JT turbo: 3000 mile update

[Michael Gough]

Hello list,
About a week ago, my JT turbo conversion passed the 3000 mile mark. For the
most part, it is completely reliable and the power is incredible. The
orriginal writeup can be found over at
http://www.metrocomputing.net/gtworld/members/0005/mgough2.htm

That writeup contains all the information from initial conversion. Since
then I've changed a few things.
1. The intercooler- the stock 5kt unit I was using is CRAP. It is a double
pass, and very inefficient. The new intercooler I'm using is from a 2.2
Shelby Dodge turbo. It is a very good intercooler. It is about the same size
as the Audi unit, but it is single pass, and has much larger tubes with huge
amounts of internal fining. I have it mounted in front of the radiator, and
I have a switch so I can turn the rad fan on high if I want even more
cooling from it. Soon I will install a dedicated fan just for the IC so that
I can run it all the time. It is really neat after a hard drive to touch the
inlet side of the IC and nearly be burned, and then to touch the outlet side
of it and feel that it is cold.
2. Vac advance/boost retard canister on the distributor- When I first did
the conversion, it knocked (I have a knock light) at around 6psi with 6°BTDC
initial advance (at idle). I retarded it all the way down to 3°BTDC initial.
Even with this timing, it would still knock sometimes, usually in 3rd gear
after the IC got heated up enough to be useless (see #1 above) When I
installed the better intercooler, I also installed a vac advance/ boost
retard canister from an '82 5kt (It's really a vac advance/vac retard, but
since it travels both ways, hooking up one line will make it advance in vac
and retard in boost). With this canister on the distributor, I am able to
set the initial advance at idle to 8°BTDC and I have no knocking at all at
8psi of boost. I have yet to expirement with more timing, 8° is as much as
I've gone so far.
I still haven't replaced the very small downpipe. I have a large downpipe to
install when I get around to it. Right now it pulls with authority to about
4500RPM, and continues pulling harder than stock (naturally aspirated) to
about 5000RPM where it just falls flat on its face.
The fuel system seems to be working out OK. Between the extra injector, and
never reving past 5000rpm, it doesn't lean out (with 8psi)
That's all for now, I'm working on EFI right now. I'm collecting the
injectors, harness and making a rail. I am planning on starting the EFI
project around the beginning of the year.
I was hoping I would have some 1/4 mile times by now, but I still haven't
fixed the cracked windshield :( so the track won't let me race. I'll have
some numbers (1/4 mile time and trap speed and 0-60) on it before I convert
to EFI.
That's all for now I think, email me if you're currious about anything
Mike