Yes the ecu is limiting the revs as max is 800°c, dont change it max means max, best find out why your temps are high.

Is your temp probe reading normal room temp when turbine is cold ?

What tail cone do you have?

" until you hear the engine start to run of kero, then disengage starter and switch off gas. " What does that sound like ? What am I listening for ?

ed

the jj1800 what size is the turbine wheel?
what engine is this comparible to as well

The 1800 uses a nominal size of 66mm for the turbine wheel and is similar to the JetCat P-80 for size.

Cheers,
Smithy.

Thanks.

I have assembled it again. The last run seemed better yesterday although start max. temp reached to 800 degrees. I raised the fuel level (it always belowed the engine before and is higher than fuel line inlet) when rotor hung at 31K rmp then rotor dramaticly ran up to idle speed. However the engine still had a aglow and flame tail cone with EGT 760 degrees. I pushed throttle a little after stabilizing for a few seconds and the engine speed increased to 100K rmp while EGT decreased to 620 degrees that eliminated the tail flame. But EGT got back to above 700 degrees and flame came out of tail again when throttle restored to idle.

This phenomenon should be caused by bigger gap between turbine blade tip and NGV shroud, right?

Another thing is whether fuel level should be above the engine fuel line inlet during running.

You said ECU controlling of EGT is right. High EGT makes engine hang start. But why do the fuel level affect engine start?

I have a set of 66mm turbine wheel, NGV and shaft for KJ66. I can't use JJ-1800 out case directly due to NGV flange difference between KJ66 and JJ-1800. Do you have the size of JJ-1800 outer case special rear side diameter? Thanks.

Good advice, if all thing mechanical are OK

Try Gaspers advice below (he built and designed most of the current FADEC-ECU working today)

1) Test if your TX is correctly aligned. Just go to the second screen on the fadec ("Pulse=.." ) and check that at full throttle the percentage at right side of the first line is 100%. Then check that at "OFF" it is at zero and the value increase linearly with the throttle movement. If not, check your TX.

2) Set the throttle curve to "Full Expo".

3) Set the accel delay to 60, decel to 20 and stability to 100.

4)Start the engine and accelerate to full power click by click.

5)Once at full power look at the pump power (right side of the RPM reading), and anotate/remember this number.

6)Set idle.

7)Move to the menu "pump limit" and set the value to a 15-20% higher than the value you read. If the engine arrive at full power at, say, 300units, set to 360. If you do it with the engine running could be that the rpm drop at idle, simply ignore it, it will self calibrate in few seconds.

8) Go to full power again. The engine will take longuer to arrive, wait for that the fadec calibrates the full power again.

9) Once at full power, decrease to idle, but by one click at time, waiting 2-3s between clicks to give time to the fadec to calibrate the curve.

10) Once at idle, calibration is done. Now you can play with the throttle. If you find that now it is too slow, just decrease the accel delay to have faster accelerations and decel delay to faster decelerations. Usual values are <20, but this depends of your taste.

This is the "complete" procedure. No need to play with anything else.

Paul

The temp probe reads normal room temp. No problem on that. The turbine balance is almost perfect. No abnormality with its revolutions on lower RPMs. The tail cone is the latest from Jetjoe ..somewhat smaller diameter thanlast year models. I will measure the inner diameter and post it tonight.. do I have to shorten it ? The thrust of the turbine is significantly lower at 137,000 RPM ... If I shorten the tail cone I will also lose thrust but I will probably reach 160,000 ...

Your high EGT's at start up could be just having the gas on too long, looking back through the readings I downloaded of my last 51mins the egts are at there highest just as the gas is being turned off at around 25K so watch the display and get the gas off no more than 25K, you only need it on long enough for the turbine to run on kero.

620K seems high at 100K mine would be about 470°c

Have you tried it at full throttle ?

Fuel level should not effect things as the pump controls the flow

Yes shortening the tailcone will effect the thrust, but there is a big increase in thrust from 137K to 160K, Your EGT's are higher than they should be, do nothing yet, Post the dimensions of th tailcone, length & diameter at end.

I don't believe high EGT caused by gas on too long. Because I turned off gas at once kero is burning at less than 20K rmp.

I did not run it at full engine due to no enough fuel.[img][/img]

It could be possible that fuel level affect fuel flow by using poor JJ pump, isn't it?

One cause I think may be poor performance as high EGT at all phase of engine runing. I have no choice to do.

leave start fuel on till 25k and start fuel slower. Is your tail pipe glowing on start?make sure your temp probe is not too deep in cone or it could be in a bad location . you can rotate tail pipe and probe. what diameter tail cone? what make of ecu ?

Hi again,

I measured the tail cone with caliper:

length: 45,5 mm
diameter: bairly 41,5-41,7 mm

Maybe this is the reason... what do you recommend?..

Mine has 36 mm lenght!!! and 45 mm diameter

my best hand fitted motor is 43.5 dia and 43 long. You don't want to run it too hot very long as you can melt the rear oring to the rear bearing and lose preload. unless you have a 1200 it will be to constipated to get maximum rpms.
pm me your address and I have 1 extra shorted cone I can send you for xmas. 46.25mm dia. You could shorten yours 1mm at a time just don't run long over 750 ,less than 700 shouldn't hurt it.

A long time ago I read about a guy that build and sells CC....
Does anyone know about him??

I cant remember his name or his web page []

Thanks!!!

That tailcone is the same as mine, 45 long and 42 dia I only measured it roughly but they look to be the same.

myring
jj1800 outer case diameter is 109mm
length is 129.5
diameter at ngv 70.75mm
ngv inside 68.07
turbine wheel about 68mm
case bolt pattern is 82mm dia 8 3mm bolts

Hi Myring

Idle is often when the EGT is highest, but your temps are too high. If you can notice any hot spots on the tail cone at idle , then I would suggest that you may have an uneven burn problem, either to do with the combustion chamber or a blocked fule manifold (more likely).

I have seen blocked fuel manifolds cause engines push the flame out of the exhaust and the needles on the JJ-1200 are only 24g so any small amount of dirt or flux from the soldering process could be blocking one or more needles.

Good luck.

Yes the two pieces tail cone is glowing during start. EGT probe is installed correctly within 2mm protruding in gas path. Regal makes the ECU.

Absolutely this engine has a real hot start. Do you know what rmp the engine can reach by starter driving solely?

I send you a pm.. Thanks for your help...

What temps do you read at 160,000 rpm with this cone?...

I have a similar one on 1 motor and it runs in the mid 600s. here is a shortened one and a long one.

Will the single piece tail increase thermal impact on the rear of bearing and shaft? Did you see blue color on them?

I don't think you will hurt bearing from thrust . wren ss has 18 or so. most 54s use grw 688 in back for the heat.