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Ur-Q engine mod questions...
Although I don't really have the budget to complete the 2.5L engine I started
putting together for my Ur-q earlier this year - buying a new house will do
that to you! -- circumstances are such that I now need to either get it back
on the road within the next 90 days or so, or start looking for another car
for my girlfriend to drive to work since we won't be able to carpool too much
Fortunately, thanks to the magic of credit, I can scrape together the
necessary funds to accomplish either one but since Paula really likes my '89
200q and I'm coming to the conclusion that my once-mint Ur-q isn't so mint
after all, I'm leaning toward popping for a new motor rather than a new car
(I've already ruled out just replacing the head that cracked ... if I'm going
to all this trouble, I don't want to be doing it again it in a few years).
I've got most of the details sorted out except one: What compression ratio
should I run? Part of me says to keep it low so I can pile on the boost (the
additional 400cc of displacement should be able to overcome much of the turbo
lag that's so annoying with these cars) but another part of me is intrigued by
the idea of running high-compression motor and low boost ... put another way,
the choice is between a 7:1 CR and 16-18psi of boost or 10:1 CR and 5-7psi.
I'll be using an RS2 comp turbo, OEM two-piece manifold and 3" downpipe and
exhaust, and if everything works out, I'll eventually go to an EFI system but
at least initially, I'll be using the OEM C.I.S. setup.
Does anyone have any experience with either of these approaches? My primary
concern is being able to run pump gas -- around here, the best I can get is 92
octane -- but I'm willing to run an octane booster, if absolutely necessary.
I'm sure there are a few serious engine-builder types out there and I'm open
to any advice they have for me...
Jeff Goggin (still using a work account!)