mods. CLICKY

Then follow the mods done to this machine... CLICKY

So you can be this quick (note the white na6)... CLICKY

Note the camera car is a stockish NA8 seen here... CLICKY

[Steampunk]

Personally if i had $620 to spend on shiny intake stuff i would save up a bit more and go for a pnp megasquirt... then you could make a complete custom dodgy intake and have a MUCH better base for future mods. CLICKY

NOW you're talking my language homeboy

[Matty]

When I got my nb8b a few weeks back I couldn't beleive the crappiness of the intake. I websearched my ring out and found nothing definitive. I've read all the arguments posted here and yet no-one actually has any empirical evidence to prove anythng. The only article of any real value was the flow testing conducted by autospeed that shows the restrictions in the system.

I did that testing, not autospeed (they just published it).

You're right, I too have seen no empirical testing beyond what I did there (I did try a prototype duct between the TB and AFM that gained another 3cm improvement. But that was all on an NA6, which is quite a different beast.

Surprised you think the NB intake is so crappy, it looks pretty good to me. Of course, noise is one of the factory criteria that may be different to yours...

Also even more surprised that you read my article, but didn't test anything yourself before replacing it all.

Now that I have an NB (well, when it comes back from the shop) I might get around to testing the intake on it. However as I have no intention of replacing it this may take some time. Gotta find my old manometer too...

[Fatty]

matty, i think there was also some testing done in the \"performance handbook\" . iirc they put a car on a dyno, fitted various intake setups (one including the rx7 afm) and measured the results. i don't think they go into a lot of details in the book tho, or publish any actual data. one thing that i do recall tho - they reckoned the rx7 afm is a waste of time unless you are running heaps of boost. ie the stock unit is not that restrictive (altho many people seem to think it is. how they reach this conclusion, i don't know... other than internet / chinese whispers)

[Okibi]

It would be great to see your results Matty.

I'm sure there's a few Vic members who'd be happy to help you out if/when needed.

I'd love to see the facts on airflow as well as different methods for reducing air temperature.

Is there a noteworthy reduction in airflow through the inclusion of more bends, does the 2 90\" bends in a cowl intake reduce their performance?

Whats the air temperature differences between the area in the cowl and the air flowing just after it passes over the exhaust manifold?

[Matty]

Fantastic piece of plagarism on behalf of autospeed then.

I come from a nissan background and this is a common mod on na sr20's and rb 20/25's. I am no engineer, nor do I understand much about it but common sense says the most effective route will be the shortest with the least restriction. That is the basis for my experimentation.

On what basis did you think the nb8b was good? I just saw 1.5m of bent different size hose with a number of choke points. As I said I am new to mazda but it's the most convoluted OEM induction system I have ever seen.

I didn't do it for noise. It was a genuine attempt to extract more torque. The fact that I had not seen anyone do it just made me keener to try (I also accepted that there was probably a good reason why no one was doing it )

Why would I test the existing plumbing? If my mod reduces torque (as determined through a before and after torque curve map) to a degree were I believe the gain in throttle response is offset by any drop I put the original kit back on and start again.

As I said, I have very little idea about the technical side of it. I work on very basic principles and am happy to have my concepts disproven (preferably by myself) which is why I will be doing more than seat of the pants testing.

Cheers

nonono, autospeed asked me to write that article for them. No plagiarism, I have the authoring credit.

I suspect the NB intake is good based on inspecting it and my experience with the NA6 measurements.
The AFM-TB duct is a decent size (in the context of the power level of a standard engine) and has nice large bends in it.
The air flow meter is a hotwire design that is usually less restrictive than a vane meter. (can probably pop out the mesh for a fractional improvement)
The airbox - I haven't really looked closely at, but the snorkel is shorter than the NA's and comes to the front so will be sucking cooler air.

But until it's measured, anything else is heresay. Personally I don't see the point in "improving" something without knowing how good it is to start with, or without measuring your results...

I'm not at all saying you can't improve on it, but I suspect the improvements in flow will be small (cold air is another matter).

[stevesports]

the only intake modification i've made is actually remove the snorkel and attached a hose that feeds air from a opening near the right hand side headlight (if viewing at the front of the car). I have tried a pod filter but it felt like the lower end and midrange struggled a little, so i put the airbox back in. I think removing the mesh would be my next intake mod, or possibly changing the intake tract to something smoother (but not too wide of course).

i think the ultimate would actually be a aftermarket ECU such that you would remove the AFM and operate under a MAP system.

[davamb]

... a aftermarket ECU such that you would remove the AFM and operate under a MAP system.

Don't understand Steve. Thought you would always need some form of air metering - determining just how much air the engine is gulping and thus how much fuel to add to the mix. How do you do it with mapping? Is it mapped in n-space against the butterfly angle for this parameter?

[Woo]

MAP= Manifold Absolute Pressure

continue

[stevesports]

yeah should have made that clear =]. Anyway, anyone know the cheapest way to swap the AFM for a MAP sensor that suits the MX5's stock ECU?

[Fatty]

anyone know the cheapest way to swap the AFM for a MAP sensor that suits the MX5's stock ECU?

there is no cheap way to do this and retain the stock ECU, i did heaps of research into it .

IMO the cheapest way to go to a MAP sensor, is the Megasquirt. not sure if the MS workes on nb8bs yet , either?

if you must retain the stock ECU there is a piggyback unit you can buy from an american company but it's pricey. i've forgotten the details... it was a while ago when i was looking into it

[Steampunk]

... a aftermarket ECU such that you would remove the AFM and operate under a MAP system.

Don't understand Steve. Thought you would always need some form of air metering - determining just how much air the engine is gulping and thus how much fuel to add to the mix. How do you do it with mapping? Is it mapped in n-space against the butterfly angle for this parameter?

re

Aftermarket EMS'ses reads MAP and TPS and IAT (Inlet Air Temperature) and wideband Lambda sensor to attain optimum air fuel ratios.
They all have base maps just to get you going, but ultimately, you will have to tune the fuel and ignition tables to get the

[Steampunk]

... a aftermarket ECU such that you would remove the AFM and operate under a MAP system.

Don't understand Steve. Thought you would always need some form of air metering - determining just how much air the engine is gulping and thus how much fuel to add to the mix. How do you do it with mapping? Is it mapped in n-space against the butterfly angle for this parameter?

re

Aftermarket EMS'ses reads MAP and TPS and IAT (Inlet Air Temperature) and wideband Lambda sensor to attain optimum air fuel ratios.
They all have base maps just to get you going, but ultimately, you will have to tune the fuel and ignition tables to achieve whatever results you are after; ie. power or economy.

[davamb]

Thanks guys. I understand now.