Pipe from LPG vaporizer to top of air box???

What does this pipe do. Want to fit a K n N (cheap arse carboot Max power equivalent) cone filter as my airbox is all cracked up.

not sure what the pipe does (I've never had an LPG setup), but I'd just buy (or make) a short metal pipe with a pipe stub for that pipe, to join the filter to the air intake.

Wanna buy a new airbox instead? I've got one

Not trying to detract from you selling it HJ, but I personally think the standard airbox is a useless piece of junk :p

I put one on my old 1.3 hijet for a couple of days, and it made null difference, apart from making loads of noise.

That standard 'useless peice of junk' airbox stops the car from ingesting water when you hit flooded bits of road. Plus it keeps the cab quiet. And I bet Daihatsu spent way more money developing it than you can even imagine. If cone filters were actually the best choice all the manufactures would save a small fortune and fit them in the factory.

Gullible boy racers always think it too, I've tested honda air boxes in the past, changing them for a cone filter looses you loads (and I mean loads) of mid range power for the gain of a fraction more power right next to the rev limiter - pointless. Might make it sound faster mind you. I've got some dyno printouts from ten years ago somewhere in a box in the loft.

its perhaps a little different on the 1.3....

on the 1.0L, the air intake travels forwards, and then sucks air through the drivers side chassis rail!

and yes, it did make more noise.....but it just helped the comedy factor on my hijet....

as gaining or loosing power, mine did run considerably better with a cone filter.....
I found I didnt need to change down as often on the same hills.....


whether a 1.3 is a different airbox setup, I dont know......




and cone filters/high flow filters/etc can gain a little bit of power across the range IF the standard air system is too restrictive or, if the fuelling is adjusted to suit.
now the hijet 1.0L airbox was restrictive and had a blanked pipe spur off the air intake pipe (between the chassis and airbox), which 'reduced' EFI induction noise, but which in turn would hamper the intake flow a little.


the problem with gullible boy racer types, is they generally hack their exhaust apart, fit a high flow silencer, and then a cone filter (sucking hot engine bay air in), and then think the noise means more power....
which it clearly doesnt, and now their engine is running lean.

that annoying gurgling popping/rumbling noise their cars make on the over run is the result of the lean mixture creating unbalanced surging pulses down the exhaust pipe.



now manufacturers do try and fit the most unrestrictive intake they can, but obviously most people wouldnt be happy with the intake noise of a cone filter, so they have to design airboxes for the best flow while remaining as quiet as possible.
just the same as the exhaust system.


now the ideal air intake system, is a tuned velocity trumpet, with a smooth radius on each intake port running completely unfiltered for the least restriction possible.
the length of the trumpet can be tuned to suit (or change) the torque characteristics of the engine.

similarly, the exhaust system should be designed to allow a good amount of flow, with a bit of port scavenging to ensure the engine runs at its optimum.
hence why tubular manifolds are the most effective. the runners need to be a certain bore and a certain length to compliment the intake system.
the length and bore of the runners however, can be tuned to alter the torque and power characteristics of the engine.

as for silencers are NOT good for power, no matter how free flowing they are.


however, as we all know, a vehicle running an open intake isnt going to last long due to dirt/dust/etc, and a straight through exhaust system is just too loud.....

so exhausts are produced to a cost (usually horribly designed cast manifolds with random runner lengths), and the silencers are then utilised to help scavenge by providing a bit of back pressure.







Please understand, the reason I have written this, is so you understand I am NOT a 'gullible boy racer' type, and am infact someone who has spent a lot of time reading and understanding the mechanics and physics of engines, and their intake and exhaust systems (including 2 strokes), and have even applied certain parts (the tuned intake and exhaust part), to home building jet engines.

so yes, some air filters/boxes might be very well designed for a completely stock engine, but if the fuelling is tweaked to suit a high flow filter, power should be gained.
of course, the engine porting and valve sizes, and also the compression also play an important factor, but in general, most engines are conservatively tuned for the best reliability possible....

A- you forgot to mention that the blank stub on the intake creates a back pressure which can restrict or help scavenging and produce swirl in order to mix the air/fuel in the cylinder head.

And I will have to dig out my bosses copy of 2stroke exhaust design it's from the sixties and the maths made my head spin.

The main reason for that stub is reducing intake noise (by playing with the harmonics of a negative pressure wave)....

as for the 2 stroke tuning, A Graham Bell wrote a fantastic book about it
I understood a lot of it (and parts of it subsequently were used to tune my valveless pulsejet....)





incidentally, a expansion chamber will usually run as a poorly designed valveless pulsejet

Wow lots of words on this thread. The chap at the car boot I got it from said i'd get at least an extra 30bhp if I fitted it so I may as well at least give it a go to see what happens. Might even get two for 60bhp + an ebay chip = 90ish bhp extra power

Go for it, if the man at the car boot told you it must be true you could have the first 1000hp hijet on the road.

How beastly would it be with the back full of a ton of them. Eat a veyron anyday.

and all that money they spent making the only engine that is cooler than a V8, a W16

Totally down the drain, what were they thinking? Hell they just needed a corsa with an electric fan super charger, some neon washer jets, a power resistor of fury and 50 cone filters.

Oh dear god I forgot about the massive advantages of the power resitor of fury, crap anyone got one spare I really think I should have one and I just can't wait.

what about covering the entire fuel line from the fuel tank to injectors with fuel magnets?

that should gain an extra 100hp

oh yeah and I'll just have to be careful not to spoil the look of the loose fit braiding and alloy jublee covers.