What are the cons? 3.0 case w/ 3.2 crank rods P's&C's

[peon77]

I bought a half complete basket case 3.0 engine. I want to build the engine on a tight budget with good used parts whenever possible. I have a good 3.0 crank but I'll have to buy rods and P's&C's. I know that there is no replacement for displacement, so I think using the rotating assy from a 3.2 is my best bet for cheap HP. Am I correct? Is it a straight forward drop in and go, or are there details I need to be aware of with this modification? What are the forum suggestions?

P.S. I know about the 3.2 rod bolt problems.

Thanks
Pete

[john walker's workshop]

same basic case as a 3.2, so no problem. early 3.0 carrera and turbo cases are different, using a 2.7 crank and rods.

[peon77]

Is there any issues mixing 3.2 pistons with the SC Nikasil cylinders?

[ChrisBennet]

Originally Posted by peon77

I bought a half complete basket case 3.0 engine. I want to build the engine on a tight budget with good used parts whenever possible. I have a good 3.0 crank but I'll have to buy rods and P's&C's. I know that there is no replacement for displacement, so I think using the rotating assy from a 3.2 is my best bet for cheap HP. Am I correct? Is it a straight forward drop in and go, or are there details I need to be aware of with this modification? What are the forum suggestions?

P.S. I know about the 3.2 rod bolt problems.

Thanks
Pete

The 3.2 gets its displacement increase from the crank (longer stroke). If you are using your 3.0 crank, there aren't any "budget" displacement increases that I know of.
Your cheapest solution is used 3.0L rods+pistons+cylinders.

Some data points:
- 3.2 rods won't fit on a 3.0 crank - different rod journal size.
- Both 3.2 and 3.0 have the same bore - 95mm.
- 3.0 pistons have a different wrist pin size than 3.2 pistons
- Pistons come in 4 different diameters and I forget how many different weights so mixing and matching isn't practical - buy 6 P&C's as a matched set.
- Cylinders come in 2 different heights
- To get a 3.2 from a 3.0, the usual path is to use 98mm P&C's. The resultant combination is called a 3.2 short stroke.

[snbush67]

Originally Posted by peon77

Is there any issues mixing 3.2 pistons with the SC Nikasil cylinders?

No problem in the cylinders but I think the pin spacing is different than the 3.0's so you may have some height issues.

I have a complete set of SC 3.0 matched pistons and cylinders from a running car. Cheap! PM me if you are interested.

Shane

[haycait911]

I'm building the same engine. 3.0 case, 3.2 crank/rods, JE pistons, webers. I'm all about the torque, the 3.2 'stroker' as opposed to a 3.2 'short stroke' should help me out with that. current engine..............

3.0 dyno day - a pleasant surprise

[peon77]

The 3.2 gets its displacement increase from the crank (longer stroke). If you are using your 3.0 crank, there aren't any "budget" displacement increases that I know of.
Your cheapest solution is used 3.0L rods+pistons+cylinders.

If I were to sell the 3.0 crank, I think I could buy a 3.2 crank for about the same money. 3.2 rods seem to be more plentiful than 3.0 rods, then Id just need to find the 3.2 P's&C's. Looking at the classifieds it seems to me that there are allot of used 3.2 P's&C's that are out of spec. Which are easier to find, good 3.0 or 3.2 P's&C's?

Don,
If I build a 3.0 I will do what you did on yours, it is quite remarkable.

[KTL]

You'll want to do some research in the engine rebuild forum. Lots of good information in there. I know Henry Schmidt is a big fan of the 3.0 rods. I recall reading recently that he believes resized 3.0 rods are the way to go in lieu of using the 3.2 rods. It's not just because of the better/larger bolt size. It's the rodl ength/stroke ratio.

Agreed its not easy nor cheap to mix & match 3.0 & 3.2 parts due to the different aforementioned dimensional issues. But it can be done. In terms of doing it on a tight budget, mixing and matching is clearly not the way to go.

Used, useable condition 3.0 rods can be found for a good price. Might as well stick with those. Same goes for 3.0 pistons that people have dumped to do a 3.2 or greater short stroke. 3.2 cranks are for some reason much more expensive than 3.0. That bucks your budget again right there. But as Henry has pointed out, the 3.2 pistons and cyls are cheaper and better to acheive an improved rod length to stroke ratio

Offset Connecting Rod Bushings?

Can I use 95mm 3.2 (84-89) cylinders on my 78 sc 3.0 motor

[haycait911]

budget-wise, build the 3.0. you'll pay more for a 3.2 crank than you can get for your 3.0. the increase of .2 displacement will cost you a fair bit. 3.0 parts and goodies are plentiful and not expensive. my approach to a budget-build, like my 3.0 is this.

buy and put together everything you'll be using, except cams. look for deals and be a little flexible. once you have your main components together, call John at camgrinder. tell him what you have and what kind of power you want.

Dougherty Racing Cams - my experience


cams are the 'heart' of an engine.

three things are key.

1. pistons to match your induction.

2. cams to make the kind of power and torque you want, where you want it in the rpm range.

3. a dizzy to match your cams.


please note: all above info/advice is worth exactly what it cost the rebuild forum is a good resource. not as much traffic as here but more specific, it helped me immensely.