hi, i need help, who can explain me the corret setings for start pump in ( ACCEL 2 ), because the jet cat manual explain about ( ACCEl 1 ), min 0.10 and max 0.20, and i did it in 0.15: but i lose tha data for ACCEL 2, and the turbine is aborting the start, for HI EGT when is reching 975 grades celcius and 35000 rpm's what is the meaning of ACCEL 2, wht can i do?

thanks for you help.

Hi,

Sorry I am out of the country so I can't ask Wilcox right now about what the normal Uaccel2 voltage range is.

i would start by raising your U-accelr1 and lowering U-accelr2 a bit. It could be that the U-accelr1 is too low and U-accelr2 is overcompensating. I will try to talk to Wilcox later to get you some more help.

Regards,

Thanks Matt,

i will apreciate your help about the meaning of (U-accelr 2) and the best range for this

i saw in the jet cat book:

normal range for (ACCELR 1) is 0.10 to 0.20, factory default is 0.20 after several hours of usage is better to lower it from 0.20 to 0.10, i underested that, yesterday i adjusted (ACCELR 1 ) in 0.15 and 10% of gas, and the turbine started very nice, i flow for 10 minutes no problems ( 2:00 pm and 7000 fts AGL and 15 celcious wather temperature),
at 4:30 PM i tryed to start again, it was imposible, I made a mistake, i changed and forget the factory range in (U-ACCELR 2), i don't understand the meaning of (U-ACCELR 2)
the turbine book doesn't explain about the range of (U-ACCELR 2 ) this is my big doub because the turbine doesn't start again

I see Matt hasn't been able to answer this yet, so, from what Bob Wilcox told me, U-ACCEL 2 is the pump voltage the ECU uses during the short open loop period that occurs after the propane shuts off (around 19,000 rpm). It's the only time the system runs open loop.

I don't remember the exact range but both my P-70 & P-80 are set to .750v. If I recall correctly, my Titan was set around .850v.

Generally, if U-ACCEL 2 is set too low, the engine may stagnate, hesitate or accel slowly after the propane shuts off. If set too high, it will blow flames. For instance, I had to run the Titan up to around 1.050v to get it to start the way I thought it should. You should look for a consistent rate of acceleration of the engine.

It's also been my experience that engines that don't accelerate well on start or don't make it past 35K-40K, all else being equal, have a not so good pump. A weak pump is also indicated if the pump will not start or is slow to start at U-ACCEL 1 = .200v indicated by the engine running on the propane only for more than a second or two. In this case, U-ACCEL 1 can be increased slowly until the pump starts reliably.

Hopefully, Matt will get more details.

Thanks Thud for reply me

I understood that (u-accerl 1) start the fuel pump after ignition and i`m confused with u-accerl 2 loop ¿is a second fuel flow to the chamber to stabilizated?

i`m in stanby for more opinions,

As I understand it, U-ACCEL 2 is just an initial pump voltage the ECU uses for the rpm ramp up after coming off the propane, just like U-Accel 1 is an initial pump voltage the ECU uses after the propane lights off. It's not a stabilization factor nor a loop, just a fixed starting point.

Think of it like this:

Engine starts on propane and the pump starts at U-ACCEL 1. Engine goes thru a first ramp up til the propane quits at ~19K. Pump now goes to U-ACCEL 2 and engine continues to ramp up to 55K. Hopefully, the second ramp up is a seamless continuation of the first. U-ACCEL 2 provides a starting point to make that happen. I expect that U-ACCEL 2 is set to adjust the pump to match the combined effective fuel flow of propane & kerosene at propane cutoff otherwise the end pump voltage of the first ramp up might not be enough to continue engine acceleration.

Hi guys,

Rick has it right, these are 2 software variables that control the start of the turbine before the control loops take over.

Also, I note that it says in the manual that you_might_need to lower this after the pump breaks in a bit, but it is not a matter of course, so everyone should not run out and start adjusting these parameters unless the operation of the turbine becomes unsatisfactory.

Let me know what turbine you have and Bob will look up the defaults. We thought a hard reset might set them back to a default but we are not sure., Better to tell me the type of the turbine, unfortunalley we might not be able to get an answer until Monday.

Regards,