Modern Vespa

This has been a long term project on and off over the last 18 months. The idea is easy, sound waves flow up and down the intake and if things are proportioned right then at the right speed you can have the high pressure wave hit just as the valve is closing to ram just a little more charge into the cylinder.

I had an idea of the range of length that would give the best power but on the GTS the max power is quite a bit lower than the max speed due to the gearing. So rather than try and boost the max power the idea was to extend it or move the max power to a higher RPM range.

This ideal bell and replaceable bits of aluminum tube was produced to test out different lengths.

And... ?

Scooter Porn you dogs I think I know where this is going

Bow chika!

Will this need to be retuned for say, the 4v Mallosi upgrade? Or will it work anywhere?

Ya know, the Ducati WSBK guys used to (I assume they still do) run a setup that dynamically altered the length of the intake to keep the intake wave optimized. I'm guessing they used a complicated closed-loop control system, but you could get much of the way there without a complicated system.

For the LSR bike, you could fabricate a tube that slides inside one of the tubes you already have (think trombone). It'd be relatively straightforward to rig it up with a cable control so Jess could adjust the length manually while he's rolling. All he'd have to do is tune for maximum velocity.

Just a thought...

Yes and no.

To get the max power out of the stock GTS you would target the improvements to ~8000 rpm, but to improve power at cruising speeds you'd want to move that up to maybe 8500 rpm. By Malossi's graphs the V4 head develops max power at 8500 rpm and we are bounded by the rev limiter at about 9200. So here again targeting the 8500 rpm range would be in order. So the same intake should work on both setups to provide more power at and around 8500 rpm.

The down side to a tuned intake is that at other engine speeds (in this case 7250) you have a low pressure wave that hits the intake valve just as it's closing.

Using a good tack to help with the butt dyno we zeroed in on the length we though best. I'd really like to get some time on a real dyno to verify but you work with what you have. Here's the setup with the filter installed, don't know why I don't have a shot of it on the bike.

With a CVT you don't need a really wide power band, so you can mostly tune the engine for a single PRM and then tune the variator to keep it there.

Ahhh (insert face palm emoticon here), good point. For the LSR bike, though, it might still be useful to be able to tweak the intake ISO the last bit of horsepower.

BTW, I didn't say it, but nice work on what you've done. That's the coolest scooter pron ever.

It gets better. Or worse, depending on your perspective.

Gotta love doing things via that all mighty "butt dyno". It is an amazing tool.

Yes... this a different tool than the "DynoButt" or "DinoButt" or DynaButt"

DynoButt - Trademarked butt dyno

DinoButt - the original, no longer in production.

Dynabutt - Pink, marketed to women (Dinah)

Hahaha! I guess I should reserve judgement until I see what you all come up with for aerodnamics. At 100mph, the wind is not your friend...

When they start talking about full fairings I will get concerned...

I found that with the power booster installed and a bad O2 sensor...
I was able to get the 250 GTS up to 155 km/hour.

However I was getting stalling problems at idle.

I have since replaced the O2 sensor and pulled the power booster,
Now, I'm lucky to get the scooter up to 130 km/hour.

So, Keep up the experimenting, There is something in there...


Somewhere.

I wonder if Ruben can add some extra snaps and straps and get the ScooterSkirt to act as a fairing and close up the gap between the front fairing and rear wheel cowlings.

Thinking more like this:

Patrick, I'm delighted to see someone else doing some serious tinkering. I found that chopping 1 inch off the induction pipe had disastrous effects, so obviously the engine is quite sensitive to this tuned length.

Eagerly awaiting your conclusions, and hoping I will be able to use them somehow with the Piaggio airfilter. I don't like the noise of the pod filters.

Mike

And it is very loud.

my gts custom k&n intake & Oil Breather Tank

The straight setup was fine for testing but placed the filter over the rear wheel and you had to leave the bucket out. On bikes other than the GTS there's no room there so it's not even an option.

So, we bent the intake 90deg to following the route of the original intake. This places the filter approximately where the stock filter is.

Here's a rendering of the bent intake. We are still looking for the right shade of silicone to cast it from.

Chrome it!

Here's the actual item, printed in nylon.

"Printed in Nylon!" how great/amazing is that what a great tool

And mounted up....

R

8)

Is it fast(er)?

The scooter above doesn't look like a Piaggio Vespa GTS.

If you rename this thread to ( I killed a !@# ) with this intake you would get twice as many views, Nice works NorCal guys. It seems long over due that the Scooters are getting a T une

It isn't FFS.

Learn to read.

So here is a silly question for you Oops...

could you do the same for any bike?

By that I mean design an intake and then have it "printed and shipped" to a customer? No stock sitting around, just print it out?

So someone might say "I got a 2010 300gts, I want a tuned intake for 7000rpm"

and you could just send off the drawing?

Yes it can be done but it's not worth the engineering effort to make that many. I could make them in a variety of lengths intended to target a specific RPM but I think it would be of more value to offer a complete solution that works. IE "use this intake with the V4 head on the GTS, such and such pipe, and Xg rollers"

Before making it available I want to run it on a real dyno to quantify the improvement. I also want to see how well the nylon holds up.

I have followed similar threads on other scooter forums. I admire your tinkering but I also feel the nylon will be the downfall. Somehow you will need to use thick ABS plastic of polished aluminum, even if it costs more. You can count me in for one when they are finished.

Stainless steel is a printing option, believe it or not. It's significantly more expensive, though.

Oooh, could you print one of these, please?

I think it is amazing you could do it all, even if you went with "matched" parts. Makes more sense that way.

Just the business model would be staggering. I pay you to custom design a part for me and it gets made as a one off and shipped to me... stunning.

If, as Jess says, things can be printed in SS, you could make some very interesting custom parts for a scooter.

Not just performance parts, but functional/cosmetic parts as well.

Maybe. The SS printing process isn't especially cosmetic. It's got a rough-ish surface to it.

Not after I get my hands on it with my 1800 grit sandpaper and polishing wheel. It will damn near look like chrome.

Get busy Patrick.

hate to zombiefy this thread, but what was the results of the tuned pipe length, we found some pretty good results from just switching to a K&N pod filter on the stock pipe... but this really interests me...

The results are inconclusive so far.

The length and shape of the stock pipe does a good job of inertial ramming so sticking a pod on the end maintains that. We were aiming to take advantage of the resonating sound waves in the length from the valve face to the throttle body. That length is way too short on the stock setup so the bell extends it.

But we have no idea if we actually got the length right or not and would need some dyno time to figure it out. We ran the bike with a Malossi head and 259 kit at the scooter land speed trials in 2010 and took second with it against the 300s (278cc).

So, anyone in northern california have some dyno time they'd like to offer?
It would take about 10 runs to dial in the right length of the intake and exhaust.

Is there a built in velocity stack or just the straight pipe on this?

A velocity stack, in theory, would help widen the band where the tuning is effective as well as reduce the tendency for the lower end of the band to not generate enough vacuum with a free flowing intake.

Again, in theory...