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914World.com _ 914World Garage _ Pitch the pistons?

Posted by: tumamilhem Jan 9 2013, 02:48 PM

I have a 1974 2.0 engine. I understand replacing the 94mm stock pistons to 96mm pistons will add an additional 80 cc or so to 2056 cc. Is this correct? And if so, would I need to make any changes to the mechanics to make the system run properly, fuel injection for example? Or will everything run efficiently as is if the larger pistons are installed? Looking to increase power while keeping the engine.

Thanks in advance for your input!

Posted by: Cupomeat Jan 9 2013, 03:01 PM

Lots of people go to the 96mm bore to give them a little more displacement and power. SO, what is needed;

1. Obviously the correctly done installation of pistons and cylinder, with a little of "fix it while you are in there" may lead to having the heads rebuilt or other. Take the time to do it right otherwise you may chase your tail as to the cause of any problems you may have.

2. Compression ratio - You'll need to properly measure your combustion chamber size, in order to get the right compression ratio. Some say that about 8.5 to 1 is all you should ever hope for (or lower) without other work.

3. Induction, although it is only about a 5% increase in displacement, you should plan to verify your air fuel ratio and take whatever steps are needed to bring it back to stock. As I believe you have stock D-Jet (for a 2.0l) you will have to figure out how you want to do that. SOme of the D-Jets had a "mixture" knob on the controller, but I think that was no longer provided on the 74 2.0.

People have quoted an honest 115hp (with D-Jet) from a 2056cc that was built properly, so that should be a fun little powerplant.

Posted by: rhodyguy Jan 9 2013, 03:12 PM

as above. it's about everything else except the the displacement increase. not an install and go deal. start adding 0s.

Posted by: tumamilhem Jan 9 2013, 09:29 PM

About what would it cost to have this done (properly) the first time?

I'll need to make a list of what the mechanic needs to do so nothing is missed or overlooked. So according to the 3 things above, those are all I need to have done in that detail?

Thanks for your input, guys!