nitrous on a big block

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11-12-2012, 09:26 AM
bel_mor

nitrous on a big block

have been thinking of buying a nitrous kit for awhile. but having an engine with mostly stock parts (ie. cast crank, stock rods, factory forged pistons.)I am a bit nervous as to how much (if any) of nitrous I can safely use with out any catastrophic failures. The engine is a 402 it has stock heads(299241 i believe) and stock bottom end it has 10.5:1 compression it has a comp cam 288ar solid roller camshaft. the car runs 12.40's in the 1\4 mile on a mt 26x8.5 drag slick. would like to get it into the high to mid 11's if possible. any input would be great
11-12-2012, 12:03 PM
34_40

I think you can get away with a 50 HP "shot" easily. I believe when you get to a 100 "shot" (and above) you then have to begin adding additional fuel to prevent leaning the fuel/air mixture and causing detonation. I think your goal should be achievable..
11-12-2012, 12:52 PM
Dave Severson

What rear gear are you running, and what RPM are you turning at the line???
11-12-2012, 01:56 PM
bel_mor

Quote:

Originally Posted by Dave Severson

What rear gear are you running, and what RPM are you turning at the line???

just about 4500 at the finish line 3.08:1
11-12-2012, 02:05 PM
pat mccarthy

with the rigth tune like others have said :) is key .but the stock big block bottom end is one of the best in stock form if built right in the first place .120/ 150 shot should be fine . make sure fule system is up to it and be sure you under stand that you must take timming out of the engine with the more Nos you add and bettter fuel is a must. more gear would not hurt your goal
11-12-2012, 02:19 PM
Dave Severson

Quote:

Originally Posted by bel_mor

just about 4500 at the finish line 3.08:1

That's not even a decent street gear!!! Something in the 3.50 to 3.70:1 range would help a lot!!!!

With the big cam, do you have a higher stall speed converter to match up with it??
11-12-2012, 03:07 PM
bel_mor

Quote:

Originally Posted by Dave Severson

That's not even a decent street gear!!! Something in the 3.50 to 3.70:1 range would help a lot!!!!

With the big cam, do you have a higher stall speed converter to match up with it??

:LOL: yeah thats the usual reaction when i tell em what gear it has.. it came factory with 3.73 but.. the carrier is out of a camaro and that was lowest gear that will go into it. the trans is a b&m th400 with a 3200 stall
11-12-2012, 03:09 PM
pat mccarthy

start with a 3.50 to a 4.10 rear gear first
11-13-2012, 10:10 AM
rdobbs

Good nitrous kits are not cheap. Personally I would stay away from the stuff
with a stock build and go with at least 4.11 gear. Gears are cheaper than an
engine. I have nitrous but never use it.
11-13-2012, 10:28 AM
pat mccarthy

Quote:

Originally Posted by rdobbs

Good nitrous kits are not cheap. Personally I would stay away from the stuff
with a stock build and go with at least 4.11 gear. Gears are cheaper than an
engine. I have nitrous but never use it.

if it has forged pistons it,s not really stock if 375hp or 425hp trw /gm.. gm never used a stock small dome 325/350 hp in forged Oem . but all were cast pistons but after market in speedpro piston.in the stock Gm o port close chamber dome shape . any gm bbc rod but the 65/67 3/8 rods with oilers and thin beam 3/8 late 80to 90s .rebuilt with arp or srp bolts can and will hold 600hp. same with cast crank . block can take all the power he could every make in a 396 hi 600s on the stock block two bolt main EZ with not much work good main cap bolts or studs but not needed been there done it .so with the right tune for Nos there can be a learning curve like i said even with the best parts you can turn good parts in to junk .....yep and like i told you the Nos should not be on top of that blower engine :) never use it less you want to rebuild it