Hey everybody, I'm a newbie and appreciate any info... I am rebuilding what I believe to be a 2.0 type IV.
( just purchased a 1972 914 2.0 type IV, as a project car)(obviously not an original motor)
One of the piston cylinders is shot so I am looking on ebay at buying a new set of pistons and cylindes. The pistons and cylinders I have right now are 96mm. (which I found a replacement set) But my delima is that I also found a set of 104mm. my question is ... they are both a 71mm stroke can I maybe slam in the 104mm set and be ok. Will I need to change anything with the cam or valves? And most importantly is it really going to be worth the hassle vs getting more performance.
The motor has a set of two dual webber carbs and n ice oil cooler etc. I would really like to get some screaming performance out of this motor , so any suggestions would be cool. I am also looking to put a six cylinder in it later as well. But I figure I will run on this little guy until then and see how it does.

thanks!!!!

The case would need modified to accept the larger bore cylinders. I'll let the experts on the board take over from there...

Hey, be truly progressive in size! Use a set of 6 1/2 inch bore piston cylinder assemblies from a Continental TSIO 520 aircraft engine!!

Talk about torque!!

Stick to the 96s - that will give you a nice healthy, reliable 2056cc engine. If you want more later, you could build a big type 4, 2270 on up, but realize that when you go above a 96mm bore, the cast iron cylinders are no good. You also didn't mention if you were going to keep the stock fi - anything really larger than a 2056 requires drastic changes. If you want larger bores, Nickies are a way to go. Do a search for any of the following terms and you'll find lots of info - "nickies", "big type 4", "2270", "2056", just to name a few. Another good place to start to see what's available for the type 4 is type4store.com, as far as cams, heads, etc.

Yes, a 2270 utilizes a 96mm bore and with heads and matched cam, can be made reliable in a 2270, as Jake has done, especially when coupled with a DTM. I was just trying to get the point across that regardless of stroke, not to use any cast iron cylinder larger than 96mm - that's all. Nickies will help any engine, but are most definately not necessary on one of Jake's 2270s.

If you can't afford 2K worth of head work to properly fill those bores along with a proper cam the 104 bore will MAKE LESS NET POWER than a more efficently configureed, easier to buil, longer lasting, cooler running 96mm bored engine.
BIGGER IS NOT BETTER!!!!!

HMMMMMM...sounds like the 104mm is going to be more trouble than its worth, so next question would be where do I start if I want more horse power with what I got? Motor already has a beatful set of webber dual carbs....(came with) It was a running car at some point so I am going to assume that it has the right cam for the carb set up. So where should I start next?

Listen to a couple of Jake's radio programs. The content will assist you in all your rebuild questions. Follow the link on his signature.

-pt

Don't assume your cam is the correct one for carbs. Lots of people and mechanics had a hard time with the FI and swapped over to carbs. That doesn't necessarily meant they tore down the whole engine to replace the camshaft at that time, a stock cam and carbs do work together, although not all that well.

Don't spend a dime.
Research for 6 months and then weigh the options.

I have 22,000+ posts on the subject at www.shoptalkforums.com I have nearly another 5,000 here and almost 200 on my new forums that just opened last week.
Utilize the search functions on all these sites and then look to Google to do the rest..
Then isten to ALL my Radio shows..

I try my hardest to help people build these engines smarter, not larger. You'll find that due to this I put most of my enthusiasm into the 96mm bore, the result has been 50 HP per cylinder of output with no loss in reliability or longevity...

ok , your right, lots of research to do. I would be very happy with 50 horse per cylinder. I thank all of you for your input.