Turn stock 620 cylinders or buy 750 cylinders for FBF Big Bore Kit

Started by csorin, March 08, 2011, 12:59:05 PM

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csorin

Hey guys,

I'm interested in the Fast by Ferracci 750 high comp pistons for my 2004 620ie.  It seems there are two options:

1.  Send your cylinders to FBF to get turned for ~400 bucks
2.  Source some 750 barrels for ~150 bucks

The latter would definitely be the more frugal route, but I'm worried about some possible pitfalls.  Could the 750 barrels be scored?  Wrong diameter?  Just plain worn out?

Another question for this kit:

Can I use my 620's stock ECU?  What kind of 'tuning' is involved to get this running smooth?  Re-mapped ECU?  PCIII? 

I've read all about engine replacement being the smarter route, but on the other hand, many swear by the larger pistons.  Not having to drop the entire engine, source new headers, ECU, wiring harness, possibly clutch, respring for the new weight, etc leads me to the simpler solution.

Speeddog

Possible pitfalls, but no FHE:

750 cylinder spigot may be too big for the 620 cases.

You may end up with really high compression using 750 high comps with 620 heads.
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csorin

Here's the kit I'm looking at:
http://www.ferracci.com/store/cart.php?m=product_detail&p=749

Compression is either 10.8:1 or 12.0:1.

I've read on here and the older forum of folks sourcing cylinders from 750's (possibly 800's as well).  No one mentioned problems with the two mating up.  Again, my concern would be buying a used cylinder and finding that it needs to be refinished.  If sending my cylinders to Ferracci for boring and replating at 400 bucks is the safe, reliable way to go, I might just pony up the cash.


brad black

from memory, pre 2002 750 cylinders will be different at the oil gallery at the RHR and the locating dowel is 45 deg or so off centre, not on the LH side.  get 800 ones and they should be fine.
Brad The Bike Boy

http://www.bikeboy.org

csorin

What kind of 'tuning' am I looking at?  Reflash ECU?  PCIII?  Just reuse the 620 map and go?

As for the cylinders, I found a couple on ebay for $250.  What am I gaining, if anything, by spending $150 more at FBF to turn my 620 cylinders?