gt17...
Turbo Mini Forums

we are in concorde fab , you can see why i was happy to see the saab upgrade at 235 bhp ,i think that will be enough for my mini if i ever get there .¬!!!

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

okey doky , back again with some more info data trauma whatevvver!!
so i was setting the car up on the data logger ,and got some graphs etc these show rpm and boost to show how soon the turbo comes in



this is mixture in red ,rpm in black ,and boost in blue shows a few gears of boost ,and how the boost stays in with fluctuation of rpm




this is graphic representation of mixture versus boost and rpm red rich blue lean










unfortunately , i then thought lets try more boost , it was ok on 10 but at 12 it did its blimmen smoke screen again , so it wasnt the two head gaskets !!!
so i wipped the head off (ooooer) and found that the guide seal on no1 had been pushed off the guide ,i m guessing by ex pressure ,as the boost rose it pushed up the appalingly huge guide clearance and just shoved that sucka out of the park ! se pics .oily oh yes .so its a chance to naff off the big guides and get some nice tight slim waisted sexy guides errr sorry my mind wandered there .







also a chance to put in some bigger mini spares valves !!silver lining

regards
robert

Edited by robert on 28th Nov, 2006.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

forgot to stick on the other ports for oiling comparison as you can see ,theres little bit on the other exhausts and none on the inlet .

regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

ouch! but all in the quest of fun,

i think i could be easily converted to datalogging

Im pretty sure I never ran seals on my exhaust guides, only the inlet.
Exhaust back pressure should take care of any oil trying to get down ????

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

well thats just what ithuoght steve . then i had a rethink and thought , ok , what happens when you shut the throttle...the turbine is hooning along at say 100k rpm ,and then theres no exhaust gas coming out of the cylinder ,and the cylinder itself is under vacuum ,so couldnt the turbine start to suck on the port ,along with the cylinder ,effectively the turbine acts a compressor for that short space of time where the throttle is shut ,.just a thoery though , no scientific proof measured as yet .
regards
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Hi robert!
like your testings and manner to work.
also like the boost treesholld,
I think it would be a good thing to mesure tip with this turbo, this sort of boost/rpm necessitate a very small turbine inlet (about 0.65/0.7 sq in), worrying about the 5000 rpms tip.

yes i was thinikng that fab , i think i'll try to get a couple of bigger a/r's for better top end , i dont need boost at 1400 really ! the big diesel vans have some bigger sizes.
regards robert .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

shiny spankyness!!!! 31mm 21-4-n yummyness..oh yes.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

jesus christ you work fast, not long ago this was an idea in your head

thanks nic , well i had to get it done before i go to van for christmas , couldnt bear the thought of it sitting there with no head !
i still have to find out if its actually possible to run inserts with a 31mm valve , i guess ill find that out when i get it really hot and under pressure .heres hoping .

Edited by robert on 4th Dec, 2006.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

as usually, nice work!
about the turbo (apologies if 'im a bit insistant ), and correct if you feel I'm wrong,
but this turbo have a very small turbine wheel (44 mm),it need a large trim to allow it to flow , then the 0.47a/r used on it is a middle sized a/r (not that bad)
I had very good spool and (quasi no)little lag with larger turbine wheels (47, 52mm), combined with middle sized a/r. I would prefer to keep that sort of a/r (about0.5) and rather lowering it if needed (about 0.4) to keep an efficient nozzle and use a larger turbine wheel with a lower trim to have more "torque", "power recovery" (hope it's understandable) from the exhaust gases. I think saab did use it has they didn't need to produce real boost, just a torque booster...
cheers
fab

i agree fab ,
its a next thing if it turns out that this is just too restrictive ,is to get a 2252 sort of turbo with the same compressor side .

i feel that the next a/r up the vans use ,i think its a .55, would be worth a go ,

but having said that , i think that to get 235 bhp from the saab on an upchip , would mean a good 12 to 15 psi ,at a guess ,which is a real test of the turbine , on 2 litres capacity , and suggests to me that this 44mm turbine may just flow a lot more than one would expect , remembering that if one can make a wheel produce torque above the efficiency expected of it ,then a lot of the gases will go down the wastegate hole ,and not even have to go down the volute .
i also think that if one looks at the t3 , it has a far flatter angle on the exit blades on the turbine wheel , than the 17 ,and subsequently ,this would create more back pressure than you may expect from a 48mm outlet ,or whatever it is .

i am like you
very interested to see how it does on the higher boost levels , another thing to consider ,is that although this is a 44 mm wheel , its outlet is 38.2mm which is actually bigger than some of the gt20 /t25/t2 etc. , as you say its all going to come down to whether the wheel and housing design create enough torque to make higher boost , but i feel that the vans running this turbo with 19 to 22 psi as stock are an encouraging indication that it will be ok .
regards robert.

