I have 2 considerations.

A)Edelbrock performer RPM heads 64cc to make 10.3:1

or

B)Edelbrock Performer RPM heads 70cc with thick gasket to hit low 9:1 BUT run 50-100 shot of nitrous.

Any input will be helpful. Gotta love the exhaust note of higher compression engines, but 10.3:1 rules out future nitrous unless I buy my gas in 55gal drums.

Might as well put all engine info up.

61-70 2 bolt block 3970010 "high nickel"
stock iron heads 3970126
-bored .030 over
-4 valve Forged pistons
-edelbrock eps intake
-edelbrock 600cfm carb
-Xtreme energy crane cam 262H I believe
-zero decked

Well first off lets clear up a couple things----neither option is better or worse for the addition of nitrous---it can be used in either case as it cools the air charge and helps with detonation---- the aluminum heads allow for higher compression because they cool the air charge better again helping with detonation. You appear to have the right pistons and block but neglected to mention some very important information in determining if you can safely use nitrous-----the crankshaft and rods get stressed very much by nitrous so they better be up to the task ---I would strongly recommend a forged steel crankshaft and at least shot peened rods with good bolts if not H-beams. That being said it looks to me like your engine would be very happy with the small chamber heads and premium pump gas and even a little dose of the giggle gas..................Dan

Well I know all internals are balanced, but I believe they are the stock rods and crank. I just rebuilt this engine not even 5K ago so swapping the crank and rods is not on the table. Do you by chance have any good reading on nitrous effects on different compression ratios. I understand the danger in nitrous is mostly cylinder pressure, not CR. How would the 10:1 ratio react with moderate nitrous, 50-100hp using 93 octane?

Really detonation and lean condition is your biggest foe when using n02. Adding too big of a shot on a weak engine is going to kill the engine. Most people say that up to say 100 Hp shot is not going to hurt a stock off the shelf engine. Every engine has a limitation and you need to know where yours is so you don't get overboard and say things like Oh no, what is that sound?!?!

How sure are you about the Compression numbers? 10.xxxx sure sounds like a lot for a 350 that is .030 over sized. Flat pistons with only valve reliefs cut in them, in my understanding, don't necessarily determine their compression. The combustion chambers do. Flat piston with Valve relief are lower compression than ones without a valve relief cut in them.

The end results will be to bolt them on then do a compression test to determine the real compression of the engine.

I run the Performer RPM heads, Airgap Intake on premium gas. My pistons are flat two valve relief and my heads are 64 cc combustion chambers. I'm at about 9.5 actually I forget what it precisely was but it's not what I figured it to be. I can and have ran Mid Grade Fuel although it does better with premium. My ignition is MSD 6A and I've never really noticed any signs of detonation. MSD makes the 6AL which has a rev limiter, good to use when using No2 they also make an Ignition with a two stage controller for N02 specifically.

More over thing fuel delivery. N02 is going to require gas be delivered with it. Some stock fuel pumps will not put enough fuel in the N02 system and the carb to sustain the engine. You get lean and that is not good.

Engine builders and No2 users are usually at odds.
Engines that are running and suddenly change fuel sources adding 100+ HP will stress most internal components. I have heard that most engines that run N02 have short lives due to the sudden change and high rev extreme enviorments. Lower compression ratios are best for higher shots.
Dish pistons help prevent valve contact.
My 02 is use a cheap motor (305 is still my choice). Try it and see if you like it before you explode lots of money. There is a lot of trial and error
(lots of error) in N02. IMO The reason it has such a bad reputation is the quick CHEAT power it allows. While lots of serious engine builders spend BOKOS of money buildind a well thought out SAFE motor. I say safe because of the broken crank at speed factor. It is better to try a small fire cracker then to spend lots of money and get hurt right off.
Now if you want to spend lots of money, go for the altered fuel class cars. where you run the same Hi pro fuel all the time.
T

Most people get in trouble with nitrous because they don't do their homework and get to liking it too much----as a general rule kits are rated as to the MINIMUM amount of hp they add---and that is experienced at higher prms where there is already a good amount of airflow through the engine---a 100hp kit will add 100hp to the engine in the 6000rpm range but the kit flows the same amount of fuel and oxidizer even at low rpms where it may add 160-175 hp and the engine is lugging with cylinder pressure lasting much longer and that is when the damage gets done. If you run a high stall converter there is less of a concern for damage but it still exists of course---personally I always build the bottom end of the engine like I am going to run it in a fuel dragster and then I can get silly with it later if I choose.....I have seen many cracked crankshafts due to nitrous---I say go small or not at all if the bottom isn't ready for it

10.3:1 - Accomplished by
-4 valve pistons (6.1cc)
-zero decked
-.041 comp. thickness gasket
-64 cc head

Truck block - perhaps rods and crank are a smidgeon better than most stock? - 2400rpm T/C - 200r4(500hp) - planned MSD 6AL box with blaster 2 coil - using accel header(yellow) plugs.

Now could I run aftermarket fuel pump, 10.3:1 with 50-100hp shot on 93 octane without blowing anything up?

From you r description of the parts in your engine I would expect it to be very responsive and torquey. Generally speaking you can get away with 11.0:1 with aluminum heads on 91 octane. I'd say go with the 64cc heads with reasonable port sizes. The difference in flow should be far better than your existing heads. You may be surprised how well it runs just after that change. Personally I don't care for nitrous, but that's my opinion. Build it to run well naturally aspirated, and have power all the time.

Devin

WHAT HE SAID 8)