t18a96 turbo jet

[sub22b]

The evap tubes are fairly close to the flame tube i wasnt sure what size to make them when i built them but i actually made a smaller set at the same time but they got used in another engine i was building. So i will engineer some more and design them similar to your set that way im not pushing fuel against one side of the trunk. I had a good look at the combustion chamber and i dont seem to have any carbon build up after the run this morning so hopefully that was just a one off. I will measure and count how many holes i have in the flame tube and i will post them up shortly.

Cheers Nick

[sub22b]

Ok so the flame tube holes are primary 51 holes at 5mm. secondary 20 holes at 8.5mm and the 3rd set are 12 holes at 12mm the tube is 8 inch by 510mm long

[racket]

Hi Nick

Not enough hole area :-(

Generally we need the comp wheel inducers area as our total flametube ( including evap inlet area) hole area

Currently your 51 X 5 mm holes = 1,000 sq mms
20 X 8.5mm = 1,135
12 X 12 mm = 1,357
-----------
3,492 sq mms

This is only enough holes for a 67mm diameter comp inducer , a 4.5"- 115 mm inducer would require 10,260 sq mms of wall hole area , or roughly 3 times what you have , I'd say your comp has gone into surge at 20 psi P2

Cheers
John

[sub22b]

Hmmm ok i really did screw up my maths some were big time. owell i can always drill more better than having to weld up holes. I will work out how many more i need and start drilling. Then i will find a better boost gauge than can read 20plus psi and try again with some new evap tubes. Thanks heaps been a huge help. I will keep you guys posted on how i go. Im looking at buying a gokart frame this weekend and once the engine is running 100% with an afterburner which is another worry i have i will be installing it on the gokart and seeing how fast it will go down the quarter mile.

Cheers Nick

[racket]

Hi Nick

Before you start drilling holes, have a good think about the evaporators first as the placement of your Primary zone wall holes will need to be determined by the evaporator positions .

If you reduce the length of your flametube wall a bit and fit an end cap to it that allows air between the flametube and ouert can end cap you won;t need to worry about it running very hot, it'll also allow air into the inlets of your evaporators .

Do a bit of a rough drawing and pass it past us first so we can make constructive comments before getting into cutting metal .

We'll be looking forward to checking out the kart build :-)

Cheers
John .

[smithy1]

Aug 3, 2016 23:44:15 GMT -5 sub22b said:

Im looking at buying a gokart frame this weekend and once the engine is running 100% with an afterburner which is another worry i have i will be installing it on the gokart and seeing how fast it will go down the quarter mile.

Cheers Nick

This will be interesting indeed...your turbo is larger than my GT6041 powered kart.... so in theory it should produce more thrust. The afterburner is the hard bit....physically making them is rather easy, making them work nicely is the trick..

I'd love to see some progress pics.

Cheers,
Smithy.

[sub22b]

Yea im worried about the afterburner it may take alot of time to sort out. But a update from the weekend is im now in the process of rebuilding the turbo it decided it no longer wanted bearings. It looks like it has had a hard life before i got it so a rebuild and a clean and then it should be back on again.

[smithy1]

Aug 8, 2016 4:12:29 GMT -5 sub22b said:

Yea im worried about the afterburner it may take alot of time to sort out. But a update from the weekend is im now in the process of rebuilding the turbo it decided it no longer wanted bearings. It looks like it has had a hard life before i got it so a rebuild and a clean and then it should be back on again.

Do you have a link for the bearings/repair kit?? Will need a repair kit for mine in the future I suspect.

Cheers,
Smithy.

[racket]

www.turbomaster.info/eng/

Smithy , you won't need a kit for another 20,000 hrs ;-)

I have one here if you need it.

[smithy1]

Aug 8, 2016 16:43:07 GMT -5 racket said:

www.turbomaster.info/eng/

Smithy , you won't need a kit for another 20,000 hrs ;-)

I have one here if you need it.

LOL...20,000hrs..! Pppppfffttt...I must have done at least 7 hours total...

Thanks for the link John. I'd like to have one on hand...just in case..!

Cheers,
Smithy.

[sub22b]

Hi guys i have got a kit coming 210nzd so fairly cheap i thought. I also found out that the t18a96 is atleast 20 years old so i may need to find a newer model at some point possibly a hx80 or gt6041 but for now the old girl will see another day and will post some rebuild photos when the kit arrives.

cheers Nick

[racket]

Hi Nick

LOL, don't worry about it being 20 years old , my TV84 turbo I used in the bike was a reconditioned unit back in the early '90s , and it performed OK ;-)

The main thing is the size of the "hole in the front" especially for thrust engines as theres generally not a lot to be gained by pushing the engine from a P2 of 35 psi to 45 psi as it gets harder and harder to make the extra velocity at the exhaust nozzle from the higher P2 , especially if the engines comp wheel is a large Trim unit .

There'll be a few of us looking forward to those rebuild pics :-)

Cheers
John

[smithy1]

Aug 10, 2016 0:07:48 GMT -5 racket said:

Hi Nick

LOL, don't worry about it being 20 years old , my TV84 turbo I used in the bike was a reconditioned unit back in the early '90s , and it performed OK ;-)

The main thing is the size of the "hole in the front" especially for thrust engines as theres generally not a lot to be gained by pushing the engine from a P2 of 35 psi to 45 psi as it gets harder and harder to make the extra velocity at the exhaust nozzle from the higher P2 , especially if the engines comp wheel is a large Trim unit .

There'll be a few of us looking forward to those rebuild pics :-)

Cheers
John

LOL ....yep, even the GT6041 isn't a new design...I've noticed the 6041 starts beating the air to death after the P2 gets over ~40psi ....I suspect there's very little if anything to be gained after that. She seems happiest in the 35-38psi range.

Cheers,
Smithy.

[racket]

Hi Smithy

Yep , the GT6041 map sorta "fades" once past ~32 psi , theres only an efficient?? 5 lbs/min increase in mass flow at 45 psi where efficiency has dropped to 68% from the 78% at 32 psi , getting flogged to death is a perfect description .

Theres another GT60 comp wheel of 48 Trim vs your 6041's 56 Trim , this is a similar 48 Trim to our TV94 wheels ~98mm ind 141 mm exd , its used in the CAT versions of the GT6041 turbos whereas yours is the "competition" version , the 48 trim wheels efficiency is ~72% at 45 psi P2 with a mass flow of ~155 lbs/min vs the 56 Trim wheels 165 lbs/min , the lower flowing wheel would produce a better power outcome if both were run at 45 psi .

Your 56 Trim wheel at 30 psi is pumping an efficient 79% and 155 lbs/min , whereas the 48 Trim only 77% and 130 lbs/min , yep , your's is happiest at that 35-38 psi :-)

I'd imaging my >56 Trim 12/118 comp wheel will behave similarly and is the reason why the engines been designed for a "modest" P2 ............once we get past a 56 Trim the wheel starts becoming a mass flow rather than pressure wheel , which is OK for a thrust engine , but only just acceptable for a shaft horsepower unit .

Cheers
John

[sub22b]

Hey guys would there be any benefit to making my combustion chamber slightly shorter or should i leave it the size it is as it works well? Cheers Nick