Thread: econo horsepower

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I am just getting started on this 72 nova and wonder how much horsepower I can expect stock piston 400 standard bore 76 cc head 234 lift at 50% and 300 duration headers large enough holley gm hei and no pulleys at all elec fuel pump and how much nitrous could I use before kaboom? Any ideas or coments are really helpful.

You have mumbo-jumboed this explanation, but if I can make it out, you are using a cam with 234 degrees of duration @ 0.050" lift in a stock block, stock head 400.

The motor will make less horsepower than it did stock.

I don't know how much N2O it will take to grenade it, maybe a 250 shot would do it. I'm just guessing.

Originally Posted by techinspector1

You have mumbo-jumboed this explanation, but if I can make it out, you are using a cam with 234 degrees of duration @ 0.050" lift in a stock block, stock head 400.

The motor will make less horsepower than it did stock.

I don't know how much N2O it will take to grenade it, maybe a 250 shot would do it. I'm just guessing.

Richard,now you are acting like me.
The stock 400 heads will really choke it up.
Look at some aftermarket heads with a port volume of 180 to 190,run the same cam,get you comp. ratio up to 10 to 1,Victor intake,750 dbl. pumper,and you should have around 400 hp.
Run a 3.73 to 4.10 gear,and a 3,500 stall.
If it has stock cast pistons you will start to blow holes in the tops of them around the 175 to 200 hp level.

"Richard,now you are acting like me."

Is that a good thing or a bad thing?

eric you must be talking rear wheel power huh do you mean 180 cc chamber heads compared to 76 cc chambers what?

Originally Posted by old68novaman

eric you must be talking rear wheel power huh do you mean 180 cc chamber heads compared to 76 cc chambers what?

I am speaking of the intake port volume not the combustion chamber size.

Originally Posted by techinspector1

"Richard,now you are acting like me."

Is that a good thing or a bad thing?

I don't really know.
I can really be a smart a-- at times.
Most of the time I mean well,really I do.

Power is a function of moving air into and out of the motor. Eric is saying that the volume of the intake ports in the stock 400 heads is too small to be able to provide the cylinders with a good dose of air on each intake stroke. Sort of like you running and trying to breathe through a straw.

These 400 motors were designed to move Impalas full of people and large station wagons full of kids and junk. The intake runners were cast quite small in comparison to a performance cylinder head because the factory wanted to make huge torque down low in the rpm range to move these heavy hulks. So, they designed them with a long stroke and small intake runners.

Oh, and another thing. These motors were very low compression because they came into vogue during the Arab Oil Embargo. We couldn't get much oil from the middle east and so all the oil was refined into cat piss, low octane pump fuel. The factories had to lower the static compression ratio so the motors would be compatible with the available fuel.