ESE's works engine tuner

[MotleyCrue]

Looking at the Lambda on the dyno they have a really linear A/F ratio, a Mik or Keihin is all over the place as the circuits overlap.

I have heard people say the opposite about Lectrons but no doubt they never had a Lambda sensor on their engines, probably never even had a Lectron on their engine either. Thanks for all the Lectron info.

[J.A.W.]

Interesting, everytime I see anything on the internet about FBG its always to do with big powerful 4 cylinder 4 strokes. To be honest I never heard of an H2 and never clicked on the H-2 tab on the FBG site before.

Yeah, Paul Gast still sponsors them big ol' 2Ts in drag racing comps.. see here..

http://www.cycledrag.com/long-live-t...ord-in-memphis

[wobbly]

One last point about the Lectron is that as it has no idle circuit in front of the slide, it can be run at a very steep downdraft angle to straighten out the
flow into the reedblock.
This is worth plenty of Hp.
If you sat a Mik or Kehin at those angles they would spew fuel from the bowl directly thru the idle circuit ( not having it drawn up thru the jet well by vacuum )
especially with the fuel surging to the front of the bowl under brakes.

[TZ350]

The Dam Question!

Chambers has fitted an exhaust port dam to his RG50 cylinder. It was hand shaped out of alloy and is held in place with a screw and sealed with Balzona epoxy.

We hope to get to test it on the dyno in the next night or two.

The top of the exhaust port is 85% wide and the dam fills the lower part of the original exhaust port and tapers out to the pipe diameter at the end of the exhaust duct.

[J.A.W.]

The Dam Question!

Chambers has fitted an exhaust port dam to his RG50 cylinder. It was hand shaped out of alloy and is held in place with a screw and sealed with Balzona epoxy.

We hope to get to test it on the dyno in the next night or two.

The top of the exhaust port is 85% wide and the dam fills the lower part of the original exhaust port and tapers out to the pipe diameter at the end of the exhaust duct.

Cool, & so - how long do you reckon on it lasting at WFO 'til the epoxy burns off, the exhaust pulse loosens the screw & it gets blown out?

If it does show a dyno-measured improvement, will you then weld it in?

Or, re-configure it - as a moveable 'power-valve' type set up?

[crbbt]

just wondering what the octane rating of the avgas you were running in that TZ Wob?

also I've been meaning to ask about ATAC chambers. can any valve be used? or does it have to be a butterfly valve to direct the flow into the chamber?

[wobbly]

The fuel is 100 Avgas,its higher octane than what is sold in OZ that is LL100.
The ATAC does not need to "direct " the flow, as I have always used the butterfly so that when its open its in line with the header axis.

[husaberg]

just wondering what the octane rating of the avgas you were running in that TZ Wob?

also I've been meaning to ask about ATAC chambers. can any valve be used? or does it have to be a butterfly valve to direct the flow into the chamber?

The fuel is 100 Avgas,its higher octane than what is sold in OZ that is LL100.
The ATAC does not need to "direct " the flow, as I have always used the butterfly so that when its open its in line with the header axis.

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[crbbt]

Thanks for your response!

[AndreasL]

wobbly, a EngMod question if you don't mind...

When designing a exhaust duct using EngMod, I think it's ExMach that should be used to check if we go sonic or not?
ExPMach, measured at the port(?), goes through the roof (>3) when the port opens so that can't be the right thing to use...

So what I'm planing is to reduce my exduct end area untill we are about to kiss sonic.
Can it be that simple really? Probably not...

Using ExMach, do we like to place our virtual transducer att the smallest cross section area of the duct, i.e. just before the header (if not using some sort of adapter/spigot that is). Normally I run it at 0mm but that might not be the best thing in this case?

Do you have a graph from "a decent engine" showing what to look for regarding exhaust duct speed?

Now, lets see how wrong I am...

