How's this engine combo idea.....
 

Hey Folks
I was just pondering stuff, and wonder what y'all's thoughts were for a 2.0 build:
stock crank and rods
100mm pistons
bored stock cylinders
40idf webers
mallory dizz-izzle
some sort of large cam, what do you recommend/have exp.with?
all pieces balanced and rods/pistons matched

Anyone do this formula, does it make sense, estimate for HP, blahblahblah. Local race shop for machine work, and assy myself. It seems this would work reasonably well, and gain a bit over 100hp, but then again I'm not the biggest brain in the box. Or sharpest knife in the drawer. Or..........

Cheerio
Jeff

Ah, you might be gettin' a bit thin on the boring out of stock cylinders from 94 to 100 (don't even know if there is that much meat in them). If there is, you may really effect cylinder stability and heat transfer.

You can make 100 HP easily with the stock displacement. Carbs, cam, and compression will take you over. A little head work and a good exhaust will put you well and truly over.

Don't go over 96mm on stock cylinders (the 93s from the 1.8 or the 94s from the 2.0 only, please!) or the walls get rather thin.

A 2056cc (96mm bore, stock 71mm stroke) can pretty easily make 125 HP with the right cam and compression. And yes, carbs to deal with the cam. Or aftermarket EFI.

--DD

I have a Set of Scat 100mm pistons and Cylinders If you need a set. Steve

Wow......

That combo needs some work...

Howdy Jake,
Whaddya dink? What's it need/not need in your opinion?

Dave, how do you measure the stoke?

It's the distance that the piston travels from "full up" to "full down". If the engine is together, measure down the cylidner to the piston top when the piston is at TDC, then rotate the crank until the piston is all the way down at BDC and measure down the cylinder again. The difference is the stroke.

If you have a crank sitting on the bench, then set it against the edge of the bench. Measure the distance from the edge of the bench to the near edge of the rod journal closest to the edge. Then measure the distance from the edge to the near edge of the rod journal that is farthest from the edge. Yes, make sure the crank is lined up as parallel to the edge of the bench as you can. The difference between the two measurements is the stroke.

--DD

I think the engine configuration you've chosen so far is going to explode into tiny, oily, metallic pieces. I totally agree with Dave on this one. If you are going with 100mm pistons, I strongly suggest you find corresponding cylinders. The heat from the automatically increased compression and friction surface will crack those bored-out, cast iron cylinders in less than 20,000 miles.

Assuming this engine is for a 914, go with stroke for power, and low-end torque, something 914's didn't get a lot of.



Second, 96's are the largest dependable piston size you can go with, unless you use Nickies. One word - Bucks!!!

Cam choices? You have to take into account that cam lift and duration directly affect the entire valve train. More lift and duration means more spring tension needed to close what you opened, and more spring tension means sturdier valves, because stock valve keeper grooves will tear clean off the valve stem with too much spring tension.

Basically, this all means head work. One word - Bucks!!!

The question you should be asking yourself first, is what kind of power you want to make, how long do you want it to last, and what are you willing to spend.

Then base your configuration on the answer to those questions.

Ahhh yes, thats why I like this place - thanks so far everyone, it's always good to get sound answers from people in the know. I thought you could bore the stock cyls, but I didn't know how much. Looks like I'll be buying the P/Cs together as a kit.
What's involved in clearancing (correct term?) the case and getting the heads to fit? I like the 100s Otto, I could very well be interested.
But if the work involved is too much, then I'll maybe go with 96 or 96.5s?
Just all preliminary, getting ideas as I get closer....

You will need to open up the case and the heads for the 100mm P-C's. Otto

Mmm, 100mm Birals! I didn't know Scat had done them; I thought they were all Oettinger.

I would assume that the case and heads would have to be milled to fit them. I am sure the heads would have to be--1.7 heads should be milled to fit any cylinders larger than the stock 90mm ones. (Yeah, I know 96mm slip-ins are available, but they're waaaaay thin!)

--DD

stock crank and rods:

AT LEAST Upgrade them to some better bolts, and try to lighten them a tad. They weigh 800 grams +/-


100mm pistons
Okay, but how are you gonna feed that 4" bore??? Stock heads WILL NOT cut it.

40idf webers
Severely under carbureted.

mallory dizz-izzle
Great, its the best.

some sort of large cam, what do you recommend/have exp.with?
Hmmn, large cam..... What is the application? whats your altitude? What kind of CR are you wanting to run? Valve sizes in those heads?? Theses must be taken into consideration to make a cam recommendation.


all pieces balanced and rods/pistons matched
Cool, make sure whoever does it indexes all the parts for reassembly or the balance job is wasted. I offer balance work and have the best machone in this industry..

Jeff,

If all your looking for is a push over 100hp, you can get that with a couple simple changes; Euro pistons (high compression), WEB #73 cam, either 40-44mm Weber carbs or stock FI.

You'll see 90+ HP to the wheels (that's about 115 at the flywheel).

Enjoy!

Hmmm, I see, I see (scratching my chin). I forgot about the heads for a moment (DUH). OK, I checked out Otto's site, and there are 96s and 96.5s. How about one of those, with stock heads, 40idfs, mallory, and a cam? - that doesn't sound too crazy. I'd like it to rev, but would sacrifice a large power surge for a long steady pull from low to upper rpms.
I'm not too far from Watkins Glen (New York), and would like to take it there for an occasional DE maybe. Does that type of driving require a certain type of power characteristic?
Is 120-130hp reasonable, with diligent balance/tuning? I see you mentioned that Dave :) , it sounds about where I'd like to be.

Rock On!

Jeff