Back again..!... The GT6041 powered "Green Beast"..!

[pitciblackscotland]

Feb 11, 2015 0:20:27 GMT -5 smithy1 said:

Hi All,

Finally had a chance to run the "Beast" with it's new pipe today...luckily I'm not like John and was able to have the battery in the camera charged...  Sorry John...couldn't help myself..!

Only have a relatively small amount of fuel going through the spray ring causing it to run a little on the lean side during A/B due to it having 0.020" "Stainless Lockwire" in the holes, I'll remove every second wire and see how it goes then. All in all not a bad result. I'll also need to open up the "supplementary flame show" fuel supply a bit more...I guess it's better to be able to open up an orifice rather than have to make them smaller..  Still have some fine tuning and adjusting to go but it's all heading in the right direction.

As usual, the "Beast" starts and runs up to idle nicely now....I've got the start procedure down nicely now and is fairly quick for a "blower start". Still have the max P2 set at ~35 psi so have plenty of room to play with. Idle rpm is ~23k and could probably come down a fair way to help give a nice fluffy flame, self sustain appears to be fairly low, (thanks to John's nice efficient combustion chamber), @ ~15500rpm, max rpm still an unknown at the moment due to the rpm sensor no being happy in direct sunlight....but for starting duties and up to idle it's very useful....thankyou for that idea Anders.

A few numbers: A/B Pipe exit diameter: 106mm, Idle EGT: 525c, full noise EGT: 605c, Full noise with A/B EGT: 660, oil pressure cold: 65-70psi, oil pressure hot: 52psi. P2 @ idle 4.5psi, P2 @ max rpm 34.5psi...

www.youtube.com/watch?v=hdr_FX3dGF4&feature=youtu.be

Cheers,
Smithy.

Nice one Brett Looks nice and green were you are,has summer finish up already in NSW

Cheers,
Mark.

[Johansson]

I feel sorry for the lawn.

[smithy1]

Feb 11, 2015 3:00:35 GMT -5 Johansson said:

I feel sorry for the lawn.

So do I..

[smithy1]

Feb 11, 2015 2:55:53 GMT -5 pitciblackscotland said:

Feb 11, 2015 0:20:27 GMT -5 smithy1 said:

Hi All,

Finally had a chance to run the "Beast" with it's new pipe today...luckily I'm not like John and was able to have the battery in the camera charged...  Sorry John...couldn't help myself..!

Only have a relatively small amount of fuel going through the spray ring causing it to run a little on the lean side during A/B due to it having 0.020" "Stainless Lockwire" in the holes, I'll remove every second wire and see how it goes then. All in all not a bad result. I'll also need to open up the "supplementary flame show" fuel supply a bit more...I guess it's better to be able to open up an orifice rather than have to make them smaller..  Still have some fine tuning and adjusting to go but it's all heading in the right direction.

As usual, the "Beast" starts and runs up to idle nicely now....I've got the start procedure down nicely now and is fairly quick for a "blower start". Still have the max P2 set at ~35 psi so have plenty of room to play with. Idle rpm is ~23k and could probably come down a fair way to help give a nice fluffy flame, self sustain appears to be fairly low, (thanks to John's nice efficient combustion chamber), @ ~15500rpm, max rpm still an unknown at the moment due to the rpm sensor no being happy in direct sunlight....but for starting duties and up to idle it's very useful....thankyou for that idea Anders.

A few numbers: A/B Pipe exit diameter: 106mm, Idle EGT: 525c, full noise EGT: 605c, Full noise with A/B EGT: 660, oil pressure cold: 65-70psi, oil pressure hot: 52psi. P2 @ idle 4.5psi, P2 @ max rpm 34.5psi...

www.youtube.com/watch?v=hdr_FX3dGF4&feature=youtu.be

Cheers,
Smithy.

Nice one Brett Looks nice and green were you are,has summer finish up already in NSW

Cheers,
Mark.

Afraid not Mark...was well over 30c today...humidity ~82% too.