[adegnes]

So what I'm planing is to reduce my exduct end area untill we are about to kiss sonic.
Can it be that simple really? Probably not...

Interesting "thesis"!

[AndreasL]

Interesting "thesis"!

I'm running some rough sims right now and we are getting closer to sonic when makin the duct area smaller...as expected.
But with a single port, we might push it to far using this crude "technique"...

[wobbly]

Here is a KTM250 for road racing I have worked on.
This isnt anywhere near "full noise " as it needs powerband width to cope with a 1500 rpm drop into 5th gear.
The Ex port at the face goes well sonic as the piston opens and closes - so the lifted floor has nothing to do with flow velocity, its all to do with A port short circuiting.
I am going to try a big radius on just the floor of a lifted port to see if it raises power by increasing the outflow Cd, without affecting the short circuit reduction down the sides
where the corner rads are.
The transducer is set at the smallest area in the duct ( the cylinder face ) before the oval/round transition spigot, and this gave the best power - going smaller did not gain any power.
Going bigger did loose immediately, and it seems that in many engines going to around 0.8Mach at the exit seems to work best..
The stinger venturi just goes sonic for a short period, but again, this was the smallest area for best overall power without deto.
I could go bigger, and then i would need to add timing or increase com to compensate to lift the TuB number- and this lost band width.
As I have stated a hundred times the 75% area at the oval face will get you close every time, as will the 90% area for a single port.
Just remember that the sim will reduce the volume of the duct in a linear fashion, as you neck down the exit area, and this is the correct approach - not just weld up the last 20mm
as its easy to get at.
Also the sim has no idea there is a wall in front of the piston at BDC if you lift the port floor.
It cannot therefore adjust for any improved scavenging or trapping efficiency due to reducing the A port short circuiting - all its doing is reflecting the affect on in and outflow from
a smaller port/duct exit.

PS - what is a "rough " sim.

[TZ350]

Attachment 317346

Chambers RG50 with a push and go ignition made by rewinding a race stater from a Loncin Race ignition for 12V to power the Ignitec. The Loncin rotor has a RG50 center bolted into it.

Attachment 317342

The cylinder was modified for full reeds, a boost port and Boyesen like ports that got through to the top of the B transfers.

Attachment 317343

The setup was run with two stage glass fiber reeds (Blue line) and heavier carbon fiber reeds (Red line).

Attachment 317341

Then to see if the Boyesen like ports were doing anything worth while they were blocked off (Red line). Lost a bunch of top end but picked up some useful drive coming onto the pipe.

Attachment 317345

Then the open duct between the boost port and B transfer ports was closed off (Red line).

Attachment 317344

Blue, first run, Boyesen and Boost Duct open. Red Boyesen closed. Green, Boysens blocked plus Boost and B Transfers blocked off from each other.

The next move will be to keep the opening between the Boost and B Transfers blocked off and open the Boyesen like ducts up again.

The ambition is to run an RG50 and go better than 15 rwhp with it.

The last couple of weeks has all been about proving everything one step at a time..... After 160 plus runs the 85% width exhaust port is holding up well. so getting there bit by bit and lots more things to try, like an exhaust port floor dam and a new 14K+ rpm pipe.

The Dam Question!

Chambers has fitted an exhaust port dam to his RG50 cylinder. It was hand shaped out of alloy and is held in place with a screw and sealed with Balzona epoxy.

We hope to get to test it on the dyno in the next night or two.

The top of the exhaust port is 85% wide and the dam fills the lower part of the original exhaust port and tapers out to the pipe diameter at the end of the exhaust duct.

Red line is with the exhaust port dam, no other changes.



Blue 95mj, Red 85mj, Green 105mj



Blue is where we started at the very beginning and after a lot of hard work and careful step wise development we have worked our way to the Red line. .......

[peewee]

we have worked our way to the Red line. .......

but your dam went all the way to the transfer tops or no ? that what it appears from the photo. how tall was dam at blue line ?