turbo difference
Turbo Mini Forums

can anyone tell me the difference between this turbo:
1.T2
2.T3
3.T2/T3
4.T3/T4
5.GT15
6.TDO4H
7.TDO4L
8.TDO4LH

does all the model,let say,T3 have the same AR?

i'm confused....:(

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Best bet would be to learn how to read compressor maps and work from there, plenty of info and links on here try a search

This thread would really require a massively long answer, and seeing as im at work and on TM i have more than likely got the time to write it up, how ever i am lazy! its friday afterall!

The easiest way to describe it is, as im sure you know they are all different models. T2 is a "small frame" turbo that will tend to create boost earlier in the rev range but die out sooner than say a T4 and will also not be as efficient at high boost or just wont be able to make boost above a certain figure lets use 20psi for example!

However you then have the T3, bigger than a T2 but not as big as a T4, so, you get later boost and a higher boost threshold than a T2 but not as much lag or as high of a boost threshold as a T4.

The T2/T3 turbo's are hybrids, giving you some of the characteristics of both turbos that they are made from depending on how they are built!

The GT15 is a modern turbo with alot better wheel design to increase efficiency and spool up time while also having a higher boost threshold than the older T range. The GT15 is a small frame turbo and will spool very very quickly.

TD04 i would need to research as i havent really looked into them but im sure you could find out on google.

As for ARs no, there are many different variations of each turbo with different AR numbers. Have a read of the tech section of turbobygarrret.com and that will give you a better indication of what they all mean.

Generally the larger the AR on the turbine wheel the latter it will build boost.

The best thing you can do is read through the Tech section on garretts website, it will help you no end!

thanks alot all..
ok,lets say i want to use a turbo with my 998cc.
which one is the better?
it will be used as drag machine
it will be using 12g940 head
which one is the best to use?

also,i will build one 998 turbo for street
which turbo is the best?

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I know little but the GT15 or the T2 for the street.

If something is worth doing, it's worth doing half of.

what about T3?

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I reckon that a T3 will be a bit big for a street 998. Might be alright for the track/drag if you can keep the rev's right up.

If something is worth doing, it's worth doing half of.

oh.
the best head for 998 drag?
12g940?
or is it fine using 12g295?

p/s:what car does come standard with T3 turbo except metro?

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Don't know about the head.

However the T3 was fitted to many cars. Escort RS Turbo & Sierra Cosworth to name 2. However these T3's were a different specification to a Metro T3 and almost certainly would be no good on a 998.

If something is worth doing, it's worth doing half of.

i see..
so what about the GT15 or T2?

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Sorry I'm going to have to step out of this thread.

I am not experienced enough to answer all of your questions and most of this information is available if you use the seach feature on this site.

http://www.turbominis.co.uk/forums/index.php?p=search

Make sure you tick the search post body box.

If something is worth doing, it's worth doing half of.

it's ok.
thanks for your help.
it help me alot..
hehe

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Actually a T3 wouldn't be a bad choice on a 998 drag car if you had one stuck in the corner of your garage, but I wouldn't go to the effort of buying one.

all my race 998s have 940s and all my street 998s have 295s. Take what you want fro that.

As for turbo choice, there isn't much data for anything other than the T3 (metro) GT17 and T3(R5). Ther is one being built with a GT20 and one with a GT15, but these aren't tested yet.

The 'safe' advise is to use a T2 on the road and a GT17 for the drag car. There may be (well most likely are) better options, but like the rest of us you'll have to slave over some maths, look at hundreds of compressor maps, then jump in and wnjoy the experiment!

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

wil_h!
i really love your minimag featured car!
the 998 turbo.
your car inspired me to built one turbo.
actually,here in malaysia the metro turbo are super rare!turbo mini is also super rare.thats why i got a lot of question to ask about the turbo.
the difference between GT15,GT17 and GT20?

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Cheers, nice to have world-wid adoration!!!!

As has been explained above, turbos are rated by how much air they can flow and what psi they can generate.

The GT 15 will flow enough air for 150bhp, the GT17 about 250bhp and the GT20 200 to 250.

Additional to this is the boost threshold, i.e when will you get boost.

For a 998, on the GT15 around 2krpm. the GT17 around 3.5krpm and the GT20 I have no idea, but at a guess 3.5krpm also.

As a comparison the T3 from a metro is a bit later to spool than the GT17 on a 998.

But remember, the boost threshold will be affected by the static CR and cam profile.

Edited by wil_h on 4th Dec, 2009.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

ok.
if i plan to use GT15 on my 998,with CR of 8,what is the safest boost to run?
i'll be using mg metro cam

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8:1 is very low. The GT15 should be ok for 15 psi, so you could run higher CR, more like 8.5 would be better.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

owh.so if standard piston with standard chamber 12g940 head capable of that CR?
wat car does come standard with the GT17 turbo?

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The GT1752 is fitted to Saab turbos (9-3s and 9-5s).

You will need to have dished pistons and enlarged chambers on a 940 to get a decent CR on a 998.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

oh.
so if i take the GT17 from the saab,do i just can bolt it on or need to modified it?
what piston can we used for 998 turbo?

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Not to be rude, but all of the questions you ask have been covered in other peoples threads when they have actually built what you are talking about. You won't get far on here if you are not willing to go and read those threads and find some of this out for yourself.

THANKS TOM.
1 more question,is it fine using garret ar48 for my 998?i'l be running the maximum safeset boost for mini engine can stand.is it gonna b ok?

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Yes i moved to the darkside

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I think he meant will it perform ok, not will it blow up.