The Scat (what a name!) catalog has a 103 mm big bore kit for the 914. Could I use these pistons & cylinders with my 2.0 case without any machining? What kind of hp and torque curves would this combination produce with a street cam optimized for mid-range power and torque? If it's well balanced, it should be a free-revver considering the stock stroke is retained, no? Btw, what are some of the bore/stroke numbers for the flat-six motors?

Thanks

That is a lot of questions!
1. 103's require case and head machining.
2. HP? easy question-many answers.
3. Yes
4. Don't know

I wonder what kind of engine dyno simulation software Jake Raby uses - it would be interesting to plug some numbers in and see the corresponding hp and torque curves. A few years ago, I read about the software that BMW bought for designing their engines - I wonder if it's dropped in price in the mean time. (IMG:style_emoticons/default/laugh.gif)

here's the answer to the last Q:

http://www.pelicanparts.com/911/technical_...hassis_info.htm

Going with a bore that big and a cast iron cylinder is asking for trouble....Some of this trouble is:

Head leaks- those darn out of round non square cylinders leak like a sieve and need 5-6 studs to keep from it...

Oil temperatures- The bore size is increased 9mm over stock thats a whopping .360 about 3/8 of an inch!! Cooling that oil takes alot of work..

Head studs- the TIV has a non square stud pattern, it does not like a huge bore......Also the studs are 2 different lengths from top to bottom, and that makes for uneven expansion rates...uneven expansion warps the cylinder and even the heads and starts head leaks!

heads- After you get them sealed off, you have to flow the air that a piston that big can move....not happening cheaply or easily!

I felt so strongly and had so many problems with those pistons (actually anything over 100mm) that I REFUSE to use them any further. Every 100mm+ bored engine I build gets LN Engineering Nickies, or I won't put my serial # on it...simply too risky!

alot of guys disagree with this, and thats fine....I can make 180 ponies from a 96mm bored engine with some stroke and correct cam and head selection and do so for 80-100K miles....I have seen 103s last 10% of that time before they have a head leak or worse.

They are simply not needed, and until we correct some issues with cylinder heads and borespacing, they are a simple waste of money.(in my opinion)

As for my software, I use Engine Analyzer Pro, coupled with old fashioned trial and error...

Thanks for the great information, Jake. I've decided that I'm going to just rebuild my 2.0 to stock specs (using the Euro pistons and cylinders) and build, or buy, a big-four sometime in the future. I'm going to do a web search for the software now but I'll probably get "sticker shock".

For anyone who's interested, you can download and try a demo version (beta) of the latest Engine Analyzer Pro software but you have to phone Performance Trends and ask for an unlocking code everytime you want to use it.