ESE's works engine tuner

[F5 Dave]

So what if you did a side entry with a venturi nozzle?

[cookie1965]

Once you have ground off the Gannet shit try shoving the stinger up inside the end of the baffle, up to the parallel section is best, 1/2 way along is not.

Interesting, when I built my last set of pipes I stuck the stingers back down the cone because I'd read that it would cut down the noise and we run at a track with very restrictive noise rules (88dB). I finished up another set of pipes yesterday, welding in the stingers the same way, not really paying a lot of attention to how far in they went but more to how far they stuck out to keep the silencers from extending past the rear tire. My last pipes were quiet enough and made decent power (enough to run with the leaders anyways). When you say "1/2 way along is not" are you suggesting they'd make more power if they went in that far or that they'd be quieter?

[F5 Dave]

the ye olde experiments of Jennings suggested the stingers should be fully in or fully out, but half in & half out caused loss of performance. i can't explain why, but follows the mantra of test everything.

Wob is talking about the exit mid section as pictured as the 1/2 way along. Peter Steadman ran his like this on the KV I borrowed. I wondered if a venturi nozzle here might amend any stinger issue. Wonder if anyone has tried it?

[wobbly]

Yes, when the stinger entry is about 1/2 way along the rear cone ( when shoving it in from the exit end ) power is lost.
I have tested the full in stingers and found no loss in power - and to my surprise no change in temp or internal pressure.
Depending upon how the rear cone is terminated, then having the stinger exit from the mid section may be better or worse - dunno, but it wont be any quieter, as you
are drawing off from the same low pressure wave intensity area..

[2T Institute]

I'm looking at getting an old TIG sorted; got to be better than the 'Gannet Gun'.

Put the MIG torch down
Step away from the welder
keep your hands where I can see them


Reminds me of the first pipe I made except yours fitted better

[wobbly]

The venturi nozzle is there to do one thing - the stinger is a resonant length tube and strong pressure gradients leap up and down it off atma.
When a strong negative sign wave launches down the stinger it can, and does, destroy some of the positive pressure wave that ultimately stuffs the cylinder
with the A/F sitting in the Ex duct, as the piston approaches Ex closure.
Adding a tapering cone after the true pressure bleed venturi helps to prevent this bad wave affliction from affecting the "in pipe "action.
Was invented by Helmut Fath - my hero - for the Honda factory team that ran Freddy in 250/500 the same year, it had one stinger 450 long, and one 150 long.
The new nozzle invention, took away the length effect of these disparate stingers, making tuning each much easier - and closer .
Thus using a nozzle in the belly is not going to have enough effect on this low intensity zone to make much difference.
BUT, being a 2 stroke it will probably work superbly, just to piss me off.

[husaberg]

The venturi nozzle is there to do one thing - the stinger is a resonant length tube and strong pressure gradients leap up and down it off atma.
When a strong negative sign wave launches down the stinger it can, and does, destroy some of the positive pressure wave that ultimately stuffs the cylinder
with the A/F sitting in the Ex duct, as the piston approaches Ex closure.
Adding a tapering cone after the true pressure bleed venturi helps to prevent this bad wave affliction from affecting the "in pipe "action.
Was invented by Helmut Fath - my hero - for the Honda factory team that ran Freddy in 250/500 the same year, it had one stinger 450 long, and one 150 long.
The new nozzle invention, took away the length effect of these disparate stingers, making tuning each much easier - and closer .
Thus using a nozzle in the belly is not going to have enough effect on this low intensity zone to make much difference.
BUT, being a 2 stroke it will probably work superbly, just to piss me off.

While we are on Pipes Wob
the brackets for the chamber i always ran were a folded section on the belly (contoured and welded either side of the belly section) as a mount secured with springs as per MX bike with a flush stub at the front. With the (tight fitting) slip on stinger again secured with springs at the rear with more very small folded brackets. What is the best way to make the brackets on the pipe and stinger to avoid cracking?
This is the closest i can find to a decent picture of it including the irrigation tubing silencer.

Nothing to do with the post but seen it and loved it.
Stealth cafe racer (i guess 350LC motor?)

[koba]

I've built my first pipe so I can insert a venturi, restrictor or blanking plate in either the end or the side of the pipe.
I hadn't really considered the pulse effects much, I was more focused on tuning the pressure retained in the pipe.
I think I may have a bit of a play with back vs side and see if it makes any difference.
Annoyingly my testing is going to have to be somewhat subjective.

It will be ages away but I'll post my impressions when I've tried it. (not really results due to subjective nature of testing)

EDIT: I may have to increase the diameter that this sits in I meant it to be 23mm but the pipe I found was smaller. Maybe should have gone bigger again to give me maximum options for size of the verturi.

[koba]

Nothing to do with the post but seen it and loved it.
Stealth cafe racer (i guess 350LC motor?)

I don't really see the stealth in that?

[bucketracer]

Hi TeeZee I know you have been looking at cutting the side of your pistons next to the transfer ports.

These are Mercury outboard racing pistons, so it looks like the idea is a good one and it can be done OK.

[Frits Overmars]

I may have to increase the diameter that this sits in I meant it to be 23mm but the pipe I found was smaller.

Sounds like "I didn't mean to start smoking, but I found a packet of sigarettes" , Kuba .

[cookie1965]

Yes, when the stinger entry is about 1/2 way along the rear cone ( when shoving it in from the exit end ) power is lost.
I have tested the full in stingers and found no loss in power - and to my surprise no change in temp or internal pressure.
Depending upon how the rear cone is terminated, then having the stinger exit from the mid section may be better or worse - dunno, but it wont be any quieter, as you
are drawing off from the same low pressure wave intensity area..

Thanks Wobbly, I measured mine last night and the stinger is about 70% of the way along to the junction with the parallel section. My last pipes would have been more like 60% of the way. Something to play with on the dyno I guess, to find out how much difference it makes.

[wobbly]

This rear mount will not crack - even in stainless.
Forgive the poo.

[richban]

Hi Guys

Hey I was wanting to start working with an EGT setup and have it fitted and running all the time. Question. I don't want to create any kind of reversion in the header. How far into the pipe will I have to have the probe protruding? Another thought was when I make my stainless header could I strap the probe to the outside of the pipe and lag over it. Or even just tig it on. What ever I do I will be starting with a dyno session to record temps at the correct AFR. What do you reckon? I would prefer to not have anything in the header at all but I am at the stage that I really need to tune with EGT.

Ta.

[Haufen]

Hi Guys

Hey I was wanting to start working with an EGT setup and have it fitted and running all the time. Question. I don't want to create any kind of reversion in the header. How far into the pipe will I have to have the probe protruding? Another thought was when I make my stainless header could I strap the probe to the outside of the pipe and lag over it. Or even just tig it on. What ever I do I will be starting with a dyno session to record temps at the correct AFR. What do you reckon? I would prefer to not have anything in the header at all but I am at the stage that I really need to tune with EGT.

Ta.

Mine's in the middle of the header, did not cost any hp at all. For fast and accurate readings that's the place the probe needs to be, I suppose.