computer controlled turbo technology

[Ken Keith]

Hi Ameer,

Thanks for the response.

So, if MC's are optimized for what they have to work with, how 
come the 1.8t's are supposed to be so much better?  No lag, 
"elephant's back" power curve, etc.

How are these characteristics achieved, and can they be achieved 
with an MC?  It's okay if I don't understand this right away, it's just 
a question I've been thinking of.

I was at the VW dealer, checking out the screws I should have 
bought for my Passat cupholder, and I saw a Jetta 1.8t taking off 
on a test drive.  I could hear the whine of the turbo (that's bad, isn't 
it?), and it took off nicely.  I tried not to think about it.  It looked like 
alot of fun.

Thanks,

Ken

On 23 Jan 2001, at 16:06, Ameer Antar wrote:

> Most aftermarket boost controllers do what your talking
> about...different boost levels, precise control. Apexi AVC is nice,
> but expensive, and isn't a complete package for the 5kt's. You use the
> supplied valve on the wastegate, but you also need something to
> control the boost going to the ECU to stop fuel shutdown.
> 
> Also, you don't want to have more boost at low rpm's, b/c at low rpm,
> the volumetric efficiency of the engine is high [means engine takes
> actually takes in 95%+ of spec 2.266L. This extra efficiency makes the
> effective compression very high...risking detonation. Volumetric
> efficiency goes down at high rpm...maybe 75-80% at 5 grand. It's ok to
> add more boost in that range. If you even look at the boost map on the
> stock 5kT ECU's, the boost is set lower at 1k rpm at about 1.04bar. At
> 5 grand, it's up to 1.42bar. This is right from SJM. Not only that,
> it's really hard to get full boost at 1500 rpm...
> 
> -ameer
> 
> At 01:05 PM 1/23/2001 , you wrote:
> >Hey all,
> >
> >Why is it that the new 1.8t ECU has so much control over the
> >boost?  If MC motors also have the WGFV and such, what is the
> >difference that allows so much more control on the new 1.8t?
> >
> >Is it just the resolution and processing power of the newer ECU?
> >
> >I wonder if someone could make up an interface that controls the
> >stock MC parameters that the ECU does, but allow for more control,
> >like an overboost function or higher boost at lower rpms like the
> >1.8t.  Maybe something running off a laptop or something.
> >
> >Then you could add on other things that came about later one, like an
> >elevation sensor (or ambient air pressure sensor).
> >
> >I guess for the trouble, one would go for a stand alone ignition
> >system.  But even those don't control boost, do they?
> >
> >Does Eric's EFI'ed Max Q retain the stock computer to control
> >boost?  What controls boost when one goes to EFI?
> >
> >Thanks,
> >
> >Ken
> 
>