Up Into Fourth
Posted 11 September 2013 - 10:43 PM
Slightly off subject ...
I'm waiting for someone to make a dyson cyclone type device , to spin out debris from the air , with no restriction in flow -
- could build in a ram induction pipe to boost air flow at certain revs as well
I knew someone with long straight twin ram pipes in a mini - thru the speedo hole , it was un-useable , due to noise , but went well
Speeding Along Now
Posted 11 September 2013 - 11:49 PM
Not to be harsh, but those mesh "filters" pictured above will do absolutley nothing other than restrict airflow & most likely cancel out any power increase the ram pipe gave in the first place.
Phil.
I know, but filter socks will also reduce airflow (even more than the mesh filters), the best filter in combination with ram pipes (they're actually stub stacks) are those ram air kits from MED (http://www.med-engin...es/ram-air-kits) but they don't fit in my car because it's LHD and the brake cylinder is in the way, the mesh filters are still better than nothing and I have my reasons why I've bought them...
Edited by RedRallyMini, 12 September 2013 - 12:07 AM.
Crazy About Mini's
Posted 12 September 2013 - 12:02 AM
I don't see the point of ram pipes on a road car, as they will only increase power within a certain rev band, and decrease it or make no improvement elsewhere. Considering that most of us need to drive our cars, of all sorts, over a wide rev range, any resonant performance enhancer is of limited use.
But if, on the track, your engine spends a lot of time in the rev range to which the ram pipe is tuned, that is another matter altogether, and they will be useful.
The same considerations are true, to an extent, for tuned exhausts. The ultimate performance accessory, the turbocharger, almost eliminates resonances in the induction and exhaust tracts, so the performance is boosted over most of the rev range. But not everyone wants to fit one of those, with all the butchery it requires to fit it in, and there is the problem of turbo lag. I think they are best on diesels, and my 3 most recent daily drivers have been turbodiesels, as will the next, eventually.
There are mechanically complex devices such as variable length ram pipes, which can adapt to the engine speed, but you would need some kind of computer and a reliable actuator for control. The turbocharger is simpler....
Crazy About Mini's
Posted 12 September 2013 - 08:11 AM
Not to be harsh, but those mesh "filters" pictured above will do absolutley nothing other than restrict airflow & most likely cancel out any power increase the ram pipe gave in the first place.
Phil.
I know, but filter socks will also reduce airflow (even more than the mesh filters), the best filter in combination with ram pipes (they're actually stub stacks) are those ram air kits from MED (http://www.med-engin...es/ram-air-kits) but they don't fit in my car because it's LHD and the brake cylinder is in the way, the mesh filters are still better than nothing and I have my reasons why I've bought them...
Plenty of LHD cars with them fitted, also the kit is not as big as it seems in the pics.
Speeding Along Now
Posted 12 September 2013 - 09:31 AM
Not having a ram pipe of some sort effectively makes the carb inlet smaller so I'd fit one on any car road or otherwise. As for gwire mesh filters, they are worse than nothing IMO. The offer no filtration for the stuff you actually want to prevent from going into the engine and then restrict flow just for good measure
Crazy About Mini's
Posted 12 September 2013 - 09:33 AM
Was trying to post something but got lost
Ram charging and med stacks are a different kettle of fish.
What med engineered is a device to simply gets rid of the vena contracta effect at the carb mouth.
Ram charging is a different engineering matter. And debatable too.
According to the maths i've done to improve top end breathing on twin HS2s, by adding a 1.75" pipe at 5000 rpm i have a ram charge if the wave is able to bounce back 28 times. Not sure its got enough energy for that.
Theres a formula based on cam timing, carb choke size, ram length and number of bounces but thats where i hit the nail on my head.
It doesnt take in account that we're talking about the bounces from the inlet valves up to the eng of the pipe, not taking in account inlet manifold ports and carb lengths.
Crazy About Mini's
Posted 12 September 2013 - 09:45 AM
Well, let us see. 5000rpm is 83.333 revs per second, or 12 milliseconds per rev. The speed of sound is 1126ft/sec at sea level, so a wavelength is 12ms*1126ft/sec = 13.512 feet. The first length which is useful is a quarter wavelength or 3.378 feet. Call it 1 metre.
But it is worse than that, as the siamesed port layout results in two adjacent pressure pulses every 2 revs, i.e. two pulses 6ms apart every 24ms, so the primary resonance would need a 2 metre pipe, and to ensure filling of the second cyliner, there would need to be a 1/2 metre section too.
With the Mini's head design it is not going to be good. Two cylinders will not be filled correctly. That is of course assuming twin carbs. With a single carb and the manifold as short as possible between carb and head it is not quite so bad, and the 1/2 metre ram pipe might be useful. So it will need to be bent forwards and run over the top of the engine, with the intake behind the grille. I think that needs a bonnet bulge.
Crazy About Mini's
Posted 12 September 2013 - 10:00 AM
Yeah siamese porta are a pain in the bum when it comes to tuning, you'll always have 2 cylinders not filling correctly unless you have a scatter pattern cam.
According to vizard a short ram is always best, but surely, if it needs 28 bounces to work at 5000 rpm, you'll need 48 to work at 2500..that said i cant make a reason why in real world it improves midrange when its designed for high revs, maybe its just the effect of a better flowing and probably faster air speed, not ram charge.
Speeding Along Now
Posted 12 September 2013 - 11:41 AM
Plenty of LHD cars with them fitted, also the kit is not as big as it seems in the pics.
I'm sure it won't fit mine without placing the brake master cylinder somewhere else, I already have to bend the brake pipe to fit the twin hs6 like it is in the picture and I've heard from people (with LHD cars) who've bought the MED kit that it doesn't fit...
Speeding Along Now
Posted 12 September 2013 - 11:52 AM
Not having a ram pipe of some sort effectively makes the carb inlet smaller so I'd fit one on any car road or otherwise. As for gwire mesh filters, they are worse than nothing IMO. The offer no filtration for the stuff you actually want to prevent from going into the engine and then restrict flow just for good measure
Having no airfilter IS worse than mesh filters, I know they offer no filtration, I know they restrict airflow, but without them leaves or stones could get in there and when you're working on the engine you could drop a nut or a bolt in there, I've seen that happen before, the whole engine and head was ruined chances that this would happen are small but you never know...
Super Mini Mad
Posted 12 September 2013 - 12:41 PM
Chaps, this had been a thoroughly good read :)
Crazy About Mini's
Posted 12 September 2013 - 12:46 PM
Plenty of LHD cars with them fitted, also the kit is not as big as it seems in the pics.
I'm sure it won't fit mine without placing the brake master cylinder somewhere else, I already have to bend the brake pipe to fit the twin hs6 like it is in the picture and I've heard from people (with LHD cars) who've bought the MED kit that it doesn't fit...
Sorry havent realised you're using twin HS6, they're not so common in the mini scene
Speeding Along Now
Posted 12 September 2013 - 01:38 PM
Sorry havent realised you're using twin HS6, they're not so common in the mini scene
Yeah, they're pretty rare in the mini scene, I actually wanted a Weber 45 (or 40) but they're ff-ing expensive and I don't want to cut the bulkhead so I bought these for a very good price (€90-€40(sold the MGB manifold)= €50) at the Antwerp classic salon. 
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