[alfa] Turbos

[Eric Storhok <alfa@xxxxxxxxx>]

Ben
Having gone through the turbo installation once, I'll try to answer your 
questions:

1) Size of turbo- Garrett T3, or Mitsubishi off an Eclipse, which I think 
is a TD04 16G.  I have a turbo map from a few MHI turbos- they are quite 
nice.  Garrett is over rated, I think.  Size does matter- if you can find a 
compressor map, then you can make sure that your peak air flow, pressure 
ratio...  are correct for your car.

2) 3K-Warner are the best, Mitsubishi are a close second, Garrett- third, 
and IHI last.  Dealt with them all at work.

3) If you want serious power- you'll need EFI.  Not only to properly and 
consistently deliver fuel, but just as importantly, control the 
spark.  Once you get past a few psi of boost, you need the control.  We use 
Electromotive, but there are quite a few options out there....  For the 
most part, you'll be fine with a single set of injectors- with modified 
injectors, one can easily get 70 lb/hr, which will be enough for a LOT of 
air flow.  For an intake manifold, you can use a manifold from a Bosch 
injected Spider- you'll have to cut some pockets in the head for the 
injectors, AND you have to make something to hold the manifold together 
other than the rubber tubes as the boost will push it apart (ours did it a 
couple of times....).  Carbs + turbos are not a good combination.

4)  Hopefully you can see this picture: 
http://photos.groups.yahoo.com/group/alfa2002k/vwp?.dir=/&.src=gr&.dnm=All+Done!+Engine.jpg&.view=t&.done=http%3a//photos.groups.yahoo.com/group/alfa2002k/lst%3f%26.dir=/%26.src=gr%26.view=t

but you can use an air to water intercooler.  We used one from a Toyota 
Celica All Track, which fits perfectly on top of the engine....  It's 
cooling radiator is much smaller, and will easily fit in front of the main 
radiator.  If you are only looking at up to 7psi, you probably don't need 
an intercooler.  But beyond that, you'll need one.

5) Qutie a few turbos have both wastegates and blow off valves integrated 
into the housings, especially the Mitsubishi's.  Once you get that part 
figured out, then we can talk about modifying the system to get more 
boost.  Most modern turbos have pretty modest base boost pressure settings, 
and allow a computer control it via a vacuum solenoid.  The blow off valve 
is a must- it will keep the compressor from stalling on closing the valve, 
which also helps its durability.

6) 8:1 is a safe compression ratio.  For our car, we machined the pistons 
from 9:1 to 8:1, but that is because we has a very tight budget.  There are 
low compression pistons available for Alfas, in the US, Paul Spruell sells 
low compression pistons, and I would bet that Bennica does as well.

7) Things that you will HAVE to do- drill holes in the engine to: 1) supply 
oil to turbo, 2) drain oil from turbo, 3) supply collant to turbo, 4) 
return coolant from turbo.  After that, since you already have forged low 
compression pistons- better rods help, lighter flywheel wont hurt...  all 
the basics.  You WILL have cooling problems unless you make the radiator 
bigger.

8) 200-250 hp would be easy.  Much more than that, and other things will 
start breaking, and you'll need to beef up things to make them 
survive.  From what I hear, the transaxle will take about 300hp before 
regularly breaking things.  400hp- that will require a lot of structural 
work on the block.  More than that- well the 700hp that Bennica reportedly 
makes would cost a fortune- I mean a HUGE fortune.  I'm working with a 
group who wants 500hp, and it's a pain- our previous 400hp engine failed in 
a rather spectacular manner on the Salt Flats.  I think our turbo spider 
makes somewhere north of 200hp at 13psi.  We are going to swap the cams, 
and run the boost to 15-16 psi, and hope for <14 sec 1/4 miles.

9) if you go with EFI, then you can keep the catalyst, and keep it operating.

If you don't can't see the pictures- I'll mail them to you 
directly.   Nothing to criticize, while I love the normally aspirated 
Alfas, our turbo is a major kick in the rear to drive- it is a ROCKET.

Eric Storhok
Ann Arbor, MI, USA

AROC Detroit Homepage:  http://www-personal.umich.edu/~alfa/index.htm
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