ESE's works engine tuner

[Flettner]

My pipes are a compromise, one I like at the moment for the mid and low range power, top end is great but shorter pipes with steeper cones would be better, for top end.

[F5 Dave]

What if it's rainy season? Some sort of creek crossing scoop mechanism?

[katinas]

My pipes are a compromise, one I like at the moment for the mid and low range power, top end is great but shorter pipes with steeper cones would be better, for top end.

One of Honda's solutions, but of course not the same as sliding header.

[Peljhan]

The second reason: sealing. The circumferential gap that has to be sealed, is three times shorter for the trombone system. That means three times less leakage and three times less friction.

Video courtesy of Rimar Motors:
http://www.youtube.com/watch?v=0odVz...ature=youtu.be

Frits, you forgot about downside of sealing on the header compared to sealing on the belly, the temperature! Header heats up three times more than belly.
Do you know how sealing was done on this rimar engine trobone pipe? I am thinking about some kind of piston rings in combination with fiberglass rope?

[wobbly]

I tested the ATAC system on the BSL500. With a volume close to the cylinder displacement ( bigger or smaller wasnt better ) and a very short tube right at the header start with a solenoid operated
butterfly valve in line with the flow, it made 28% more power below the pipe.
It used a solenoid as the valve had to snapped open at a specific rpm, ramping open or closed lost power big time.

The only time it was useful was in testing a Pukekohe, where if the bike was geared to pull over 300Km/H we did not have a low enough 1st gear to get off the hairpin - a scenario not seen at any GP track.

[Flettner]

I tested the ATAC system on the BSL500. With a volume close to the cylinder displacement ( bigger or smaller wasnt better ) and a very short tube right at the header start with a solenoid operated
butterfly valve in line with the flow, it made 28% more power below the pipe.
It used a solenoid as the valve had to snapped open at a specific rpm, ramping open or closed lost power big time.

The only time it was useful was in testing a Pukekohe, where if the bike was geared to pull over 300Km/H we did not have a low enough 1st gear to get off the hairpin - a scenario not seen at any GP track.

In vinduro I have to get out of the 'hairpin' every second corner.

[Flettner]

What's the deal with two angle reverse cones? Why are they used?

[wobbly]

Two , or even better three angle, rear cones are used to manipulate the power curve by changing the amplitude and duration of the return plugging wave fronts shape.
If you start with a single rear cone , this can be changed to a progressively increasing angle three cones, starting very shallow, and ending in a steeper angle than before.
This gives more power everywhere - and the amount of overev generated is set by the length/angle of the final steeper cone.

If you have a PV that closes a T port, or all the ports in a 3 port, you can divide the rear length into three equal cones, starting steep, and getting progressively shallower.
This geometry looses front side, but the PV eliminates that issue, and this setup gives a huge increase in upper front side and peak, but the shallow last cone allows plenty of overev.
Dead perfect for road racing, or in an end use such as 500cc oval dirt track mini sprint cars, where they use one gear and rev it to the moon.
In that case I used semi steps ( 1/2 moon, top and bottom ) on the manifold face to pump up the bottom end, and the rear cone to generate the peak and overev needed.

A very powerful tool to tailor the power curve to the end use.
In your case Flett, an ATAC would give you more bottom end than you could wave a stick at - and easy to operate with a solenoid connected to any rpm switched supply.

[Storbeck]

I tested the ATAC system on the BSL500. With a volume close to the cylinder displacement ( bigger or smaller wasnt better ) and a very short tube right at the header start with a solenoid operated
butterfly valve in line with the flow, it made 28% more power below the pipe.
It used a solenoid as the valve had to snapped open at a specific rpm, ramping open or closed lost power big time.

The only time it was useful was in testing a Pukekohe, where if the bike was geared to pull over 300Km/H we did not have a low enough 1st gear to get off the hairpin - a scenario not seen at any GP track.

I fear I'm about to ask a stupid question, but here we go anyway.

Is there any use adding one of these to a 2 into 1 pipe? I'm thinking the leg of the manifold going to the other cylinder pretty much acts as an atac at all times, so adding an additional chamber may be pointless.

But, I'm playing around with watercraft that use parallel twins and 2 into one pipes. I recently built a motor with relatively high ports and not surprisingly it is great mid to top, but very weak down low to the point that it's hard to get an impeller that works.

As a watercraft the obvious thing to try is water injection but it has the same issue of the pipe not heating fast enough when it gets up in the rpms so top end power suffers, which makes it all kind of pointless, could just build a motor with lower ports.

But if there is any benefit available from something like an atac volume I think I could fabricate it relatively cheap/easily. Exhaust valves would help too but that's not so easy.

We use 2 into one pipes like the one pictured, I was thinking stick the atac volume as indicated in the picture. The extra volume in the manifold is still less than a cylinder worth of displacement, I haven't measured but I'd estimate about half.

[Flettner]

Two , or even better three angle, rear cones are used to manipulate the power curve by changing the amplitude and duration of the return plugging wave fronts shape.
If you start with a single rear cone , this can be changed to a progressively increasing angle three cones, starting very shallow, and ending in a steeper angle than before.
This gives more power everywhere - and the amount of overev generated is set by the length/angle of the final steeper cone.

If you have a PV that closes a T port, or all the ports in a 3 port, you can divide the rear length into three equal cones, starting steep, and getting progressively shallower.
This geometry looses front side, but the PV eliminates that issue, and this setup gives a huge increase in upper front side and peak, but the shallow last cone allows plenty of overev.
Dead perfect for road racing, or in an end use such as 500cc oval dirt track mini sprint cars, where they use one gear and rev it to the moon.
In that case I used semi steps ( 1/2 moon, top and bottom ) on the manifold face to pump up the bottom end, and the rear cone to generate the peak and overev needed.

A very powerful tool to tailor the power curve to the end use.
In your case Flett, an ATAC would give you more bottom end than you could wave a stick at - and easy to operate with a solenoid connected to any rpm switched supply.

I already have a full powervalve system, closing both ports.

[wobbly]

Flett, the ATAC power increase I quoted of 28% was with a servo operated full PV system as well.

[husaberg]

It's not like I've got room on an off road bike to move the pipe.

I'll report back when I have a working (tested) example. You don't know how simple my system is, yet.

I see the pictures, hardly off road friendly ��

the way i see it you dont need a lot of room as its gets shorter
chuck a fork gator over it still way less complicated tnan camchains valve etc.

but seriously, cagiva on the v93 ran a pV and atac system together in parallel (well series)

[Frits Overmars]

One of Honda's solutions, but of course not the same as sliding header.

Tried and tested by my German buddy Björn Enke.

[Frits Overmars]

Frits, you forgot about downside of sealing on the header compared to sealing on the belly, the temperature! Header heats up three times more than belly.
Do you know how sealing was done on this rimar engine trombone pipe? I am thinking about some kind of piston rings in combination with fiberglass rope?

No I did not forget and yes I know how Richard sealed the sliding header but I do not feel at liberty to divulge his solution here: that's up to him.

I fear I'm about to ask a stupid question, but here we go anyway.
Is there any use adding one of these to a 2 into 1 pipe? I'm thinking the leg of the manifold going to the other cylinder pretty much acts as an atac at all times, so adding an additional chamber may be pointless.

Not a stupid question at all, and you even nailed the main problem: one leg of the Y-pipe functions as an ATAC volume to the other leg of the Y-pipe at all times.
That atac-volume of a Y-pipe will kill power when a real ATAC knows when it's time to close.