ESE's works engine tuner

[Frits Overmars]

I suspect the real problem with the 28hp cylinder and over rev deto may be insuficent blow down time area, but to increase that, I fear the curve will become more like the Blue 30hp line.

What is there to fear? The blue line is already better everywhere; you just need to gear it 15 % shorter than the red line.

[koba]

What is there to fear? The blue line is already better everywhere; you just need to gear it 15 % shorter than the red line.

And better than most other buckets everywhere too!

[TZ350]

I have been trying to find the posts that talk about pipes and collate and edit them. There is heaps of it and pages 620 630 640 650 660 670 680 690 700 and 730 have un edited collections of raw material. If your interested in expansion chambers they are worth a look. Pages 710 and 720 talk about crankcase volume and inlet length.

P659

Any engine with a case leak will run rich, despite all the head scratching thinking it will suck air and go lean.
A leak will compromise the pumping part of the cycle,and the bigger the leak,the less fuel/air mixture is pumped.
If you jet down seeing a rich plug, it will seize, because then insufficient fuel/oil, is being ingested.
So unless you have pressure tested the whole engine before hitting the dyno, you will not be sure you have an accurate baseline.

If you have the RAD from the dyno runs plus the egt for optimum power then its easy to set up at the track.
BUT - beware, having only the drum inertia will not load the engine sufficiently , for long enough, to simulate the jetting required for roadracing.
For this you need a heap of eddy current load control to slow the acceleration rate in the higher gears of an all gear blast.
Then you can see the egt stabilise when at full noise for long enough, in 6th gear.

Just did this on Saturday at Taupo with one of the RZ400 - F3 racebikes.
The ref egt for max power in 6th on the dyno was 1255.
The RAD at Taupo on the day was 102 so I needed to go up one jet size from what we had at the RAD 99 dyno ref.
The egt max after practice one ( with the longest straight we now run on ) was 1235/1275, so went up one more on the LH side and 2 on the RH.
This gave max recall from the next run of 1197/1204, thus I could see we had full control of the egt and a split of 2 jets.
Ran 4 by 20 minute sessions like that, and from a full noise plug chop at the end, I would now add 1* of timing to the RH side, and go back to a 1 jet split with one size leaner overall.
This then gives us a new baseline at 102 RAD.
Safe as houses, and fast as hell when you have all the info, and good plugs that read both ignition advance and jetting.

P664

thanks the one thing l have changed is the expansion chambers and was ok before . l know the stingers are not the best . bent up years ago so will replace them first

You should be able to get someone to machine up a nice precision nozzle and then just use any old piece of tube to get the exhaust into the muffler. With a bit of thought you could have replaceable inserts of different size. I've tried different nozzles and got interesting results on the dyno.

P671

Any sim you are using to design any part of a 2T engine, and dont take full account of the ignition timing regime - is a waste of time.
I can design a completely shit pipe, and with ignition tricks, make it work 1/2 way reasonable - in a sim and on the dyno.
But its impossible to design a really good pipe that will work well in reality, if you dont define exactly the ignition curve it will see when running.
You can change the temp in the header as seen by the egt probe, from 450 to 650C by simply taking away 4 degrees of timing when in the overev,so the pipe that before had a vertical power drop off
at 13500, now holds 50 + Hp out to 14500.
Same with having the solenoid powerjet scenario,you can easily make a pipe that will spin to 14,000 in the sim, but sadly it has no mid power to speak of at all.
Change the A/F ratio from 12:1 to 14:1 past torque peak, and a MUCH longer pipe, now has a ton of mid, then holds its torque up long enough for that " too long " TL to work at least another 1000 rpm than before,due to
the burning mixture now dumping a huge heat load out the port.

You will spend more time and money friggin round with the old unknown ignition just over a longer period than biting the bullet for a programmable.
I went through this with suspension, spent countless hours rebuilding shocks, buying shims and seal heads. Finaly bought a set, bolted them on set the rebound and have not touched them since. They work 100 times better than my best efforts.

MOTA is a massive compromise especially on the ignition side. However it will provide some useful info on the return wave timing which is what you should concentrate on. As Wob has said probably 100 times and it's worth repeating "big depression/lowest pressure at BDC" and return wave arriving before the exhaust port closes. Get that right then look to get the rpm peak where you want it, finaly jiggle the TL length %'s to what Wob has already posted. Viola no more shit pipe.

P681 to P710 is yet to be farmed for information.

Flowing the wrong way between Transfer Open and BDC is not the result of a too-early returning exhaust pulse, but of insufficient blowdown time.area.

What I meant was the instant just before Transfer Closure. The stuffing pulse from the exhaust should not arrive at the cylinder just yet, but at rpms under the powerband it will, raising the pressure in the cylinder while the transfers are still open.

