intake snorkel

[Brian ROSEN]

Culturally we stand a world apart, I DON'T THINK SO

"....[/Iam currently building an engine from a case that has been tigged to open the crankcase to allow much bigger transfer ports, have sourced a conrod from a Jap outboard, mated it to a rg500 main bearing, running a kx250 piston increased the capacity to 248cc from 200cc, etc;etc;...." By all means do that, quite a different kettle of fish from souping up a GS! I can remember 'tuning' a 250cc Villiers (or was it 200cc to start with?) two-stroke, padding out the crankcase, varying the exhaust length to achieve an incedible output - for a kart. Or how about three vertical downtubes through the bonnet feeding three double choke Carbs on a Bristol engine fitted into a Lotus? Once again for the racetrack. Or going back further - what about a rocket motor fitted WITH a jet engine to a fighter plane ? - I didn't contribute much to that but it was another way of getting up to speed (and height) quickly. BUT don't mess up your lovely GS!!!

 

[davidblythe]

Do you have the optional rack fitted on the front of the leg shield? If so I recommend attaching a half bag of cement to it.

25bhp? how wide will the power band be? Is there a mod to improve the cable gear change these days?

My LI 150 with standard engine performed somersaults and pirouettes shortly after being introduced to ice at about 50mph on a corner some 38 years ago

re the rack Dont do Mod, scooterboy very different

will be about 19ft lb of torque around 6000rpm, changing the length of the front pipe before it starts to taper for the first cone can move the powerband around significantly, lots of expansion chambers on the market for Lammys

gearchange is no issue with nylon lined cables and careful assembly with quality components

 

[F104]

anyone tried http://www.rainbowbmw.com/wshop/ind...eyword=intake&category_id=121&product_id=2524

If you did your thesis on the intake system surely you have an idea of what the wunderlich intake would do? But I'd like to see the thesis as well, can only learn from it as test bench date is invaluable.

Whether you consider the intake valve 'gulping' air in from the airbox via the intake port, or the airbox 'gulping' air in from the outside world via the snorkel, the effect is the same. In either case you've got a cyclically varying flow through a tube that has a certain length and diameter

Ok, but my bet is the gulping thru the snorkel is far less to non existent. On each valve opening it sucks air from an airbox 5-6 times the size of a cylinder's displacement. That has to have a dampening effect, more so when the entrance to that airbox is limited by the snorkel. By removing the snorkel, I expect the gulping will become pretty audible..
I might be completely wrong..

 

[F104]

anyone tried http://www.rainbowbmw.com/wshop/ind...eyword=intake&category_id=121&product_id=2524

If you did your thesis on the intake system surely you have an idea of what the wunderlich intake would do? But I'd like to see the thesis as well, can only learn from it as test bench date is invaluable.

Whether you consider the intake valve 'gulping' air in from the airbox via the intake port, or the airbox 'gulping' air in from the outside world via the snorkel, the effect is the same. In either case you've got a cyclically varying flow through a tube that has a certain length and diameter

Ok, but my bet is the gulping thru the snorkel is far less to non existent. On each valve opening it sucks air from an airbox 5-6 times the size of a cylinder's displacement. That has to have a dampening effect, more so when the entrance to that airbox is limited by the snorkel. By removing the snorkel, I expect the gulping will become pretty audible..
I might be completely wrong..

 

[F104]

I tried it..

First installed a water manometer, made simply from transparant plastic hose, and went for a drive. To my surprise no clear signs of any restriction

Then took (2010 bike) the right front metal panel off, so the snorkel gets ram air. That resulted in a 4-5" reading at 90 mph. Scientifically it should be 4" pretty exactly at that speed, without the "leak" the running engine causes. Closing the throttle made it go up to 5". So i guess the open end of the manometer sitting behind the screen (low pressure area) caused it to be off by 1"

Took the snorkel off, and no change in sound at all. Didn't even drive it as it was clear it would not be better than having ram air.

So the snorkel is much less of a restriction I thought it was, would benefit from ram air, but that also poses a problem in the rain as every droplet of water goes straight in...

 

[Martyn H]

First installed a water manometer, made simply from transparant plastic hose, and went for a drive. To my surprise no clear signs of any restriction

Then took (2010 bike) the right front metal panel off, so the snorkel gets ram air. That resulted in a 4-5" reading at 90 mph. Scientifically it should be 4" pretty exactly at that speed, without the "leak" the running engine causes. Closing the throttle made it go up to 5". So i guess the open end of the manometer sitting behind the screen (low pressure area) caused it to be off by 1"

Took the snorkel off, and no change in sound at all. Didn't even drive it as it was clear it would not be better than having ram air.

So the snorkel is much less of a restriction I thought it was, would benefit from ram air, but that also poses a problem in the rain as every droplet of water goes straight in...

Which could be read as "The manufacturer did a good job in the first place".

 

[autogs]

your right, I am never going to have fun or think for myself again, going to join the IAM and smoke a pipe from now on whilst maintaining the status quo

am currently building an engine from a case that has been tigged to open the crankcase to allow much bigger transfer ports, have sourced a conrod from a Jap outboard, mated it to a rg500 main bearing, running a kx250 piston increased the capacity to 248cc from 200cc, barrell has been welded to suit the case and accept a much larger reed valve, skimmed the head and reprofiled it to suit the revised crown height, using packer plates to achieve the port timings i want with a 2mm increased stroke on the crank. ported the exhaust port to 65% increased the timed area of the transfer by widening the secondary tfr aiming more at the centre of the piston, raised the boost port and uisng a reedvalve from a banshee, exhaust will be built to suit the port timings

to what effect, to get a geninue 85mph out of a Lambretta from 62mph as standard, 25bhp instead of 8bhp

why, because I can and standard bores me rigid

Culturally we stand a world apart, no offence meant

 

[davidblythe]

First installed a water manometer, made simply from transparant plastic hose, and went for a drive. To my surprise no clear signs of any restriction

Then took (2010 bike) the right front metal panel off, so the snorkel gets ram air. That resulted in a 4-5" reading at 90 mph. Scientifically it should be 4" pretty exactly at that speed, without the "leak" the running engine causes. Closing the throttle made it go up to 5". So i guess the open end of the manometer sitting behind the screen (low pressure area) caused it to be off by 1"

Took the snorkel off, and no change in sound at all. Didn't even drive it as it was clear it would not be better than having ram air.

Hit 6000 rpm with no snorkel and the induction noise is there big time

 

[davidblythe]

half a snorkel

Done a 100 miles since I cut the snorkel in half, doing a 250 mile trip tomorrow

wont say too much yet about the differences in power delivery, suffice to say the autotune is adjusting the fuelling quite a bit, will post the two graphs after the run once the autotune has settled down