Aftermarket / Performance Sealed Airbox Type Air Filters

[V8RX7]

I have supercharged my MX5 and it's making approx 250bhp

I am cutting through the firewall to get cold air from the base of the windscreen, I want to duct that to a sealed airbox type filter

I've seen the various offerings from Ramair, Pipercross etc but they don't appear to be much different to the chinese copies at 10% of the price

Has anyone any experience of the cheap type - I'm happy to swap out the filter for a better one but I do wonder how different they are in reality

I'm more than happy to use a std OEM type if one will fit

The other option is to use a paper element (my preferred option) and build a cold air box around the duct.

Essentially how different are these (most expensive first)

https://www.ebay.co.uk/itm/Pipercross-C7000-Cerami...

https://www.merlinmotorsport.co.uk/p/itg-universal...

https://www.ebay.co.uk/itm/Pipercross-Venom-Univer...

https://www.ebay.co.uk/itm/RAMAIR-Performance-Encl...

https://www.ebay.co.uk/itm/3-Carbon-Fiber-Cold-Air...

[designforlife]

A sealed CAI from the firewall drawing that nice cool air below the windscreen will always be the best option...however if you do go open cone or cone with a heatshield, just try and keep it away from the manifold and hotter air.

On my mk2 mx5 I had a 180 degree silicone elbow and open cone, didn't have heatsoak issues.

It's one of those things, if you have the budget you can get some really nice JDM induction kits, but on a car thats already FI i doubt you'll see much of a tangible difference to performance.

Here's the racing beat kit that I replicated, cost me about £50 in bits-

Edited by designforlife on Thursday 17th January 09:21

[V8RX7]

designforlife said:

but on a car thats already FI i doubt you'll see much of a tangible difference to performance.

That's the thing... it's been dyno proven that superchargers really don't like sucking.

Increasing the TB size alone gave over 10bhp

Some ducted 4" flexi pipe around the engine bay - that cost 15bhp

[designforlife]

If you have the budget and want the best gains, this was supposedly one of the best/the best induction kits for the mk1-

Jackson racing CAI -

https://www.ilmotorsport.de/shop/article_detail.ph...

To be fair I spent about that on a carbon fibre CAI for my DC5 and it was worth every penny...and these higher end kits have a very OEM quality fit usually.

[V8RX7]

designforlife said:

If you have the budget and want the best gains, this was supposedly one of the best/the best induction kits for the mk1-

Jackson racing CAI -

https://www.ilmotorsport.de/shop/article_detail.ph...

To be fair I spent about that on a carbon fibre CAI for my DC5 and it was worth every penny...and these higher end kits have a very OEM quality fit usually.

I recently sold one - the quality is very poor for the price

As I mentioned mine has to be as short an intake as possible hence it's just a 90 degree bend then one of the mentioned boxes and another elbow through the firewall - total length approx 18"

[GreenV8S]

I added a cold air intake (not on an MX5) by adding a box to draw cold air from a gap in front of the windscreen and poking the intake through the side with a conventional cone filter inside the box. If it's near the center of the screen it'll be in a high pressure zone - near the corner more likely to be negative, although tbh the difference is going to be minimal at realistic speeds. It did give a nice short run, very cold air source and increased induction noise - which I saw as a benefit, but ymmv.

Later on I replaced this with about a five foot run out to the front grill. It ran fractionally colder but not much in it, and similar pressure drop. I think the longer run balanced out the air having to fight round corners to get into the air box. Whatever approach you use, make sure the intake has a smooth bore and constant internal area, and is insulated from underbonnet heat.

[stevieturbo]

At only 250hp...I'd be using a factory paper filter as a first option. Even a very small OEM filter will easily offer more than enough flow for that low power.

[V8RX7]

stevieturbo said:

At only 250hp...I'd be using a factory paper filter as a first option.

Even a very small OEM filter will easily offer more than enough flow for that low power.

Yes as stated that's my prefered option

If that were correct then why do manufacturers use such different sizes ?

A sub 200bhp car can have one twice as large as a 1.0 car

Also the inlet / outlet sizes are far too small on many - as stated dyno proven 10bhp gain increasing throttle body size so sucking through two smaller openings will lose that.

Hence looking at the aftermarket