3.3 turbo mods
 

A friend of mine has a 3.3 turbo with a bad cylinder so a rebuild is planned. He wants to bump the displacement to 3.5. What are the ramifications of this change? What sort of fuel injection changes will be needed?

i dont think you will need to do much at all if its JUST an increase in displcement. Perhaps you could have your metering head played with to supply slightly more fuel across the range

It is my understanding that a 3.5 requires the case spigots to be bored out for the larger cylinders, 3.4 are a bolt on.

Thanks guys. I can deal with machine work to get the larger P&C's to fit. My real concern are mods needed to the fuel delivery system. Do you have an experience on what needs to be done that this system when you go to 3.5?

"adomakin": Do you know if the modifications to the metering head are tuning adjustments or does it need to be rebuilt?

Nothing (as long as you don't plan to increase the boost).

CIS doesn't know what it sits on, it is just metering the air. 2L or 4L, it doesn't give a damn, as long as airflow is within it's margins.

In general, that's true. However, you must verify that the car is not running lean at idle and/or max RPM, otherwise you can damage the engine significantly...

-Wayne

Volume bump from 3.3 to 3.5 while retaining original boost level will keep air flow well within same envelope. 3.5L bump is moving exactly as much air as stock 3.3L boosting 0.1 bar extra ;) CIS will provide fuel for roughly 1.0 bar w/o problem so I'm quite confident that his fuel system is up to task....

Yes, it's always good to verify that car is not running lean (and has enough oil in the engine and no flat tires), but in this case it's probably unecessary for any other reson but pure functionality check after he reassembles engine back (in case he bumped something).

IMHO, paying premium to bump volume to 3.5 is not worth it. 0.1 bar of boost is worth as much as that .2L volume bump...more volume is of course better (lower spoolup, less revs, more torque) so it's a matter of money.

CIS will be OK with 3.5L and up to roughly 0.9 bar of boost...

3.5L and 0.9 bar -> 350-360hp on ROW 930...42lb/min mass flow.

The cylinders are already getting thin at 3.4. For a turbo engine I wouldn't go any bigger. You can buy JE pistons and get your cylinders bored and plated, which will save a bit over new P&Cs.

Tell your friend to dump the CIS and go for EFI.

Dean