[racket]

Hi Smithy

LOL, nice camera work ;-)

Numbers looking good , yep , more A/B fuel to get those TOTs up ~750 C at max rpm , maybe even a tad more A/B nozzle diameter ( 110mm ID ) if it looks like it wants even more fuel .

She's "squealing" nicely , love the "pops" and thunder , yep ..... you should be pretty happy with that for a first try , definitely "ballpark"

Cheers
John

[smithy1]

Feb 11, 2015 4:16:44 GMT -5 racket said:

Hi Smithy

LOL, nice camera work ;-)

Numbers looking good , yep , more A/B fuel to get those TOTs up ~750 C at max rpm , maybe even a tad more A/B nozzle diameter ( 110mm ID ) if it looks like it wants even more fuel .

She's "squealing" nicely , love the "pops" and thunder , yep ..... you should be pretty happy with that for a first try , definitely "ballpark"

Cheers
John

Thanks John.....I'll do my best to make the old "beast" sing...and make you proud..

Cheers,
Smithy.

[racket]

Hi Smithy

Heh heh , you'll make her more than "just sing" , there was some serious noise coming out of that pipe :-)

Cheers
John

[smithy1]

Hi All,
Small update on proceedings with the "Beast"....With the engine and A/B running pretty sweetly, I've decided to fit extra fuel tank/s and an oil cooler to the system, I'm hoping to be able to get a good 10mins of run time. Needless to say, the oil will become a tad warmer than would normally be the case, hence the oil cooler. I noted after testing two weeks ago the oil temp was rather higher than I would like, I did 5 tanks worth of testing with only ~20mins in between each run and the oil temp was getting up there, the tank was quite hot to the touch and approaching ~80C at a guess, longer running would see it go considerably higher.

john, (and everyone else I guess)....Any advice or recommendations on what type of fuel tanks/fuel cells I should/could fit?? Obviously there's not a lot of room available but I plan on using the space where the normal side pods would live, making mounts and or brackets won't be too much of an issue. The oil cooler will be a "sandwich plate" affair and will also be "fan forced" so it need not be in the direct air flow as such.

Cheers,
Smithy.

[madpatty]

Hi Smithy,
I too fitted a DIY Oil cooler to my engine a few days back....tube and fin type(20 pass- fan cooled).

I have yet to test it....What should be the target temperature range for the oil?

Cheers,
Patty

[racket]

Hi Smithy

Good to hear she's singing nicely :-)

Maybe a largish ( 20 litres??) pod tank on one side only to make entry and exit from the kart a bit easier than if theres a pair of tanks, I think I've seen something similar on a "turbo kart" somewhere , it was on the side where the IC motor went to "balance" the seating thats a bit to the other side.

Depth of tank is going to be important to prevent air getting into the system , probably 250 mm depth as a minimum

A thought ...........sealed alloy tank thats connected to current tank with fuel pump pickups from new tank , return to original tank, with perhaps a fuel to oil cooler in bottom of new alloy tank to dissipate heat from the oil before it goes to the turbo , a coil of alloy lube pipe immersed in fuel will keep temps down whilst giving the fuel a bit of preheat .

Cheers
John

[pitciblackscotland]

Hi Brett,
Mmmmm you may have to build your own fuel tanks to go along side were the side pods are just like this chap has done.

Cheers,
Mark

[smithy1]

Thanks guys,

I might do as John has suggested, just run a single tank on one side so I can still get in and out of the beast without blowing a gasket..!

Mark, those tanks look excellent, perfect for the application.

Cheers,
Smithy.

[smithy1]

To continue from Ander's thread.

@ John,
I'm not seeing anything like 750c TOT...even at full noise, (35psi P2), TBH it's only ~600-610C dry ATM, seems to vary a bit from one run to the next , it's never high or dangerous though...and very close to 500-540C @ idle ~3.5psi P2. I don't really know what it is at full noise and wet though..! More testing required...

I took the kart to my mate Dave's place, you remember Dave with the little Daihatsu jet van..?? He says G'day BTW..!

