BXProject

[Philhod]

Exactly Doc, the veins do two jobs, or I should say have 2 effects.
One is more efficiency at lower speeds ( reduced lag) and 2, it does this by moving the air from blade inlet to exhaust as fast as possible.

Same as best cylinger head design is to move the gas across from inlet to exhaust as fast and smooth as possible.
A turbine is just another engine and obeys roughly the same engineering features really

[docchevron132]

So that explains why Garrett's are more flexible at lower RPM's then..

Feel like stripping the turbo out on the bus now and see if I can make that a bit more enticing! After all, it is REALLY derated!

[Philhod]

What little I've read up on bus and coach turbo's suggests that there are about 4 alternative turbine designs available, which just replace the one you have.
Given that there would be quite a bit of govenor, err, adjustment to get the best from any changes, it would also suggest it would have quite an effect on fuel economy too!!

[docchevron132]

Well, Cummins offered a variety of turbo's for the 6CT, mine is common for road use spec engines...

Non wastegated unrestricted, so the only thing limiting the boost is the amount of exhaust gas you can move!!

I mean, as is it's quite impresive, it'll blow 2 bar at 1100RPM (peak torque!) but itronically it seems less effiecient at higher engine speeds, like it's only blowing 1.2 bar at 2200RPM, near thr MGS of the engine...
Nevr quite worked out why since there is no wastegate so I'd have thought it would just keep blowing harder the higher the engine speed, unless the veins are designed to work better at lower RPM as per what you said above like....
hhmm....

[Philhod]

You just explained what this is all about, eminently, also proving to me that the faster you spin, the more the efficiency drops off, in your case over 25%.
If a big one loses over a third, that also says that the smaller the turbo the less the drag but still substantial so I will go ahead with my err experiment.



Well draw a plan out on the pub table on Sat pm

[docchevron132]

That could be an issue though, I mean, the landlord might not like it if you take his table away with after....

[Bx Bandit]

Don't tempt me, I've nicked a 4 seater sofa at 2.00 am before now!

[Philhod]

I was sat discussing forging large rings, with a bunch of Blacksmiths, round a pub table, once.
(like you do) We had to hire a 10 ton crane to get it outside after

[docchevron132]