Deck height, compression ratio, and valve relief flat top pistons, In a 2.0 Options

[emerygt350]

Ok, my question of the day:
Put my new 96mm pistons and cylinders on and measured deck height, .033 all the way around. Let's say .032 to be conservative.

I will not be running head gaskets.
The calculator gives me
8.8 CR at .033
8.6 CR at .043
8.4 CR at .053


The pistons have a valve relief (pretty large) cut. I am shooting for 8.4 CR.

Heads are in the shop so I can't check the CC yet.

Everything I read says .04 - .06 for deck height. With the valve relief do I need to worry about going lower? If I had dishes would you measure from the edge of the piston or the dish?

[technicalninja]

.048 wouldn't bother me with forged but...

If I had it out, down as far as you have gone, it would go all the way.
I'd know exactly how much bearing clearances I had, and the basic condition of all the lower end parts.
I would NOT put a stock camshaft, stock rods, or stock compression height pistons back in.
I'd do a bunch of little things that you are not doing.
I'd change quench, rod length, compression height, cam profile, pushrods, bore size.
If the crank requires grinding, I'll have it offset ground. (I think it's good to go as is)
I did a bit of weight reduction measurements a month back and found 3 1/2 lbs. of reciprocating weight to dispose of (without going to exotic parts). That's a BUNCH.
I'd drill extra holes for rear main seal drain back.
I'd try to find a reverse lip rear main seal.
I'd smooth the combustion chamber and port profile the head (mild porting).
I'd have the heads heavily fly cut.
I'd lap the cylinders into the heads.
I'd ceramic coat the piston crown and combustion chamber. I might use a heat dispersing coating on the outside of the cylinders and heads. (Still researching this)
I'd do all of the oil system mods.

I purchased a nice core 2.0 from 914sixer and am currently entertaining re-using the stock 2.0 crank with the above mods. I may re-use the Mahle cylinders and have them bored out to 96mm. It's a actually more expensive than buying new cylinders but I've seen way too many complaints on the forum regarding the quality of currently available new parts.
You, yourself, wanted to re-use pushrod tubes and I agree with you.

Jake Raby killed a new flywheel for me just recently. His machining .300 material of a brand-new German flywheel was an eye opener for me.
His advice- find used real VW stuff from the 70s. I have four...

What I'd prefer to do is find a good 78mm crank but the costs associated with the stroker build quickly escalate to greater than the price of a used conversion engine.

I haven't built a performance engine with greater than .042 quench in 20 years.
All my stuff is streetcar (and crappy fuel) based and quench is paramount to me.

If you're shooting for 8.3-1 you are fairly detonation resistant just because of low compression and it is far less important.

A water pumper below 9.5-1 is an appliance motor to me (not worth going hard) but this is not normal in the air-cooled world.

It appears that the T4s most of you are running have bigger cams and lower compression (a full point) than water cooled stuff.

So, I'm a builder and have to rip it all the way down. I cannot resist the urge...
You should do you, if you want conservative, stay conservative. It's cheaper.

I'd have no issues running your combo down to .040 but I wouldn't actually do it.
I'd do more!

I'd expect a proper 2055 build, with the above mods to generate 125 HP at the flywheel using normal supporting pieces (dual 40s or stock FI / 123 distributor / premium fuel / conservative tune).

My two liter will have 9.5-1 (or higher) and a cam profile nearing 300 degrees of duration.
I will run LESS than .040 quench on this motor but it will be blue-printed, balanced and assembled by an OCD pin-headed bitch.
With a modern sequential COP FI system and E/85 fuel I want to hit 125 at the wheels which is getting close to doubling the stock power

My first 914 was a stock 1.7l with a big bore kit in it (1911?). It was assembled by me when I was 16/17. I didn't know what I was doing back then but it still was great fun and was one of the early builds that started my automotive career.
I didn't even know about quench back then...