The damage, what has caused this?
Turbo Mini Forums

I agree with your logic fab however the lads are running mapped ignition which alters ignition timing with respect to boost pressure as well as with respect to rpm, so even though the T2 will make boost sooner, the ignition is retarded as the boost rises.

You have it right there Tom, but the ignition map was based on the T3 and I have now retsred the map at the 'coming on boost' stage so that it is earlier in the rev range. safe to say we will be sticking at 15psi boost for the rest of the season.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

in this heat i think we all need a lie down pete, until you look at the states 42 degrees and upwards in the southern states urrrgggh

oh fab ,you cant compare two a/r nos from different design turbos ,they can only really be compared on the same model turbo eg a t3 .25 and a .36 . regards robert.

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

I've learn't a lot from this thread, hopfully we can stop it happening again.

Some very friendly local machine shops have have done me a massive favour and we should have the block back tomorrow. Then we'll put it all back together and, if all goes well, we'll be out racing on Saturday.

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

Fingers crossed for you guys that you can have it fixed and back out for the next meeting, good luck!

retarding your ignition does up your EGTs thou...

But it shouldnt be a problem for a t2 or a t3 :)

Aled

AlexF

I had the same problem when I swapped the T2 on my best friend engine for an m45 blower. to began I kept the ignition curve as it was with the turbo (cr , cyl head etc being the same ), but after two first runs,I found lot of dets from 1700 to 3500 rpms, (before we were using an hybrid t2 with gt turbo cup specs which was coming really on at 3500 rpms), I didn't understood as I also though that the boost retard would correct the ignition curve, but in fact we had to retard the base map as much as 12° at some points (2500/3000). In fact after after discuting the trouble with a canadian dragster supercharged dragster specialist it seem that the boost increase the ve in such a margin that if you were setting your ingintion curve at a point which were not in the boost curve you had to correct the bad ve with lot of advance then if you are know charge your intake it completely reverse the process you now need a lot of less advance , the boost correction only help in a small margin , it can't correct a bad base map.
fab

About t2/t3 a/r
Robert I agree that they are two different turbos, but not that different in design the T2 being the small brother . the gt turbo t2 is really flowing more than the mg mety T3 his 0.35 a/r being smaller than a t3 0.35 a/r but it is really a quater bigger than the t3 0.25 a/r. I will not show the calcs etc because of time and it'll certainly be boring.But logically the gt turbo being a bigger capacity, with higher boost and higher power it's an evidence that his turbo can't be lower in flow than the mety T3.
best regards
fab

i think that what your missing fab is that the t2 was made a fair bit later than the t3 ,which has a huge great turbine wheel ,and was really a very bad design of turbo for the 4 psi 7 psi metro ,but was all that garrett had at that time to offer bl,and even if it had a a/r half the size of the t2 ,(which was designed to cater for the lower flow engines and subsiquently had a smaller turbine wheel and oulet and housing even thuogh its a/r may be a higher no) may well flow more that turbo simply due to the big diff in outlet size....
anyway ,its all moot !!
the best thing is to get some data from the car ,and then see ! regards robert

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

Again the same old problem rears its head!

Pressure is not a true indication of AIR FLOW!

17psi on a t3 is not the same quantity of air per second as a t2 at 17psi.

Hence the igniton curves are likly to be different for each turbo.

Alex

Edited by AlexF2003 on 21st Jul, 2006.

AlexF

I'm not missing a lot of things about t2's and T3's I know which is the first , why bl had a t3 and not the t2, why the T2 came on etc etc , I also know the efficiency of both for a lot of revs /charges/capacity, can calc the best wheel comp trim , and make highflow hybrids.I just have tested a douzen of different T2/t25 wheel trim and a/r on the mety a seri.
but in fact you now agree that the T2 0.35 have a bigger flow than the t3 0.25. it's just what I said.

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