Air intake upgrade?

[MR2Kyle]

Is there anything you can do/buy that increases the air intake? Is it hard to make a cold air feed? Could i use the vent on the side of the car and then buy a scoop to cool the bay?
Thanks

[LimeyMk1]

The vent on the side is, believe it or not, where your stock air inlet takes the air from on a Mk1b.

A possible improvement for that would be to run a smoother, wider bore, pipe round the boot (replacing the stock pipe) to the airbox. It's a bit of a convoluted route and could be condidered to be a bit restrictive in stock form.

Going direct from the side vent would probably mean crossing over the top of the exhaust manifold which would be somewhat counterproductive.

Most cold air feeds for things like the K&N 57i cone filter take air from the bottom of the engine bay but I've found they do direct a lot of dust and dirt up into the bay.

Most folks just pop a cone filter onto the throttle body (with a short extension pipe) and leave it at that.

[elbon50]

A company in Cheshire, who prepare Mk1s for racing, use the whole rear boot as an airbox, with a scoop under the boot floor

One member on here used a modified vent/scoop from the O/S, fitted to the N/S into the side of the rear boot

[SuperRedMR2]

A company in Cheshire, who prepare Mk1s for racing, use the whole rear boot as an airbox, with a scoop under the boot floor

One member on here used a modified vent/scoop from the O/S, fitted to the N/S into the side of the rear boot

I don't see how that'd work well, mainly as the boot floor is higher than the bottom of the car, unless they've made an inverted tunnel to channel the air in, still a lot of work involved.

I did consider removing the fan on the right hand vent, then fixing a hardpipe from there over to the throttle body, but as limey says it's counter productive due to the heat from the exhaust manifold as well as find somewhere else for the fan to sit.

I'm getting my car back tonight and will be making a route to have a flexi pipe come from the hole where the gearbox sits and the left hand rear wheel, coming up over the battery with a sort of funnel/box covering my air filter - it'll look crap I imagine but i'll have to see (and if it clashes with my engine cover).

[stenky]

get a side scoop from paul and route it to the intake. much shorter than the side vent.

i have removed the original air box from the boot and mounted apexi cone there (70mm silicone elbow 45*). air feed tubing from side vent is left intact. also removed the resonator from engine bay (another 45* elbow, but the bend is less than that so trimming the hose was tricky). i am running european AFM car so cant just ram a cone onto throttle body and feed some fresh air from a side scoop

[Tiamat]

I now have a set of the "bunny ears" so will plumb my intake into the scoop and see if it makes a difference or not.

Obviously once I have finished rebuilding the front end...

[elbon50]

I now have a set of the "bunny ears" so will plumb my intake into the scoop and see if it makes a difference or not

Wow, those will have set you back a bit I think

The ones I've seen were about £90 each

[PW@Woodsport]

It intrigues me why people think feeding more air into a Mk1 engine bay is going to increase power?

There is already a massive updraft of air coming up through the bay from the road surface, so much so that if you leave the engine lid open it will literally lift up and float at 70mph. The bay gets all the cold air feed it could possibly want, all you're doing adding a side scoop is causing more drag, it cannot provide more power.... that is a totally unbiased opinion as i actually sell the scoop!

To work, the side scoop would not only need to lower the intake temps but would also need to negate the airflow coming the other way, but the air being fed by the scoop is the same temp as the air coming up from underneath the car.

Say it does manage to add more air to the bay (it can't due to the already massive upward flow, but for arguments sake let's say it does) , how is that air at the same temp as the upward moving air helping?

I studied this in some detail many years ago and it really doesn't add anything, what i did come up with was the fact you could ditch the Aw11 plenum, and fit an AE86 one instead, do a little basic replumbing and you could use the offside engine bay fan hole as a place to mount the induction kit and pipe that directly into the throttle. I used this location on the V8 Mk1 and it is the best possible place for the air filter to get the coldest feed possible.

In short, you'll never get the engine bay temps cooler than Toyota already do by adding roof scoops, there is too much upward airflow which just negates anything the scoops do.

I think even using the AE86 plenum and filter in the OS vent hole you'd be lucky to see a 1 or 2bhp gain.

As for this...

A company in Cheshire, who prepare Mk1s for racing, use the whole rear boot as an airbox, with a scoop under the boot floor

That is just turning the boot into a parachute.... epic fail.

[PW@Woodsport]

Most folks just pop a cone filter onto the throttle body (with a short extension pipe) and leave it at that.

That is pretty much the best idea, it gets more cold air supply in the bay than the sidevent can supply piped into the boot, no need to do anything else

[SuperRedMR2]

As for this...

A company in Cheshire, who prepare Mk1s for racing, use the whole rear boot as an airbox, with a scoop under the boot floor

That is just turning the boot into a parachute.... epic fail.

HAHAHA

[MartG]

Most folks just pop a cone filter onto the throttle body (with a short extension pipe) and leave it at that.

That is pretty much the best idea, it gets more cold air supply in the bay than the sidevent can supply piped into the boot, no need to do anything else

Or fit a cone filter in the boot if noise levels are an issue

[elbon50]

I have a cone filter in the boot

With all the trunking from the O/S vent removed

Seems OK

[Red Wedge]

Sorry to bump an old thread but it saves me starting a new one and this is a relevant question.

What is the diameter of the inlet on the plenum?

I want to get some silicone hosing to fit a K&N cone filter I've bought and want to make sure I get the right diameter.

Also, is there an ideal length if I'm just running it straight off the plenum?