Anywho, I had to replace both A/B pumps due to them leaking from the outer case seal...yep....both of 'em were leaking ...anyway, I had to check to make sure the new pumps work , and they obviously do...and they don't leak either, which is a relief... so on Tuesday, as usual she fired up easily ...here's a vid:

m.youtube.com/watch?v=-MLVFHBubk4

As you can hear, she squeals a tad during A/B, even at low P2's...

So...should I open the exit diameter? I'm guessing I probably should, it's currently at 106mm diameter, same as the comp inducer which is probably ok for a dry system but with the A/B running I'm suspecting it's not real happy with the mass flow.

On a side note....I noted the oil tank was very hot to the touch after just two back-to-back engine runs....pressure is still ok at ~50psi. I now have the oil cooler kit and will be installing it over the next week or so....I opted for -10an fittings and hoses so there's as little restriction through the system as possibe, temp sensor & guage will be fitted to the turbo inlet side of the system...It's a sandwich plate type setup and quite neat and bolts straight up to the existing pump housing...just need to find a suitable place for the cooler core to live, I think I went a bit overkill on the cooler core though, it's the size of a small block of flats... so I might opt for a smaller unit in the near future..as long as I can keep the oil temp under 120C or so I'll be reasonably happy.

Cheers,
Smithy.

[racket]

Hi Smithy

LOL, you're treating her too kindly

Heres some numbers I have ...........

70,000 rpm 3.65 PR ( 39 psi P2) at 74% effic. with 2.75 lbs/sec - 165 lbs/minute flow

175 deg C rise in compression , 190 C for T2 on a "cold??" winters day at 15 C

~150 deg C drop through turb stage assuming 78% effic

3% pressure drop across combustor, therefore a 3.54 PR going into turb stage at 900 C - 1173 K for calcs

We need a 2.046 PR across turb stage to power the comp which should leave an around 1.73 PR - 10 .7 psi total in the jetpipe.

Now I started to make some assumptions at this point to determine the actual PR across the turb stage to account for the velocity out of the turb exducer , I came up with a total PR of ~2.39 across the stage .

Now the Garrett turb stage map gives a Correct Flow of 93 lbs/min thru the 1.47 A/R scroll equipped stage

Using a 1173K temp and a 3.54 PR along with the 93 lbs/min corrected flow , the actual flow worked out at 163 lbs , pretty close to our 165 lbs/min assumption of flow .

Our non A/B calcs .............1.73 PR @ 1023 K should give us a temp drop of ~117 deg C through a 90% effic jet nozzle at 906 K EGT and a velocity of 1720 ft/sec for a thrust of ~147 lbs .

Density will be ~41 cubic feet/ pound so ~112.75 CFS requiring ~9.44 sq ins of jet nozzle , or ~3.46 inch dia - 88mm , theoretically without any adjustment for boundary layer etc etc , I'd normally add on a couple of mms , so 90mm would be reasonable .

Now for the A/B

If we apply the "normal?" ............double the CFS because of temperature rise , and divide by 1.4 for velocity increase ( square root 2 = 1.4 ) , we get an area of ~13.5 sq ins , or 4.15 " dia , or ~105mm for the A/B nozzle , to allow for any "turbulence" and boundary layer a 110mm ID nozzle might be required and thrust at ~205 lbs

Cheers
John

[smithy1]

Yeah, you're probably right, I am a bit "soft" on her..! OK....so you'd suggest I leave the pipe as is then, or open up to 110mm and just wind her up a bit higher P2 wise...

As you're well aware, there's plenty of "adjustment" left for fuel throttling, there's the adjustment on the fuel metering valve itself and an adjustable throttle pedal stop, both of which are currently set to only allow 35psi P2, I should be able to get out to the Drag strip on Wednesday next week to do a couple of engine test runs, I doubt I'll be allowed to run up the track though...

I now have both a hot streak and a RR250-C20B igniter in the pipe just downstream of the flame holder, the hot streak is activated via an independent switch on the steering wheel, the igniter is activated when the A/B pumps are running, also via a switch on the steering wheel.

Cheers,
Smithy.