I'm quite sure the turbo on my mondeo only kicks in at just under 2000rpm, so I'm thinking is it possible to fit a turbo and wastegate etc. and then run the whole thing through a switch so I can have "sedate mode" and "scare the passenger" mode?
have you been watching mad max, with the switch on/off supercharger? lol
i don't think its really possible, unless you spend big money on systems where you you can alter the boost while driving etc.
[Edited on 18/4/09 by blakep82]
as kool as it would be to have a big switch labelled 'TURBO' on the dash. i cant see the point. if you want to drive carefully, back off the
loud pedal...
wastegates are old hat now. its all about VGT.
Ooh new stuff what's vgt?
Just fit a hugely oversize turbo - no boost till it's really working , then loads till it goes BANG
Good point, maybe I could steal a truck turbo from work 
quote:
Originally posted by Ninehigh
Ooh new stuff what's vgt?
variable geometry..... something!
it has been done many times with superchargers by replacing the drive pulley with the electronic clutch from an a/c compressor and rigging up an
appropriate switch.
I believe it can be done with the wastegate on a turbo but sorry I'm a bit light on how!
damn, must post faster!
its easy, just fit any turbo, get a really low pressure wastegate spring, then use a bleed valve (£10) to adjust the boost, the difference between 3psi of boost and 15 psi could be as much 200 bhp depending on set up.
quote:
Originally posted by aerosam
damn, must post faster!
Ok I'm looking round for units and they're mostly saying something like "Suited for 200+bhp"
Would that be the original engine power or the increase in power? If it's the latter £750 for triple the power is well worth the money to me!
It's the original power isn't it? 
I'm with dinosaurjuice - why?
You can control the boost/power with that pedal under your right foot. Why ad more complexity/expense?
Liam
Oh yeah it's just an idea, to see if it's at least theoretically possible. I get the feeling that the speed I drive at will be governed by
two things though, one being the "testicular fortitude" of myself, the second being the capability of the vehicle to stay on the road... If
I can restrict the second one when I should I might live longer lol.
Really it's for economy, doesn't matter how much power the engine can give when I'm doing 65 in motorway traffic so why not cut that
fuel drain in those times and I can open it right up for the racetrack? I agree with the extra complication though
Jasper has a little gadget box on the dashboard with a button to switch between 2 different boost settings. It's just done by varying the waste
gate I believe.
It's fitted to his 200sx engined car.
Approx £350 from the states IIRC. Ask him for details.
Cheers,
James
I didn't know Mondeos had turbos, or is it a weasel, in which case you'll need all the boost it already has
ATB
Simon
quote:
Originally posted by Simon
I didn't know Mondeos had turbos, or is it a weasel, in which case you'll need all the boost it already has
ATB
Simon
No, it won't I'm afraid. A diesel designed with a turbo, and (effectively) running without (which I guess you're suggesting, part time
at least) will be gutless.
My Espace turbo comes in around same (2000) rpm, but I think that it's a deffo economy thing. If I drive (in top) at 1800 rpm (approx 50mph)
I'll get well over 50mpg, if I'm over say 2200rpm, approx 75, I'll get 35mpg - all down to being in the turbo "always on
mode". Below the 1800 rpm while accelerating, you can hear the turbo (a vgt jobby obviously mapped to provide boost while accelerating, be off
boost asap, but, naturally needs boost some point (being approx 2000rpm to provide enough ooomph to carry job on).
ATB
Simon
Thing is I'm talking on the locost, wouldn't the non-turbo mode be just as powerful as it would be without the turbo? The engine I have in
line doesn't have one now...
What I'm saying is would fitting a turbo on afterwards and then having that turbo not running for a period choke the engine or would the air come
through in the same manner it previously did?
[Edited on 19/4/09 by Ninehigh]
vgts been around for a wee while, lots of marine applications have them, and i believe some porsches use it to...
basically theres a ring of vanes that open and shut depending on gas flow, so you get higher pressures for lower velocity by reducing the inlet size.
could probably use a diagram here
At low boost times, i.e. when you're cruising along on a trailing throttle, in petrol engines that is pulling a vacuum and in diesels feeding
very little fuel, the turbo just idles along spinning just fast enough to pass the air needed and supplying zero boost, so it is a negligible
restriction to air flow, most probably no worse than the normal air filter.
So there is no point trying to pull it out of the induction system in those circumstances.
The answer to a switchable boost increase is a switchable bleed valve in the pressure sensing line to the wastegate and a suitable fuel/timing curve
in the ems or one that is also switchable and of course the right selection of turbo that is happy at both boost levels.
i'd have a read up on how turbos work, at cruise with no load they are not using anymore fuel than a N/A engine. They only use more fuel when
they are creating positive boost which occurs when you put more load on the engine.
You can switcheable boost for £10, just buy a cosworth amal valve, it is a solanoid which switches between high and low boost. All manufactures use
something simiar, the wastegate is set to a low pressure and the ecu controls the solanoid that can increase it. Its a safety ,measure so the ecu can
reduce the boost to prevent pinking if the engine runs hot etc.
sorry ivan, didnt read your post until after i had posted.
quote:
Originally posted by Antnicuk
i'd have a read up on how turbos work, at cruise with no load they are not using anymore fuel than a N/A engine.
But it may as well be true for the OP's situation. Cruising in traffic off-boost it is true to say that removing the idling turbo from the
system will give negligable mpg gains. That's because the mpg damage is done, as you say, by the relatively low CR of his turbo engine, not the
presence of the turbo. What he really wants is an adjustable CR button - not really an option!
liam
What's CR?
quote:
Originally posted by Ninehigh
What's CR?
Here's an interesting idea of using a small turbo (quick spool, no nasty power surge mid corner, higher CR possible) to boost torque at low revs
with minimal engine changes required.
http://autospeed.com/cms/A_111106/article.html
While it's a waste of time according to the big bhp is better pub debates, but as the adage goes torque wins races. Would certainly make a peaky
engine much more tractable on the road. Small turbos cost peanuts relatively as they're the ones replaced by people seeking big bhp. Might well
suit a BEC.
I'm still undecided...
[Edited on 20/4/09 by iank]
I've always said peak bhp figures are only relevant if you constantly drive round at 5000rpm, where torque is the real shove you need.
I read something about low pressure turbos in Saabs and that looks like a really good idea, especially if I don't have to do much engine
fettling!
Give prodrive a call, they may sell you a variable CR engine. I'm guessing it cost a couple of quid like, but maybe.
Oh I've got a brilliant deal on an engine already. 1.8 BMW unit, cost? I got to wait until he's broken the car apart and I have to let him help me build it!