I'm looking at tearing down the 455 in my GMC and building it up. With it all stock engine, trans, open rear w/2.56 gears I ran 14.6@93mph. The reason for wanting a teardown is I don't know the 'contents' of the engine, and it's been knocking on start-up for about 4 months now. What I really want to do is build an engine to specifically take a large dose of nitrous. I'm looking to keep compression within the limits of 92octane; I can easily get 110 and 114 octane, but don't want to pay for it on a regular basis. How much nitrous can stock '70 crank and rods handle? Plans call for 200hp shot minimum, with possibilities of a 300hp maximum. Can the block withstand these pressures along with 10:1 (or more) static compression ratio? 400-450hp at the rear wheels would be my ideal power range before nitrous. With my current combination, calculators are telling me that I'm at 256rwhp right now :ball: . Car weight: 3950lbs + My weight: 150lbs = Total weight 4100lbs *looks for a fat pig smiley, LOL*. My reason for posting this is to ask what parts are not up to the task of handling this type of power adder, and to hear from others who have maybe done something like this. I want to know what parts give the best bang for the buck with nitrous, I know that nitrous engines are different animals than N/A, or boosted engines. Or, if you have thought about building an engine like this but don't have the cash or time to do it, give me a list of what you wanted to use, your reasons for using, and I'll build it! I want the best output with the 200-300hp shot of nitrous. I'll stop rambling on for now and wait for a few replies with questions, suggestions, or answers to some of my questions. Thanks, Charles I guess I should put in my requirements for this engine: #1--- Run on 92 octane fuel, under normal driving conditions (race gas 'ok' when going racing) #2--- Enough vacuum to operate power brakes. #3--- Run cool enough (under 210*F) (have 31x19 dual 1-1/4" core aluminum radiator) at steady speeds. Fuel economy is not of concern as it is only driven, maybe, 3 days a week.
So you are looking for 450 RWHP (maybe 550 at flywheel), then you are gonna add about 300HP of nitrous? Total around 850HP? -Bob Cunningham
you will get better response in the race form, i think you will need at least forged pistons,after market rods and a block grittle, or just get the new block by P.A.E.
My stock crank has a 2.200 Chevy journal and held up good(stock stroke). There is no guarentee with this stock stuff but when money is tight you tend to take your chances. 10.0 comp, pump gas, nitrous, no problem. I would shoot for a 170-190 running temp. If you setup your combo with 180-190 cranking compression, which will depend on cam AND cc's, you shouldn't have much if any problems running cool. Spraying 300Hp and getting the motor to take it is 2 different things. If you want to get 300Hp of nitrous in the motor you better cam it for nitrous not to mention building it to take the abuse. Just so you know a 230 duration intake will give you too much cranking compression with 10.0 to 1 to so plan on going bigger than that if you want to spray it on pump gas. For a street engine, consider 9.0-9.5comp, good pistons, stock rods, 5500-6000rpm, 230 range intake duration with 112-114LC and 245 on the exhaust, good flowing heads.This will give you plenty of vaccum, should run 180 degrees and and take 200-250 Hp nitrous. Look for a tight 11" converter with a balloon plate, and you'll have to run a single plane unless your willing to run a direct port nitrous kit -"Fogger"- with a dual plane.
