View Full Version : Twin turbo question
I've read all the post re heat, flow problems, lag from a big turbo etc.
Has anyone thought of a twin-turbo application? Why or why can't it be done (no space?)? I saw M-Developments' post on a big turbo - could you use a K03 together to combat lag? I know a squirt of nitrous can be used to this effect....
???
:cheers:
Just read my question and used my head and now know why there isn't such a thing:redface:
max_torque
01-05-2003, 16:32
Absolutely anything can be done, but cost is a major issue!
2 turbo's and plumbing is expensive, heavy, tricky to package, requires clever electronic control to get nice driveability. Is more likely to fail due to component failure (2x as many bits after all!)
no OEM is going to do this(cost is current no1 condsideration for all OEM's), you or i could do it, but do you really wanna spend £20k on your engine?
as you say nitrous will be easier antilag. or the latest developments in variable geometry turbines, or even electrically assisted CHRA's is going to be the way forward. (except the OEM's will combine these with downsizing so don't expect a 2.0l engine, more like a 1.2)
for most people something like 250 bhp to 300 from a 1.8 is going to be enough for the road which is easiliy obtainable with a std install of single turbo charger.
Dormouse
01-05-2003, 21:02
Hmmm, what about a turbo charger AND supercharger Lancia s4 stylee :D :D
Dor.
max_torque
02-05-2003, 08:39
Well if you've got a good memory you may remember that Citroen sport france had an AX back in the early 90's that was based on the french only market 4wd AX (fiat panda 4x4 rival!)(as in a rival for the most pointless application of 4wd, also carried admirably by the subaru justy, which had 4wd but only enough power for 1 of them!)
But in this case they added a big turbo and a supercharger to the AX 1.3 litre engine, and i seem to remember were finding something like 350 odd bhp, which in a 800kg, kevlar 4x4 micro car is probably enough! (in fact car was later banned from French rally series when the re wrote the rules to exclude exactly this kind of "cheating"
It also carried the title for the most stuff crammed under a bonnet of a small car, in fact the exhausts (2 of, 1 for turbine exit, 1 for wastegate exit - no silencing at all) exited in front of front n/s wheel!:p
utter_hatred
09-05-2003, 13:43
Umm, dumb question time again...
Whats a CHRA?
:redface:
max_torque
09-05-2003, 21:50
a "CHRA" is a Central Housing Rotating Assembly, this is what people like Garret etc call the basic bearing and shaft assembly usually housed in a steel casting between alluminium compressor housing and cast steel turbine housing. For an electrically assisted turbocharger the actual shaft that links the turbine and compressor wheel beomes the centre of a AC motor, allowing the shaft to be spun up to the 60krpm or so to produce boost at low engine speeds. This is possible with current material and control technology, but the turbocharger peice cost is just about 3 times higher, so as far as i am aware it it not yet production viable.
Having said that by 2006 in the states, TIER II emission regs and taxation are being phased in, which require a manufacturer to meet a "fleet average" pollution target, which may require this kind of technology combined with downsizing to meet.
utter_hatred
10-05-2003, 11:19
Ta. Thanks for the understandable explanation!
If you`ve got a question on banking process design, I`m your man!
(Useful, huh?)
So I take it a proper CHRA would be rather more useful than the plastic hairdryer "TurboZet" - remember them?