Well? I can get ehr forged slugs for like $150 more, but the buildup is going to be expensive. (406 strong arm kit from Speed-O-Motive - http://www.speedomotive.com./newpage6.htm)

This will be a TPI motor, running about 150HP of nitrous, with either a super ram or miniram, and a 6500RPM redline (big cam!). Are the 5.7' rods long enough?

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86 IROC-Z, Retired for winter, weird oil leak (drains out in about 3 minutes), new 355 other than that, TPI, 700R4, edelbrock headers, removed AC/Air pump, heater plate conversion - no heater (loL). 14.8@90MPH

Next project (think I'm going to scrap the IROC)- mid 80's monte carlo, 383, edelbrock performer RPM intake, cam, holley double pumper carb, sportsman 2 heads, NOS. Hoping mid/high 12's on motor, mid 11's on spray.

 

with only 150 shot of nitrous, should be no problem.

 

The KB 400 pistons are pretty heafty. You should be alright. however, you have to run some real large ring gaps with KBs. And with NOS they are even larger still. I really did not like that. If your going to go NOS I would really beef the bottom end more. including an aftermarker I beam rod. Look at it this way, your talking about 550 to 600 hp. Why risk it when all you need is a couple of hundred more bucks and youll never have to worry about it again. If you have some expensive heads you will thank yourself in the long run.

 

i disagree. i'd never use hyper pistons with n2o. spend a little extra and buy forged pistons.

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ICON Motorsports

1st & 3rd
MM Black Diamond Lodge 538 F&AM

 

I don't agree with the logic, but, I know someone that has been using stock bottom end 400s with hypertec pistons (they aren't even KBs, they are speedpros ) and a 250+ hp shot for over 2 years. To my knowledege, the only failure he had was when he was still running a single 3/8 fuel line and it leaned out.
This was on a 3600 lb second gen fbody with 3.42 gears. Which would be under NOS loads much longer than a ligher third gen with better gearing. I don't think my third gen would have been able to use NOS in any gear except 4th and then it would have been only for about 5 secs.

[This message has been edited by jcb999 (edited April 06, 2001).]

 

What really kills Nitrous engines is detonation and lean conditions. Simply put forged pistons can withstand more abuse. If you have your nitrous system set up correctly and use timing retard and don't lean it out the KB's will work. But if you goof, you'll know it quick. As far as the bottom end. I'd get 6 inch rods if you are buying new rods and pistons anyway.

 

I'm planning a 150HP shot with my KBs, but I also plan on taking quite a few precautions to make sure I don't blow it up too. Window switch, fuel pressure cut off, etc.

As for rods, the 6" would be good for a 400, but I would go with 5.7s on a 383 due to the piston skirt length and nitrous combo...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-