15 replies to this topic

[Bluemini]

Ok then, I was wondering the other day what the effects of ram charging would be on a mini. What I was thinking of doing was fabricating a pipe from the carb to the front of the engine bay, but instead of keeping it the same diameter all the way through, I was thinking maybe have it wider at the opening tapering it to the size of the carb mouth. My theory being that air traveling down a tube that gets narrower will speed up. Am I right and would there be any benefits from it? I know normal ram charging doesnt make much difference with the pipe being the same diameter all the way along its length, but would this way be any better? Has anyone else tried it or got any ideas that they think might work? If we can get a few ideas toghether and some pro's and con's, then I'm gonna try it. Come on guys, hit me with your ideas... :grin:

[The Roadie]

Grest idea, but I was under the idea that SUs don't like ram charging. Does anyone know any different?

[lewis]

wouldnt it need filtering? like a foam filter

like an itg sock end etc

[Bluemini]

If the SU doesnt like it, then I always have the Weber to try it with, but would rather stick to the SU...

Filtering isnt too important, as some carbs run without filters and just have trumpets, but if it was needed then I could fit one in somewere.

[The Roadie]

Yeah get a Webber on it, it'll drink fuel, but it will sound cool and have more power, which is the bit that matters.

[Bluemini]

Yeah, but I want to try somat different, I've done the Weber thing already, they do sound good, but like you say - fuel economy!

[Dan]

I seem to remember seeing an equation somewhere which proved that ram air didn't work on any motor, until you were doing at least 100 mph or something like that, but I could be wrong. I'll have to see if I can dig it out. I like the idea of playing with the shape of the inlet duct though, could be lots of tuning to be had from improving flow to the carb body, and would get the noisy inlet duct away from the bulkhead.

The thought of running any engine with no air filter sends shivers down my spine. Even the old works tea strainers are better than nothing, at least they keep large wing-ed things out of the carb.

[bluebottle]

if you read vizards tuning the A series, he has a fair bit on ram charging.

[mighty_mini]

HIFF44?

[Rob]

If you were to use a ram pipe which goes from a large diameter to a narrow one you would have to change the carb needle because you would get a weak mixture at high speed as your existing needle would not be profiled to suit a 'forced induction'. You would have to get a richer needle. But the problem here would be at low speed the mixture would be to rich therefore lose power at the lower speed. It would be alright if the roads were empty but as you know there not!

Does this sound right?

[Bluemini]

Would it not be a similar principal to the turbo tho? They have forced induction and dont have any fueling problems... Except Daves

[Rob]

Turbo's are forced induction but you dont have to be moving like you would with a ram pipe. At low speed the ram pipe is not recieving much air. Turbo an the other hand is forcing air in at any speed as it is working off exhaust gas speed not air speed.

[Bluemini]

I see your point, at low speed its sucking rather than being pushed.
Maybe some kinda fuel injection system would be beneficial then?

[jeffberg]

the turbo may always be on. But it only runs at high rpms,
so wouldn't it be the same at idle as not having a turbo at all
and thus it would be sucking not ram charging?
so it would seem it would be ok
but i dunno
maybe a turbo has something to counterract that?

[neil_g]

you cannot force air into a normally aspirated engine. you may however be able to make the air denser by "ramming" as much cold air at the filter ready to get sucked up..

it is nothing like forced induction as you would not even come close to the pressures generated by a turbo or supercharger.