So the fresh charge gets pushed back into the crankcase, leaving little of it in the cylinder. And on top of that, just after the transfers close, that stuffing pulse reverses sign and direction, and sucks what little charge is left in the cylinder, out...

Loss of heat should be avoided all right, but if you want power, it is more important to avoid detonation. The part of the exhaust duct where washed-through fresh charge temporarily resides, should be kept cool to avoid heating up that charge.

And it is much simpler watercooling an exhaust duct that is part of the cylinder, than cooling a duct that is part of the pipe.....

Deto Sensor.

I have just been putting on my knock gauge on the bucket and when I run her in the drive with the sensitivity set half way, reving the bucket up the gauge went off like a christmas tree and I am wondering what others have there gauges set to?
The gauge is from http://www.knockgauge.eu and the sensor is off a subaru car. It's mounted on a 100cc LC two stroke on a head stud straight onto the head with nothing inbetween if that is any help.

We have one of those but only learning about these things ourselves. And this is how we think it works if that's any help.

Knock rings in the cylinder like a bell.

The ringing has a frequency that depends on the size of the cylinder, bigger the cylinder/combustion chamber the lower the frequency.

The adjustment on the knock gauge selects this frequency much like tuning in a radio station.

The adjustment on the knock gauge is not about adjusting the loudness of the radio station.

To tune the knock gauge in you adjust the knob until you see two strong green lights when accelerating.

We think the two green lights indicate the knock gauge is tuned in properly.

It would worry me if I was seeing the red deto light at this point and start backing the ignition off or richin it up.

On our first dyno runs with the knock gauge we saw perfect green on the pull and red xmas tree lights on the run down so it was detonating badly on run down with a closed throttle.

TeeZee's is set at about a 1/3rd.

We would love to hear more from someone with experience using one of these knock gauges.

If you can get your hands on an oscilloscope it works a treat. We just used one on the UoA dyno with a WR450. Mounted sensor on the side of the cylinder. Knock showed up as huge spikes on the oscilloscope. Well above any other noise. Then again it was on a steady state eddy current dyno. Things might go a bit quicker on one of those inertial thingys. #4StrokebutStillRelated

Been away winning races so will reply now re the deto box.
Calibration is easy, turn it down real low such that the green lights do come on when doing a full throttle run.
Keep turning it up till you get a deto indication somewhere in the powerband, going up on full throttle, or as TeeZee found, when backed off on the overun.
In short - believe what you are seeing, if it shows deto on the overun, then, its got deto in the overun.
This MAY not be an issue when racing as you MAY not damage anything detoing for a short period under these conditions.
But,of course if you have a TPS this means you can use a 3D map, and its easy to pull out a couple of degrees of timing at that point, and the deto will go away - simple.
I found that maximum performance on the dyno meant you had short flickers of deto at nearly all rpm on full throttle,and it lights up when you hit the limiter.
I do several pulls at 1/4, 1/2 and 3/4 throttle,running up against the dyno load, as well as running down on the overun. to generate the TPS driven curve shape.
This enables you to dial up the max advance needed everywhere, then go into the software and back the whole curve down 1 to 2 degrees.
Now you have a good curve shape that the engine actually needs, and any issues on track, can then be taken care of by the box switching the retard input to pull out 2* to prevent unforeseen meltdowns.
I havnt used the deto setup on an aircooled, but I suspect that the deto ringing frequency signal is much bigger amplitude than a watercooled cylinder,meaning you get a much quicker indication of deto approaching.
Means its very sensitive to adjustment, but I say again, if it is flashing deto at one rpm and not at another, then believe what you are seeing, just turning it down so it does nothing, is dumb.

The piezo sensor will easily show the missfire from hitting the limiter, so it will also show a big end knock, as well as the piston hitting the head.
Dont know about excessive piston slap , but probably.
Plenty of "noise" sources in a 2T.

[wax]

And crunching numbers on a laptop beats shagging about with jets at $9-$12 a pop and a carb thats a prick to get at (like most bikes) anytime.

There is a lot that is attractive about EFI.

Does it run a map sensor or some one of measuing air flow. As the pipe changes in temp ie after a long run down the straight the power band is going to come on in a different place due to the gases moving faster in a hot pipe. unless your measuring airflow Im not sure how your going to get around the constant moving goal posts. A carb as crude as it is measures airflow.

[TZ350]

you just need to gear it 15 % shorter.

We tried that at Taumarunui, went up two teeth on the front, from 13 to 15 but still had deto issues at the end of the main straight and badly compromised gearing on other parts of the circuit.

[TZ350]

Does it run a map sensor or some way of measuring air flow.

Yes a map sensor, but to be honest I don't know much about it yet, its a bit of a leap of faith. But I am confident I will be able to figure it out and I am hanging my hat on the fact its all been done before locally with an off road 350 2-Stroke that is regularly run in pretty difficult conditions.

