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Re: [T3] Questions about engine size and improving torque


On 16 Apr 2004 at 15:41, Roush, Norman wrote:

> I am considering the following
> combinations of crank and PCs:
> 
> Crank		PCs		Displacement
> 69mm 		88mm		1678
> 69mm		90.5mm		1775
> 74mm		88mm		1800

Bore is a lot cheaper than stroke. Berg has some max recommendations for type 3 
engines, but I don't know what this is actually based on. I think he says heat, 
but he doesn't make his reasoning clear.

> The 1678 and 1775 may need an increase in fuel pressure and the 1800 may
> need an increase in fuel pressure and larger injectors.  I would be
> using these components:
> 
> Counterweighted 8 dowel crank
> Std heads but with some mild porting and polishing 3 angle valve job
> Std cam
> Std rods
> Verified good used case
> Std weight 8 dowel flywheel
> Full flow oil system
> All moving parts dynamically balanced

As long as you're not planning to drag race and pop the clutch, and are going 
to use a standard flywheel, you really don't need the extra 4 dowels. I like 
the idea of the longer dowels, though, so I switch to those. I had to modify a 
reamer to do this, however.

Get Berg's head porting white paper and follow it thru. Good head work is 
virtually free HP. Better breathing would also require a small increase in fuel 
pressure, and I think you should be able to use the stock injectors thruout the 
range you're considering here.

Make sure you have the B brain for your FI. My 68 was a VERY nice car with a CW 
crank, balanced driveline, ported heads, and full flow filter.  

> I would really appreciate you ideas about these possibilities as well as
> suggestions for compression ratios. 

Consider what you want to use for fuel. That pretty much determines the CR you 
can tolerate.

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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