RE: Power loss at>4800 rpm

[HAREST@allenbrook.iix.com]

Another solution for that TAP supplied generic SAMCO hose is to swap over to
an 85 turbo throttle body.  Same function etc, just round instead of
teardrop shaped...

-Stott

> -----Original Message-----
> From:	Colin Barfoot [SMTP:colin_barfoot@email.msn.com]
> Sent:	Monday, May 11, 1998 8:10 PM
> To:	Paul.J.Timmerman@jpl.nasa.gov; QUATTRO@coimbra.ans.net; Orin Eman
> Subject:	Re: Power loss at>4800 rpm
> 
> To recap I had a problem when running with boost levels greater than 10
> psig
> where under full throttle I would acclerate hard to 4800 then accleration
> would stop, while boost would stay the same, whether set to 10 or 16
> psig(via SK(r)).
> I checked the standard advice - full throttle switch -OK, vacuum and boost
> hoses OK, timing, spark plugs OK, oxygen sensor OK no improvement found. I
> even tried making the fuel mixture a bit richer (so that the tailpipe
> carboned up) but to no avail.  Data point is the car would top out at 200
> kph (123 mph) up hill or down hill
> 
> Then by chance on Christmas eve my starter failed - fixed it followed by
> the
> alternator failing on the way home from work at 9:00 PM boxing day, with
> the
> new starter a ground fault was fixed and the combination of more voltage
> and
> charging circuit ground removed improved things probably 50% so that while
> acceleration slowed still it didn't stop and would eventually pick up - a
> little above 5500 RPM Data point - top speed  now 205 - 210 kph.
> 
> Solution 1: ensure full voltage is available.
> 
> The next thing that I did was to have the VW dealer have the fuel
> injection
> set up to stock, i.e I leaned out the mixture quite a bit until it was
> juct
> a couple of degrees richer than stock.   Things were then much improved so
> that there is now only a bit of a reduction in acceleration at around 5000
> rpm, after which it picks up strongly again.
> 
> Solution 2: don't run too rich run just a couple of degrees above spec for
> best power.
> 
> The next problem was that the TAP silicone hose kept blowing off at the
> "cam
> shaped" lower intake manifold point, it seems that while it wasn't cut
> perfectly it stayed on fine for almost a year,but now seems to have
> stretched so that at about 10 psig the stretch was enough to pull the hose
> off, this also worked to limit power - top speed (up ~ 15  degree hill 200
> kph)
> 
> Solution 3 used two clamps, one on the hose adjacent to the throttle body
> to
> compress the hose against the manifold and prevent it from stretching and
> deforming where it sould pull the hose off the second clamp - arranges so
> that the slots (for the wrom gear) dig into the hose as close as possible
> tothe cam point on the manifold.
> Data point - still accelerating strong at 235 kph (had to slow for
> turnoff)
> 
> Now, I am enjoying the power without worrying about the slowdown when
> passing at 4800 rpm.
> 
> Hope this helps
> 
> Regards,
> Colin
> 86 5000 CD Quattro 325,000 km
> 
> PS Clarke P. congratson your 86 Quattro - will you have it out for the
> regional slalom championship?
> 
> 
> 
> 
>