Could you point me in the general direcrtion of a suitable turbo?
Turbo Mini Forums

I think my turbo's gone, it was a perfectly good unit with littel to no play and no smoke when i installed it and for the 2 months i have had the car on the road, until lthe last few days.

the engine is a 1.4 16v rover k-series (not an A i know, but you gentlemen know your oions) which spins to ~7500rpm the turbo is a T25 from a rover 620. Running anywhere between 15 and 20 psi of boost depending how the clutch feels that day. Would this boost level have killed it?!

The turbo makes plenty of boost by 3000rpm full boost around 3250/3500 ish.

when i upgrade the clutch i'll be lookign at running even more boost untill something in the engien gives. so ideally i'd liek a turbo that will cope with 25psi, 30 at a push, and not spool up later than my current unit. Some rough pointers where to start looking would be appreciated. at the moment im thinking one of them GT-series T25 or T28's tho yet to sit down and do the maths, as i only condemmed that turbo a few minurtes ago :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

20 psi is a bit high for at25 but it should have withstand with this longer, what about your oil line (coming from, and does it point down and above the oil level?
are you looking for a budget turbo (have to do with what's available)? or a new one?

I don't think you'll find a turbo that does what you want to be honest...



"30 at a push, and not spool up later than my current unit"....


Pick one - or the other - but not both :)






25lb alone is around a 2.80PR; 30lb is close to 3.15!

Just take a look at the range of turbo's available... VERY few push that kind of pressure ratio - let alone at the flow you need...

Edited by turbodave16v on 8th Dec, 2006.

lol thought it may have been a bit of wishfull thinking. oil feed comes direct from the oil filter housing (filtered) i have noticed that on alot of aftermarket turbo kits that the oil feed line has a restrictor, mine does not, is this necesary? if so what size ID restricor should i try make up?

the oil drain goes into the sump above the oil level, well as far as im aware, it never gave me any trouble up untill a few days ago. tho it did smoke rather badly at a RR day a while back, and then stopped, car was idleing for about an hour or so.

Cheers dave, i see what you meen even a GT28RS would be struggling wiht 25psi, the efficiency up there is pretty narrow WRT air flow, and my engines tiny so wil lfall pretty far to the left :S

Maybe a good time to up the compression ratio a tad and stop abusing boost?

I can get the just of working out whether a turbo is suitable for a certain boos tover a rev range, but how does one go about figureing out when the turbo will start to make boost? is it as simple as plotting along the vertical line to the far left?

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

yes - plot the airflow at 2000, 2500, 3000, 3500rpm at 2/3 psi and you'll start to build the picture on where the boost will happen on the compressor....
But that of course needs the compressor to spin!

IE if you pick a 28RS and specify the larger turbine - it ain't going to spin the compressor enough at 3000 rpm to make boost.

Easiest thing is if you have a benchmark - a stake in the ground if you will. You can then build on that.


A 28RS will boost higher than the map shows btw - you just have to study the compressor speeds and make a judgement how far more they can be pushed. Obvioulsy - efficinency and life drops the further out of the compressor map you go.



There is a way of reducing the flow of the compressor however - effectivly bringing the whole map to the left - by drilling holes around the intake of the compressor... I've not tried it myself however - but know a guy who races at my local drag strip who does it to his turbo's if he experiences compressor surge. I'll speak to him more about it when i see him again next season...

Edited by turbodave16v on 3rd Oct, 2007.

when you write untill last days, does your turbo only smoking or have too much side/radial play?
as wrote a t25 will wistand with 20 psi more then 2 mounth, if it gone in this time, there is something wrong, what about your oil feed pressure?restriction is mainly used for bb turbos but can have benefitial if you have to much pressure (oil)
about your pr/flow target look at the gt2259 map it should give what you need

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

little bit of an update, got soem free time to play with the car today, the turbo how has tonnes of play in it, to the point where the wheel can easily touch the housing with the bearings dry :( its fucked. on teh bright side the engine appears to be in good health!

I have a spare T25 sitting hee which i'l throw on to get me back on teh road, but ideally i dont want this hapening again. I dont have a dump valve, is this a sign of damage from compressor surge?

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.