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Discussion Starter · #1 ·
I am building a 400 sbc bored 30 over with flat top pistons, I will be installing an MSD box and more than likely set the rev. limiter to around 5250rpm. So that being said, should I build the motor for nitrous, forged pistons, etc..., or since this motor will not see that high of rpm is it pretty much a waste of money. The forged pistons are twice as much as the other ones.
 

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Be careful if you do.A guy here just blew up a brand new GTO here at the track the other day.His hood flew about 100 feet in the air.And he will have fun explaining that one to his Ins.. :pain: :sweat:
 

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Just stuck
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Cast pistons can be used with nitrous but only with a small shot. If you don't know much about it, you need to study up on it or you will melt your engine no matter what pistons you have in it. I've never used it but a good friend does but is real conservative with it and so far, he hasn't burned any holes in pistons yet. His car runs high 9's on motor and low 9's on a 150 shot in the 1/4 mile. The biggest drawback is not setting it up right or something malfunctions and it's just another addition of parts in a system that has to work right or things can go very wrong very fast.
 

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im not real sure why you would put a 5200rpm limiter in it, if the bottem end is balanced correctly a stock sbc crank can spin to 6000-6500, just not for long periods of time, but this most motors, what cam would you use that topped out at 5200rpm, remember that if it is a cam that makes it power band to say 5000 then it will still make good power for another 500-600rpm, if you shift too earlier then will end up too low in the rpm band in the next gear, and get smoked, and when you run nitrous it makes you power band go up as well normally by a good 600-1000rpm so if you would normally shift at 5500rpm not you would likely shift at 6100-6200, you can run up to around 150 shot on "hypers" but the rest of the motor has to be set up for it as well, personaly i hate nitrous and when i see a car that runs it i tend to lose a little respect for the person using it, again this is my opinion, i will give much more respect for a guy running 10's on all motor than a guy running 9's on the bottle, i watched horsepower TV this weekend and they took a 05' bone stock mustand GT and put 125 shot in it, it went from like 250rwhp to 340rwhp, which is a lot, but think about the guy who built his motor from scratch and is making 330-350rwhp, which is around 420hp to the crank, now all of a sudden this guy who spent 500.00 bucks on a nitrous kit and put it on a stock car is making the samething, who are you gonna give the respect to and who are you gonna look at like a jack-whole IMO
 

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man i just read my last post and i seriously need to pr-read these before i submit them, you would think never went to school, sorry :(

nitrous on an all out drag car i understand, im still not 100% fond of the idea but i understand, but most other situations i think it is cheap and sneaky
 

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My 2 cents worth
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cranky1 said:
Cast pistons can be used with nitrous but only with a small shot. If you don't know much about it, you need to study up on it or you will melt your engine no matter what pistons you have in it. I've never used it but a good friend does but is real conservative with it and so far, he hasn't burned any holes in pistons yet. His car runs high 9's on motor and low 9's on a 150 shot in the 1/4 mile. The biggest drawback is not setting it up right or something malfunctions and it's just another addition of parts in a system that has to work right or things can go very wrong very fast.
My experience with nitrous, you must use a timing retard set at 10 degrees when the button is pushed, and by the way don't push that button then crank it over to start. The intake manifold will fly about 100 feet up. :thumbup:

I saw this happen, when a upset father launched his son's drag boat, and from a safe distance away, they had a few more words. He then pushed that button (more than a second or two) then cranked it over.
 

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Decadent pianoplayer
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High compression doesn't mean all that much when it comes to nitrous.
It's does push the limit a bit but there are other concerns.
Should you build for nitours or not? Well, what do you want to do with your car?
Seen Fast & furious too many times and want it for the cool factor? Forget it.
Weekend warrior? Fine. Bracket racing? Forget it. and so on......
You can use hypereutechtic pistons up to around 100 shot. No more
But if you have an engine with say 300 horses N/A then the pistons aren't the only thing. Balanced rotating assembly, good rods, enough fuel etc etc.
For every 50 hp you need to back the ignition off by ca 2 degrees on a wet system. A little more if you're feeling careful. Nitours engines are killed by, mainly two reasons.
1) Fuel loss.
2) Too advanced timing
Both will create the lovley scenarios decribed earlier
 

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My 2 cents worth
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When I was the crew chief of a 1/4 mile drag boat, we used a dual stage nitrous system. The first stage added additional race fuel, and the second stage was a foggier. The second stage was never used, and we would go through 50 lbs of nitrous during qualifying, and racing. We were running un-blown fuel jet.

The total cost to change to nitrous, and with other renovations, such as electronics, major engine build for it, jet pump work once again for it, cost $65K.

My 'druthers' it would have been blown, but the boat owner was the boss. :thumbup:
 

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Hotrodders.com Moderator
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engine

I would put forged pistons in it anyway, since it's mainly used as a drag car. The KB forged line is about $200 more then the hyper.

I would also put a "kit" on it. I have plenty of customers spraying there engines with zero issues. The dope gets a bad rep because people don't take the time to understand what there doing and they break stuff.

I even have engines with Hypereutectic pistons in them and 100/150 plates and no issues. Becasue the guys listen to me about how to set the system up.

Keith
 

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Decadent pianoplayer
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My post was not directed to you k-star. Just saying that in the long run supercharger would be cheaper, especially since he doesn't seem to be too concerned regarding gasmilage. Besides a Procharger or similar would not make it that much more thirsty in common driving.
 
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