Edited by robert on 5th Dec, 2006.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

hum..
not sure about the high hp saabs, 190 2l were using a t25 with late wheels
and the 175 2l a gt2052 (same as the rover one) I agree that this comp wheel have a large efficiency as being used both in genuine very low pressure and high ones;
about the turbine it's only used on low pressure application (I also think that the than's large capacity low power (about 2.8 110 hp) doesn't use that much boost, so this turbine only help to improve torque , this can be confirmed by is large trim (76)making it an ineficient but highflow one.
I doesn't try to disapoint u about this turbo (as I also like these hsg high flow design) and as we generally learn from tried stuf , than theorical ones, it's good to see how it'll do,but I wouldn't play with fire if I bet that you'll get both responsivness and power in using a more efficient turbine (58 trim about 70 75% instead of 60% eff) with the same a/r, specially with a lower capacity engine.

i will have to contradict you fab!! in a friendly way of course ...

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

hmmm double post

Edited by robert on 5th Dec, 2006.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I am looking forward to the results from this with great interest.

Fab, what options are available as far as turbines and AR housings are concerned .....??

Edited by RogerM on 5th Dec, 2006.

Every day is a school day ...........

How fast and how expensive ...... the same question...

no contradicton there,
I like your set up, just though how to improve it !
your price/perf is very good, and sometimes the best isn't the better!
but if I had money , would give a larger turb wheel (or the same with lower trim for lower boost) to improve this nice set up

Edited by fab on 6th Dec, 2006.

ok back to working on this a bit , been trolling round setting the megajolt ,and mixture without a rr .
so far seems to run well ,no smoke ,bit flat after 5 wondering if the valve springs are all ok but maybe too much advance ,
one interesting thing .
did some runs with my new gtech pro rr i got as a pressy!!
ill try to post up the data but i dont know if itll work .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

hope this works , this is still on 5.5 psi .so not bads so far .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

i take it that was on your very long and flat drive?

Ive gotta get myself one of those dataloggers....

exactly nic ,its usefull to live near an airfield .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I've been researching the GT1752 a bit more, following on from some discussions yesterday on the "998 High Boost Head" thread.

The GT1752 compressor impellor is 52mm dia, a 55 Trim and uses a 0.53 A/R compressor housing.

No map exists in the public domain for this compressor.

The closest that Garrett get to this is the GT2056 which appears to be a scaled version of the GT1752. It has a 56mm dia impeller, 55trim and 0.53 A/R housing.

http://www.turbobygarrett.com/turbobygarre...751578_comp.gif

If they are geometrically identical, then you can predict the performance of the GT1752 from the GT2056 map.

The scale ratio is 52/56 = 0.928 or 92.8%

The pressure ratio will therefore vary directly with the scale ratio. Hence a pressure ratio of 2 becomes 1.84.

The air flow will vary with the square of the scale ratio - 0.862 - 86.2%. Hence an air flow of 20 lb/min becomes 17.2

I used these rules to predict the performance of my T2 before we had a T2 map and the results were very close.

This is then absolutely ideal for a 1293 on 15 psi - 78% efficient.

Edited by Paul S on 26th Feb, 2007.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

3.4mm and 4.3 mm are the two different tip heights for the 55 trim 56mm wheel

4.1 and 3mm are the tip heights for the 55 trim 52mm gt17 wheel ,

i think it may be that these dimensions are going to affect the characteristics of the maps ,
i know that the wheel in mine is the 4.1mm but unless we know the tip hieght for the 56 mm wheel map can they really be compared like that axel , it may be the map your looking at is the 3.4mm ..what do you think ?
if you look back at the interpolation that fab did a few pages back , i think it ties in with your calcs though .
i think that range wise its going to be good whatever , its just above 20 psi where the question of whether its a high boost design comes into it , i found the fact that its used on the 18psi and up diesel vans as stock encouraging the idea that it may work well over 20 psi ,the proof will be in the trying !
regards robert.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I find this turbo a very interesting prospect. The more I hear the more I think it's worth a try for a daily driver type engine. What it'll do at high boost will probably only come to light when somebody is brave enough to try it if there is no map available ..... and I'm not that brave :)

Every day is a school day ...........

How fast and how expensive ...... the same question...