And if it does not work out, there is plan "B" the CVT system, which I am still gathering the parts I need for.

[Frits Overmars]

I suspect the real problem with the 28hp cylinder and over rev deto may be insuficent blow down time area, but to increase that, I fear the curve will become more like the Blue 30hp line.

What is there to fear? The blue line is already better everywhere; you just need to gear it 15 % shorter than the green line.

We tried that at Taumarunui, went up two teeth on the front, from 13 to 15 but still had deto issues at the end of the main straight and badly compromised gearing on other parts of the circuit.

I think one of us is missing the point. You suspect that increasing the blowdown time.area will lessen the overrev deto. I agree.
Then you fear that by increasing the blowdown time.area your 28 hp curve will change into a 30 hp curve that is shifted 15% higher up the rpm scale.
But your fear is unfounded; the 30 hp curve simply is better. If you plot it over the 28 hp curve, using a 15% smaller rpm-scale for the 30 hp curve, you will see that the 30 hp curve completely encloses the 28 hp curve.
If you use that 30 hp curve and fit a 15% shorter gearing compared to what you used with the 28 hp curve, the bike will behave as before, but with more power everywhere and probably less overrev deto.
BTW: fitting two teeth more up front, from 13 to 15, is gearing it 15% longer, not shorter.

[TZ350]

the 30 hp curve simply is better. If you plot it over the 28 hp curve, using a 15% smaller rpm-scale for the 30 hp curve, you will see that the 30 hp curve completely encloses the 28 hp curve.

30 hp curve completely encloses the 28 hp curve?


28hp-green (actually three different runs overlaied together) 30hp-purple (at first I thought it was drawn in blue)

Are we looking at the same graph? The 28hp deto in the overrev zone cylinder is on the left and the ugly 30hp one on the right.

I thought a big fat torqe curve was the right thing to aim for. And that the 28hp's torqe curve would give better drive out of the corners.

The 30hp one is the one that I thought worth plumping up in the lower rev range with power valves in the side ports. From running EngMod simulations I figured this would give me a much better 30hp torqe curve and get rid of the over rev deto to boot.

[twotempi]

EngMod2T tells me that I can have both, a much wider flat torqe curve than the 28 and more than 30hp, and I want it all

You forgot the next line !!

And I want it now

[wobbly]

What Frits is saying is that if you added 3 teeth to the rear of the 30Hp bike, to give the same terminal speed as the 28Hp setup, then you would
have more power available everywhere.

[Frits Overmars]

30 hp curve completely encloses the 28 hp curve?

Yes, if you rescale it 15% to the left.

28hp-green (actually three different runs overlaied together) 30hp-purple (at first I thought it was drawn in blue)
Are we looking at the same graph? The 28hp deto in the overrev zone cylinder is on the left and the ugly 30hp one on the right.
I thought a big fat torqe curve was the right thing to aim for. And that the 28hp's torqe curve would give better drive out of the corners.

Torque means nothing without revs. And it's not crankshaft torque but rear wheel torque that makes you accelerate. If you gear that 30 hp curve 15% shorter, rear wheel torque in each gear will be 15% higher at any given crankshaft rpm.

The 30hp one is the one that I thought worth plumping up in the lower rev range with power valves in the side ports. From running EngMod simulations I figured this would give me a much better 30hp torqe curve and get rid of the over rev deto to boot.

You can still do that although it will not nearly give you the low down grunt of a trombone pipe. How are those CVT plans coming along?


EDIT: I see that while I was struggling with English, Wobbly came up with a much shorter and probably easier to understand answer.

[kel]

What Frits is saying is that if you added 3 teeth to the rear of the 30Hp bike, to give the same terminal speed as the 28Hp setup, then you would
have more power available everywhere.

Ha ha, my suggestion for 2 extra teeth to the back was pretty damn close. Now if I can just figure out how to give usable feed back on suspension and carb set up I'd be the complete test pilot package

[dinamik2t]

Here is what Frits implied, TZ:
(red being the 30hp curve, moved 1500rpm to the left)

[wax]

How are those CVT plans coming along?
.

Ahh the best of all the worlds

[rgvbaz]

Here is what Frits implied, TZ:
(red being the 30hp curve, moved 1500rpm to the left)

To really rescale the graph in terms of changing the graph you need to move the point by the % change in gearing, not just 1500 rpm, so for each rpm point on the 30hp curve times it by say .9 (12.8/14.2) so at the end of the overrev on the 30hp curve 14.2 x .9 = 12.8 rpm

for 15hp occurs at 9400 rpm on the original curve rescaled it would occur at (9400 * .9) = 8460 rpm.

Dave