To supercharge a 3A or not?

[nocones77-vw at yahoo.com (nocones77-vw@yahoo.com)]

I agree with Dan on this one. 

If you have the money, I'd go with the forged pistons. For reference, mine are JE pistons that have the piston crown shape similar to the PG (Corrado G60) pistons, but have a shortened skirt to run 144mm rods instead of the PG's short 136mm rods. IIRC, they cost somewhere around the $500-$600 range.

The forged pistons will not only be easier to tune due to not messing up the combustion chamber shape, but they'll also be much more resiliant to detonation that would melt cast pistons, so you're less likely to blow things up if you make a mistake in tuning. I believe that that $500 investment has re-couped itself several times over as I went through the process of building this car. I've made some really bone-headed mistakes that probably would have killed the engine, but I think the pistons saved the day. And they'll handle more boost than the Lysholm can ever dish out.

But if you're careful about tuning and don't go too crazy with the pulley, stacked headgaskets will work fine as a starting point.

For the record, 10:1 compression isn't impossible to supercharge. And you can run higher boost ranges with it too, but it is just really sensitive to detonation so you have much less room for error in the tuning or issues like bad fuel. My setup is supposed to be somewhere between 9:1 and 9.5:1, but I've never measured it myself.

And I believe you've already said you're going to do it, but don't even bother building this thing if you don't plan to intercool it (and do it well). IMHO, that's like buying a $15k diamond ring and then being unwilling to pay to have it sized for her finger. A big waste of time/money/energy...

Neal

----- Original Message ----
From: Dan Bubb <jdbubb@verizon.net>
To: Phil Boeye <rocco_phil@yahoo.com>; Scirocco List <scirocco-l@scirocco.org>
Sent: Monday, April 3, 2006 10:14:50 AM
Subject: Re: To supercharge a 3A or not?

Well, right off, your engine's 10:1 CR or thereabouts.
So, that will limit how much boost you can run. Not sure what the limit is, maybe 5-7 psi, and that may be all the car can reasonably handle unless you're running really sticky autocross tires.
Two ways to lower the CR are stacking headgaskets or getting a custom thicker headgasket or installing forged pistons. Either headgasket solution will compromise your combustion chamber shape somewhat although plenty of people do it.
Forged pistons are ~$570 + the cost of boring the block and other miscellaneous costs.
Other than that, just getting everything in good shape should suffice.
Dan

From: "Phil Boeye" <rocco_phil@yahoo.com>
Sent: Monday, April 03, 2006 9:26 AM
Subject: To supercharge a 3A or not?


> So I have this nice 3A/JH (Eurospec) motor and I would
> like to fun F/I for autocross.  I am thinking
> supercharging as I want the instant throttle response.
> Plus, I have a new Lysholm charger.  :)
> 
> What exactly would have to be done to the 3A block
> (25k miles) and Eurospec JH head?  I might add I also
> have the obligatory p&p'd intake and Neuspeed TB along
> w/ a Euro dizzy.  As well as all the makings for a
> Digifant I conversion.
> 
> Kind of curious, because I think the motor is worth
> more to me in potential upgrade value than what I
> could get for it.  IOW, the money it would cost to get
> a new setup would be quite a bit more than I could
> recoup on a sale of this motor.  So I'd like to
> optimize for power if possible.
> 
> -Phil
> 
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